Technical guide | Steam boilers (PDF 12 MB)
Technical guide Steam boilers 1 Contents 7 Foreword 9 Introduction 11 A Utilising steam 12 History of steam generation 15 B What is steam? 16 Wet steam, saturated steam, superheated steam 18 19 B.1.2 B.1.3 Thermal capacity Application areas Contents 21 C Components of a steam boiler system 24 Steam boilers 26 32 38 41 42 C.1 C.1.1 C.1.2 C.1.3 C.1.4 44 Economiser (ECO) 46 Steam superheaters (SH) 48 Combustion system 49 49 50 51 52 C.4.1 C.4.2 C.4.3 C.4.4 C.4.5 54 Water treatment 58 59 60 C.5.1 C.5.2 C.5.3 64 Condensate management / treatment 65 65 66 67 69 C.6.1 C.6.2 C.6.3 C.6.4 C.6.5 70 Pumps 71 73 C.7.1 C.7.2 74 System-dependent thermal equipment 75 75 75 76 76 C.8.1 C.8.2 C.8.3 C.8.4 C.8.5 78 Pipework system 80 Flue system Steam boilers Boiler equipment Multi-boiler system Steam boiler in standby mode Waste heat boilers Combustion air Liquid fuels Gaseous fuels Dual fuel burner Wood combustion Chemical water treatment (CWT) Osmosis systems Thermal water treatment (TWT) Low pressure condensate High pressure condensate Condensate treatment Sampling cooler Dosing corrective chemicals Feedwater pumps & control Condensate pumps Mixing cooler T.D.S. expander and lye cooler Exhaust vapour condenser Feedwater cooler Feedwater preheater 2/3 82 Internal system demand 83 83 C.11.1 C.11.2 84 Insulation of pipes, tanks etc. 85 85 C.12.1 C.12.2 86 Control system 87 C.13.1 88 Rules and regulations 88 C.14.1 93 D Component layout 96 Steam boiler selection 96 98 99 D.1 D.1.2 D.1.3 102 Product range 103 104 105 106 108 D.2.1 D.2.2 D.2.3 D.2.3.1 D.2.3.2 Steam boilers Flame tube temperature monitoring (FTTM) Economiser (ECO) operation ECO output Amortisation Economiser (AECO) 110 113 116 D.2.3.3 D.2.3.4 D.2.3.5 Utilising condensing technology Superheater (SH) operation Pressure / heat maintenance – steam boiler 118 Combustion systems 119 120 121 122 125 D.3.1 D.3.2 D.3.3 D.3.4 D.3.5 128 Water treatment 129 130 132 136 139 D.4.1 D.4.2 D.4.3 D.4.4 D.4.5 Internal power demand Internal thermal power demand Thermal insulation Protection against the formation of condensate Main functions Legal framework Steam boiler selection Selection of the boiler pressure level Waste heat boilers Variable-speed combustion air fan O2 control Amount of fuel / fuel demand Combustion air, supply air ducts Acoustic emissions from monoblock / duoblock burners Total deaeration system Partial deaeration system Chemical water treatment system (CWT softening system) Function description – reverse osmosis system (RO) Water analysis, general explanations Contents 142 Condensate management 143 144 D.5.1 D.5.2 150 Pumps 151 160 D.6.1 D.6.2 162 Sizing the thermal equipment 163 168 171 174 180 D.7.1 D.7.2 D.7.3 D.7.4 D.7.5 182 Pipework 183 188 196 210 219 219 224 226 227 229 232 233 D.8.1 D.8.2 D.8.3 D.8.4 D.8.5 D.8.5.1 D.8.5.2 D.8.5.3 D.8.5.4 D.8.5.5 D.8.5.6 D.8.5.7 236 Flue system 237 239 240 242 D.9.1 D.9.2 D.9.3 D.9.4 244 Internal system demand 244 248 D.10.1 D.10.2 253 E Requirements and regulations 254 Basic requirements and regulations for the licensing procedure 254 E.1.1 265 268 271 E.1.2 E.1.3 E.1.4 Function description of open vented condensate systems Function description of sealed unvented condensate systems Feed pumps – criteria for design and operation Condensate pumps – criteria for sizing and operation Mixing cooler T.D.S. expander Exhaust vapour condenser Feedwater cooler Sampling cooler Pipework Speciﬁcations – materials, welding work Pipework calculations and sizing Strength, expansion, support spans, clearances, routing / mountings Notes on design engineering of selected pipework systems Steam pipes / steam distributors Condensate pipes and systems Boiler lye and blow-down lines Feedwater – softened water – drinking water Exhaust vapour, waste steam and discharge pipes Fuel lines Waste water and ﬂoor drainage systems Planning and design information for connection pieces Sizing the ﬂue system Chimney connection and design Common ﬂue system, merging of ﬂue gas ﬂows Internal electrical system demand Internal thermal system demand Licensing procedure according to Section 13 of the [German] Health & Safety at Work Act Overview of German licensing procedures Overviews and summary of application documents and their compilation Overviews for compiling the application documents 4/5 272 Principle requirements and regulations for the installation of steam boilers 273 273 274 277 278 279 E.2.1 E.2.2 E.2.3 E.2.4 E.2.5 E.2.6 283 F Operation 284 Operating modes 284 286 287 F.1.1 F.1.2 F.1.3 293 G Appendix Technical data collection and tables 294 [A 1] Installation of category IV land-based steam boilers Installation of category III land-based steam boilers (TRD 802) Steam boiler system installation room Acoustic emissions Transportation and handling Earthquake protection Operating modes Standards and regulations governing operation Inspection intervals for boilers according to the Pressure Equipment Directive 296 297 298 302 304 305 306 309 313 314 315 316 317 318 319 320 311 322 323 324 325 Standard circuit diagram; other diagrams can be found in the cover inside pocket [A 2.1] Thermal insulation of pipes [A 2.2] Contact protection insulation [A 3] Technical Guide on water quality – extract [A 4] Sketch of steam boiler container system [Tb. 1.0] SI units / conversion table [Tb. 1.1] 1. Conversion table – BTU / BHP / KW / t/h [Tb. 2.0] Steam table (saturation state) [Tb. 2.1] Properties of superheated steam [Tb. 2.2] Properties of saturated steam [Tb. 2.3] Enthalpy/Entropy [Tb. 3.0] Internal pipe roughness [Tb. 3.1] Pipe friction factor / Reynolds number [Tb. 4.0] Pressure drop in steam pipes [Tb. 4.1] Pressure drop in steam pipes – example [Tb. 5] Conversion for the units of water hardness [Tb. 6] Re-evaporation in condensate expansion [Tb. 7] Pipe cross section for given steam parameters – example [Tb. 8] Pressure drop in water pipes for a particular ﬂow rate – example [Tb. 9] Flow velocities (standard values) [Tb. 10] Steam boiler inspection checklist Literature references 326 Keyword index 336 Imprint Introduction 6/7 Foreword The global energy situation is characterised by ﬁnite natural gas and mineral oil reserves, simultaneously increasing consumption and signiﬁcant price increases. Furthermore, ever increasing CO2 emissions are heating up the atmosphere, leading to dangerous climate change. This forces us to handle energy responsibly. We need greater efﬁciency and increased use of renewable energy sources. As the largest consumer of energy, the industrial sector can make a signiﬁcant contribution towards essential energy savings and CO2 reduction through the use of innovative and efﬁcient heating technology. The comprehensive product range from Viessmann includes system solutions for every type of energy source, which minimise consumption of resources for convenient heat provision and reliable steam supply, and help protect the environment by reducing CO2 emissions. Whether it be steam boilers with integrated economisers and downstream condensing heat exchangers for oil or gas combustion, or wood-burning (biomass) steam boilers for generating process steam with downstream economisers, Viessmann has the suitable solution. The integration of heat recovery systems requires precisely coordinated individual components to achieve maximum efﬁciency and to keep costs under control. This must be based on proper system planning. Viessmann began with the development and production of powerful boilers for generating steam several decades ago and can therefore call on extensive experience. We would like you to beneﬁt from this experience through this compact planning manual. In selecting the subjects to be covered, we have given priority to planning and engineering reliability in the layout of steam boilers and their components. After all, proper planning and professional design are fundamental prerequisites, not only for the trouble-free and efﬁcient operation of a steam boiler system, but also for the safety of people and the environment. I am convinced that this planning manual will be of welcome assistance to everyone involved in the design of industrial steam generation systems. I wish every success to all those who use it. Dr Martin Viessmann Introduction Vitomax production plant, Mittenwalde 8/9 Introduction This steam manual is intended as a supplement to such literature as the "steam" technical series and the sales folder for steam industrial systems, with a focus on the design and sizing of steam generation systems powered by the fuels oil, gas and wood (biomass), as well as waste heat boilers up to a generator output of 75 t/h. The manual must therefore be considered as a "guideline" for the approach to be taken in seeking a conclusive generator concept on the basis of Viessmann-speciﬁc "main components". System and heating engineers, planners and production engineers will be able to use this manual in conjunction with the aforementioned technical brochures as an additional reference work. In spite of thorough checking, we cannot completely rule out errors in the content or printing errors that have been overlooked. Viessmann expressly accepts no liability for such mistakes. As a consequence, Viessmann accepts no responsibility for the correctness of statements made in this publication. Likewise, Viessmann accepts no liability for any material damage, personal injury or ﬁnancial loss arising from the use of this manual. 10/11 A Utilising steam The aim of this manual is to explain the principles of steam generation in steam boilers and describe the layout of components in a steam boiler system. The properties of steam differ considerably from those of the more frequently utilised heat transfer medium, i.e. water. Consequently, we must ﬁrst turn to some fundamental considerations regarding the medium "steam" and steam generation. We will then introduce the individual components of a steam boiler system and provide information on its design, installation and operation. Where reference is made to standards and legislation, we refer exclusively to European regulations. By way of example, German regulations are also taken into consideration, but these cannot necessarily be applied to other countries. This manual only deals with the generation of steam and does not address the subject of "hot water boilers". The contents relate to "landbased steam", in other words the stationary generation of steam, and consciously exclude the features associated with mobile generation, e.g. on board ships. 11 A Utilising steam 12 History of steam generation A.1 Objectives History of steam generation Steam has been known to man since the ﬁrst utilisation of ﬁre. It occurred then as it does now, unintentionally on quenching the ﬁreplace with water or during cooking. First considerations regarding the technical utilisation of steam are attributed to Archimedes (287 to 212 BC), who designed a steam canon. Leonardo da Vinci (1452 to 1519) made ﬁrst calculations on the subject, according to which an 8 kilogram ball would be propelled 1250 metres when ﬁred from such a canon. Denis Papin is credited with the practical execution of the pressure cooker (circa 1680). This ﬁrst pressure vessel was already equipped with a safety valve, after a prototype exploded during initial experiments. The utilisation of the steam engine from circa 1770 made it essential to take a closer look at the process medium water, both theoretically and in practical terms. 12/13 Fig. A.1-1 Visualisation of boiler house Practitioners included James Watt and Carl Gustav Patrik de Laval, who both became wealthy men as a result of marketing their machines. B.1 What is steam? 14/15 B What is steam? In the context of this manual, we are not dealing with mixtures of air and steam, but exclusively with dry steam generated in sealed unvented systems (steam boilers). Note Steam arises from the liquid or solid phase due to evaporation or sublimation1). In the physical sense, steam is gaseous water. The pressures referred to in this manual are exclusively positive pressures, unless explicitly stated otherwise. Over time, the evaporation of water generates a dynamic equilibrium where the same number of particles are transferring from the liquid or solid phase into the gaseous phase as are reverting from the gas. At this point, steam is saturated. How many particles switch from one phase to another is largely dependent on the pressure and temperature of the system in question. 15 B What is steam? 16 Wet steam, saturated steam, superheated steam 18 B.1.2 Thermal capacity 19 B.1.3 Application areas 1) Sublimation: direct transition of a material from the solid to the gaseous state without prior transformation into a ﬂuid. B.1 Foreword Wet steam, saturated steam, superheated steam Water evaporates at constant pressure on application of heat. Steam, on the other hand, condenses on cold surfaces to form the ﬁnest droplets. Fig. B.1–1 Properties diagram At this point, the steam consists of a mixture of ﬁne droplets and gaseous, invisible water. This mixture is referred to as wet steam (Fig. B1.1-1 and B1.1-2). Critical isotherms Liquefying ice under pressure Critical point 221.2 Melting point Pressure [bar] 1 Normal boiling point 0.006 Triple point 0.01 100 374.15 Temperature [°C] Density ̖ at 100 °C and 1.01325 bar: 0.598 kg/m3 ; speciﬁc thermal capacity: cp= 2.08 kJ/(kg·K); thermal conductivity: >0.0248 W/(m·K); triple point: 0.01 °C ฬ 273.165 K at 0.00612 bar; critical point: 374.15 °C at 221.2 bar Above the critical point, steam and liquid water can no longer be distinguished from one another in terms of density, which is why this state is referred to as "supercritical". This state is irrelevant to the application of steam boilers. 16/17 Fig. B.1.1–1 Properties diagram Water Wet steam Steam Boiling the tank content Heat supply Convection inside the steam boiler x=0 x>0 x = 0.2 x = 0.8 x<1 x=1 Wet steam, superheated steam, e.g.: x = 0.8 means: 80 % of the water is available as steam saturated steam From a chemical viewpoint, supercritical water has particularly aggressive properties. Below the critical point, steam is therefore "subcritical" and in equilibrium with liquid water. If it is heated further in this range following complete evaporation of the liquid to a temperature above the associated evaporation temperature,"superheated steam" is created. This form of steam contains no water droplets whatsoever and, as far as physical characteristics are concerned, it is also a gas and invisible. The borderline between wet and superheated steam is referred to as "saturated steam" or occasionally also as "dry steam" to differentiate it from wet steam. Most tabular values concerning steam relate to this state (see chapter G2, table 2). Fig. B.1.1–2 T-s diagram 400 Critical point x = Percentage by mass, steam [%] % % % 20 x= 0% 0 10 = = 80 x x x= 100 x = 60 % 200 x = 40 % 300 0 Temperature [°C] Evaporation heat: 2250 kJ/kg –100 –200 –273 0.0 2.0 4.0 6.0 Eutropy [kJ/(kg · K)] 8.0 10.0 In the T-s diagram, the range of wet steam extends to the critical point at Changes in state of water at 100 °C and 1 bar pressure 374 °C and 221.2 bar B.1.2 Thermal capacity Pressure cooker The beneﬁt of steam as a heat transfer medium is its considerably higher thermal capacity compared with water (Fig. 3). For equal mass and temperature, the thermal capacity or enthalpy of steam is more than 6-times greater than that of water. The reasons for this lie in the substantial energy required to evaporate water, which is then contained in the steam that has been created and is released again upon condensation. This behaviour is well known from boiling water, for example (Fig. B.1.2-1). Fig. B.1.2–2 Temperature Fig. B.1.2–1 To evaporate the contents of a saucepan, a considerable period of time is required for heat absorption via the hob or hotplate. The energy transferred during this period serves exclusively to evaporate the water; the temperature of the water or steam remains constant (100 °C at standard pressure) (Fig. B.1.2-2). This results in a substantial advantage for steam as a heat transfer medium: Compared with water, only one sixth of the mass needs to be moved to transfer the same amount of heat (Fig. B.1.2-3). Evaporation characteristics Boiling temperature Boiling x=0 x = 1 Time Fig. B.1.2–3 Thermal capacity Wärmeinhalt Wasserdampf: 2675,4 kJ (1 kg, 100 °C, 1 bar) Wärmeinhalt Wasser: 417,5 kJ (1 kg, 100 °C) Wärmeinhalt [kJ] 18/19 Fig. B.1.3–1 Steam boiler system Slovenia/ Novo Mesto, pharmaceutical production B.1.3 Application areas Steam is used in many industrial processes as an energy source and as a medium for carrying chemical substances. Typical application areas are, amongst others, the paper and building material industry, reﬁneries, the pharmaceutical industry and processing of food on an industrial scale. Steam drives turbines for the generation of power, vulcanises rubber products and sterilises packaging. The generation of steam for industrial purposes and its "handling" differ signiﬁcantly in some points from conventional heat generation in heating technology using water as the heat transfer medium. In particular, high pressure steam generation in the higher output range requires special equipment for the systems concerned. Typical applications for stationary steam generation: Steam turbines, Steam heating systems (thermal energy transfer medium), Chemical processes: as an energy source and a carrier of reagents, Food processing industry (fruit juice production, breweries, pasta and cheese production, dairies, large bakeries); also for sterilising, Fertilizer industry, Vulcanising rubber products, Pharmaceutical industry for sterilisation purposes and as a carrier of therapeutic agents, Building materials industry, Paper industry, Reﬁneries (cracking crude oil), Wood processing (wood forming), Generation of a vacuum by displacing air and subsequent condensation. StoVerotec Deutschland in Germany, Vitomax 200-HS, 4t/h, 16 bar 20/21 C Components of a steam boiler system Steam generation requires a wide range of thermal equipment aside from the steam boiler for preparing the feedwater or recovering energy, as well as pumps, burners and other ﬁttings. In contrast to hot water boilers, steam boilers are continuously supplied with "fresh" feedwater. So that the constituents of water, such as calcium, magnesium, oxygen and carbon dioxide, do not permanently damage the steam boiler over the course of time with pitting corrosion or limescale deposits, for steam boiler. Furthermore, burners, ﬁttings and pumps are required to provide the steam boiler with the necessary energy. The interplay between all of these components forms a steam boiler system. example, appropriate measures must be taken to remove substances that are harmful to the system are described in the following chapter. The main components of a steam boiler 21 C Components of a steam boiler system 24 Steam boilers 26 32 38 41 42 C.1 Steam boilers C.1.1 Boiler equipment C.1.2 Multi-boiler system C.1.3 Steam boiler in standby mode C.1.4 Waste heat boilers 44 Economiser (ECO) 46 Steam superheaters (SH) 48 Combustion system 49 49 50 51 52 C.4.1 Combustion air C.4.2 Liquid fuels C.4.3 Gaseous fuels C.4.4 Dual fuel burner C.4.5 Wood combustion 54 Water treatment 58 59 60 C.5.1 Chemical water treatment (CWT) C.5.2 Osmosis systems C.5.3 Thermal water treatment (TWT) 64 Condensate management / treatment 65 65 66 67 69 C.6.1 C.6.2 C.6.3 C.6.4 C.6.5 70 Pumps 71 73 C.7.1 C.7.2 74 System-dependent thermal equipment 75 75 75 76 76 C.8.1 Mixing cooler C.8.2 T.D.S. expander and lye cooler C.8.3 Exhaust vapour condenser C.8.4 Feedwater cooler C.8.5 Feedwater preheater Low pressure condensate High pressure condensate Condensate treatment Sampling cooler Dosing corrective chemicals Feedwater pumps & control Condensate pumps 22/23 78 Pipework system 80 Flue system 82 Internal system demand 83 83 C.11.1 C.11.2 84 Insulation of pipes, tanks etc. 85 85 C.12.1 Thermal insulation C.12.2 Protection against the formation of condensate 86 Control system 87 C.13.1 88 Rules and regulations 88 C.14.1 Internal power demand Internal thermal power demand Main functions Legal framework C.1 Steam boilers Vitomax 200-HS; 3.8 t/h, 13 bar in Belgium Steam boilers There are different types of steam boiler. Starting with kettles for boiling water to steam engines and stationary steam boiler systems for industrial purposes or steam boilers in power stations for generating power. Viessmann only manufactures steam boilers in the low and high pressure ranges up to 30 bar for the generation of saturated or superheated steam, which are described in the following text. 24/25 3 Vitomax 200-HS, type M235 C.1 Steam boilers Fig. C.1–1 Thermal capacity (enthalpy) of steam Heat content water steam: 2777.0 kJ (1 kg, 180 °C, 10 bar) Heat content water steam: 2675.4 kJ (1 kg, 100 °C, 1 bar) Heat content [kJ] C.1 Steam boilers A steam boiler is a sealed unvented vessel designed for the purpose of generating steam at a pressure higher than atmospheric pressure. "Conﬁning" the steam increases the pressure and consequently the boiling temperature. This also increases the energy content of the generated steam (Fig. C.1-1). The various boiler types can be differentiated either by their design, combustion system or fuel type. Aside from their design, steam boilers are deﬁned by their steam output and permissible operating pressure. Essentially, two designs are available for the generation of high pressure steam in the higher output range: the water tube boiler and the ﬂame tube/smoke tube boiler (also referred to as shell boiler) Fig. C.1–2 Cross-section through a steam boiler In the ﬁrst type, water is contained in tubes that are surrounded by hot gas. This design generally takes the form of a high speed steam generator up to a pressure of approx. 30 bar or as a water tube boiler up to approx. 200 bar. Flame tube/smoke tube boilers cannot provide such pressures on account of their design principles. In these boilers, hot gas (ﬂue gas) ﬂows through tubes that are surrounded by water (Fig. C.1-2). Depending on size, these boilers have a permissible operating pressure of approx. 25 bar and deliver, for example, 26 tonnes of steam per hour. Flame tube/smoke tube boiler operating principle Beyond the steam output described here, there are also double ﬂame tube boilers designed according to the same principles that deliver up to 50 t/h. The main differences between this and other ﬂame tube boilers is the arrangement of 2 ﬂame tubes, each with separate hot gas ﬂues, and 2 corresponding burners. The design of the ﬂame tube/smoke tube boiler is suitable for meeting the demands made of steam generation by the majority of production processes – particularly in respect of pressure and steam volume – safely and economically. 26/27 Fig. C.1–3 Vitomax 200-HS Fig. C.1–4 Vitomax 200-HS with integrated ECO Vitomax 200 HS oil/gas high pressure steam boiler; Vitomax 200 HS oil/gas high pressure steam boiler with steam output: 0.5 to 4 t/h mounted ECO; steam output: 5 to 26 t/h Where low pressure steam (up to 0.5 bar) is required, this design is also the conventional choice. In Germany, more than 50 % of operational high pressure steam boilers are shell boilers of the three-pass design; a description that also applies to the Vitomax 200 HS (Fig. C.1-3 and Fig. C.1-4). The design principle of shell boilers is characterised by their large water capacity, a large steam chamber and the resulting excellent storage capacity. Consequently, this type of boiler guarantees stable steam provision, even in the case of wide and brief load ﬂuctuations. The three-pass design enables particularly economical, clean and hence environmentally responsible combustion. At the end of the combustion chamber, hot gases ﬂow through a water-cooled reversing chamber into the second pass. The hot gases arrive at the third pass through another reversing chamber near the front boiler door. Both hot gas passes are designed as convection heating surfaces. Since the hot gases exit the combustion chamber through the rear reversing chamber and no returning hot gases surround the ﬂame core – as is the case, for example, in a reversing ﬂame boiler – the ﬂame can release more heat and is therefore cooled down more thoroughly. This feature, combined with the reduced dwell time of the hot gases in the reaction zone, reduces the formation of nitrogen oxide. The large evaporator surface combined with the favourably designed steam chamber and integral demister ensure the generation of almost completely dry steam. The three passes and consequent rapid heat transfer allow high steam output to be achieved with very short pre-heating times. Heat transfer within the passes is split as follows: 1st pass and reversing chamber approx. 35 % 2nd and 3rd pass/smoke tube pass approx. 65 % Maximum steam boiler output is determined by the European standard EN 12953 and is compulsory for all manufacturers. C.1 Steam boilers Fig. C.1–5 Vitomax 200-HS Sanovel / Istanbul Single-ﬂame tube shell boilers can be manufactured with an output of up to 26 t/h when using gas as fuel; for fuel oil, The design of the Vitomax 200-HS is characterised by the following special features: Generously proportioned steam chamber with low steam chamber load and integrated steam dryer ensuring high steam quality Expansion clearances according to trade association agreement. The distances between the smoke tubes as well as the clearances between the smoke tubes and the casing and the ﬂame tube are all well above requirements. This guarantees that the shearing force on the facing ﬂoors caused by different linear expansion in the smoke tubes and the ﬂame tube is lower. The beneﬁts for the operator are a long service life and trouble-free boiler operation. Cracking of the corner stays is unheard of in Vitomax boilers Water-cooled burner operation. Vitomax boilers are designed in such a way that burners can be mounted without refractory linings (exception: rotary cup atomisers ). This guarantees a constant temperature around the burner head, which in turn the maximum output is 19 t/h. Maximum permissible operating pressures are up to 30 bar, depending on output. leads to consistently low NOx emission levels. There is no reﬂection from the refractory lining. Refractory linings must be run dry according to a deﬁned program, which extends the commissioning period. These are also wearing parts Water-cooled rear reversing chamber. Vitomax boilers are designed in such a way that the rear ﬂue gas reversal is completely water-cooled. As a result, energy latent in the ﬂue gases is made available exclusively for heating the water. Fireclay bricks, which are still used in the industry in some places, heat up until they are red-hot and have an effect on the ﬂame on account of their radiation, resulting in increased heat radiation from the boiler. Furthermore, ﬁreclay bricks are wearing parts requiring regular inspection and replacement as necessary 28/29 120 mm composite thermal insulation ensures low radiation losses Vitomax boilers are equipped with a sufﬁcient number of inspection and access ports to reach all important points inside the boiler for the purpose of inspection. This leads to the longest possible intervals for internal inspection. See chapter F.1.3.2 Where corner stays are used, they must be arranged in pairs. The stresses are well below the permissible levels speciﬁed in the steam boiler agreement [Germany]. Low stress in the component => longer service life Vitomax boilers comply fully with all applicable regulations The ﬂame room geometry fulﬁls the minimum standard according to the BDH guideline. The boiler/burner combinations in use are therefore non-critical Easy to open boiler doors and a cleaning door at the end of the boiler facilitate maintenance, hence reducing operating costs Reliable technical speciﬁcations that stand up to every scrutiny Viessmann cooperates actively in the drafting of new guidelines and regulations, thus setting new standards that represent state-of-the-art technology C.1 Steam boilers Fig. C.1–5 Pyroﬂex wood combustion steam boiler Wood combustion high pressure steam boiler The MAWERA Pyroﬂex FSB high pressure steam boiler with an operating pressure of 6 to 25 bar can be used in conjunction with the Pyroﬂex FSB ﬂat moving grate combustion system (combustion output 1 to 2 MW) and Pyroﬂex FSR (combustion output 1 to 15.3 MW). The Pyroﬂex FSB and FSR combustion chamber for wood fuels (biomass) is described in chapter C.4.5. The boiler is designed as a 2-pass boiler with cooling screen. The heat transfer is split as follows: 1st pass approx. 80 % 2nd pass approx. 20 % The design of the Pyroﬂex FSB / FSR steam boiler is characterised by the following special features: Modular construction – employable for the Pyroﬂex FSB and Pyroﬂex FSR wood combustion system Boiler can be positioned either directly on the combustion chamber or freestanding Lowest thermal stresses due to the cooling screen design Simple geometry of the parts subjected to pressure Low operating costs due to the 2-pass design (low pressure loss on the ﬂue gas side) Low radiation losses due to 120 mm composite thermal insulation Large steam chamber, large evaporator and an integrated demister for improved steam quality Stable cover on top of the boiler included in the standard delivery – this simpliﬁes maintenance and protects the thermal insulation from damage Alternatively designed as a boiler control platform A pneumatic cleaning system is available as an option that increases the boiler runtime 30/31 In some countries, test points are required for monitoring the ﬂame tube temperature in the case of boiler output greater than the following values: > 12 MW for oil combustion and > 15.6 MW for gas (see also table D.2.2-1) Such measuring points can be easily integrated into all versions of the Vitomax 200-HS. On the basis of corresponding national regulations, temperature capturing systems with a minimum of six test points in the ﬂame tube are currently required in the EU member states. The capturing points detect impermissible wall temperatures (permissible wall temperature = f (ﬂame tube material)) and break the boiler safety chain (with burner shutdown). Thermal combustion output (MW) Old New Natural gas 13.65 18.20 Fuel oil 10.50 14.00 In addition to the normative limitation according to DIN EN 12953-3, design limitations must be provided according to the regulations (TRD 306 clause 11) that are "compulsory for all manufacturers" and that in the ﬁnal analysis are an important criterion for determining the rated steam output (see notes on selecting a steam boiler in chapter D 2). In addition to the applicable trade association agreement, monitoring of the ﬂame tube temperature is required in Germany according to DIN EN 12953-3 as a compensatory measure in respect of a possible increase in output. Flange connector with shield Level 2 Flame tube temperature monitoring system Level 1 Fig. C.1–6 Fuel (Flame tube) Control panel (Flame tube) Temperature test ports at the ﬂame tube wall Note Where DIN EN 12953 or the TRD + applicable trade association agreement are employed, the combustion heat can be increased by 1/3 compared with the 'old' TRD regulations trade association agreement 1894/1 in respect of the ﬂame tube design (subject to material thickness, the material itself, the internal diameter and the fuel). C.1 Steam boilers C.1.1 Boiler equipment The scope of the steam boiler encompasses all safety equipment, control, display and shutoff equipment, the feedwater pump module, the combustion system (burner) and a control panel for activating all boiler and burner-speciﬁc control equipment. The selection of which individual components are added to the steam boiler is governed by the system operating mode and the fuels required by the user. Fig. C.1.1.1 Boiler equipment Pos. 20 and 40: Quantity (1 or 2) depends on country-speciﬁc requirement Fig. C.1.1.2 Feedwater pump assembly 32/33 Fig. C.1.1.3 Boiler equipment 1 2 3 4 5 6 Platform Control panel Integral ECO ECO-boiler connection line Feedwater pump (module) Burner 10 11 12 15 Level electrode (e.g. NRGT26-1) Level electrode (e.g. NRG16-51) Level electrode (e.g. NRG16-50) Conductivity electrode 20 21 22 23 24 25 26 27 28 30 Safety valve Ventilation shut-off valve Steam shut-off valve Feedwater shut-off valve Feedwater non-return valve Blow-down shut-off valve Blow-down valve T.D.S. shut-off valve T.D.S. valve Shut-off valve for ECO draining 40 41 42 43 44 45 46 Water level indicator Nanometer Maximum pressure limiter Pressure transducer Straight-through shut-off valve with cap Dial thermometer Sampling cooler C.1 Steam boilers Fig. C.1.1–4 Blow-down valve Fitting out is based on TRD regulations and/or EN standard 12953 using high quality systems to the extent that they are approved by regulations. The basis for approval is provided by the corresponding EN standards or, where such standards are unavailable, the appropriate VdTÜV datasheets. This product selection process enables a high level of system availability and reliability. Blow-down and T.D.S. valves on the steam boiler are of particular importance. They are required to ensure a consistently reliable operation of the steam boiler. During operation, sludge deposits form inside the boiler that must be removed periodically. Fig. C.1.1–5 Automatic blow-down Blow-down A special valve is used for this purpose (Fig. C 1.1-4), the sudden and brief opening of which and the associated suction effect remove solids from the boiler ﬂoor. The valve is opened manually, or automatically via a blow-down program controller in the case of unmanned operation, for a duration of 2-5 s. Blow-down valves should ensure secure and powerful closing by means of special design features. This is optimised by installing the cone from below, i.e. spring force and boiler pressure combine to produce the maximum possible closing force, hence ensuring that the valve closes securely in spite of the operational contamination. In the case of so-called multi-boiler systems, non-return valves must be provided in the discharge pipe (EN 12953-6, paragraph 4.6.3). 34/35 Desalination With steam generation, the salts dissolved in the water stay behind and increase the salt concentration level of the boiler water, primarily at the water surface. For that reason, the T.D.S. electrode is located in the upper section of the steam boiler at the same height as the water level. An excessively high salt concentration results in the formation of a solid crust, reducing the heat transfer and leading to boiler corrosion and foaming, whereby the foam can become entrained in the steam and have a detrimental effect on the downstream system. This reduces steam quality and the arising water backup places additional strain on valves. In addition, the function of the water level controllers that ensure an adequate water level in the boiler would be impaired. For that reason, regulations require monitoring [equipment] covering the boiler water quality, which shuts down the boiler system if the maximum permissible values are exceeded. Essential requirements for the quality of measurements are described in the VdTÜV datasheet "Water Monitoring Equipment 100" (WÜ 100) and form the basis for approval of the measuring systems. Of particular note here are the measuring quality, automatic temperature compensation and the display of temperature-compensated actual values. T.D.S. valves are employed as a preventive measure against the boiler system shutting down in the event of excessive conductivity. The T.D.S. controller with limit signal activates the T.D.S. valve and also drains the boiler water. The level controller makes up the water loss with treated feedwater, hence reducing the conductivity within the boiler. Fittings designed especially for this purpose are also used on the T.D.S. valves. Water is drained through the stepped aperture at full differential pressure (boiler / heat recovery) noiselessly and with little wear. Conductance is measured continuously by a T.D.S. electrode ﬁtted inside the boiler; it triggers opening of the T.D.S. valve to a greater or lesser extent when a speciﬁed set value is exceeded (Fig. C.1.1-6 and C.1.1-7). Fig. C.1.1–6 T.D.S. valve Fig. C.1.1–7 Automatic desalination For illustration purposes, the two valves are arranged opposite one another. In reality, they are located next to each other on the boiler wall C.1 Steam boilers Note "Specially designed" devices must be used as water level limiters. The need for a "special design" arises if regular checks take place automatically in the electrical and mechanical parts of every device. If faults occur in the test sequence, heating must be shut down automatically and transferred to a safe state. The limiters must comply with the requirements speciﬁed in EN 12953-9 and an additional risk analysis must be carried out in accordance with EN 12953-6, paragraph 4.3.2, for every limiter function and appropriate levels of functional safety established. Note: Typical requirements regarding the safety integrity level (SIL) of boiler safety systems are never lower than 2. Function of the level electrodes Example: boiler equipment for 72 h unattended operation (BosB 72h). See also chapter F.1.1. Each steam boiler is equipped with 2 connectors with an internal diameter of 100 and associated foam protection according to EN 12953-9, paragraph. 2 electrodes are mounted in each connector. Possible combinations are WB+WR or WB+HW. Two WB electrodes must not be mounted in a common ﬂange. Fig. C.1.1–8 Electrodes, controlled operation Set WB – Water shortage limiter WR – Water level controller HW – Maximum water level limiter In the case of operation without continuous supervision, the water level must be controlled in accordance with EN 12953. The regulations do not specify anything in respect of the quality of level control, i.e. periodic and continuous control units may both be used. Conductive multiple electrodes are often used for controlling the interval; these switch a pump ON/OFF and issue additional alarms by means of the different lengths of the electrode rods. Continuous control units are preferred for systems > 2 t/h. A capacitive, continuously active probe is used for capturing the ﬁlling level in this instance. A set value controller is used to activate the control valve or the FU pump for continuous topping up. Furthermore, EN 12953 requires two independently operating devices that prevent the water level falling below the minimum value (limiter electrodes for min. water level NW). These limiter electrodes must be built into 2 connectors with corresponding protective pipes. According to TRD 604, an automatically operating device (limiter electrode for max. water level HW) must be mounted on the boiler for 72 h unattended operation (BosB 72h), which reliably prevents the maximum water level being exceeded. Therefore, four electrodes are required for monitoring on the water side according to 72 h unattended operation (BosB 72h). 36/37 Fig. C.1.1–9 Electrodes, min. alarm Fig. C.1.1–10 Max Min Electrodes, max. alarm HW NW Safety chain LWL-alarm! Safety chain LWL-alarm! Boiler protection: see chapter D1 The limiter electrodes for minimum and maximum water levels safeguard the boiler operation with regard to exceeding or falling below the HW and NW water levels respectively. On response from the limiter electrodes, an intervention is made in the safety chain and combustion is shut down and locked out. In the case of the HW electrode, shutting down combustion is only required if the downstream heating surfaces could be at risk. Otherwise, the HW electrode only intervenes in the topping up device, switching it off until the electrode re-emerges. C.1 Steam boilers C.1.2 Multi-boiler system Multi-boiler systems (Fig. C.1.2-1) are used for reasons of security of supply that must be guaranteed by the steam boiler system, for example in hospitals for sterilisation purposes or when there is a varying demand for steam over a given period (day/night, summer/winter). Another reason for implementing a multiboiler system is the combination of a wood combustion (biomass) steam system with an oil or gas steam system. The wood combustion (biomass) steam boiler is generally employed as the base load boiler. Oil and gas steam boilers are used as peak load and fail-safe boilers. Temperature and steam pressure levels are maintained in oil or gas steam boilers by built-in indirect coils. The energy required for this purpose is provided by the wood combustion (biomass) steam system. Fig. C.1.2–1 AMH Hospital, Chorzow, Poland – 3 high pressure Vitomax 200 HS steam boilers with 2.4 t/h (8 bar) supplying steam for the heating system, the laundry and sterilisation Steam boiler system in a hospital The question as to how many boilers with what output should be installed must be considered in terms of the security of supply and ensuring the lowest possible operating costs. With a single boiler system, account must be taken of the fact that the boiler output range only depends on the control range of the combustion system. Advanced gas burners with high output can be regulated down to approx. 1/8 of maximum boiler output. The boiler switches to intermittent operation if steam demand falls below this control range. Systems comprising several boilers are predominantly operated with a sequential control. The sequential control allows boiler operation appropriate for the steam demand from a viewpoint of the most economical operating mode and a high security of supply. Economical operation results from the reduced number of burner start events and boiler operation in the medium load range with low ﬂue gas losses and therefore higher efﬁciency levels. 38/39 The sequence control PLC determines which boiler is the lead boiler and the sequence of other lag boilers. Boilers that are currently undergoing modiﬁcations, for example, or those that are not required for a longer period as a result of reduced steam demand and have therefore been preserved must be removed from the sequence control. Fig. C.1.2–2 Annual load curve or annual demand line 4500 4000 Total heat output 3500 Biomass heat 3000 kWh/h th In principle, every boiler is equipped with its own boiler control unit and can be regulated and operated on a stand-alone basis. The usual type of control unit is a programmable logic controller (PLC). Sequence control, also by means of a PLC, is higher ranking than the individual boiler control units. 2500 2000 1500 1000 500 0 0 2000 4000 6000 h/a The annual load curve or annual demand line portrays a practical application of a wood combustion (biomass) steam system (rated output 1500 kW) in combination with an oil or gas steam boiler 8000 C.1 Steam boilers Fig. C.1.2–3 Steam shut-off valve motor The lead boiler is changed automatically after a predeﬁned period in a predeﬁned sequence in accordance with the PLC programming. A lag boiler can be added to the sequence if, for example, the operational boiler runs at an output level of 80 %, for example, for a speciﬁed period. The lag boiler is ﬁred up and the motorised steam shut-off valve opens after the system pressure has been reached (Fig. C.1.2-3), allowing the boiler to feed steam into the steam manifold. Motorised steam shut-off valve Fig. C.1.2–4 PLC touch panel A boiler is shut down when its output falls below 35 %, for example. The lag boiler becomes inoperative and the motorised steam shut-off valve closes. Pressure is maintained in the backup boilers using a second control pressure that is lower than the required steam system pressure. This control system ensures the rapid availability of the boiler in the event of additional demand and the pressure vessel is protected against corrosion occurring during idle periods, as well as repeated loads. PLC touch panel on the "Vitocontrol" control panel Fig. C.1.2–5 "Vitocontrol" control panel All the actual setting values for the sequential control must be deﬁned separately for each system and speciﬁed via the PLC (Fig. C.1.2-4 and Fig. C.1.2-5). "Vitocontrol" control panel with PLC touch panel 40/41 C.1.3 Steam boiler in standby mode In the case of multi-boiler systems where, for example, one steam boiler is used additionally once a day for covering peak loads, it is recommended that this peak load boiler is kept under constant pressure. The same applies to weekend production stoppages. In this particular case, the steam boiler(s) is/ are kept under pressure, preferably at a low pressure level. This guarantees that the steam boilers can deliver steam to the production process at short notice and that, with the involvement of the thermal water treatment system, the boiler system is protected from oxygen ingress. C1.3.1 Ways of maintaining pressure A Pressure maintenance by means of combustion A second pressure level with a slight overpressure (4 bar for example) is stored in the PLC. The burner system raises the pressure in the boiler to the speciﬁed level. The burner enters standby mode as soon as the pressure sensor in the boiler signals that the set value has been reached. The thermal water treatment system must also be included here. This means that the TWT container must also be kept under pressure to avoid oxygen ingress. B Pressure maintenance by indirect coil In the case of multi-boiler systems, the boilers can be kept under pressure by means of an internal indirect coil that is built into the waterbearing part of the pressure vessel. The supply of heating steam is controlled to maintain the required parameters. This presupposes that one steam boiler is always available to supply medium to the indirect coil (Fig. C.1.3.1-1). Alternatively, the steam controller in the indirect coil feed line can be dispensed with in the event of constant parameters, according to which the internal indirect coil can be designed. So that all boilers can be run alternately as lead boiler, it is recommended that each steam boiler is equipped with an internal indirect coil. Fig. C.1.3.1–1 Pressure maintenance by indirect coil C.1 Steam boilers Fig. C.1.4–1 Waste heat boiler WB/ DR 1 DR 2 DB WR WB2 SIV D CHP & ' LFE DR DB WB D SIV LFE WSA ABV PK ASV Pressure regulator Pressure limiter Water level limiter Steam connector Safety valve Conductivity electrode Water level indicator T.D.S. valve Sample cooler Blow-down valve C.1.4 Waste heat boilers Waste heat boilers utilise the heat present in ﬂue gases from combustion processes or in hot exhaust air ﬂows from industrial processes to generate hot water, saturated steam or superheated steam. Function and layout Viessmann waste heat boilers are designed according to the ﬂame tube/smoke tube boiler principle. In so doing, hot ﬂue gas is directed through pipe bundles, where heat present in the gas is transferred to water inside the boiler body. By contrast, in ﬂue gas heat exchangers, the water ﬂows through pipe bundles while the ﬂue gas ﬂows around the pipes inside the heat exchanger housing. Flue gas heat exchangers are preferred when using "cooler" ﬂue gases for generating DHW. WSA ABV PK ASV Flue gas collectors are attached to the inlet and outlet sides of the waste heat boilers, where cleaning apertures are located and ﬂue pipes connected. To minimise radiation losses, the waste heat boiler is ﬁtted with 120 mm composite thermal insulation with a painted sheet steel jacket. Like all Vitomax boilers, the waste heat boiler stands on a base frame that spreads the load across a large area of the ﬂoor. 42/43 Fig. C.1.4–2 Single ﬂue waste heat boiler There are two different types of Viessmann waste heat boiler: Waste heat boilers without additional combustion. Here, only the ﬂue gases/exhaust air ﬂows are used to heat water or generate saturated steam Fig. C.1.4–3 Vitomax 200 HS shell boiler for generating steam with additional waste heat ﬂues Hot water or steam boilers with waste heat utilisation. These are conventionally ﬁred boilers that make additional use of waste heat The choice of which boiler type is employed depends on the customer-speciﬁc conditions of use C.2 Economiser Economiser (ECO) An economiser is a ﬂue gas/water heat exchanger that is integrated into the steam boiler or mounted as a separate assembly on the ﬂue gas collector or behind the boiler. With steam boilers, such economisers are used to preheat the feedwater. They help to improve the energy yield and hence increase the efﬁciency of the boiler system. The ﬂue gas temperatures at the boiler outlet are approx. 60 – 80 K higher than the temperature of the saturated steam. Due to the laws of physics, this value cannot be further reduced economically during the heat transfer. From this comparatively high ﬂue gas temperature, a combustion efﬁciency of 88 to 91 % is calculated at 100 % boiler output. Consequently, the ﬂue loss can be as high as 12 %. The German Immissions Act (BImSchV) requires a maximum ﬂue loss of 9 %. Therefore, in many cases, feedwater preheaters (economisers – ECOs) are used in steam boilers to achieve values below this limit. This is also the most economical way to improve efﬁciency. In principle, ECOs are located downstream of the 3rd pass in shell boilers or downstream of the 2-pass boiler (wood combustion (biomass) boiler Pyroﬂex FSB / Pyroﬂex FSR) and reversing ﬂame boilers. Here, ﬂue gases are cooled down further by the boiler feedwater ﬂowing in countercurrent fashion (Fig. C.2-1). The thermal layout is established in accordance with the given parameters of ﬂue gas volume and temperature, feedwater volume and temperature and the required ﬂue gas temperature downstream of the ECO. 44/45 Venting via the roof Safety valve discharge pipe Fig. C.2–1 Viessmann (Mawera) wiring diagram – steam boiler Feedwater TI PI TI Vitomax 200 HS or Pyroflex FSB/Pyroflex FSR Drain Diagram for an ECO that can be isolated with valves and bypass Depending on the size of the heating surface, ﬂue gases are cooled to approx. 130 °C. There are two sizes of economiser in the product range for Vitomax steam boilers, for cooling ﬂue gases to approx. 180 °C or 130 °C (standard) respectively. Economisers are available for the Pyroﬂex FSB / Pyroﬂex FSR as standard for cooling ﬂue gases to approx. 130 – 180 °C subject to pressure level. Fig. C.2–2 Without economiser The feedwater is heated from 102 °C (inlet temperature) to approx. 135 °C (at a ﬂue gas temperature of 130 °C). Upon customer request, different values can be calculated and offered. Hence, a combustion efﬁciency of 95 % is achievable (Fig. C.2.-2 and Fig. C.2-3) at an operating pressure of 12 bar. Fig. C.2–3 With economiser 200 . . . . . . . . . . Boiler efficiency [%] Boiler efficiency [%] . . . . . Boiler output [%] relative to the rated output A B C D E F G H I Operating pressure 5 bar Operating pressure 7 bar Operating pressure 9 bar Operating pressure 12 bar Operating pressure 15 bar Operating pressure 17 bar Operating pressure 19 bar Operating pressure 21 bar Operating pressure 24 bar . Boiler output [%] relative to the rated output A B C D E F G H I Operating pressure 5 bar Operating pressure 7 bar Operating pressure 9 bar Operating pressure 12 bar Operating pressure 15 bar Operating pressure 17 bar Operating pressure 19 bar Operating pressure 21 bar Operating pressure 24 bar Boiler efﬁciency, including radiation losses, as a function of operating pressure (residual oxygen content in ﬂue gas 3 %, feedwater temperature 102 °C) C.3 Steam superheaters Steam superheaters (SH) Many industrial applications make speciﬁc demands of the steam parameters. Fig. C.3–1 Vitomax 200-HS Vitomax 200-HS with superheater, 22 t/h, 10 bar, in production, (installed in Lithuania) In some processes, steam is required at higher temperatures than those available at saturated pressure. This makes it necessary to superheat the steam. For this purpose, Viessmann has designed speciﬁc steam superheaters that are installed between the second and third pass of the Vitomax 200-HS. With such a solution, the superheater can generate steam at a temperature approx. 50 K higher than the saturated steam temperature. 46/47 Fig. C.3–3 Steam boiler with regulated superheater Superheated steam M Saturated steam Fig. C.3–4 Steam boiler with unregulated superheater Superheated steam Saturated steam C.4 Combustion systems Combustion system Burners are entrusted with the task of making the energy content of fuels available in the form of heat. Normally, liquid and/or gaseous fuels undergo combustion in shell boilers. Increasingly, however, wood combustion (biomass) steam systems are also being used, with a gas or oil steam boiler acting as a peak load backup. 48/49 C.4.1 Combustion air Gas and oil can only burn with the addition of oxygen (air). For this reason, every burner is ﬁtted with a combustion air fan. Depending on the arrangement, a differentiation is made between mono and duo-block burners. Mono-block: fan mounted on the burner Duo-block: fan mounted separately The combustion air fan is designed to deliver the necessary stoichiometric air volume plus the required supplement of approx. 10 % to bridge the system-speciﬁc pressure drop. This includes the pressure drop of the boiler, the burner, the economiser and the ﬂue gas silencer, as well that of the connecting pipework. To ensure clean combustion and a long service life of both the boiler and the burner, the temperature of the intake combustion air should be between 5 °C and 40 °C. In addition, the air should be free from corrosive constituents, such as chlorine or halogen compounds. C.4.2 Note Liquid fuels Fuel oils are categorised as follows: HEL: extra light fuel oil, net cv = 42.7 MJ/kg Heavy fuel oil1): heavy oil, net cv = 40.2 MJ/kg DIN 51603 T1 and T3 describe the minimum requirements for the aforementioned fuel oils. Furthermore, there are oils, particularly in countries outside Europe, that cannot be assigned to the above categories, but that are commonly used for combustion. Oils differ in composition from country to country. There are different burner versions for the various oil types. A differentiation is made between pressure atomisers, steam pressure atomisers and rotary cup atomisers. Pressure atomiser Here, oil is atomised into an oil mist by means of pump pressure through a nozzle. These burners are primarily used to atomise light fuel oil (Fig. C.4.2-1 and Fig. C.4.2-2). Fig. C.4.2–1 Pressure atomiser burner (Source: Weishaupt) Fig. C.4.2–2 Cross-section through a pressure atomiser burner Primary nozzle Secondary nozzle 1 Secondary nozzle 2 Primary air Secondary air Secondary nozzle 3 (Source: Weishaupt) 1) The comment on page 72 C8.5 must be observed in the combustion of heavy fuel oil/masut and a steam boiler with economiser. C.4 Combustion systems Note For the dimensioning of fuel lines, see Section D.8.5.6 Steam pressure atomiser Here, oil is atomised in the burner head with the aid of steam. This process is usually only employed in output ranges above those of the shell boilers considered here. C.4.3 Rotary cup atomiser (also referred to as rotation atomiser) Here, the oil is fed into a rapidly rotating cup on the facing side. Oil migrates towards the chamber due to the rotation and conical internal shape of the cup and is ﬁnely atomised at the edge of the cup due to the centrifugal force and the effects of atomising air being expelled at high velocity. Natural gas is a gas consisting mainly of methane (CH4). Its consistency may vary subject to its origin. Rotary cup atomisers are preferred for the combustion of heavy fuel oil (Fig. C.4.2-3). They are also suitable for the combustion of light fuel oil, oil residues, such as oil-grease mixtures or degreasing residues, for animal fats or cooking oils as well as for rape seed oil. Gaseous fuels Here, we shall consider the natural gas group. No further consideration is given to LPG or town gases due to their minor signiﬁcance. Normally, natural gas contains such constituents as inert gases (non-combustible constituents) and even heavy hydrocarbons. Natural gas is heavier than town gas, but lighter than air. Natural gas E: net cv = 36 MJ/kg Natural gas LL: net cv = 32 MJ/kg In many cases, biogas or sewer gas can be mixed with natural gas; frequently, both gases can also undergo combustion without adding natural gas. The change in net caloriﬁc value must be observed when mixing gases in order to identify the need for any burner adaptation and/or use of a special burner. Fig. C.4.2–3 Rotary cup atomiser Generally speaking, the sulphur content of the gases used must be considered when designing a system, as high quality materials, such as stainless steel, are required for ﬁttings that are in contact with the gas. (Source: Saacke) 50/51 C.4.4 Dual fuel burner Fig. C.4.4–1 Oil/gas low NOx pressure atomiser These are generally burners that can be operated with gas or oil (Fig. C.4.4-1). Switching between fuels take place manually or automatically, for example, based on blocking times prescribed by the gas supplier that require a temporary changeover to oil. This version is preferred for larger systems to safeguard continuity of supply. (Source: Saacke) Fig. C.4.4–2 Vitomax 200-HS with oil burner C.4 Combustion systems Fig. C.4.5–1 View of the MAWERA Pyroﬂex ﬂat moving grate combustion chamber Fig. C.4.5–2 Fuel types (wood fuels) C.4.5 Wood combustion Apart from companies directly involved in the timber industry, an increasing number of business enterprises and industrial concerns (non-wood processing) are opting for wood (biomass) as a fuel. This is subject to less severe price ﬂuctuations than fossil fuels, it is sourced from more politically stable regions and, due to its sustainability and CO2 neutrality, wood makes a signiﬁcant contribution to a future worth living. The MAWERA Pyroﬂex FSB and FSR are used as the wood combustion system (combustion chamber with ﬂat moving grate) in steam systems. The essential difference between the Pyroﬂex FSR and the Pyroﬂex FSB is the volume of the combustion chamber and the size of the grate, where the Pyroﬂex FSB represents the more compact wood combustion system. Due to the inertia of combustion, the quantity of steam present in the boiler must be shut down using a separate valve in the case of quick-acting steam consumers. Structure and function The Pyroﬂex ﬂat moving grate is not only suitable for the combustion of biomass but also for burning special fuels with an elevated ash content or fuels containing a high proportion of foreign matter, e.g. sand, metal residues, etc. The major beneﬁts of Pyroﬂex ﬂat moving grate combustion are, on the one hand, the ability to use different biogenic fuels and, on the other hand, a lower dust content in the ﬂue gas, due to the static fuel bed. Low NOx reduction technology The combustion chamber is supplied as standard with low NOx reduction technology for fuels with a high nitrogen content. The low NOx combustion chamber is a twostage combustion chamber with an air stage for reducing NOx emissions. In addition, this effect is ampliﬁed by the use of a ﬂue gas recirculation system. The geometry of the combustion chamber in the reduction zone (primary zone) and the oxidation zone (secondary zone) was developed by means of fundamental research on our test facility. 52/53 Fuel discharge / fuel transport Mawera push-bar discharge systems or silo discharge systems are employed for drawing fuel from silos or bunkers. Chain conveyors, push bars or tubular screw conveyors can be used as fuel transport systems, subject to structural situation and the fuel grain size. Fig. C.4.5–3 Sectional view of the Pyroﬂex ﬂat moving grate combustion system 1 7 Flue gas dust extraction Multi-cyclone separators for fuel-dependent clean gas dust levels of < 60 to < 150 mg/Nm³ (standard oxygen content 11 or 13 %) are employed as ﬂue gas dust extraction systems. For clean gas dust levels of 10 to 50 mg/Nm³, fabric ﬁlters, metal fabric ﬁlters or electric ﬁlters are employed, subject to fuel used. Mawera Logic The system is controlled and regulated by the Mawera Logic microprocessor control unit with touch screen. A modem for remote maintenance, a process control system (MaVis) and a tele-stand-by unit are also available. The design of the Pyroﬂex ﬂat moving grate is characterised by the following special features: Minimal radiation losses due to complete insulation of the entire boiler system Static ember bed resulting in signiﬁcantly lower emissions Flame temperature control system with integrated, adapted residual oxygen regulation State-of-the-art microprocessor controller regulates the system with automatic detection of fuel moisture content, modulating from 25 to 100 % load subject to compliance with the prescribed maximum emission levels 2 3 Controlled burnout due to ﬂat moving grate divided 2 or 3 times with different speeds High levels of resistance to wear due to generously dimensioned grate area, as well as water cooling in the case of the hydraulic slider being used Low grate throughput due to overlapping, pre-tensioned grate bars; permanent automatic ash removal 1. 2. 3. 4. 5. 6. 7. 4 5 Secondary air injection nozzles Low NOx combustion chamber Flat moving grate Fuel supplied by means of hydraulic slider or screw conveyor Primary combustion air supply Automatic combustion chamber ash removal Flue gas recirculation “via grate” C.5 Water treatment Water treatment The purest form of naturally occurring water is rainwater. However, rainwater contains gaseous (solute) elements absorbed from the atmosphere. Essentially, these are oxygen, nitrogen and carbon dioxide, with sulphur compounds ("acid rain") also being found increasingly. When rainwater soaks away into the ground, further substances are picked up by the water, such as iron and lime. The composition of the water therefore also depends on the path it takes on "passing through" the ground. The purpose of water treatment is the provision of treated water that has no detrimental effect on the boiler operation. This means that spurious constituents of the water must be removed or bound by adding chemicals. Surface water, well water or pretreated drinking water can be used as raw water (i.e. untreated water for boiler operation). Constituents, such as suspended matter, turbid matter, organic contaminants, iron and manganese compounds, can be present in surface water and well water that need to be removed in the preliminary water treatment stages. These pre-treatments are not required for drinking water. 54/55 General explanations The water-steam system is subject to quality requirements regarding permissible constituents. Depending on the pressure stage of the generated steam, limits must be complied with that are speciﬁed in the technical guide "Standard values for water quality", chapter G1 (A3). The feedwater must be treated in order to comply with these standard values. The processes employed for this purpose generally comprise a combination of chemical and thermal water treatment. The hardeners contained in the untreated water are bound together and extracted in a softening system (see also chapter C.5.1 Chemical water treatment). Furthermore, gases are dissolved in water that are released on heating the water in the steam boiler. These gases would inevitably result in corrosion inside the steam boiler as well as the downstream steam system. For this reason, the top-up water from the softening system is thermally treated, i.e. deaerated, in a deaerating system together with the condensate returned from the consumer system (see also chapter C.5.3 Thermal water treatment). To ensure that the required residual oxygen content in the feedwater (0.02 mg/l) is maintained, chemicals are added to bind the residual oxygen. The exclusive use of chemicals to bind the entire quantity of oxygen is uneconomical in most cases. C.5 Water treatment Note Feedwater and boiler water requirements are deﬁned in EN 12953 Part 10, TRD 611 and in the Viessmann technical guide "Water quality“ (Fig. C.5-1, Fig. C.5-2 and chapter G1 A3). Fig. C.5–1 Requirements for saline boiler feedwater Permissible operating pressure bar 0.5 ู PS ู 20 General requirements PS > 20 Colourless, clear and free of undissolved substances pH value at 25 °C >9 >9 Conductivity at 25 °C μS/cm Only standard values applicable to boiler water Total of alkaline earths mmol/litre < 0.01 Oxygen (O2) mg/litre 0.05 < 0.02 Bound carbon dioxide (CO2) mg/litre < 25 < 25 Iron, total (Fe) mg/litre < 0.2 < 0.1 Copper, total (Cu) mg/litre < 0.05 < 0.01 Oxidability mg/litre < 10 < 10 Oil, grease mg/litre <1 <1 Organic substances --- See comment < 0.01 (Ca2+ + Mg2+) (Mn VII ൺ Mn II) as KMnO4 Note In general, organic substances are mixtures of different compounds. The constitution of such mixtures and the characteristics of their components when subjected to boiler operating conditions are hard to predict. Organic substances can decompose into carbon dioxide and other acidic products that Note The TRD and EN 12953 require "appropriate treatment and monitoring of the feed and boiler water" for the operation of steam boilers. Fig. C.5–2 would increase the conductivity and result in corrosion and deposits. They can also lead to the formation of foam and/or coatings that must be kept to the minimum levels possible. The TOC content (Total Organic Content) must also be kept to a minimum (<10 mg/litre). Boiler water requirements Saline operation, Low salt operation, feedwater conductivity feedwater conductivity > 30 μS/cm Permissible operating pressure bar 0.5 ู PS ู 20 ≤30 μS/cm PS > 20 PS > 0.5 General requirements Colourless, clear and free of undissolved substances pH value at 25 °C 10.5 to 12 10.5 to 11.8 10 to 11*1*2 0.1 to 1.0*1 Acid capacity (KS8.2) mmol/litre 1 to 12*3 1 to 10*3 Conductivity at 25 °C μS/cm < 6000*3 See Fig. C.5-3*3 < 1500 Phosphate (PO4) mg/litre 10 to 20 10 to 20 6 to 15 Silicic acid (SiO4)*4 mg/litre Pressure-dependent, see Fig. C.5-4 Notes on Fig. C.5.2: see technical guide on water quality, Appendix A3 56/57 Fig. C.5–3 Max. boiler water conductivity Maximum permissible boiler water direct conductivity, subject to pressure Fig. C.5–4 Max. boiler acidity ࿆This level of alkalinity is no longer permissible > 20 bar ࿇KS 8.2 – value in mmol/l Maximum permissible boiler water silicic acid content (SIO2) subject to pressure C.5 Water treatment C.5.1 Chemical water treatment (CWT) Softening by means of ion exchange The alkaline earths calcium and magnesium are dissolved in water in the form of ions. These elements are referred to as hardeners. Under the inﬂuence of heat during boiler operation, these compounds would form "boiler scale" that is deposited as a solid coating on the heating surfaces. This coating prevents heat transfer from the combustion to the water side. Initially, this would result in higher ﬂue gas temperatures and therefore in reduced efﬁciency. As the boiler scale thickens, the absence of cooling of the heating surfaces leads to their destruction. For this reason, water standards stipulate softened feedwater. Process of boiler scale formation CaCO3 under the inﬂuence of heat: Ca(HCO3)2 ----> CaCO3 + H2O + CO2 Fig. C.5.1–1 CWT Double-pendulum softening system Systems with ion exchange resin are used for softening the water. Ion exchangers are spherical synthetic resins with absorbed active groups. As an active group, ion exchangers for softening water have absorbed sodium ions. When the hard water runs over the ion exchanger, the absorbed sodium ions are exchanged for calcium and magnesium ions that are dissolved in the water. The hardeners that are detrimental to boiler operation are thereby removed from the water. Once the ion exchanger is exhausted, i.e. all sodium ions have been exchanged for calcium and magnesium ions, it is regenerated with a sodium chloride solution (rock salt). The sodium ions are channelled over the ion exchange mass in the excess and displace the absorbed hardeners. Thereafter, the ion exchanger is operational again. This process can be repeated without limitations. Charging: 2R – Na+ + Ca++/Mg++ ---> R2 – Ca++/Mg++ + 2Na+ Regeneration: R2 – Ca++/Mg++ + 2Na+ ---> 2R – Na+ + Ca++/Mg++ R = ion exchanger In principle, a differentiation is made between three operating modes: Timer-controlled, working according to set times Amount-controlled, working according to set delivery amounts Quality-controlled, continuously monitoring the quality of the feedwater These systems can be designed as single or duplex systems. Single systems are designed for intermittent operation, i.e. no softened water is available during the regeneration phase (several hours). Double-pendulum softening systems are compulsory for continuous operation. Viessmann supplies this double-pendulum softening system in different output sizes. The softening module comprises a fully assembled system with two columns of ion exchangers, a salt solvent and the control unit. It can be used without further installation work (Fig. C.5.1-1). The softened water output between two regenerations is speciﬁed during commissioning and is derived from the system size and the hardness of the untreated water. The system operates fully automatically and must only be replenished with rock salt to achieve regeneration. One exchanger is always available as there are two ion exchanger columns. At any time, the second column is either being regenerated or on standby. 58/59 Decarbonisation: if hardeners (Ca2+ + Mg2+) are present along with hydrogen carbonate (HCO3-), also referred to as m-value or alkalinity, the (Ca2+ + Mg2+) content corresponding to the hydrogen carbonate content can be removed by means of a slightly acidic cation exchanger. The released CO2 is expelled via the deaerator. The total salt content is therefore reduced by the amount of carbon hardness (HCO3-). For a boiler feedwater treatment system, the remaining hardeners (permanent hardness) must be removed by means of neutral exchange (softeners, very acidic ion exchangers in Na form). C.5.2 Osmosis systems In recent years, osmosis systems have been used increasingly for water desalination (Fig. C.5.2-1). Osmosis is a physical process that functions without chemicals, and is therefore very environmentally friendly. The yield of desalinated water (permeate) is approx. 80 % of the water employed. During osmosis, the untreated water is forced through a membrane with a pressure of approx. 30 bar. The pores of the semipermeable membrane allow the water molecules to pass through (diffusion); the solute salt remains on the entry side and is extracted from the system. It should be noted that the untreated water must not contain any solids prior to entering the osmosis system, and that the hardeners are stabilised prior to entry (using ﬁne ﬁlters and dosing). Solids would block the membrane pores, leading to a rapid reduction in system performance. Osmosis systems should be operated as continually as possible and are therefore usually equipped with a buffer tank for the permeate. Fig. C.5.2–1 Osmosis system C.5 Water treatment Fig. C.5.3.1–1 TWT C.5.3 Thermal water treatment (TWT) With steam boilers, these compounds result in dreaded pitting corrosion. Localised erosion can occur incredibly quickly, particularly in the area of the feedwater inlet. It is therefore vital to extract the dissolved gases from the boiler feedwater. One proven means to this end is thermal feedwater deaeration. Water can only store a limited amount of gas. The storage capacity can be calculated according to Henry's law (English chemist, 1775 – 1836), subject to partial pressure of the gas and the water temperature. For example, water contains approx. 8 mg O2/kg at a temperature of 25 °C. Total thermal deaeration system Fig. C.5.3.1–2 TWT The solubility of gases reduces as the water temperature rises (see Fig. C.5.3.1-3 and C.5.3.1-4). In extreme cases, i.e. when water evaporates (the situation in a steam boiler), all dissolved gases are released. The gases frequently form other compounds. The free oxygen can, for example, combine with the ferrous steel of the boiler. Total thermal deaeration system Fig. C.5.3.1–3 Solubility of oxygen 16 14 12 10 8 O2 [mg/l] 6 4 2 0 0 20 Temperature [°C] 40 60 80 100 Solubility of oxygen depending on temperature at 1 bar in pure water Fig. C.5.3.1–4 Solubility of carbon dioxide 3500 3000 2500 CO2 [mg/l] 2000 1500 1000 500 0 0 20 Temperature [°C] 40 Solubility of carbon dioxide depending on temperature at 1 bar in pure water 60 80 100 60/61 Fig. C.5.3.1–1 Total deaeration system Vapour outlet Additional water feed Condensate feed Deaerator Heating steam Feedwater tank Feedwater Source: Powerline C.5.3.1 Total deaeration Total thermal deaeration is the most effective method for removing gases dissolved in feedwater. In the deaerating system (Fig. C.5.3.1-1), feedwater is freed from practically all gases by heating it to close to boiling point. Parallel to removing the dissolved gases, the water is also held with low applied steam pressure at a temperature of 105 °C to prevent renewed absorption of gases. It should be noted that, apart from fresh water, condensate too can be fed into the system; this must also be deaerated. Total deaeration has proven to be the best solution in the great majority of cases. The term total deaeration always implies deaerating with a slightly positive pressure (approx. 0.1 to 0.3 bar / low pressure). The term "low pressure" therefore describes a process that is run at a pressure slightly above ambient pressure. Operation with positive pressure ensures that contact between the feedwater and atmosphere and the redissolution of gases is prevented. The total deaeration system comprises the deaerator and feedwater tank assemblies. The deaerator is mounted directly on the feedwater tank, in the form of a dome (Fig. C.5.3.2-2). Depending on the requirements for feedwater quality, different types of thermal deaerator can be employed. Notes on the constitution of boiler water can be found in Fig. C.5-1 and C.5-2 (chapter C 5). Compliance with the speciﬁed limits is a prerequisite for the reliable and cost-effective operation of a boiler system. An O2 content of 0.02 – 0.05 mg/litre must be maintained in the feedwater for shell boilers, subject to boiler pressure. C.5 Water treatment C.5.3.2 Partial deaeration The term partial deaeration refers to deaeration undertaken at atmospheric pressure. Partial deaerators are permanently connected to the atmosphere via the ventilation line. Partial deaeration is the simplest form of thermal feedwater treatment. The somewhat greater demand for oxygen binders associated with these deaerators (see chapter C.5.1 Chemical water treatment) is deemed acceptable. The partial deaerator (Fig. C.5.3.2-1) is equipped with components for the distribution and irrigation of the supplied freshwater and the returning condensate. Heating steam for expelling gases is supplied via a lance that Fig. C.5.3.2–1 is installed centrally in the lower part of the tank. The steam supply is, in its simplest form, matched by a mechanical thermostat and regulated to 90 °C. Fresh water is topped up via an electric level controller. Partial deaerators are predominantly used in boiler systems with low output and pressure. Partial deaeration system Additional water feed Condensate feed Air vent valve Heating steam Overﬂow Feedwater Source: Powerline Fig. C.5.3.2–2 Partial deaeration system 62/63 The most commonly used form of deaerator is the irrigation deaerator In the irrigation deaerator, the condensate fed back into the system and the added freshwater are ﬁnely distributed over so-called cups and brought together with the heating steam in stages by the irrigation process (hence the term "irrigation deaerator"). Water heating and the expulsion of released gases also takes place in stages. The development of this deaerator into an irrigation deaerator with an integral re-boil facility (two-stage deaeration) has proven to be particularly effective. Today, deaerators are made completely from stainless steel, to prevent corrosion. The feedwater tank is designed to hold an adequate amount of boiler feedwater. The tank is connected to the deaerator via a so-called tank neck. Fig. C.5.3.2–3 TWT with feedwater pumps Feedwater tank with mounted irrigation deaerator The feedwater tank is equipped with a heating lance to receive and distribute the heating steam. The steam introduced in this way heats the feedwater to 102 °C. The lance is ﬁxed centrally in the lower section of the tank. In the case of single stage deaeration, the lance is sized for the throughput of the entire heating steam. In the case of two-stage deaeration, the lance is designed to keep the stored water hot. In both versions, partial cooling of the feedwater and the resulting redissolution of gases is prevented. The feedwater tank (Fig. C.5.3.2-3) is equipped with valves for regulating the heating steam, the ﬁlling level and for safety as well as displays required for operation and monitoring. C.6 Condensate management / treatment Condensate management / treatment Depending on the technical processes in the area of steam application, the steam can be introduced directly into the product or the process concerned. In such cases, no condensate is returned. In the majority of applications, however, steam transfers its heat via a heating surface, where it condenses. The condensate is then returned to the boiler system for further utilisation. From a technical viewpoint, there are two different types of condensate return. C 6.1 Open vented systems C 6.2 Sealed unvented systems 64/65 C.6.1 Low pressure condensate In 90 % of all steam boiler systems, the condensate is returned via open condensate tanks. At operating temperatures in excess of 100 °C, this involves re-evaporation. Approx. 5 to 15 % of the weight of condensate turns into re-evaporation steam, subject to pressure level. Naturally, apart from energy losses, water losses also occur that must be made good by topping up with fresh water that has been subjected to appropriate water treatment. Aside from these losses, the condensate in open systems also absorbs oxygen that can then lead to oxygen corrosion in the condensate system. Fig. C.6.1–1 Condensate tank C.6.2 High pressure condensate Fig. C.6.2–1 Tank In the case of high pressure condensate systems, the condensate is returned in a sealed system (approx. 10 % of steam boiler applications). Under these conditions, no losses can occur due to re-evaporation. At the same time, inﬁltration of air-borne oxygen into the condensate system is also prevented. Such systems are appropriate if they operate at a pressure of at least 5 bar and a permanently high level of condensate return is present. It should be noted that all pipework, valves, pumps and containers must be suitable for this pressure. The containers (e.g. condensate collector (Fig. C.6.2-1), feedwater tank) are pressure vessels that must be monitored in accordance with the PED and are therefore subject to monitoring by an approved monitoring body (ZÜS). When planning new systems and also in the energy assessment of existing systems, a decision must be made as to which system to use. Substantial operating costs can be saved through optimum condensate management and utilisation of the re-evaporation steam. Condensate collector tank C.6 Condensate management / treatment C.6.3 Condensate treatment Due to the technical processes and on account of corrosion products, condensate may be contaminated with foreign bodies. Water quality requirements must be met, however, since the condensate is re-used as feedwater. Typical condensate contaminants that may occur are: Mechanical contaminants (corrosion products) Onset of hardness (DHW or service water leakage in heat exchangers) Ingress of acids and lyes (unintentional mixing during the heating of acid or lye baths) Oil and grease (food processing industry, oil preheaters) Subject to the degree of contamination, provision is made for the necessary water treatment processes, such as ﬁltration, degreasing, softening and complete desalination. It should be noted during the design of such systems that the boiler regulations specify the provision of automatic analysis devices to monitor the condensate in the case of operation without constant supervision (see chapter D.4.5). When contaminants are detected in the condensate, the contaminated condensate must be removed from the water-steam cycle. Fig. C.6.3–1 The sampling points must always be located in the condensate inlet, upstream of the collector tank, to prevent contaminated condensate from ﬂowing into the tank. The condensate must be removed by means of three-way valves. Regarding the contaminants, a distinction is made between products that increase conductivity, such as acids, lyes, untreated water, etc., and substances such as oil, grease, whey, etc. Substances that increase conductivity are monitored with a conductivity capturing system; oil, grease etc. are monitored with photo-optical measuring systems, so-called oil and turbidity detectors. Both systems, along with hardness measurement, are available today in tested and WÜ 100-approved versions. With 72 h unattended operation (BosB 72h), condensate monitoring for oil turbidity must be implemented with redundancy. In this case, a second sensor is installed downstream of the 3-way valve. Reason: this also monitors the function of the 3-way valve. Please note: on connection of the second monitoring device, burner and pumps must undergo a safety shutdown in order not to contaminate the downstream containers up to and including the boiler. The 3-way valve is preferably a pneumatic valve. Pneumatic valves assume a safety position in the event of a fault (e.g. membrane defect). Condensate monitoring Condensate inﬂow 3-way valve 1st sensor 2nd sensor Source: Gestra 66/67 C.6.4 Sampling cooler Fig. C.6.4–1 Sampling cooler The chemically and thermally treated feedwater is tested by means of sampling and corrected as necessary by dosing chemicals. In the case of 24 h unattended operation (BosB 24h), the boiler feedwater must be analysed once a day and every 3 days for BosB 72h. The boiler (feed) water is cooled down and relieved of pressure by means of a sampling cooler (Fig. C.6.4-1). It can subsequently be analysed without risk. The process described above is tried and tested plant technology. However, when monitoring and operating this technology, faults can occur from time to time. For that reason, Viessmann has developed an analytical concept to reduce the potential damage caused by the chemical composition of water as far as possible. Furthermore, this method of water analysis enables a more economic operation of steam systems. Depending on the requirements made of the system, the analysis technology can be extended or reduced and is ﬁtted, where necessary, in an analysis rack. Fig. C.6.4–2 Water analysis C.6 Condensate management / treatment Fig. C.6.4–4 Integration method 5 Steam to the consumer 9 13 Top-up water 11 2 HK 1 Bypass Feedwater control valve Blow-down valve Raw water 14 3 PK 12 O2 pH 16 4 O2 pH 7 6 Cooling water Mixing cooler 8 1. Steam boiler with combustion system 2. Thermal water treatment 3. Boiler feed pump 4. Softening system 5. Chimney 6. T.D.S. expander 7. Mixing cooler 8. Cooler tank or drainage 9. Boiler system control panel 10. Condensate tank 11. Hardness check 12. O2 and pH test 13. Higher-ranking control panel with PLC for transferring data 14. Sample cooler for analysis 15. Conductivity test 16. Dosing of corrective chemicals 17. Oil turbidity test ÖT LFS 17 15 10 Condensate from the consumer 68/69 C.6.5 Dosing corrective chemicals To maintain the alkaline level of the feedwater, to bind the residual hardness and to bind the residual oxygen, corrective chemicals are added to the feedwater downstream of the ion exchange or osmosis. For this purpose, a number of products are offered by water treatment companies. The water treatment companies should always be consulted regarding the conditions of use. Viessmann supplies complete dosing stations, usually in combination with the thermal water treatment system. Fig. C.6.5–1 Dosing station C.7 Pumps Pumps Boiler feed pumps supply the steam boiler with water in accordance with the required steam output. A differentiation is made between intermittent and continuous level control. The relevant control variable for this purpose is the ﬁlling level of the steam boiler. 70/71 C.7.1 Feedwater pumps & control Fig. C.7.1.1–1 Version 1 Chimney Steam to the consumer Feed facilities (generally 2 x 100 % pumps) must ensure reliable coverage of "water losses" arising due to steam being drawn off and desalination or blow-down, and make them up respectively. Stringent requirements in accordance with TRD 401, 402 and 802 are made of their design (delivery head and amount) and availability. C.7.1.1 Control panel Top-up water Steam boiler with combustion equipment Thermal water treatment (full deaeration) Chemical water treatment (softening) Boiler feedwater pump Blow-down valve Raw water Intermittent level control Cooling water The water level is regulated between two adjustable switching points, i.e. "pump ON" and "pump OFF". The signal of the level electrode affects the pump. T.D.S. expander Mixing cooler Drainage Condensate container Condensate from the consumer This can be regarded as the simplest solution for steam boilers without an economiser and output up to 3 t/h. This version is not recommended for steam output above 3 t/h or when using an economiser. C.7.1.2 Continuous level control by means of feedwater control valve and optional bypass Fig. C.7.1.2–1 Version 2 Chimney Steam to the consumer Control panel The control aims to maintain a near constant level in the boiler that corresponds to a speciﬁed set value. The actual value is continuously monitored by a level probe and compared with the set value in a controller. Opening and closing the feedwater control valve regulates the level to the required set value in the case of load ﬂuctuations. A certain amount is returned to the feedwater tank via an adjustable minimum volume line. This so-called bypass line is designed to protect the pump from falling below a speciﬁed minimum pump rate. Top-up water Steam boiler with combustion equipment Thermal water treatment (full deaeration) Chemical water treatment (softening) Bypass Blow-down valve Feedwater control valve Cooling water T.D.S. expander Mixing cooler Drainage Boiler feedwater pump Condensate container Condensate from the consumer Raw water C.7 Pumps C.7.1.3 Continuous level control by means of feedwater valve with spillback This is an alternative to Version 2, whereby both valves (feedwater control valve and bypass valve) are combined into a single valve. As soon as the main ﬂow falls below a certain ﬂow rate, the spillback non-return valve (bypass) opens wide enough so that the required minimum pump rate can always be drawn off. Fig. C.7.1.3–3 Version 3 Steam to the consumer Chimney Control panel Top-up water Bypass Steam boiler with combustion equipment Thermal water treatment (full deaeration) Chemical water treatment (softening) Feed-water control valve with spill back Blow-down valve Cooling water T.D.S. expander Mixing cooler Drainage Fig. C.7.1.2–2 Source: RTK Control valve with bypass Boiler feedwater pump Condensate container Condensate from the consumer Raw water 72/73 C.7.1.4 Continuous level control by means of variable speed pump control The control aims to maintain a near constant level in the boiler that corresponds to a speciﬁed set value. In the event of load ﬂuctuations, continuously variable speed control (here with a mounted inverter) is used to adjust the pump rate to match the changing demand until the set level has been achieved. This demand-dependent speed optimisation saves electric power. It can also save the installation of control valves upstream of the boiler. Fig. C.7.1.4–4 Version 4 6WHDPWR WKHFRQVXPHU &RQWUROSDQHO 7RSXS ZDWHU 6WHDPERLOHUZLWK FRPEXVWLRQHTXLSPHQW 7KHUPDOZDWHUWUHDWPHQW IXOOGHDHUDWLRQ &KHPLFDO ZDWHU WUHDWPHQW VRIWHQLQJ &RROLQJZDWHU 7'6 H[SDQGHU 0L[LQJFRROHU 'UDLQDJH 5DZ ZDWHU &RQGHQVDWHFRQWDLQHU &RQGHQVDWHIURPWKHFRQVXPHU The use of a variable speed pump is advisable if the control ratio of the pump is ≥ 1:4 and the control range of the feedwater pump is at least the same magnitude as the control range of the boilerburner unit. Quick control circuits (3-component control) Additional beneﬁts of a variable speed pump (inverter pump): Soft start, surge free operation on switching the pump ON and OFF NPSH The NPSH value of a centrifugal pump drops with lower speeds. This reduces the risk of cavitation Condensate pumps Condensate pumps (generally 2 x 100 % pumps) must be capable of transporting the amount of condensate accumulating on the customer side and in the system according to requirements (either intermittently or continuously depending on demand from the steam boiler system). The necessary delivery heads depend on the back pressure in the tank, pressure-side pipework losses and the density (temperature-dependent) of the medium. %RLOHU IHHGZDWHU SXPS Note In the case of quick control circuits where level control is too slow, signal values from the steam consumers can be hooked up to the control valve in order to adjust the required feedwater volume to the rapidly increasing steam demand. It is also conceivable to construct a mass balance around the boiler to facilitate rapid reaction to load changes. In this case, the ﬂow rate will be captured both on the water and on the steam side, with balancing and switching of signals to the control valve. The amount of steam is the control variable here. C.7.2 )8 %ORZGRZQ YDOYH Please note: The control range of the feedwater pump should be at least as wide as the control range of the boiler-burner unit. C.7.1.5 &KLPQH\ ˂H = ˂p pxg ˂p in bar or p in kg m3 g:9.81 m/s2 N m2 C.8 Thermal equipment System-dependent thermal equipment Thermal equipment guarantees the correct function of a steam boiler system. The components described here are necessary integral parts of a steam boiler system. Depending on the respective system concept, additional equipment that is not described here may be required. 74/75 C.8.1 Mixing cooler The mixing cooler is designed to accept all pressurised and hot waste water that occurs in the boiler system. This water is expanded to atmospheric pressure in the mixing cooler. The mixing cooler vents to atmosphere. By adding cooling water from the untreated water network via an inbuilt lance, waste water is cooled to a drain temperature of 30 to 35 °C. Fig. C.8.1–1 Mixing cooler C.8.3 Exhaust vapour condenser The exhaust vapour condenser (generally a steam/water plate heat exchanger) is designed to condense the low pressure steam vapour (steam) from the deaerator in the TWT system. The resulting condensation heat is returned to the system as recovered heat via added amounts of feedwater and/or condensate. Implementation of an exhaust vapour condenser depends on the results of a costbeneﬁt analysis. Fig. C.8.3–1 Exhaust vapour condenser Thermal water treatment (full deaeration) C.8.2 T.D.S. expander and lye cooler Fig. C.8.3–2 Exhaust vapour condenser, schematic representation The T.D.S. expander is designed to accept the boiler desalination ﬂuid and to expand it to a pressure level of 0.5 bar. The expansion steam is utilised as heating steam in the deaeration system (TWT). The residual lye is cooled down using a lye cooler before it is routed to the mixing cooler. Conversely, the softened water is preheated in this process. Above the roof Water vapour condenser Cooling water Feedwater and/or condensate Water vapour condensate Fig. C.8.2–1 T.D.S. expander with lye cooler Deaerator C.8 Thermal equipment Fig. C.8.4–1 Feedwater cooler C.8.4 Steam to the consumer Control panel Top-up water Steam boiler with combustion equipment Thermal water treatment (total deaeration) Feedwater control valve Blow-down valve Boiler feedwater pump Chemical water treatment (softening) The feedwater cooler (generally a steam/water plate heat exchanger) is designed to lower the feedwater temperature (generally to ≤ 100 °C) upstream of the chosen and implemented economisers (ECO). By reducing the described ECO feedwater inlet temperature, the additional latent heat present in the ﬂue gas can be removed and the boiler efﬁciency level increased. To take advantage of this, the required additional feedwater (softened water) from the chemical water treatment system (CWT) should be used as the "coolant" here upstream of the feedwater tank inlet. Implementation of a feedwater cooler depends on the results of a cost-beneﬁt analysis. Raw water C.8.5 Fig. C.8.5–1 Feedwater cooler Feedwater preheater High pressure condensate feedwater preheater Steam Steam Feedwater Condensate Where an economiser is used in combination with such fuels as heavy fuel oil, masut etc., it is essential that the temperature does not fall below the dew point in the boiler/ economiser. To ensure that this is prevented under all operating conditions, the feedwater is heated upstream of the inlet into the economiser to 130 °C using a heat exchanger. The heating in this case can be provided by an internal indirect coil in the boiler or another heat source, such as steam. In that case in conjunction with a steam/water tubular heat exchanger. The type of heating must be selected on a project-speciﬁc basis. A reduction in efﬁciency is consciously accepted in order to guarantee the durability of the economiser. 76/77 Fig. C.8.5–2 Steam boiler system Pﬁzer Animal Health Louvain-La-Neuve, Belgium 2 x 3.2 t/h C.9 Pipework system Pipework system All pipework, ﬁttings, steam distributors and dewatering lines required for transportation of the media must also be considered as part of the boiler house components. Essentially, the pipework system consists of the main pipes ≥DN 25 (see chapter D 8) for the following media: Steam and condensate Exhaust vapours and evaporate Feedwater and raw water Waste water Fuel oil and gas Flue gas 78/79 Fig. C.9–1 Fig. C.9.1–2 Main steam pipe Steam distributor C.10 Flue system Ahlstrom Malmédy, Belgium 14 t/h, 13 bar Flue system Flue systems are designed for the controlled discharge of ﬂue gases. Apart from the chimney, they include all the connection lines between the heat/steam generators as well as all the necessary built-in parts, such as silencers and ﬂue gas dampers. The ﬂue system to be designed and implemented for a steam system essentially consists of the following: Flue pipe together with all required built-in parts (ﬂue gas damper, compensator and, if necessary, a ﬂue gas silencer) Emission test system with operating platform, if necessary; test and calibration ports Cleaning and access apertures Chimney system with neutralising system, if required, for the arising ﬂue gas condensate In Germany, the fundamental principles of design and implementation are the expected total system combustion output together with the applicable speciﬁcations according to the Technical Guide for Air Conservation (TA-Luft) and/or the applicable German Immissions Act (BImSchV) and the applicable regional legislation. The preferred location for test points is in the chimney, taking into consideration any necessary inlet and/or outlet paths. Installation in the "straight" ﬂue is also conceivable. 80/81 Fig. C.10–2 Steam system ﬂue gas silencer Steam system ﬂue gas silencer (2x 18t/h, 20 bar) Fig. C.10–1 Flue system (Dingolﬁng) Note The required scope of emission test equipment to be installed is determined on a binding basis during the approval process by the licensing authority. It must be assumed that measurements are required, if applicable, for: NOX SO2 CO dust and/or soot value. C.11 Internal system demand Internal system demand This section considers the internal system energy demand. In order to generate fresh steam, steam boiler systems have their own internal demand for power in the form of steam, power, fuel and a small proportion of chemicals for water treatment. 82/83 C.11.1 Internal power demand The internal power demand of a steam boiler system is essentially determined by the electrical output of all drive units of the individual main components. The principle main consumers are: Combustion air fan Any existing ﬂue gas recirculation fan Boiler feedwater pumps Condensate pumps Oil pumps Rotary cup atomiser motor (if installed) Valve servomotors for such ﬁttings (if installed) as: ﬂue gas damper(s), ECO bypass damper(s), main steam shut-off valve(s), mixing and/or branching valve(s) etc. MSR control systems System lighting and emergency lighting for the boiler room Note For the purpose of minimising the internal power demand, electric drive units for pumps, compressors and fans are often equipped with inverters. During the engineering process, the system operational regime is an important condition for the use of inverters (cost/beneﬁt, see also chapters D 3.1 and D 6). C.11.2 Internal thermal power demand The following must be assessed in determining the internal thermal demand: Heating steam for TWT = as a function of condensate return losses, desalination and blow-down losses as well as losses of steam from the TWT and the mixing cooler The losses listed here must be made good by additional feedwater from the water treatment system. The system internal thermal power demand rises in line with the increase in the amount of additional feedwater to be heated in the TWT. Demand-dependent system operating conditions must always be considered in determining the internal demand of a system according to chapter C 11. The necessary approach, layout and calculations are described in greater detail in chapter D 10. C.12 Insulation Insulation of pipes, tanks etc. Insulation not only serves to protect against heat / energy loss and to protect against burning / scalding, but also serves to stabilise the system conditions. If, for example, steam lines were not insulated, then excess condensation would form in the pipes, leading to unstable system conditions. Since all the tanks, containers, and valves in a steam boiler system are joined together with pipes, a corresponding number of pipes must be insulated subject to operational parameters. 84/85 C.12.1 Thermal insulation (see Appendix A2) C.12.2 Pipework, valves, devices and tanks that are heated up must be protected against heat losses and/or contact by means of an externally applied insulation shell. Pipework, valves, devices and tanks that are cooled down must be insulated as required to prevent the formation of condensate. Subject to requirements, the preferred insulation materials are: Multi-component foam shells and/or Foam glass shells The preferred thermal insulation materials are: Mineral ﬁbre mats (glass and rock wool) Plastic jackets Directly applied foaming plastics Plastic shells for valves and pipe structures Protection against the formation of condensate The most important basis cited for designing thermal insulation in this case is the VDI Guideline 2055 and the ENEV. The party responsible for system design (system manufacturer, heating engineer) must assume responsibility for the complete technical processing and engineering of the respective insulation. Consequently, the notes in chapter D 8.3.4 and Appendix (A2) must only (see also chapter D.8.3.4) be regarded as "initial" design aids. C.13 Control system SSAO Servolux, Lithuania, 3x Vitomax 200-HS Control system 4 t/h; 13 bar Ideally, control units are switched by a programmable logic controller (PLC). A central, full graphic colour display (touch panel) (Fig. C.13-1) is used for boiler operation and setting its parameters. Fig. C.13–1 PLC touch panel This display also shows all functions with the associated operating conditions, as well as all set and actual values. The hours run by the burner and the feedwater pumps are recorded by the PLC. In the case of dual-fuel burners, the hours run and number of starts made by each individual burner are recorded separately. PLC touch panel, Vitocontrol control panel 86/87 All fault messages are recorded and reported with date and time of their occurrence. C.13.1 Main functions C.13.1.1 Burner output control The fault messages are also stored as a "history" so that the occurrence of faults, their acknowledgement and their removal is documented. The boiler pressure is measured by a probe and transferred to the PLC in the form of an analogue signal. The PLC regulates the pressure to a set value speciﬁed by the operator or a higher-ranking controller. From the deviation between the set and the actual pressure, the output controller calculates the modulation level of the burner or the respective burner stage, subject to conﬁguration. The control system (Fig. C.13-2) contains all components required for activation of the boiler-speciﬁc control equipment in steam boiler systems. C.13.1.2 Water level control Fig. C.13–2 Vitocontrol control panel The level control of the steam boiler stored in the PLC can be implemented in the form of a two-point control by starting or stopping the feedwater pumps or as a continuous control using a feedwater valve. Starting and stopping the feedwater pump(s) or the additional regulation of the feedwater valve supplies the required volume of feedwater to the boiler for maintaining the set water level inside the boiler. When two feedwater pumps are installed, the pumps are switched alternately and also in the event of a fault in one of the pumps. C.13.1.3 Vitocontrol control panel Conductivity boiler water T.D.S. control As an option, the "desalination" function is implemented by means of continuous control in the PLC. The water conductivity is captured by a probe and transferred to the PLC in the form of an analogue signal. The set value "salt content" and the control parameters are defaulted by the programming unit. When the salt content is too high, the T.D.S. valve opens to drain off the saline water. C.13.1.4 Blow-down control As an option, the blow-down valve can be activated by the PLC subject to stored values for the interval between two blow-down events and the duration of valve activation. C.13.1.5 Additional functions Activation of a ﬂue gas and/or bypass damper as well as switching to a second set value (pressure) are also integrated into the PLC. Note Necessary extension in conjunction (respective consideration) with all ancillary systems according to RI diagram in Appendix (A1). The control panel also contains the components required for fully automatic boiler operation without supervision over 24 or 72 hours according to TRD 604. These include all the "specially designed" components required for operation of a steam boiler system. Note A special design means an electrical or mechanical part of any device that automatically implements regular tests (e.g. for electrode water level meters, the insulation resistance of which is monitored, automatic function tests in immersion devices, blowing through of connecting lines in external devices). C.14 Rules and regulations Rules and regulations All the cited components are considered in the evaluation of a steam boiler system by the designated body, ZÜS (approved monitoring body) or monitoring organisation. In the ﬁnal analysis, a steam boiler system designed according to technical rules is the basis for releasing the system for commissioning. pressure equipment in Member States" (PED) came into force on 29 May 1997, granting a transition period of ﬁve years for member states. C.14.1 The PED applies to all steam boilers with a maximum permissible pressure in excess of 0.5 bar or an operating temperature higher than 110 °C and a volume in excess of 2 litres. It should be noted with regard to the content that the total volume of the steam boiler must always be taken into account. Legal framework As early as 1985, there was a call for standard technical rules to achieve a pan-European single market without trade barriers. However, different regulations concerning the manufacture of pressure equipment, and consequently steam boilers, still applied to the member states of the European Union until 1997. The "Directive 97/23/EC of the European Parliament and Council dated 29 May 1997 on the assimilation of the legal requirements for This Directive does not apply to steam boilers with an operating pressure lower than 0.5 bar and an operating temperature lower than 110 °C. Rules such as the EC Gas Appliances Directive 2009/142/EC apply to these systems. 88/89 Fig. C.14.1–1 PED diagram PS [bar] 1000 100 PS = 32 32 25 Appendix II of the PED divides combustion pressure equipment (steam boilers) into different categories (Fig. C.14.1-1). The possible module categories according to the PED are derived from categories III and IV. The module categories regulate which tests the manufacturer can carry out and which tests must be performed by an independent testing body ("designated body" according to the PED). High pressure steam boilers from the Vitomax 200-HS and Pyroﬂex FSB / FSR series as well as the low pressure steam boiler Vitomax 200-LS fall into category IV of the diagram on account of the following formula: pressure x capacity. Only the Vitoplex 100-LS boiler series (Fig. C.14.1-2) (steam boilers with a permissible operating pressure of 1 bar) with a capacity of > 1000 litres fall into category III. Category IV high pressure steam boilers are tested preferably in accordance with module G. This means that a "designated body" appointed by the manufacturer carries out all boiler tests. These tests comprise testing the draft design (checking the pressure part calculation and design features in accordance with standard speciﬁcations), checking the production processes, monitoring the build, strength test (pressure test) and a ﬁnal inspection. The body commissioned with carrying out the tests issues a Declaration of Conformity following a successfully completed ﬁnal inspection in accordance with module G. PS 10 V PS = 50 V = PS 20 0 V = 30 00 Diagram of the PED, modiﬁed 3 1 0.5 I II III V = 1000 The PED regulates all processes up to market launch of the pressure appliance. Apart from the pressure appliance itself, all equipment components with safety functions and all pressurised equipment parts fall into the scope of this Directive. according to the EHI (Association IV PS = 0.5 of the European Heating Industry, guideline regarding the application 0.1 1 2 6.25 10 100 400 1000 10000 V [liters] Note Selling and commissioning Selling is the ﬁrst provision of a product, against payment or free of charge, in the single market for distribution or use within the territory of the European Union. With the selling of a product, the inherent risk is transferred from the manufacturer to the operator. The operator's risk assessment must have been submitted Commissioning takes place with the ﬁrst use by the end user within the territory of the European Union. The necessity within the scope of market supervision to ensure that the products, on commissioning, comply with the provisions of the directive is however limited If a product is being sold in the single market and commissioned for the ﬁrst time, it must comply with the applicable directives drawn up according to the new concept. The member states of the EU are obliged not to prohibit, restrict or hinder the sale or commissioning of products that comply with the applicable directives drafted in accordance with the new concept. Furthermore, they must take all the measures necessary for ensuring that products can only be traded and commissioned if they do not represent any risk to the safety or health of persons or other interests affected by the applicable directives, insofar as the products are correctly built, installed, maintained and used in accordance with their intended purpose of the Pressure Equipment Directive 97/23/EC) Fig. C.14.1–2 Vitoplex 100 LS Low pressure steam boilers, 260 to 2200 kg/h C.14 Rules and regulations Fig. C.14.1–3 Declaration of Conformity for high pressure steam boilers (example) By the manufacturer afﬁxing the CE symbol and issuing the Declaration of Conformity, as well as providing veriﬁcation of tests having been carried out in accordance with the module derived from Diagram 5, the boiler can be sold without any trade barriers anywhere in the territory of the EU member states. EU member states must assume that the boiler satisﬁes all provisions stipulated in the applicable directives, for example the PED (assumption of conformity). For countries outside the EU that do not recognise the PED, separate arrangements need to be made between the manufacturer and the supervisory organisation of the country concerned. The manufacturer states in the Declaration of Conformity (Fig. C.14.1-3) that the steam boiler meets the applicable requirements according to the PED and other relevant directives. To indicate that fulﬁlment of these requirements, the manufacturer afﬁxes the CE designation to the boiler. Standard production boilers can be manufactured according to module B (EC type testing). In the case of this module, the manufacturers themselves carry out the tests on each standard production boiler. This is conditional on the manufacturer operating an approved quality assurance system for the manufacture, ﬁnal inspection and all inspections/tests associated with the manufacture, subject to monitoring by a designated body. Module D describes that the manufacturer has an approved quality assurance system in place for the manufacture, ﬁnal acceptance and inspection/testing of boilers. This includes preparation of the technical documentation. 1 see note on page 89 With implementation of the Product Safety Directive 2001/95/EC, a law has been created from the core provisions of the German Equipment Safety Act (GSG) and the Product Safety Act (PordSG) for reforming the safety of technical equipment and consumer products. The German law concerning technical equipment and consumer products is designated as the Equipment and Product Safety Act (GPSG), dated 6 January 2004 and effective from 1 May 2004. The GPSG serves the purpose of implementing Directive 97/23/EC with regard to manufacture and operation. The manufacture and therefore the quality requirements are governed by the 14th regulation of the Equipment and Product Safety Act (Pressure Vessel Ordinance 14.GPSGV dated 17 June 1998). This applies to the sale1 of new pressure equipment and assemblies with a maximum permissible pressure of in excess of 0.5 bar. Operational issues are governed by the regulations concerning safety and health protection in the provision of equipment and its use in the work environment, concerning safety in the operation of systems requiring supervision and those concerning organisation of operational industrial safety. The so-called BetrSichV ([German] Health & Safety at Work Act), dated 27 September 2002, applies to the provision of equipment by the employer and the use of equipment by employees at work. 90/91 Fig. C.14.1–4 Laws, regulations and technical rules Legal basis for the installation of a steam boiler system using Germany as an example Section 2 of the BetrSichV, "Common Rules for Tools", contains the assessment of hazards according to the German Work Safety Act (ArbSchG). Among other aspects, Section 3 of the BetrSichV, "Special Provisions for Systems Requiring Supervision", covers: Operation paragraph 12 Reservation of permission paragraph 13 Testing prior to commissioning paragraph 14 Speciﬁcation of inspection intervals paragraph 15 Section 4 of the BetrSichV, "Common Rules, Concluding Provisions", contains notes regarding the Safety and Health Commission paragraph 24. The Safety and Health Commission (ABS) is the successor to the German Steam Boiler Commission (DDA) charged with the following tasks: 1. Determination of rules in accordance with state-of-the-art technology 2. Determination of rules for meeting the requirements of the Ordinance on Industrial Safety and Health (BetrSichV) 3. Advising the Federal Ministry of Economics and Labour (BMWA) in questions relating to operational safety The ABS prepares the technical regulations for operational safety (TRBS). The TRBS substantiate the Ordinance on Industrial Safety and Health with regard to: Determination and evaluation of hazards Derivation of suitable measures – "in the application of the measures cited as examples, the operator can exercise compliance with the provisions of the Ordinance on Industrial Safety and Health." TBS 1111 and 2141 are cited as examples, in which the assessment of risks and evaluation of safety are described along with the hazards caused by steam and pressure. Section 2 of TRBS 1111: "The employer is responsible for conducting the risk assessment and the operator for carrying out the safety evaluation." Section 2.1 "Operational parameters" of TRBS 2141, Part 1: "Operational parameters are speciﬁcations of process and material parameters, e.g. pressure, temperature, ﬂow rate, ﬁlling level, abrasiveness and corrosiveness. They result from the respective process and represent the sum of the operating modes foreseen by the employer and/or operator." D Component layout % ( ' ' % 10 $ + 4 3 5 & 9 0 6 1 & & 8 , & 2 * 7 . & & ) Steam boiler system overview 1 2 3 4 5 6 7 8 9 10 Steam boiler Control system (PLC) Integral economiser Total thermal deaeration system T.D.S. expander with heat recovery Mixing cooler Chemical water treatment Feedwater pumps Dosing stations Flue gas damper A) B) C) D) E) F) G) H) I) K) M) Steam to the consumer Discharge pipe safety valve Ventilation and drain line Water vapour line Condensate inlet Fuel feed Raw water inlet Softened water Feedwater T.D.S. line Blow-down line 92/93 D Component layout This section provides relevant "simpliﬁed" information on the sizing and calculation of the components listed in chapter C. The basis for sizing the system is provided by the "reference system" described in Appendix (A1) along with the applicable process-related economy and calculation variables. Viessmann can supply you with socalled "enquiry checklists" for actual enquiries. Please contact your Viessmann sales representative for these checklists. A correct response to the enquiry checklist is a prerequisite for precise system sizing optimally suited to the actual requirements. Viessmann ensures you have all the help you need in answering and preparing the enquiry checklist with assistance provided by the respective sales engineer. 93 D Component layout 96 Steam boiler selection 96 98 99 D.1 D.1.2 D.1.3 102 Product range 103 104 105 106 110 113 116 D.2.1 Steam boilers D.2.2 Flame tube temperature monitoring (FTTM) D.2.3 Economiser (ECO) operation D.2.3.1 ECO output D.2.3.3 Utilising condensing technology D.2.3.4 Superheater (SH) operation D.2.3.5 Pressure / heat maintenance - steam boiler Steam boiler selection Selection of the boiler pressure level Waste heat boilers D Component layout 118 Combustion systems 119 120 121 122 125 D.3.1 Variable-speed combustion air fan D.3.2 O2 control D.3.3 Amount of fuel / fuel demand D.3.4 Combustion air, supply air ducts D.3.5 Acoustic emissions from monoblock / duoblock burners 128 Water treatment 129 130 132 136 139 D.4.1 Total deaeration system D.4.2 Partial deaeration system D.4.3 Chemical water treatment system (CWT softening system) D.4.4 Function description - reverse osmosis system (RO) D.4.5 Water analysis, general explanations 142 Condensate management 143 144 D.5.1 D.5.2 150 Pumps 151 160 D.6.1 D.6.2 162 Sizing the thermal equipment 163 168 171 174 180 D.7.1 Mixing cooler D.7.2 T.D.S. expander D.7.3 Exhaust vapour condenser D.7.4 Feedwater cooler D.7.5 Sampling cooler Function description of open vented condensate systems Function description of sealed unvented condensate systems Feed pumps - criteria for design and operation Condensate pumps - criteria for sizing and operation 94/95 182 Pipework 183 188 196 210 D.8.1 D.8.2 D.8.3 D.8.4 219 D.8.5 219 224 226 227 229 232 233 D.8.5.1 D.8.5.2 D.8.5.3 D.8.5.4 D.8.5.5 D.8.5.6 D.8.5.7 236 Flue system 237 239 240 242 D.9.1 D.9.2 D.9.3 D.9.4 244 Internal system demand 244 248 D.10.1 D.10.2 Pipework Speciﬁcations - materials, welding work Pipework calculations and sizing Strength, expansion, support spans, clearances, routing / mountings Notes on design engineering of selected pipework systems Steam pipes / steam distributors Condensate pipes and systems Boiler lye and blow-down lines Feedwater - softened water - drinking water Exhaust vapour, waste steam and discharge pipes Fuel lines Waste water and ﬂoor drainage systems Planning and design information for connection pieces Sizing the ﬂue system Chimney connection and design Common ﬂue system, merging of ﬂue gas ﬂows Internal electrical system demand Internal thermal system demand D.1 Steam boiler selection Steam boiler with and without waste heat utilisation Steam boiler selection Depending on individual customer requirements for pressure and/or the amount of steam, as well as the quality of the fuel, a differentiation is made between the various boiler types and designs. The decision-making criteria are as follows: D.1 1. Fuel Biomass Waste heat Gas / oil 2. Pressure </= 0.5 bar > 0.5 bar A choice is made here, depending on requirements, between the: Vitomax 200-LS as a low pressure (NDE) steam boiler, type M233, category IV according to European Pressure Equipment Directive DGRL 97/23/EC, in three output sizes at a permissible operating pressure of up to 1.0 bar 3. Output Steam boiler selection The working basis is the steam boiler datasheet Fig. D.1–1 Vitomax 200-LS type M233 Amount of steama) (t/h) 2.9 3.5 5.0 Rated output (kW) 1900 2300 3300 96/97 and the: Vitomax 200-HS as a high pressure (HD) steam boiler, type M73, category IV according to European Pressure Equipment Directive DGL 97/23/EC. This is available in nine output sizes and different pressure levels with a permissible operating pressure of between 6 bar and 30 bar Fig. D.1–2 Vitomax 200-HS type M73 Size 1 2 3 4 5 6 7 8 9 Steam outputc) (t/h) 0.5 0.7 1.0 1.3 1.65 2.0 2.5 3.2 4.0 Rated outputb) (MW) 0.325 0.455 0.65 0.845 1.1 1.3 1.65 2.1 2.6 and the: Vitomax 200-RS as a high pressure steam boiler, category IV according to European Pressure Equipment Directive DGL 97/23/EC, for utilising waste heat The working basis is the steam boiler datasheet. and the: Vitomax 200-HS as a high pressure (HD) steam boiler, type M75, category IV according to European Pressure Equipment Directive DGL 97/23/EC. This is available in 10 output sizes and different pressure levels with a permissible operating pressure of between 6 bar and 25 bar The working basis is the steam boiler datasheet. Fig. D.1–3 Vitomax 200-HS type M75 Boiler size 1 2 3 4 5 6 7 8 9 A4) Max. combustion output MW Gas 3.8 4.5 5.3 6.4 7.5 9.0 10.5 12.7 15.7 18.2 HEL 3.8 4.5 5.3 6.4 7.5 9.0 10.4 12.2 14.0 14.0 EN 12953-3 Max. steam outputa) w/o ECO in t/h Operating pressure 5 bar 5.2 6.2 7.3 8.9 10.4 12.5 14.6 17.6 21.7 25.2 25 bar 5.0 5.9 7.0 8.5 9.9 11.9 13.9 16.9 20.8 24.2 Max. steam outputa) with ECO 200 in t/h Operating 5 bar 5.5 6.5 7.7 9.3 10.9 13.1 15.3 18.5 22.9 26.6 pressure 25 bar 5.4 6.4 7.6 9.1 10.7 12.9 15.0 18.2 22.5 26.1 a) With reference to feedwater temperature = 102 °C and Values between 5 and 25 bar can be interpolated rated output without emission requirements. Please note! When selecting an "appropriate" boiler steam output for the customer's needs, the "steam losses" to be expected due to system-speciﬁc internal steam requirements ( FD/E) must also be considered. That means: Amount of steamboiler = steam demandcustomer + amount of steam requirementsystem A supplemente) of approximately 5 to 15 % can be assumed here in the initial analysis. For example ==> amount of steamboiler = amount of steam requirementcustomer x 1.05 to 1.15 With reference to steam output b) at saturated steam pressure = 12 bar and feedwater temperature = 102 °C. c) With reference to feedwater temperature = 102 °C and rated output. d) Steam output with gas combustion. Alternative steam outputs A "precise" calculation is made by the manufacturer with the formula speciﬁed in chapter D.10.2. result from HEL and reduced combustion output. Supplement for heating freshwater e) requirement of 0 to 5 % and T.D.S. rates ≤ 5 %. Intermediate sizes can be interpolated here accordingly. D.1 Steam boiler selection Fig. D.1.2–1 Fig. D.1.2–2 Steam boiler limiter D.1.2 Steam boiler limiter Example 2 Example 1 13 bar SiVresponse pressure 25 12 bar SDB (burner locked out) 23.5 bar bar 10.5 bar DR (set value) 22 bar SDB MA DA SDB Safety pressure limiter DA Pressure sensor MA Pressure gauge MT Manostat bracket MT Selection of the boiler pressure level Setting the manostats Fig. D.1.2-2 illustrates an example of two different pressure levels for our steam boilers. The following approach is used to determine the boiler pressure level (safety level). The set value required by the customer is, for example, 10 bar. This is the value that must be available for production. A pressure sensor is mounted on the manostat bracket that transmits its signals to the controller (pressure) stored in the PLC. The pressure regulator is set, for example, to 10 bar and regulates combustion depending on the steam demand. For example, the pressure regulator switches the burner off at 10.5 bar and back on again at 9.5 bar. The start and stop values can be selected freely. A safety pressure limiter is located on the pressure side above the pressure regulator, set, for example, to 12 bar. In the event of pressure regulator failure, the safety pressure limiter serves the purpose of safeguarding the boiler from excessive pressure and locks out the burner. Reactivation can only be undertaken manually. Positioned above this on the pressure side is the safety valve that protects the boiler mechanically against excessive pressure. The valve opens to atmosphere at 13 bar. This means that a boiler with 13 bar protection is required for a required pressure of 10 bar. The equivalent also applies at a required pressure of 22 bar. A boiler protection of 25 bar would be required in that case. 98/99 D.1.3 Waste heat boilers Waste heat boilers utilise the waste heat from industrial processes or, for example, combined heat and power (CHP) modules for the generation of heating water or steam. Since the waste heat sources are manifold, the steam boiler is designed speciﬁcally for Fig. D.1.3.1–1 each individual case. Fig. D.1.3.1-1 indicates the general conditions within which Viessmann supplies waste heat boilers. Depending on the number of ﬂue gas sources and their thermodynamic design, there are single or multiple-pass waste heat boilers for one or more ﬂue gas sources. Design parameters Waste heat boiler w/o Boiler with waste additional combustion heat utilisation Proportion of output from 100 % with reference to the 10 to 30 % with reference to the waste heat utilisation total boiler output total boiler output Flue gas source Suitable for ﬂue gases from the following fuels: Fuel oil and natural gas. Other fuels such as RME, animal fat, solid fuels and waste heat from contaminated extract air available on request Minimum ﬂue gas volume from 5000 Nm3/h 1000 Nm3/h the ﬂue gas source Maximum ﬂue gas volume from 80,000 Nm3/h (from one or in total 10,000 Nm3/h (from one or in total the ﬂue gas source from two ﬂue gas sources) from two ﬂue gas sources) Maximum permissible pressure load 25 bar 25 bar 1 or 2 1 or 2 on the water/steam side Number of heating sources Design versions Plants that utilise waste heat are available in numerous sizes and designs. The requirements for waste heat boilers to be integrated into these systems are correspondingly diverse. Fig. D.1.3.1–2 Waste heat boiler, single-pass In the simplest case, a separate waste heat boiler is assigned to each ﬂue gas source. Single-pass waste heat boiler for generating steam Flue gas inlet Flue gas outlet D.1 Steam boiler selection Fig. D.1.3.1–3 Twin-pass waste heat boiler for generating steam Flue gas outlet Twin-pass waste heat boiler In cases where the waste heat boiler is very long compared to its diameter, the pipe bundle can also be split. The ﬂue gas inlet and outlet points are Flue gas outlet then both located on the same side. This more compact design is often practical for applications with smaller volumes of ﬂue gas and lower ﬂue gas inlet temperatures Flue gas inlet Flue gas inlet 100/101 Fig. D.1.3.1–4 Shell boiler for generating steam with one waste heat pass ECO Flue gas outlet, burner combustion Flue gas inlet, source of waste heat ECO for source of waste heat Flue gas inlet, source of waste heat Flue gas outlet Flue gas inlet Fig. D.1.3.1–5 Waste heat boiler Waste heat boiler for two ﬂue gas sources, single-pass In applications with smaller ﬂue gas volumes, it is also possible for two ﬂue gas sources to be connected to the same waste heat boiler. This reduces space requirements and the outlay for technical equipment. However, the ﬂue gas ducting remains completely separate in order to prevent any mutual interference D.2 Product range Product range There are normative regulations for selecting steam boilers depending on the fuel used. In principle, liquid and gaseous fuels, along with hot ﬂue gases / extract air, can be used for generating saturated steam in our steam boilers. The following fuels and heat sources are employed: Natural gas Biogas Extra light fuel oil Heavy fuel oil Masut Bio-oil Animal fat Wood fuels (biomass) Hot ﬂue gases, for example from combined heat and power modules 102/103 D.2.1 Steam boilers Note: Higher operating pressures than 25 bar are available on request. restrictions in the output range above 16,000 kg/h apply due to normative regulations. (DIN EN 12953-3 Clause 5.4 - Fig. 5.4.1 Limitation of combustion output to 14 MWtherm. / see Fig. D.2-1) The speciﬁed steam output limits apply to operation with natural gas combustion, depending on the permissible operating pressure. In the case of HEL (oil) combustion, Fig. D.2.1–1 Vitomax 200-HS, type M237 / M73A and M75A (gas and oil combustion) * The steam output speciﬁed here is a value solely for orientation purposes. The actual steam output depends on boiler pressure, the fuel used and emission requirements. D.2 Product range D.2.2 Flame tube temperature monitoring (FTTM) FTTM systems appropriate for the system in question (see tabular values) and compliant with national regulations are required for ɘ ) and selected combustion outputs (4 F the correspondingly designed ﬂame tube diameter (df): Fig. D.2.2–1 Flame tube diameter depending on combustion output (additional measures) Fuel parameters HEL fuel oil ɘ (MW) 4 F df (mm) ɘ (MW) 4 F df (mm) ɘ (MW) 4 F df (mm) Gas ≤ 12 ≤ 15.6 > 1400 > 1400 > 12 > 15.6 > 1400 > 1400 > 12 > 15.6 < 1400 < 1400 (Source: DIN EN 12953-3) In addition to DIN EN 12953-3, measures are speciﬁed as follows in the trade association agreement (version 11/2004) [Germany] and must be considered accordingly during the selection and sizing processes. Note Fig. D.2.2–2 Flame tube temperature monitoring Criterion Generally, where P355GH is used as material (only permissible for corrugated ﬂame tubes), a temperature measurement system must be installed. Also for a combustion ɘ F) and ﬂame tube output (4 diameter (df) of: GI > 1400 mm ɘ > 12 MW (oil) and 4 F ɘ > 15.6 MW (gas) 4 F Flame tube diameter ≤ 1400 mm Measures Heat load limit according to EN 12953 up to a ﬂame tube load of 12 MW in the case of oil combustion or 15.6 MW for gas combustion - applicable to ﬂame tube material P295GH. Max. ﬂame tube load of 8.0 MW in the case of oil combustion or 10.4 MW for gas combustion - applicable to ﬂame tube material P265GH. Max. ﬂame tube wall thickness of 20 mm must not be exceeded in the case of oil and gas steam boilers. A wall thickness of 22 mm is possible when boiler and feedwater are monitored, in accordance with the DDA information on installation and operation of land-based steam boiler systems, or a temperature capturing system is installed. Flame tube diameter > 1400 mm Flame tube wall temperature monitoring with 6 test points arranged offset along the circumference at an angle of 120 °C. 1st row with a clearance of 0.8 dF , 2nd row with a clearance of 600 mm downstream from the 1st row, Limit and non-equivalence monitoring, temperature limiter and internal inspection of the ﬂame tube on the combustion side at 18 month intervals, commencing 6 years after commissioning. Combustion output > 12 MW (oil) > 15.6 MW (gas) Flame tube wall temperature monitoring with 6 test points arranged offset along the circumference at an angle of 120 °C. 1st row with a clearance of 0.8 dF , 2nd row with a clearance of 600 mm downstream from the 1st row, Limit and non-equivalence monitoring, temperature limiter and internal inspection of the ﬂame tube on the combustion side at 18 month intervals, commencing 6 years after commissioning. 104/105 Furthermore, a set of standardised hot tensile tests must be conducted at 300 °C, whereby the required strength values must be adhered to and elongation at break must not be less than the corresponding value at room temperature. In addition to the speciﬁcations of the 2000/1 trade association agreement, provision must be made for an inspection interval of 18 months for internal inspection of the combustion side of the ﬂame tube. D.2.3 Economiser (ECO) operation Depending on the relevant operating parameters (saturated steam temperature = f (operating steam pressure)), two versions are usually employed for ECO operation as socalled integral ECOs. With feedwater inlet temperatures into the ECOs of 102 °C and operating steam pressures of up to 12 bara), a differentiation is made between: Type 100 - for ﬂue gas temperatures downstream from the ECO of 180 °C and Type 200 - for ﬂue gas temperatures downstream from the ECO of 130 °C Design and calculation datasheets (see technical guide for the respective boiler) for the Vitomax 200-HS steam boiler with integrated ECO, type 100/200. Subject to observation of other ﬂue gas parameters required on site, such as: Speciﬁcation of dew point temperature for cold start Flue gas bypass operation Utilisation of condensing technology in the case of speciﬁc and regulated "ﬂue gas condensation" additional ECO designs are available in combination with the respective steam boiler as "mounted economisers" and/or as "downstream economisers" in the case of separate design and calculation according to requirements. Fig. D.2.2–3 Flame tube outputs Regulation TRD with trade assoc. DIN EN 12953 or TRD with trade agreement 94/1 [Germany] association agreement 2003/1 [Germany] Oil combustion 10.5 MW 14.0 MW Gas combustion 13.65 MW 18.2 MW Material HII P265GH (max. 8 MW oil, Max. combustion output max. 10.4 MW gas combustion) Max. nominal wall thickness 17 Mn4 P295GH 20 mm 22 mm Reason: A: Insofar as EL fuel oil or E natural gas are used as the main fuel and S fuel oil, for example, is intended as a backup fuel, the heating surface of the ECO is designed for the main fuel. So that the lamellar tubes of the ECO are not contaminated beyond permissible levels during the combustion of S fuel oil and hence made ineffective or ﬂue gases contaminated with sulphur condense and destroy the ECO, the ECO heating surface is "bypassed" in this instance. Additional use can be made here of manufacturer-speciﬁc ECO designs (supplier variable). Any equipment-dependent "additional costs" are amortised in less than 6 months through the heat recovery achieved (integral ECO) from the ﬂue gas and the associated average fuel savings of 4 to 7 %, assuming an annual system operating time of approx. 6000 hours (see rough calculation example in chapter D 3.2.2). A reduction in ﬂue gas temperature using the ECO of approx. 100 K yields an expected boiler efﬁciency increase of approx. 5 %. B: If existing ﬂue systems require minimum temperatures. a) For operating steam pressures of > 12 bar to ≤ 25 bar, an increase in the saturated steam temperature occurs as a consequence of the rise in pressure (saturated steam temperature = f (operating pressure); see Tb. 2/2.1, chapter G2) and thermodynamically an analogous increase in the ﬂue gas temperature to be expected. D.2 Product range D.2.3.1 ECO output In a thermodynamic economy consideration covering the ﬂue gas heat exchanger (ECO), the necessary total ECO output (in kW) can be estimated, derived respectively from the following formula: T)*ERLOHUT)*(&2 4 ɘ (&2 [સ%[L $ T)*ERLOHU 7)*ERLOHU7air[ T)*(&2 7)*(&27DLU[ 2 $ % >@ % >@ 2 7)*ERLOHU ᚐXHJDVRXWOHWWHPSHUDWXUHERLOHUฬᚐXHJDVLQOHWWHPSHUDWXUH(&2 >r&@ 7)*(&2 ᚐXHJDVRXWOHWWHPSHUDWXUH(&2 >r&@ 7DLU FRPEXVWLRQDLUWHPSHUDWXUH >r&@ DFWXDO2YDOXHLQGU\ᚐXHJDV 2 >[email protected] LQWKHFDVHRI2UHJXODWLRQEHLQJDYDLODEOHZLWKUHVLGXDOR[\JHQ સB = estimated amount of fuel to be expected [m3/h or kg/h] સ% સB FS Note hD The economics must take into account the amount of feedwater, since this is greater than the amount of steam due to blow-down and T.D.S. losses. As no reliable values are available in this connection when sizing the system, it is usual to set steam mass ﬂow rate = feedwater mass ﬂow rate. FS h Fw H ǹ i K(m) )6[K )6K ): +L[Š.P [ = estimated amount of fuel in kg/h and/or Nm³/h = amount of steam per steam boiler in kg/h = steam enthalpy - fresh steam in kWh/kg (kJ/kg) = feedwater enthalpy in kWh/kg (kJ/kg) = lower net caloriﬁc value in kWh(kJ)/kg, and/or kWh(kJ)/Nm³ = average thermal boiler efﬁciency in % as an expected value 93.5 % (assumed selected value range: ≥ 92.5 % to ≤ 93.5 %) - and/or from datasheet as a function of boiler load and ECO version Fig. D.2.3–3 ECO with lateral outlet 106/107 Fig. D.2.3.1–1 A and B - Siegert factors = f (fuel); (constants) Fuel Constants: Constants: Constants: Constants: Factors Light fuel oil Heavy fuel oil Natural gas Town gas A 0.67 0.69 0.66 0.63 B 0.007 0.007 0.009 0.011 Fig. D.2.3.1–2 Hi – lower net caloriﬁc value in kWh/kg, (kJ/kg) and/or kWh/Nm3 (kJ/Nm3) Fuel Fuel oil (EL) Heavy fuel oil (S) Natural gas (E) Natural gas (LL) kWh/kg 11.9 11.3 -- -- kJ/kg 42,700 40,700 -- -- kWh/Nm³ -- -- 10.35 8.83 kJ/Nm³ -- -- 36,000 31,800 Fig. D.2.3–4 Note regarding the estimation of Q̇ECO With reference to the Vitomax 200-HS datasheets (in this instance, the speciﬁcations for determining ﬂue gas mass ﬂow rate using the steam output), the respective ECO total output can be determined with an increased degree of accuracy for ECO types 100/200 from: 4 ɘ ECO = (h FG/boiler - h FG/ECO) x FS x R/ ̖ FG ZLWKh FG/boiler - ᚐXHJDVHQWKDOS\DWERLOHURXWOHW Generally determined from h FG = in kW N:K1Pu T N:K 1Pu FG DQG h DQG ̖ DYHUDJHᚐXHJDVGHQVLW\RQWKHDVVXPSWLRQ ̖ DQG GLPHQVLRQOHVVIDFWRUGHWHUPLQHGIURPWKHDIRUHPHQWLRQHGGDWDVKHHWV 5 GHSHQGLQJRQRSHUDWLQJSUHVVXUHDQG(&2W\SH ᚐXHJDVHQWKDOS\DW(&2RXWOHW FG/ECO FG ECO mounted on top .:K1Pu FG NJ1Pu a) Steam enthalpy of fresh steam calculated in kWh/kg [Tb. 2/2.1] = f (available steam parameters – pressure/temperature) for superheated steam and h"FD - for saturated steam. D.2 Product range Fig. D.2.3.1–5 Economic considerations on steam boilers TFG/ECO; hFG/ECO TFW ECO h'FW= 0.001163 x TFW (kWH/kg) FS = amount of fresh steam per steam boiler (kg/h) hFS = steam enthalpy - fresh steam (saturated steam (h''FS) and/or (hFD) superheated), determined from (Tb.2/2.1) = f (available steam pressure and fresh steam temperature) TFw = feedwater temperature (°C) (deaeration temperature as a function of deaerator pressure from (Tb. 2)) h'Fw = feedwater enthalpy in (kWh/kg) Tab. 2, chapter G2 TFG/boiler ŠK(M); hFG/boiler D.2.3.2 Amortisation Economiser (AECO) The values determined in chapter D.2.3.1 would result in a payback period from the relationship: SB K ECO x H i FS; h''FS A ECO = . QECO x k B x b with the additional calculated amounts that will be required and must be provided, such as: સB; Hi; Tair KECO - expected ECO costs (in €) via a quotation that must be prepared for each case Steam boiler (SB) economics consideration with ECO (simpliﬁed) Fig. D.2.3.1–6 Heating surface temperature diagram Note The following cost functiona) may be of initial assistance as a "rough" estimate: . .(&2 [QECOLQ Flue gas outlet 300 ECO ﬂue gas inlet 250 200 kB - current speciﬁc fuel price in (€/kg and/or in €/Nm³)a) Media temperature in °C 150 a) b - expected annual hoursb) (full-load hours) of system operation to meet the total annual steam requirement. 100 50 0 100 50 Heating surface in % 150 The cost function is calculated on the basis of corresponding quotation work (Rosink, 2005/2006). b) Necessary preparations by the customer. 200 250 108/109 Example estimate calculation: with a resulting total ECO output of . Q = 365 kW ECO a energetic heating price for natural gas (H) of 0.04/kWh, but with reference to the speciﬁc consumption: N% N:K[+L N:K[N:K1Pu N% 1Pu an expected ECO price of: .(&2 [N: and the assumed annual hours under full load E = 6000 h/a $(&2 results in a payback period of: [ [[ \HDUV Note . Die determination of Q ECO has been calculated on the basis of values and calculation variables yielded with the formulae in chapter D.2.3.1: Fuel = natural gas (E) Steam pressure = 12 bar Feedwater temperature Tfw = 102 °C Flue gas temperature w/o ECO TFG/boiler = 252 °C O2 content in ﬂue gas = 3 % Siegert factors A = 0.66 B = 0.009 Lower net caloriﬁc value Hi = 10.35 kWh/Nm³ Saturated steam enthalpy h''FS Feedwater enthalpy h'fw Amount of steam in Fs Boiler load ECO type Flue gas temperature with ECO TFG/ECO Air temperature Tair Boiler efﬁciency (acc. to datasheet) ŠK(m) = 0.7737 kWh/kg = 0.119 kWh/kg = 12,000 kg/h = 100 % = 200 = 132 °C = 20 °C = 94.75 % Note Current gas and oil prices can be found on the internet at: www.heizoelboerse.de www.verivox.de; www.carmen-ev.de D.2 Product range D.2.3.3 Utilising condensing technology Condensing technology can also be used, on the basis of currently known facts, for the purpose of heat recovery on high pressure steam boilers. Additional costs are also amortised in this case within reasonable payback periods (see sample estimate). However, an essential condition here is - as constantly as possible - the availability of heat sinks at the corresponding temperature level below the water dew point in the ﬂue gas, each depending on the fuel used (see Fig. D.2.3.3-1). The improvement in efﬁciency of the steam boiler system enables a contribution to be made to environmental protection. At the same output from the steam boiler system, the level of CO2 emissions is reduced by approx. 9 % for natural gas operation (see Fig. D.2.3.3-2). With the increased values for gross cv and the increase in steam dew point temperature, use of condensing technology and natural gas operation offers better conditions than HEL. As a consequence of the chemical reaction in the combustion (oxidation) of methane &+2 !+2& Fig. D.2.3.3–1 Gross and net caloriﬁc values of natural gas and HEL fuel oil Fuel Lower caloriﬁc Upper caloriﬁc Ratio (%) Steam dew value value gross cv/net cv point in ﬂue (net cv) (gross cv) x 100 gas (°C) Natural gas (E) 10.35 kWh/Nm³ 11.46 kWh/Nm³ 110.72 58 Natural gas (LL) 8.83 kWh/Nm³ 9.78 kWh/Nm³ 110.75 58 Fuel oil (EL) 11.9 kWh/kg 12.7 kWh/kg 106.72 47 The efﬁciency of the steam boiler system (Š K(M)) is further improved and can achieve values ≥ 100 %, with reference to the lower net caloriﬁc value (net cv). The increase in steam boiler system efﬁciency (Š*) largely depends on the level of additional "available heat" (QFGHE) "extracted" by means Note Condensate yielded from HEL combustion is very acidic (pH values between 1.8 and 3.7) and corrosive due to the sulphur content in the fuel (approx. 0.2 %). Neutralisation facilities must be equipped accordingly with additional active carbon ﬁlters. Theoretically, amounts of condensate up to a maximum of 1.035 kg/kg of fuel can be produced (see Fig. D.2.3.3-2). of condensing technology and is determined from: ǹ ǹ .0[ ɘ 4 )*+( )6K )6K IZ >@ with the calculation variables as speciﬁed in chapters D.2.3.1 and D.2.3.3. theoretical maximum levels of steam condensate equal to 1.5 kg/Nm3 of fuel are produced in the ﬂue gas, in the case of natural gas combustion and pH values between 3.5 and 5.2 (slightly acidic). Prior to their discharge, these must be neutralised accordingly to pH values of between 6.5 and 9, for example using ﬁlters ﬁlled with dolomite and/or dosing equipment employing sodium hydroxide (see technical guide "Water quality standards for steam boiler systems", [Appendix 2, chapter G1]). 110/111 The previously mentioned "downstream ECO" could be included in the design as a secondary heat exchanger to the existing integral ECO. The "downstream ECO", the whole of the secondary ﬂue system and all dewatering lines must be made in this instance from corrosionresistant stainless steel. Fig. D.2.3.3–2 Theoretical amounts of condensate and CO2 generation in the case of complete combustion Fuel Max. theoretical Max. CO2 emissions (kg/kWh) with reference to amount of condensate1,2 QHWFY JURVVFY Natural gas (E) 1.63 kg/Nm³ 0.2 0.182 Natural gas (LL) 1.53 kg/Nm³ 0.2 0.182 Fuel oil (HEL) 1.035 kg/kg 0.312 0.298 As a continuously available heat sink, alongside any that might be available on site in such cases as: Low temperature heating systems DHW heating systems Low temperature process heat, technically necessary preheating stages etc. modulating, controlled preheating of the boiler top-up water (softened water, upstream of the inlet into the feedwater deaeration system) is also conceivable. 1 With reference to the amount of fuel. 2 Applicable municipal regulations must be observed on discharge into the local public sewage system (e.g. in Germany, Code of Practice ATV-DVWK-A251). One system version of a steam boiler with integral ECO and secondary ﬂue gas heat exchanger for utilising condensing technology is indicated for information in the process ﬂow diagram (see Appendix A1) on the basis of Fig. D.2.3.3-3. Steam boiler (SB) economic considerations with ECO and FGHE (simpliﬁed) Fig. D.2.3.3–3 Steam boiler economic considerations TFG/FGHE (ื 60 °C) qFG/FGHE ; qFG/CON with the calculation: qCON-heat gain in % from utilising condensing technology, calculated from: h'add/FW/O q = con (H -H ) ˞ s H i Tadd/FW/O x 100 i FGHE qFG/ECO The total FGHE heating output (in kW) and the amortisation (A) to be expected in this instance are determined on the same basis as that for the ECO in chapter D.2.3.1 and D.2.3.2. Q̇ FGHE FG/ECO -q = )+q ] FG/FGHE con x સ x H B 100 i and A= K Q̇ x Hi FGHE x K x b FGHE ECO Q̇ FGHE h' add/fw/O - h' add/fw/I [ kg h h'FW; TSW FW [a] b TFG/boiler As well as the additional amount of feedwater required for condensation of the steam in the ﬂue gas from the heat balance on the ﬂue gas heat exchanger (FGHE): add.fw= Tadd/FW/I; add/FW TFG/ECO (ุ 130°C) ˞ = condensation factor between 0.7 and 1.0 depending on coolant temperature [(q h'add/FW/I ] With inlet temperatures of the required additional feedwater "signiﬁcantly" lower than the steam dew point (see Fig. D.2.3.3-3). ǹK(M) SB FS h''FS સB; Hi; Tair D.2 Product range Flue gas heat exchanger (FGHE) Downstream from the ECO as a 2nd stage heat recovery device utilising condensing technology and the parameters for top-up feedwater inlet and outlet: h'add/fw/I = Enthalpy of additional feedwater (inlet) in (kWh/kg) h'add/fw/O = Enthalpy of additional feedwater (outlet) in (kWh/kg) Tadd/fw/I = Temperature of top-up feedwater (inlet) in (°C) Tadd/fw/O = Temperature of top-up feedwater (outlet) in (°C) add/fw = Amount of top-up feedwater in (kg/h) Example as a rough calculation: Taking the same assumptions and values as the rough calculation in chapter D.2.3.2, the additional assumptions for: Flue gas temperature downstream from the ﬂue gas heat exchanger = T FG/FGHE = 60 °C Top-up feedwater inlet temperature = Tadd/FW/I = 10 °C = Tadd/Fw/O = 50 °C Top-up feedwater outlet temperaturea) Expected price for the ﬂue gas heat exchanger ≈ €105,000b) For a calculated total FGHE heating output = Q̇FGHE 1.019 kW result in an expected payback period of: A FGHE = k Q̇ x Hi FGHE x K x b FGHE [ $)*+( [[ b ป\HDUV with an increase in efﬁciency to: Š Š ( K(M) Q̇ 1+ FGHE (h'' -h' ) S FS fw ) = 94.75 x ( 1+ 1019 12,000 x (0.7737 - 0.119) ) ≈ 107% and a top-up feedwater requirement due to the FGHE of: Q̇ add/fw= h' add/fw/O FGHE = - h' add/fw/I 1019 (0.0584 - 0.0118) 21,867 kg/h Note With reference to the amount of fresh steam selected in the calculation example, an additional gain would result on site from the heat "extracted" from the ﬂue gas by means of condensing technology of: Q̇add/gain ≈ (21.867 - 12,000)kg/h x (0.0584 - 0.0118) kWh/kg ≈ 460 kW. In the event of non-availability of an appropriate additional "heat sink", Qadd/gain remains unused and the increase in efﬁciency is reduced accordingly to the value of: Š 94.75 ( 1+ (1019 - 460) 12,000 (0.7737 - 0.119) with the payback period increasing to: a) The feedwater outlet temperature from the FGHE should always be set at a value "signiﬁcantly" below TFG/FGHE. Selected tender price. b) [ $ [[ ป\HDUV ) ≈ 101.5 % 112/113 D.2.3.4 Superheater (SH) operation Appropriately designed and controlled superheaters are brought into service based on the requirements of on-site applications. Superheated steam temperatures of 50 K above the respective saturated steam temperature can be achieved in the case of unregulated SH operation and 100 % boiler load. For customer selection of the superheating temperature differentials (Δ tSH), all the temperature losses (heat losses) between the steam boiler installation location and the consumer must be considered (see chapter D.8.3.4). A reduction in superheating temperatures to values < 50 K must also be considered subject to boiler load. Fig. D.2.3.4–1 Boiler load (%) ˂7 . Boiler load 35 50 75 100 25 35 44 50 Speciﬁc requirements concerning safety measures for preventing excessive pressure as well as the necessary pressure and temperature measuring technology in operating modes with SH are considered by the manufacturer with reference to the applicable regulations (TRD 401). Customer-speciﬁc superheating temperatures of > 50 K are possible, however, in the case of individual design in consultation with the manufacturer (see example layout). Fig. D.2.3.4–2 Mixing valve 0 Customer set values SH SB hSH hSB TSH K M/SM/S Example - rough calculation Regulated superheater in mixed operation with saturated steam: (Vitomax 200-HS; saturated amount of steam = 10 t/h, saturated steam temperature = 195 °C, pressure = 13 bar, set value temperature for superheating = 220 °C at approx. 20 % boiler load) Boiler load (%) 20a) 40 60 80 100 ˂7SH (K) unregulated 20 42 59 72 82 ˂7SH (K) regulatedb) 20 25 25 25 25 SH Fig. D.2.3.4–3 Steam superheater Standard values with reference to steam output at a saturated steam pressure of 12 bar and feedwater temperature = 102 °C With a requirement for superheating of 50 K in any of the speciﬁed load cases < 100 %, an appropriately regulated SH operating mode must be ensured by the manufacturer. Control takes place here "within the assembly" by means of ﬂexibly controlled mixing of "colder" saturated steam as a function of the superheated temperatures arising downstream from the mixing point. Note Alternatively, it is possible to install an injection cooler or a surface cooler downstream from the superheater or a controller on the ﬂue gas side to regulate the superheating temperature. a) b) The speciﬁed boiler load of 20 % in the calculation example represents a "special case". Normally, the minimum boiler load is ﬁxed by the manufacturer at 35 %. D.2 Product range Principle of admixing saturated steam Required mixing amount of saturated steam (in M/S) from: 06 6%[K6+K6% K6+K 06 NJK and the calculation variables: SB Selected steam output (kg/h) on the M/S hSB hSH h''M/S customer side Required mixing amount of saturated steam (kg/h) Steam enthalpy (Tb. 2) (kJ/kg) as a function of the customer set value (pressure, temperature) Steam enthalpy (Tb. 2) (kJ/kg) as a function of the necessary superheating temperature TSH for the purpose of ensuring the on-site set temperature Enthalpy of the saturated steam mixing amount (Tb. 2) (kJ/kg) as a function of selected saturated steam parameters with the formulations from: Volume statement -> SB = SH + M/S (kg/h) Heat statement -> SB x hSB = SH x hSH + M/S · h''M/S (kJ/h) Consideration is frequently given to selecting a boiler with higher pressure and subsequently implementing a pressure reduction by means of superheating. This approach is illustrated in Fig. D.2.3.4-4. It is, however, a purely theoretical approach. In practice, the enthalpy of superheating is used up by the wet steam content, so that actually no appreciable superheating temperature can be achieved. 114/115 Fig. D.2.3.4–4 1st and 2nd grade in Mollier-h, s-diagram for steam (theoretical consideration) h (Enthalpy) co ) r (ü ba ts = 209,5 °C ta ns = = nt 18 t= p FD ts e 2:) ic (Cho ü) ar ( 8b C = 1 9,8 ° 0 2 = ba = co tan = co nt ta ns = 8 ba ts = 188 °C tB = 185 °C ts = 175,4 °C B A p FD ts ü) r( ns RV (Choice 1:) Reduction at h=constant from A to B ü) r( 11 ü) ar ( 1b = 1 8 °C 8 =1 t tan ng ns ati co rhe = pe su C p FD ts (ü) bar °C = 8 75,4 1 = D x= (sa 1 tu rat e ds te am pip e) S (Entropy) Fig. D.2.3.4–5 Steam boiler with superheater a) At constant steam enthalpy. D.2 Product range Fig. D.2.3.5–1 Indirect coil ŠY67 +67ป [)6[K )6K IZ LQPt NIP[˂7P D.2.3.5 Pressure / heat maintenance steam boiler The principle options are portrayed and explained in chapter C.1.3.1 and Appendix A2 with 2 versions (VA and VB). Aside from the portrayed versions: (VB) Pressure maintenance by means of the combustion system and, the following results, with the calculation variables for: Šv/ST Radiation loss of the steam boiler in % FS Amount of fresh steam in kg/h h''FS Enthalpy of saturated steam = f (pB) from (Tb. 2) in kWh/kg h'fw Enthalpy of feedwater = f (feedwater temperature) in kWh/kg from (Appendix Tb. 2) kf(m) Mean heat transfer coefﬁcients in the case of free convection, according to Appendix L8, between condensing steam -> steel -> water (in kWh/hKm²) and speciﬁcations between 0.291 and 1.163 kWh/hKm2 ΔTm Mean temperature differential (in K) between the boiling point of the boiler water as a function of the operating pressure (pB) and "cooling" of the boiler water content due to radiation loss, with: ΔTmax = maximum permissible "cooling" and ΔTmin = minimum permissible "cooling" and the only permissible quotient in this case the version here: (VA) Pressure maintenance using an additional heating surface, (internal indirect coil) installed in the water chamber of the steam boiler, is the most frequently used in practice. Furthermore, it is the most economical method in terms of energy. Note The tubular heating surface (HfR - German abbreviation) must be designed as an integral "plug-in heat exchanger" (if necessary as a U-tube bundle) in the water chamber of the steam boiler (see Fig. D.2.3.5-2). The beneﬁt of this version in the case of multiboiler operation is the even distribution of heat inside the boiler. Temperature stratiﬁcation and therefore thermal stress are avoided. In the following, information and standard values are provided for the approximate design of the necessary tubular heating surface (HST): From the relationship (calculation of the heat transfer or heat ﬂux through a tube wall) ˂7 PD[ ˂7 ื PLQ the necessary tubular heating surface is calculated with ˂7P ˂7PD[˂7PLQLQ. 116/117 Calculation example for determining the tubular heating surface - HST: With assumed values for: FS = 12,000 kg/h pB = 13 bar Šv/ST = 0.35 % h''FS = 0.7744 kWh/kg h'fw = 0.121 kWh/kg kf(m) ≈ 0.727 kWh/km2 ΔTmax = 20 K = 10 K ΔTmin ΔTm =(20+10)/2 = 15 K, (selected feedwater temperature Tfw≈ 104 °C) a tubular heating surface of approx. ŠY67 +67ป [)6[K )6KIZ ป [[ NIP[˂7P Pt [ would be required. This yields a required total number of tubes n, and selected diameter 33.7 x 2.6 mm: +67 Pt G[˭/7 [˭[P Fig. D.2.3.5–2 Selected: 6 pieces Plug-in heat exchanger RW RS KB HfR dØ x DE x x DN 150 Q 2x pipe = Ø 33.7 mm KO x 1x pipe = Ø 33.7 mm Rb Tb View (x) pipe floor "Plug-in heat exchanger" as an equipment option for the calculation example Key: RW = Steam boiler tube wall RS = Tube connector with Rb = Tube plate (Rb) and DE = Hot steam inlet dished end (KB), separation plate (Tb) KO = LR ~ 4 m ~ 51 mm t 1.5 x dØ Condensate outlet dØ = Tube external diameter t = Tube spacing n = Number of heating tubes LR = Heating tube length D.3 Combustion systems Fig.: Weishaupt Combustion systems Insofar as no particular make is speciﬁed by the customer, the optimum burner is selected with regard to technology and cost-effectiveness. When sizing the burner, the fuel types and total combustion output must be considered with reference to country-speciﬁc type approval regulations (in Germany, 1st/4th BImSchV; TA-Luft and/or 13th BImSchV). A selection can be made, for example, from the external "burner product lines" offered by Dreizler, Elco, Saacke and Weishaupt. The recommendation for the control side is: Gas as fuel: modulating Fuel oil 2-stage up to approx. 2.3 t/h steam boiler output and modulating for > 2.3 t/h steam boiler output 118/119 Note Design case: Fan motor rating (N) 40 % saving Annual hours run (Ohrs) Annual saving Electricity costs (Kelec) D.3.1 Variable-speed combustion air fan Depending on the annual hours run and the associated load If applicable, with recommendation for electrical connected loads ≥ 8 kW motor rating and an expected average annual operational load of around 50 % : 30 kW : 12 kW : 6000 h/a : 72,000 kWh : €0.08/kWh 1 1yQQ Annual saving [KSC] from: Rough estimate for speed control: Where a speed controller is used on a burner fan motor, approximately 40 % of electricity costs are saved in the case of average boiler utilisation. KSC = 6000 h/a x €0.08/kWh x 12 kW resulting in an annual saving KSC of €5760 p.a. Additional beneﬁt: Reduction in the sound pressure level, because the burner fan need not deliver 100 % continuously. The investment outlay for a speed controller amount to ~ €3500, thus resulting in a payback period (ASC) = €3500 / €5760 of ~ just over 6 months. Fig. D.3.1–1 .6& 2KUV[.HOHF[1 Comparison of fan controller types 40 25 20 su con r e Pow it 15 10 5 0 kW in w tion mp W in k co nt ro l 30 rol ont c e l rott h th pe ed Power consumption of the fan motor in kW Comparison of types of fan control 35 ns r co e w Po 0.01 2 4 Burner output in MW 6 n tio p um i th w 8 s 10 With the characteristic fan curve as a function of the electrical output from: 12 (in kW), the electrical power consumption of the motor drops to approx. 1/8 on reducing the speed by a half (from n1 = 100 % load to n2 = half load of 50 %). Payback period = f (actual system load characteristics and local electricity costs). D.3 Combustion systems Note D.3.2 With O2 control for values ≤ 3 % O2, the excess air coefﬁcient (˨) is minimised stoichiometrically. The system efﬁciency is improved by values of up to 1 %. In the stoichiometric binding between fuel and combustion amount of air If applicable, with a recommendation for combustion outputs > 10 MW, for the purpose of optimum compliance with legal requirements relating to NOX emissions in the ﬂue gas A further improvement in system efﬁciency of up to 1.3 % would be possible with combined regulation by means of hooking up the CO content to the O2 controller, i.e. O2 control = f (CO content in ﬂue gas), but only for gas operationa)) O2 control Fig. D.3.2–1 Rough calculation for O2/CO control: Reduction of the O2 value in gas combustion from 3.5 to 1.0 % yields an improvement in efﬁciency of approx. 1.25 % for a ﬂue gas temperature of approx. 240 °C. This corresponds to a fuel saving (in HEL): at 10 t/h, 75 % load and 6000 h/a of 39,500 l HEL p.a. and at 15 t/h, 75 % load and 6000 h/a of 59,200 l HEL p.a. Note At a ﬂue gas temperature of 150 °C, the efﬁciency improvement is still ~ 0.8 %. Comparison of methods of fan control $"'%" # #""$#"(#! #" " a) With increasing CO content, the O2 content (excess air) can be reduced to a stoichiometric minimum (limit). However, any further reduction results in a 'sudden' steep increase in the CO content, particularly for HEL operation. With gas operation, the 'suddenness' is not as marked and therefore more easily controlled. '% $" #!" "# & 120/121 D.3.3.2 Annual fuel demand (સB(a)) D.3.3 Amount of fuel / fuel demand D.3.3.1 Fuel demand (સB) - see chapter D.2.1 (total output) Determined as a standard value from (L5) using: The requirement is determined from the speciﬁed balance equation as follows: સ% )6K )6K IZ[ સ%D NJK +L[Š.0 સ%D The efﬁciency selected here ŠK(M) must be taken from the steam boiler datasheets, loadbased and a choice of with and/or without ECO operation. After determining સB, it is possible to calculate: Combustion output (burner output) Q̇C = સ B x Hi (kW) and Rated steam boiler output Q̇SB = Q̇C x Š K(M) in kW and/or Q̇SB = Q̇C x Š K(according to SB datasheets) in kW As long as a burner report is available, the efﬁciency of the boiler can be calculated as follows: ǹ N * A, B 2GU ˽)* ˽$ $ 2GU % assuming 2 % system loss Siegert factors, see Fig. D.2.3.1-1 actual O2 content in ﬂue gas, dry ﬂue gas temperature air temperature [˽)*˽$ E[4 ɘ &[Š.[ E[4 ɘ &[Š.[ +LyŠWRW +L[Š.[Š%[ŠY E[4 ɘ &[ +L[Š%[ŠY NJDDQGRU1PD with: Q̇C combustion output (kW) Hi lower net caloriﬁc value in (kWh/kg) and/or (kWh/Nm³) b expected annual full cost hours Štot total system efﬁciency (%) ŠK standard utilisation level of the boiler according to SB datasheets (%) ŠB standby efﬁciency (%), caused by standstill of the steam boiler due to radiation and cool down assuming 0.3 to 0.4 % radiation depending on thermal insulation and boiler load = 98 % Šv distribution efﬁciency (%) depending on system thermal insulation and layout, assuming between 90 and 98 %. D.3 Combustion systems D.3.3.3 Combustion calculation simpliﬁed Determined as a practicable value from L4/L5 for gas and fuel oil as the fuel. If a "precise" determination is required, see the appropriate literature references. Here, the "precise" determination is based on given fuel analysis values. Fig. D.3.3.3–1 D.3.4 Combustion air, supply air ducts With reference to the versions referred to in chapter C.4.1 (combustion air), the combustion air required for combustion (see chapter D.3.3.3 for calculation) can be taken directly from the steam boiler installation room and/ or via separate supply air ducts from the "open air" (outside the building). Ensure that a pressure of +/- 0 mbar is available in the boiler room. Combustion air and ﬂue gas volumes L min in: Fuel Nm³ kg Natural gas (E) = Natural gas (LL) = Fuel oil HEL(S) = 0.260 · Hi 1000 VFG min in: or Nm³ Nm³ - 0.25 Nm³ kg 0.272 · Hi 1000 0.209 · Hi 0.173 · Hi 1000 1000 0.203 · Hi 1000 + 2.0 or Nm³ Nm³ + 0.25 + 1.0 0.265 · Hi 1000 with the calculation variables: Lmin - theoretical amount of air (˨=1); VFG min - theoretical ﬂue gas volume (ﬂue gas volumetric ﬂow rate) (˨=1); Hi - the lower net caloriﬁc value of the fuel for fuel oils (in kJ/kg) and/or for gases (in kJ/Nm³) With a 'minimum' possible air excess (˨) as the objective for combustion in general of between: ˨ ~ 1.1 to 1.3 ˨ ~ 1.2 to 1.5 Note Conversion of the calculated air and/or ﬂue gas volumes from Nm³/h to m³/h using: Nm3/h x (1 + 0.00367 xT) = m3/h (T= available media temperature in [°C] also in the case of disregarding the operating pressures). for gas combustion and for oil combustion, the speciﬁc air requirement (L) and the expected speciﬁc ﬂue gas volume (VFG) are yielded from: L = ˨ x L min in Nm3/kg or Nm3/ Nm3 and VFG = VFG min + (˨ - 1) x L min in Nm3/kg or Nm3/ Nm3 Option A Where air is drawn from the installation room, provision must be made in the planning process for appropriate "open air" vents. Observe the following during the on-site design of the "open air" vents: Supply air vent in the outside wall directly behind the steam boiler (standard practice) Lower edge of vent approx. 300 to 500 mm above upper edge of ﬂoor Vent aspect ratio max. 1:2 Open air vent (approximate) Avent ~ 150 cm² + (Q̇C - 50) x 2 in [cm²] with Q̇C = combustion output in [kW] (FeuVA -Brandenburg, version `97) For output greater than 20 MW, the following recommendation applies: Combustion output > 20MW: A vent ~ 150 cm² + (QC - 50) x 1.8 in cm² Where an open exhaust air vent is required, standard practice dictates the selection of 60 % of the "open" supply air cross-section 122/123 Notes Coordination necessary with the responsible authority (approved monitoring body, labour inspectorate, LaGetSi and/or planning authority) Maximum negative pressure in the steam boiler installation room 0.5 mbar = 50 Pa (TRD 403) Safeguarding "free from frost" in the installation room with air room temperatures ≥ 5 °C to ≤ 30 °C For expected air temperatures < 5 °C, provide appropriate air preheating, for example, by installing spiral ﬁn tube heater banks in and/or upstream of the "open" supply air vent, with frost protection for the heater banks. Separate room heating, e.g. by installing wall mounted air heaters, is only recommended in the case where longer interruptions in operation of the steam boiler system are scheduled for the winter months Combustion systems are usually designed for "standard air conditions" Air density – 1.2 kg/Nm³ Air temperature – 20 °C Installation height above msl – 0m and an O2 content in ﬂue gas – 3 % Air room temperatures ≥ 0 °C to ≤ 5 °C and ≥ 30 °C to ≤ 40 °C result in a decrease or increase respectively in the air volume ﬂow rate. The "ﬂuctuations" in ﬂue gas O2 content arising in this instance can be compensated for in a technically simple manner by providing an O2 regulator An association (to be observed when ordering) between changing air volumes at a constant air mass ﬂow rate D.3 Combustion systems Fig. D.3.4–1 Air calculation Densityair (kg/m³) at: Height (m) Pressure above msl (mbar) 10 °C 20 °C 30 °C 0 1013 1.247 1.205 1.165 250 983 1.210 1.169 1.130 500 955 1.176 1.136 1.098 1000 899 1.107 1.069 1.034 1500 846 1.042 1.006 0.973 Installation of deﬂectors in duct deviations (especially in the case of 90° deviations) to ensure as laminar an air ﬂow as possible If possible on site, a straight discharge section of approximately (2 to 3 x dgl) should be provided after a 90° deviation (especially directly upstream of the burner connection) With dgl - the equivalent diameter determined from: 9ɘDLU DLU̖DLUGHQVLW\ depending on air temperature and installation height, is evident from Fig. D.3.4-1. Option B With an intake from the "open air" (outside the building), "pressure-tested" supply air ducts are required to the burner. "Frost protection" for the installation room, air temperatures for combustion air and system installation heights must be observed in the same way as for option A. The following must also be observed when designing supply air ducts on site: Guarantee of air leak tightness and resistance to pressure in accordance with the expected pressure development as a function of arising duct pressure losses and back pressures to be overcome Required determination of pressure losses in the supply air duct taking account of any ﬁtted parts, such as intake silencers, heater banks, deﬂections, fabric expansion joints etc. (see calculation in chapter D 9) Required determination of the back pressures to be expected (pressure drop on the ﬂue gas side) for: Boilers with and/or without ECO (see datasheet for Vitomax 200-HS) Flue pipes taking account of any ﬁtted parts, such as expansion joints, ﬂaps, deﬂections and ﬂue gas silencers (calculation in chapter D 9) GJO [GXFWFURVVVHFWLRQ [yD[E GXFWVL]H [DE with "a" and "b", the clear lateral duct lengths Selection of sheet metal wall thickness that guarantees structurally stable operation; standard practice here is to select a sheet metal wall thickness of between 3.0 and 5.0 mm. Where a "thinner wall" is selected (≥ 1.5 to ≤ 2.5), additional bandages made from L-proﬁle steel would be required. A computed structural veriﬁcation is nevertheless recommended for deformation (buckling) For sizing required ﬂow cross-sections, values for the standard ﬂow rate of between 10 and 15 m/s are recommended, whereby the "smaller" values here are intended upstream of the burner air intake 124/125 D.3.5 Acoustic emissions from monoblock / duoblock burners Taking account of the acoustic emissions described in chapter E.1.4, "early" noise protection measures that may be required should be considered during the engineering phase. Having selected the burner type (see chapter C.4), the following values can be assumed in the ﬁrst approximation: Sound pressure level in dB(A) (measured 1 m in front of the burner) depending on burner type (monoblock or duoblock) as a function of combustion and fan output Values between 82 dB(A) and 115 dB(A) According to manufacturer speciﬁcations, sound pressure levels of ≥ 100 dB(A) can be anticipated for fan motor ratings as low as ≥ 8 kWel For expected values above 85 to 88 dB(A), provision must be made accordingly for the following noise reduction measures by means of sound insulation (enclosure) combined with sound attenuating (absorption), in accordance with the [German] workplace regulations (ArbStättV) in conjunction with guidelines speciﬁed in VDI 2058. a) For monoblock burners Use of mobile sound insulation hoods (enclosure and absorption) with a noise reduction of between 15 and 20 dB(A), depending on the type of sound absorption material employed, and b) For duoblock burners Enclosure of the "externally" positioned combustion air fan (if applicable, positioning of the fan "straddling" the boiler top and/or installation in a separate room (in the cellar for example) below the boiler). This provides a variety of design options with regard to sound insulation, positioning and the choice of sound absorption material. Depending on the version implemented, reductions in noise emissions of 20 - 25 dB(A) can be achieved. If so-called Low NOx burners are employed, it may be necessary in certain circumstances to equip the burner with sound insulation as well. Note Monoblock burners with a mobile sound insulation hood require a corresponding amount of free space in front of the burner system for dismantling the sound insulation hood. Note For fuel lines, see chapter D.8.5.6. In addition to the noise reduction options described in a) and b), the "sound discharge" (airborne noise) "into the open air" via the system ﬂue gas path (ﬂame tube smoke tubes, ﬂue pipe and chimney stack) must also be considered. Depending on the structural design of the ﬂue gas path, e.g. 2-pass and/or 3-pass boilers with/without ECO, type and number of ﬂue gas deﬂectors, attenuating noise levels in respect of the sound emissions from the combustion system of approx. 5 to 10 dB(A) can be assumed at the stack opening. If a more effective noise reduction is required, additional sound insulation measures, e.g. installation of a silencer in the ﬂue pipe and/ or in the chimney itself, can be included in the plan on the basis of permissible limits (ofﬁcial setting of limits according to BImSchG, TA-Luft and acquisition of an acoustic appraisal). Recommendation Sizing the silencer (in the case of subsequent installation in the ﬂue pipe) on the basis of noise emission measurements taken after commissioning the system. Subsequent retroﬁtting must be taken into account in the design by including appropriate ﬁtting elements. Note In addition to the burners, it may be necessary to sound insulate the gas pressure governors (ﬂow noises) and pumps as well. D.3 Combustion systems D.2.3.7 Determination of the amount of wood fuel (biomass) required The amount of wood fuel (biomass) required can be determined on the basis of the net caloriﬁc value and the required rated output. One signiﬁcant factor in this calculation is the water content of the wood fuel, together with the ﬂue gas temperature. 4 % +X [Š B Fuel demand [kg/h] Q Rated output [kW] Hu Net caloriﬁc value [kWh/kg] Š Efﬁciency Net caloriﬁc value of damp fuels +X: +XDWUR:˂KY: +XX +XDWUR˂KYX X Hu atro Net caloriﬁc value, moisture-free, in MJ/kg TS W Water content in kg/kg ˂hv Enthalpy of evaporation of water = 2.442 MJ/kg at 25 °C (standard temperature for thermochemical measurements) The following applies to typical wood at 25 °C +XX X X >[email protected] kWh/kg is also calculated instead of MJ/kg (1 kWh = 3.6 MJ) Example: Water content W = 30 %, wood moisture u = W/(1-W) = 0.15/(1-0.15) = 0.428 = 42.8 %atro +X 0-NJ N:KNJ The net caloriﬁc value Hu atro of completely dry wood is, on average, 18.1 MJ/kg (5.0 kWh/kg) for deciduous woods and 19.0 MJ/kg (5.3 kWh/kg) for coniferous woods. For calculations with typical wood (CH 1 44O0.66), the value is 18.3 MJ / kg (5.1 kWh/kg) >[email protected] The net caloriﬁc values of plant fuels are slightly less; typically, about 17 MJ/kg (4.7 kWh/kg) for grass, 17.5 MJ/kg (4.9 kWh/kg) for straw and about 18 MJ/kg (5.0 kWh/kg) for Chinese reed (miscanthus giganteus). 126/127 Fig. C.2.3.7–1 Net caloriﬁc value of wood biomass subject to the water content Feuchte Humidity u [%] u [%] = (atro) = (atro) 0 11 25 20 43 67 100 150 5.5 5,5 18 55 Heizwert Hu Hu [MJ/kg FS]FS] Caloriﬁc value [MJ/kg 44 14 Soft wood(Hu (Hu= =19,5 19.5MJ/kg; MJ/kg;ww= =0)0) Weichholz 3.5 3,5 12 33 10 2.5 2,5 Hard wood (Hu Hartholz (Hu==18 18MJ/kg; MJ/kg;ww==0)0) 8 22 6 1.5 1,5 4 11 2 0.5 0,5 00 0 0 10 20 30 40 60 50 Water contentww[%] (%) Wassergehalt Fig. C.2.3.7–2 Efﬁciency subject to the fuel water content and ﬂue gas temperature or load state 210 °C 190 °C 170 °C 150 °C 130 °C 94 92 Efﬁciency [%] 90 88 86 84 82 80 0 10 20 30 40 Fuel water content [%] 50 60 70 Heizwert Hu Hu [MJ/kg FS]FS] Caloriﬁc value [MJ/kg 4.5 4,5 16 D.4 Water treatment Water treatment Viessmann provides and offers appropriate treatment systems, taking into consideration the information and comments speciﬁed in chapter C.4, focussing here on maintenance of the feedwater and boiler water quality stipulated in the "Water quality" technical guide (chapter G1, A3) and DIN EN 12953-10, tables 5.1/5.2 (see also chapter C.5). Assignment of the individual components for the required steam output is considered according to the sequence indicated in chapter D.4.3.1. Standard series with reference to steam boiler output of up to 14 t/h are available for selection from Viessmann. This also applies to data deviating from the standard values ﬁxed in chapters D.4.1 and D.4.2 for the respective designs. In principle, if the boiler output lies between two component sizes speciﬁed in the selection series, select the next larger boiler. For system concepts with higher boiler output (steam boiler output ≤ 75 t/h), address appropriately formulated enquiries to: [email protected]). a) For system concepts with boiler output > 14 t/h, the geometric dimension to be expected here can be taken as a ﬁrst approximation from the CWT datasheet. 128/129 D.4.1 Total deaeration system D.4.1.1 Function description, standard values, design assumptions The total deaeration system comprises the deaerator and feedwater tank assemblies. To prevent corrosion, the deaerator is made completely from stainless steel. The deaerator is mounted directly on the feedwater tank, in the form of a dome. The feedwater total deaeration system is designed to remove the gases dissolved in the feedwater to a residual oxygen content of ≤ 0.02 mg/l and provides the boiler system with the water supply required for safe and reliable operation. It operates with slight positive pressure of approx. 0.1 to 0.3 bar. The returned condensate and the chemically treated top-up water are ﬁnely distributed in the deaerator by means of so-called lutes and brought together with the heating steam ﬂowing in the opposite direction by the irrigation system. The steam heats the condensate/top-up water mixture to boiling point. The released gasses are drawn off to atmosphere via a vapour valve positioned at the highest point of the deaerator. In the feedwater tank, the feedwater is fed constantly with heating steam via an inbuilt heating lance and thus maintained at operating temperature. The system is designed for a permissible operating pressure of 0.5 bar. A safety valve protects the tank from excessive pressure. A vacuum breaker protects it against negative pressure. Prerequisites for satisfactory operation: Maintenance of a constant temperature in the feedwater tank Continuous inﬂow Guaranteed unhindered extraction of the vapour Maintenance of the level in the tank Insulation of the tank Maintenance of a geodetic inlet height (Hgeo) up to the inlet suction port(s) of the boiler feedwater pump(s), depending on pump design (NPSH value), as a rule between 2.5 and 4.0 m Fig. D.4.1.1–1 Total deaeration system Vapour outlet Top-up water inﬂow Condensate inﬂow dE hE Deaerator Heating steam Feedwater tank htot D haeo Feedwater Source: Powerline Note The selection of too low an inlet height can lead to steam formation in the pump, with the consequence of "sudden" steam condensation and associated cavitation for the ﬁrst stage impeller blades in the inlet area (see also "pump design" in chapter D.6). D.4 Water treatment D.4.1.2 Total deaeration system D.4.2 Standard values Minimum feedwater retention time (Ů) in the feedwater tank ≥ 0.5 h to ≤ 1.0 h 80 % tank volume as maximum level Approximate tank volume (Vfw ) in (m³) from: D.4.2.1 )6WRW[$[Ů 9IZa >[email protected] Deaeration takes place at atmospheric pressure by means of a vent on the feedwater tank. The tank is equipped with ﬁtted parts for the distribution and irrigation of the supplied condensate and top-up water. Steam boiler T.D.S. rate (%) ~ ≥ 2 to ≤ 5 % respectively ≥ 0.02 to ≤ 0.05 [-] Feedwater is fed constantly with heating steam via a heating lance built into the lower part of the tank and thus maintained at an operating temperature of approx. 95 °C. Guide values for deaerator sizing Amount of condensate > 50 to 100 % Condensate temperature ≥ 70 °C Amount of top-up water > 0 to 50 % Top-up water temperature 10 °C Feedwater temperature (deaerator outlet) 102 °C Temperature differential using deaerator (heating) ~ 62 K Fig. D.4.1.2–1 Function description, standard values, design assumptions The partial deaeration system is designed to remove the gases dissolved in the feedwater to a residual content of 1 mg/l and provides the boiler system with the water supply required for safe and reliable operation. FS/tot Total amount of fresh steam (t/h) A Partial deaeration system Prerequisites for satisfactory operation: Maintenance of a constant temperature in the feedwater tank Guaranteed unhindered extraction of the water vapour Maintenance of the level in the tank Insulation of the tank Partial deaeration system Condensate inﬂow Top-up water inﬂow Venting Note The selection of too low an inlet height can lead to steam formation in the pump, with the consequence of "sudden" steam condensation and associated cavitation for the ﬁrst stage impeller blades in the inlet area (see also "pump design" in chapter D.6). Heating steam Overﬂow D hhGes tot haeo Feedwater L Source: Powerline 130/131 D.4.2.2 Partial deaeration system Standard values For low fresh water demands or small amounts of steam, partial deaeration systems can be purchased from Viessmann. If customer specify a requirement for partial deaeration systems with greater outputs, an increased chemical requirement for bonding residual oxygen must be expected. At the same time, the following must be observed: As previously speciﬁed, the residual oxygen content of the feedwater from a partial deaeration system is 1.00 mg/l feedwater. However, the requirement for steam boiler systems with a permissible operating pressure > 1 bar is 0.02 mg/l feedwater. This residual oxygen content requirement can only be achieved with a signiﬁcantly higher continuous dosing of chemicals than that used in total deaeration. This results in higher operating costs proportional to the hours run and leads to unwanted increase in boiler water salinity (see sample calculation below). Necessary tank sizes must be selected accordingly, analogous to the tank sizes for the total deaeration system. Example cost calculation: Use of oxygen binders in partial deaeration systems In the following sample calculation, the chemical consumption of a partial deaeration system is compared with that of a total deaeration system: Basic assumptions: The consumption of oxygen binding agents is 50 mg/mg O2 The price per kg of binding agent is set at €6.50 Boiler system with the following speciﬁcation: Boiler output amount of steam (FS): 3000 kg/h Condensate return: 50 % Feedwater temperature: 95 °C when using partial deaeration Oxygen content: 1 mg/l at 95 °C Feedwater temperature: 104 °C when using total deaeration Oxygen content: 0.02 mg/l at 102 °C Binding agent consumption: 50 mg/mg O2 Full-load hours run p.a. (b): 6000 h/a Partial deaeration example 3000 kg/h x 1 mg/l x 50 mg/mg O2 x 50 %/100 x 6000 h/a x 10-6 kg/mg(binding agent) = 450 kg/a x €6.50/kg = €2925/a Total deaeration example 3000 kg/h x 0.04 mg/l x 50 mg/mg O2 x 50 %/100 x 6000 h/a x 10-6 kg/mg(binding agent) = 18 kg/a x €6.50/kg = €117/a If total deaeration is employed, in this example €2808 p.a. would be saved in chemical costs. With expected additional costs of approx. €4200 from the use of total deaeration, this results in a payback period (A) of A = 4200/2808 ~ 18 months. D.4 Water treatment Further cost savings based on the assumptions: Increase in the T.D.S. rate (ΔA) by approx. 2 % due to increased boiler water salinity Annual reduction in T.D.S water (red) on employment of a total deaeration system: red = ΔA x FS x b = 0.02 x 3000 x 6000 = 360 x 10 3 kg/a = 360 t/a Cost saving (ΔK(red)) yielded by red and the costs assumed here for the additional feedwater of approx. €3.50/t: ΔK(red)= 360 t/a x €3.50/t = €1260/a And hence a further reduction in the payback period (Amo) to: A mo(red) = KvgA / (ΔVT + ΔK(red) = 4200/2808 +1260 = just over 12 months with Additional costs for a total KVgA deaeration system ΔVT Difference in costs for chemicals if total deaeration is employed D.4.3 D.4.3.1 Chemical water treatment system (CWT softening system) Function description, standard values, design assumptions Function description The alkaline earths calcium and magnesium are dissolved in water in the form of ions. In water chemistry, these elements are referred to as hardeners. Under the inﬂuence of heat during boiler operation, these compounds would form "boiler scale" that is deposited as a solid coating on the heating surfaces. This coating impedes the heat transfer from the combustion to the water side. Initially, this would result in higher ﬂue gas temperatures and therefore in reduced efﬁciency. Any further increase in boiler scale thickness could lead to the destruction of the heating surfaces due to lack of cooling. For this reason, the water standards specify softened feedwater. Process of boiler scale formation (CaCO3) under the inﬂuence of heat: &D+&2!&D&2+2&2 Systems with ion exchange resins are used for softening the water. Ion exchangers are spherical synthetic resins with absorbed active groups. As an active group, ion exchangers for softening water have absorbed sodium ions. When the hard water runs over the ion exchanger, the absorbed sodium ions are exchanged for calcium and magnesium ions that are dissolved in the water. The hardeners that are detrimental to boiler operation are thereby removed from the water. Once the ion exchanger is exhausted, i.e. all sodium ions have been exchanged for calcium and magnesium ions, it is regenerated with a sodium chloride solution (salt tablets for regenerating the ion exchanger). 132/133 The sodium ions are channelled over the ion exchange mass in the surplus and displace the absorbed hardeners. Thereafter, the ion exchanger is operational again. This process can be repeated endlessly. Loading: 51D&D0J!5&D0J1D Regeneration: 5&D0J1D!51D&D0J Standard values Raw water requirements: Free from mechanical contamination Free from iron and manganese constituents, at drinking water quality Maximum total hardness in raw water 30 °dH Maximum raw water temperature 35 °C Minimum runtime of a system (ﬁlter) between 2 regenerations 7 - 8 h Direct conductivity in boiler water ≤ 6000 μS/cm Residual hardness in treated water ≤ 0.056 °dH equivalent to ≤ 0.01 mmol/l Generally, use of double-pendulum systems (2 ﬁlter systems) in the case of corresponding sizing (see chapter D.4.3.1) D.4 Water treatment Fig. D.4.3.1–1 Size and parameters for the CWT system Parameter Unit Size (BG) Index 60 120 200 320 400 500 600 800 Rated capacity m³x°dH 60 120 200 320 400 500 600 800 Output (ૺL) m³/h 1.0 1.5 2.0 3.5 4.0 5.0 6.0 8.0 Ion exchanger ﬁlling l 15 30 50 80 100 125 150 200 Salt consumption per regeneration kg Brine tank volume l Filter throughput CWT softening systems - design: In the following text, 8 types of system are dealt with ﬁrstly, together with the indicated technical parameters, for steam boiler output of up to 14,000 kg/h as a function of the return condensate content and the total hardness of the raw water used (see Fig. D.4.3.1-1). Note For system concepts with boiler output > 14,000 kg/h, the geometric dimension to be expected here can be taken in the ﬁrst approximation from the CWT datasheet. The rated capacity speciﬁed in the table must not be exceeded. For system concepts with steam boiler output > 14 t/h to ≤ 75 t/h, chemical water treatment systems must be designed individually. This also applies generally to data deviating from the standard values stipulated in chapter D.4.3.1. Please address any relevant enquiries to [email protected] com. From this, the maximum permissible additional water requirement can be derived 9 DGGIZPD[ %*rG+[Ů=>[email protected] 3 6 10 16 20 25 30 40 100 100 200 300 300 300 300 520 1st sample calculation Size (BG) Water hardness Filter runtime ŮZ. between 2 regenerations = 800 = 17 °dH =7h . V add/fw(max) = BG / °dH x ŮZ [m3/h] = 800 / 17 °dH x 7h This yields a maximum permissible additional feedwater demand of . V add/fw(max) = 6.72 m3/h. Interpretation of the 1st calculation example: First approximation: For steam boiler output ( FS) > 6.72 t/h, a corresponding condensate return of ( CON) would be required on site: CON ≈ FS - V̇add/fw ̖m (t/h) Assumptions: Mean water density: ̖ m ≈ 1 t/m3 For steam boiler output ( FS ) ≤ 6.72 t/h with condensate return, the ﬁlter runtime increases successively, whereby the system-speciﬁc ﬁlter throughput must not fall below values of ≤ 10 to 20 % to ensure the speciﬁed rated capacity 134/135 2nd sample calculation Calculation of size (BG) from the equation: ᧤ > @ ᧥ $ %* ̖ )6 P &21  [Ů=[rG+ The dimensionless value (BG) must always be below the system size speciﬁed in tabular form. For example, with: Total steam boiler output On-site condensate return T.D.S. rate Raw water hardness The required assembly size %*ุ ᧤> = 8 t/h = 2.8 t/h ~ 35 % proportion of condensate = 5 % = 17 °dH FS CON A @ ᧥ [[ to be selected would be BG = 800, with the maximum permissible top-up feedwater volume, which must not be exceeded from the 1st sample calculation, of V̇add/fw(perm) < V̇add/fw(max) equal to ᧤> @ ᧥ V̇ add/fw(perm)) ื V̇ add/fw(max) ู Note Regarding system design for steam boilers > 10 t/h Based on the following assumptions: Raw water hardness = 17 °dH Proportion of condensate = 50 % Filter runtime ŮZ = 7 h Maximum ﬂow velocity through the ﬁlter system ≈ 38 m/h System construction similar to Appendix [A1] each with an expected ﬁlter diameter (DF) of: ') [෭1ɘ/>[email protected] and Ṅ L the maximum ﬁlter throughput [m³/h] 5.6 m 3/h 6.72 m3/h D.4 Water treatment D.4.4 D.4.4.1 Function description - reverse osmosis system (RO) Standard values, design assumptions The osmosis system (referred to in practice as a reverse osmosis system) desalinates the required additional feedwater to the greatest possible extent. The osmosis system operates, as described in chapter C.4.2, purely physically, whereby 70 to 98 % of the water used is recovered as desalinated or partially desalinated water. The water for which the salt content must be reduced is ﬁltered by means of pressure through a semi-permeable membrane that traps the salts (ions) dissolved in the water. The membranes in so-called modules have such small pores that the smaller water molecules can pass through, but the larger cations, anions and large organic molecules are retained. Polyamide modules can be exposed to water in the pH range 4 to 11 and modules made of cellulose acetone in the pH range 4 to 7. A temperature limit of approx. 30 °C (ideally 15 to 20 °C) applies to both materials. The pressure on the raw water side must be higher than the osmotic pressure of the raw water, which is dependent on its salt content. The salts (ions) dissolved in the raw water are retained on the raw water side (concentrate), while the desalinated water (permeate) is fed to the permeate tank on the permeate side. This way, 0.75 to 0.9 m³ permeate is collected from 1 m³ raw water. Depending on the system design, this process removes up to 99 % of salts from the original water (raw water). A softening system is installed upstream of the reverse osmosis system to prevent it from becoming blocked. In the case of systems handling < 3 to 5 m³/h, an antiscaling agent is added to the raw water to prevent blockages. The arising "slippage" in hardness in the permeate of approx. 1 to 3 % of the original hardness is then removed by means of a downstream "polisher softener". This downstream polisher softener must be designed solely for the desalinated water and the slight residual hardness of approx. 0.3 to 0.5 °dH. Osmosis systems have found their "place" in practice. Requiring very little space, they are simple to maintain and well-suited to continuous operation. Regenerating chemicals are not required. Module service lives of up to ﬁve years are currently expected. Where an osmosis system is employed, a downstream thermal total deaeration system is absolutely essential for counteracting CO2 surface corrosion. Aside from the salt content, the carbonate hardness (also referred to as alkalinity, m-value or KS4.3 value) has a signiﬁcant impact on the level of desalination required. The reason for this is the alkalinity of the boiler water, forming as a function of carbonate hardness, boiler operating pressure and available return condensate, that quickly leads to increased desalination rates on exceeding the threshold value (p value or KS8.2 value > 8 at > 20 bar, to 12 at < 20 bar). In the case of carbonate harness values > 5 °dH, operating pressure > 5 bar and condensate rates < 20 %, desalination rates of 10 % have already been achieved, justifying the use of an osmosis system. An RO system is to be recommended in the case of: Salt content >800 to 1000 μS/cm Carbonate hardness > 5 °dH and no or very little return condensate of < 10 to 20 % No or very little return condensate Boiler pressure > 5 bar as soon as the above conditions apply Always where decarbonisation has been used previously Use of an RO system leads to a reduction in the desalination rate to < 1 %. Osmosis system - standard values: Continuous operation Raw water of drinking water quality Raw water temperature ≤ 30 °C Recommended for required desalination rates (A) ≥ 8 to 10 % with reference to the amount of fresh steam ( FS) 136/137 The desalination rate (Ai) can be estimated as: a) the KS8.2 (p value as free alkalinity) - mmol/l and/or b) the conductivity - μS/cm and/or c) the silicic acid content - mg/l from ᧤ $L &RQ )6 &RQ )6 ᧥ [ 5 .5 [ >@ZLWK >WKHSURSRUWLRQRI [email protected] Con = Condensate mass ﬂow rate FS = Fresh steam mass ﬂow rate R - Values for a), b), c) present in the raw water according to raw water analysis K - Limits of a), b), c) in boiler water according to technical guide "Standard values for water quality for steam boilers" Note The resulting maximum desalination rate Ai must be set accordingly for the relevant operation. Sample calculation 1 Saline operation, condensate content 50 %: pH 8.2 ฬ KS8.2 mmol/l Conductivity [μS/cm] SiO2 - silicic acid free alkalinity, p value at 25 °C [mg/l] (R) Top-up water assumptions: 1 800 13 6000 150 [> 0.1 to ≤ 1 according to (L2)] (K) Boiler water limits 12 (according to DIN EN 12953-10) Ra)b)c) Required desalination rate Ai (%) Ai [%] Ai = (1 - 0.5) x Ka)b)c) - Ra)b)c) Aa) = 4.54 => desalination rates to be set would be: Ab) = 7.9 % > Aa) and Ac) Ab) = 7.9 x 100 Ac) = 4.74 D.4 Water treatment Note Sample calculation 2 A reduction in the proportion of condensate will result in an increase in the desalination rate. This increases the costeffectiveness of an osmosis system. Calculating the amortisation of the additional cost for an osmosis system compared with the pendulum softening system Required desalination rates ≈8% (without osmosis) Desalination rates ≈1% (with osmosis) Proportion of condensate ≈ 50 % Rated steam output ( FS ) ≈ 12,000 kg/h Rated steam pressure pB ≈ 12 bar Full-load hours run p.a. (b) = 6000 h Total hardness of raw water = 17 °dH Carbonate hardness of raw water = 6.8 °dH Necessary additional cost (Δk) ≈ €16,280 through use of an osmosis system as an alternative to a pendulum softening system; calculated on the basis of appropriate quotations (12/2007). On use of an osmosis system, an annual reduction in desalination water Red results of: 5HG ෙ$ [)6[E[ W NJ [[ W NJ WD With an assumed cost of approx. €3.50/t for the additional feedwater, an annual saving Δk(red) = 5040 t/a x €3.50/t of €17,640 results and thus an expected payback period Amo = Δk / Δk(red) = 16,280 / 17,640 of just under 12 months. 138/139 D.4.5 Water analysis, general explanations To ensure that the required residual oxygen content in the feedwater (0.02 mg/l) is maintained, chemicals are added to bind the residual oxygen. The exclusive use of chemicals to bind the entire amount of oxygen is uneconomical in most cases. The water-steam system is subject to quality requirements regarding permissible constituents. Depending on the pressure stage of the generated steam, limits must be complied with that are speciﬁed in the water quality technical guide (5811 454). The process described above is tried and tested system technology. However, when monitoring and operating this technology, faults can occur from time to time. For this reason, Viessmann has developed an analytical concept to reduce the potential damage caused by the chemical composition of water as far as possible. Furthermore, this water analysis method enables a more economic operation of steam systems. The feedwater must be treated in order to comply with these standard values. The processes employed for this purpose normally comprise a combination of chemical and thermal water treatment. The hardeners in the untreated water are bound together and extracted in a softening system (see chapter C.5.1 Chemical water treatment). Depending on the requirements made of the system with and/or without unattended operation (BosB), the analysis technology can be extended or reduced and is housed, if necessary, in a separate analysis rack. Furthermore, gases are dissolved in water that are released on heating the water in the steam boiler. These gases would inevitably result in corrosion inside the steam boiler as well as the downstream steam system. The following ﬁgure illustrates the interconnection options. For this reason, top-up water from the softening system is thermally treated, i.e. deaerated, in a deaerating system together with the condensate returned from the consumer system (see chapter C.5.3 Thermal water treatment). Fig. D.4.5–1 Alternative integration of water analysis 5 Steam to the consumer 1. Steam boiler with combustion system 9 2. Thermal water treatment 13 3. Boiler feed pump Top-up water 4. Softening system 5. Chimney 11 2 HK 6. T.D.S. expander 7. Mixing cooler 1 Bypass Feedwater control valve Blow-down valve Raw water 14 3 9. Boiler system control panel PK 12 O2 pH 8. Cooler tank or drainage 16 4 O2 pH 10. Condensate tank 11. Hardness test 12. O2 and pH test 13. Higher ranking control panel with PLC for data transfer 7 6 Cooling water Mixing cooler 8 14. Sample cooler for analysis ÖT LFS 17 15 10 Condensate from the consumer 15. Conductivity test 16. Dosing of corrective chemicals 17. Oil turbidity test D.4 Water treatment Hardness checker (HK) for softened water and condensate This is installed downstream from the softening system and, if necessary, also in the condensate pipe (see chapter D.5.3). The hardness checker continuously monitors the softened water for residual hardness, without consuming any chemicals or water. When an unacceptable level of hardness is discovered, "hard water" is indicated by a visual display and a ﬂoating contact hooked up to the PLC, one signal for the optical or acoustic relaying and/or shutdown of the CWT system. Operating principle The differential pressure transducer installed in the soft water pipe generates a slight pressure differential when there is throughput. As a result, a partial ﬂow is diverted via the hardness sensor built into the bypass and then returned into the main stream. The sensor is charged when hardness is detected. At the same time, the special resin inside the hardness sensor shrinks. A transmitter unit with reed contact triggers the visual "hard water" display. The ﬂoating contact is used to conﬁrm a visual alarm signal and/or to shut down the doublependulum softening system. O2 measurement A signiﬁcant role in monitoring feedwater is played by the continuous measurement of the dissolved oxygen concentration: Oxygen may only be present in low concentrations (< 0.02 mg/l), otherwise there is a risk of oxygen corrosion For this reason, a thermal and a chemical water treatment system are installed on the water side upstream of the boiler system. This process must be maintained continuously during boiler operation Non-continuous laboratory tests to determine the oxygen content run the risk of potentially incorrect sampling Continuous tests provide actual values at all times and can be called up at any time via the PLC memory Where TWT is installed for a multiboiler system, the amount of vapour can optionally be adapted to the prevailing demand depending on the actual amount of feedwater. This results in signiﬁcant potential energy savings (see chapter D.7.3) Operating principle Downstream of the sample cooler, a sensor comprising a cathode (gold) and an anode (silver), an electrolyte and a diaphragm are installed. Oxygen diffusion through the diaphragm is enforced by the partial pressure. A polarisation voltage is applied to the two electrodes. In a certain range, the detectable current is dependent on the concentration of the inﬁltrated oxygen. pH test (pH) The actual pH value is a measure of the acidic or alkaline nature of the feedwater. It enables the CO2 content to be determined. In other words, the lower the pH value, the higher the CO2 content. The pH value should level out between 9 and 10, and should always be > 9 in order to prevent corrosion. However, it should also never be higher than 10 in order to inhibit the formation of sodium hydroxide. Background The alkaline earths, such as calcium and magnesium, that are bonded with the water are exchanged in the chemical water treatment system (CWT) via ion exchangers for active groups of sodium ions to prevent the formation of boiler scale. In so doing, sodium hydrogen carbonate is created. By boiling under pressure, this breaks down into sodium carbonate (soda) and CO2. When even higher pressure is applied, Na-OH (sodium hydroxide) forms along with further CO2 – the so-called soda split. Since CO2 in conjunction with moisture acts just as corrosively as O2, its formation must also be prevented. Operating principle pH testing involves measuring a potential differential (voltage in mV). This comprises a reference voltage applied to a reference electrode, where the medium to be tested is in direct contact with an electrolyte and the test electrode, where an ion-selective membrane (for H+ ions) is located between the test medium and the electrolyte. In order to achieve good test results, a good electrical connection must exist between the test medium and the reference electrolyte. For this reason, a liquid electrolyte is used, whereby a small proportion of the electrolyte always ﬂows into the test medium. Conductivity test (LFM) Conductivity is tested in the condensate tank, but preferably in the condensate feed line. This detects any ingress of foreign matter in the condensate. 140/141 Where this is the case, a downstream 3-way valve drains the monitored condensate to prevent any contamination of the water inside the feedwater tank. Where there is a risk of oil penetrating the system, the conductivity test is extended to include a warning facility (see "Oil turbidity test"). Operating principle The condensate conductivity is tested to detect ionic contamination. This is done using two electrodes that have a constant voltage applied to them via a measuring transducer. There is contamination if the voltage in the electrolyte (condensate) changes beyond a permissible value. Oil turbidity test Apart from the aforementioned condensate contamination, i.e. through an ingress of hardness, salt or alkaline solutions, oils and greases may also typically enter the system. Where there is a risk of an ingress of oil, the condensate must be monitored accordingly. In such cases, the analytical equipment is extended by the oil ingress monitoring module, together with appropriate evaluation and draining equipment for the condensate to be discarded. Operating principle The oil and turbidity alarm is a visual signal. The condensate ﬂow to be measured is illuminated with a light source. A receiver unit is installed opposite the light source. As long as the condensate is not contaminated, the light signal is received unimpeded. The light beam is deﬂected in case of oil, milkiness or other turbidity. The deﬂection ensures that a fault message is issued and the condensate is discarded. The condensate is drained away via a 3-way diverter valve. The contaminated condensate must not be introduced into the public sewage system. It is discharged via so-called "de-oiling systems". Example: limit to be complied with for oils/greases ≤ 3 mg/l For values > 3 mg/l -> prior alarm with acknowledgement For values ≥ 5 mg/l -> combustion "OFF" with lockdown System control All actual values are hooked up to a programmable logic controller (PLC), where they are evaluated and shown on a graphic display. Excesses of the programmed limits are registered in the fault memory of the PLC. Actual values as well as fault and operating messages can be transferred via the integral Proﬁbus interface to higher ranking control systems. Regulation of the chemical dosing pumps based on the actual water quality generally allows excess dosing to be omitted. Optionally, the steam vapour ﬂow and hence the deaerator output can be controlled on the basis of residual oxygen testing in accordance with the actual amount of feedwater required. This results in substantial fuel savings. Analysis cabinet For conducting regular analysis of top-up water, feedwater and boiler water, Viessmann offers a cabinet with all the necessary equipment and chemicals. With this the following analyses can be carried out: Residual and total hardness KS8.2 and KS4.3 (p and m values) Sodium sulphite content (residual oxygen binding agent) Phosphate content (residual harness binding and alkalinisation) Dosing equipment for corrective chemicals To maintain the alkalinity of the feedwater, to bind the residual hardness and to bind the residual oxygen, corrective chemicals are added to the feedwater. A number of products are offered by water treatment companies for this purpose. The water treatment companies should always be consulted regarding the conditions of use. In most cases, two different dosing chemicals are used; ﬁrstly, to remove residual hardness by alkalinisation of the feedwater and secondly for binding residual oxygen. As a consequence, two dosing devices should always be employed. Viessmann offers chemicals for binding oxygen and residual hardness and raising the level of alkalinity in the boiler water. These chemicals are intended for the initial setup and can each be supplied in 25 kg canisters. D.5 Condensate management Condensate management In the following chapter, the condensate systems introduced in chapter C.6 will be examined in greater detail. There follows a comparison between an open vented and a sealed unvented condensate system with an exemplary design, in order to explain, on the basis of a clear example, when it is worthwhile employing sealed unvented condensate systems. 142/143 D.5.1 Function description of open vented condensate systems For alternative return rates (!14 m3/h) and where sealed unvented systems are used (see chapter D.5.2), address any enquiries appropriately formulated to: [email protected] Standard values Expected condensate temperature ≤ 95 °C Available tank capacity Vna)≈ 0.8 ( Con/2 to Con/3) [m3] D.5.1.1 with: Con - maximum possible amount of condensate arising (in t/h) Standard values, design assumptions The condensate station is designed to collect and return the condensate discharged by steam consumers to the feedwater tank in the thermal deaeration system. The condensate tank is connected with the atmosphere via an "open" air vent valve. Condensate is therefore drained from the consumers without any back pressure. The condensate pumps (normally 2 x 100 % pumps) return the accumulating condensate, depending on the tank level, to the deaerator in the thermal treatment system. The tanks are equipped with the necessary connectors for: Condensate inlet Condensate inlet (spare) Condensate outlet as condensate pump connection on the suction-side Ventilation, vapour extraction Overﬂow Drain Inspection port (handhole and/or manhole, depending on tank size) and Filling level display/regulator Pumps and tanks are installed on a common base frame made from steel sections and do not require any separate foundations for positioning. The ﬂoor on site needs only to be level and capable of bearing the relevant load. In order to prevent unnecessary energy losses due to re-evaporation of the returning condensate, open vented condensate systems should really only be employed where condensate temperatures below 100 °C are expected. Note Otherwise, the system described in chapter D.5.2 would be of greater beneﬁt. For system concepts > 14 m3/h to ≤ 75 m3/h, the geometric dimensions to be expected here can be taken in the initial approximation from the Viessmann datasheets. Deviating from the Viessmann tank types, versions are selected in this instance in the form of cylindrical tanks with dished ends. Pump rate of condensate pumps (V̇ CON) with feeding into the deaerator in the feedwater deaeration system (in m³/h) Assumptions Constant feeding into the deaerator as a prerequisite. Consequently: &21 ɘ &21 9 ̖ &21 [ILQ[PK] with condensate density - ̖CON as a function of condensate temperature (see Appendix Tb. 2.2) With supplement factor f, a permissible increase in pump rate, depending on deaerator design (temperature differential over the deaerator), should be considered. Values between f ≈ (1.1 to 1.5) would be conceivable here in practice. Condensate pump head (HCON) with feed into the deaerator in the feedwater deaeration system (in mWC and/or bar) from the sum of individual proportions of +&21 KKKKK[P:&EDU] with the proportions (hi) for: h1 - Deaerator positive pressure as back pressure h2 - Geometric height differential between condensate tank installation position and inlet point on the deaerator h3 - Pipe friction losses h4 - Individual pressure drop caused by ﬁtted pipe components (ﬁttings, valves etc.) h5 - Pressure gain due to positive pressure in the condensate collector (only applicable to sealed unvented systems) a) Assuming a constant condensate return ﬂow rate from the consumer. In the case of non-continuous return (unfortunately, the most common case in practice), provision should be made for an available capacity of Vn ≈ 0.8 (Con to Con/2). A precise statement from the customer regarding consumption characteristics is an absolute necessity. D.5 Condensate management Note D.5.2 An option for determining h3 and h4 is described in greater detail in chapter D.8. Given the following assumptions: h1 ≈ 0.5 bar h2 ≈ 4 mWC ฬ 0.4 bar h3 + h4 ≈ 0.15 x (h1 + h2) ≈ 0.135 bar h5 =0 this results in, with sufﬁcient accuracy, a required head of HCON = 15.35 mWC ≈ 1.5 bar Fig. D.5.1.1–1 TWT - open vented system Fig. D.5.1.1–2 High pressure condensate collector Function description of sealed unvented condensate systems Sealed unvented condensate systems are more extensive in terms of their processrelated construction than open vented systems. The sealed system tanks used here are fed with so-called high pressure condensates at temperatures above 100 °C and widely varying pressure levels. The condensate tank is a pressure vessel in accordance with the Pressure Equipment Directive. The major advantages of sealed unvented condensate systems are: No ingress of oxygen into the system from the air Steam pressure reserves in the tank can be used simultaneously for transport, the suction power of the feed pumps is lower, potential signs of cavitation in the pump can be minimised due to the pressure load Lower heat and water losses (cessation of steam vapour) Reduction to a minimum of the system internal power demand due to use of the low pressure steam from condensate expansion 144/145 The tanks are equipped with the necessary connectors, as described in chapter D.5.1, but without vapour extraction or overﬂow and with the addition of the following: Safety valve Thermal ventilation Low pressure steam outlet in the case of preferred feed into the deaerator and/or feedwater tank Steam connection for pressure stabilisation in the tank As described in chapter D.5.1, the condensate station also serves the purpose of collecting and returning condensate from/to the steam boiler released by steam consumers. Appropriate condensate pumps (2 x 100 % pumps) return the accumulating condensate, depending on the tank level, to the deaerator in the thermal treatment system. Pumps and tanks are installed on a common base frame made from steel sections and do not require any separate foundations for positioning, provided that the load-bearing capacity of the substrate is sufﬁcient. D.5.2.1 Standard values, design assumptions See open vented systems in chapter D.5.1 with additional parameters, such as: Expected condensate temperature ≥ 100 °C Pressure gain due to positive pressure in the collector h5 ≈ 0.2 bar Use of feed pumps with "low" NPSH values (e.g. side-channel pumps) In practice, the high pressure condensate is mixed with the additional feedwater in an intermediate tank and then transported to the steam boiler using high pressure pumps. See also diagrams in Appendix 1 Shortfalls in terms of additional amount of feedwater fw = FS - CON, must be supplied accordingly to the condensate collector via the thermal water treatment system. Fig. D.5.2.1–1 High pressure condensate integration with low freshwater requirement Soft water High pressure condensate e.g. 3-8 bar Feedwater tank e.g. 0.5 bar Steam Vitomax 200-HS (e.g. 13 bar) Sealed condensate container (e.g. 3-8 bar) Optional feedwater cooler Optional feedwater cooler so that the temperature differential across the economiser is not adversely affected Fig. D.5.2.1–2 High pressure condensate integration with similar amounts Soft water High pressure condensate Feedwater tank e.g. 0.5 bar Steam Vitomax 200-HS (e.g. 13 bar) Sealed condensate container (e.g. 3-8 bar) D.5 Condensate management Fig. D.5.2.1–3 Comparison of open vented and sealed unvented condensate systems Condensate system Open vented Sealed unvented Condensate positive pressure bar 0 3 to 8 Condensate temperature °C 95 133 to 158 Expansion steama) % 6.5 to 11.0 0 Heat lossb) kWh/t 49 to 83 0 Water loss kg/t 65 to 110 0 Note Back pressure levels up to 5.0 bar are quite plausible in practice and can increase system efﬁciency signiﬁcantly. For example, the following indicated heat and water losses could be taken into consideration accordingly in a cost-beneﬁt analysis (see Fig. 5.2.1-2). This high pressure condensate is, for logical reasons, introduced via a distributor located upstream of the boiler feed, in accordance with system diagram [A1], taking into consideration a necessary feed pump head and pump rate in compliance with regulations (TRD 401, Clause 3), with: Calculation example Amortisation when a sealed unvented condensate system is employed: Initial data: Pump head ≈ 1.1 x pB (bar) and Pump rate ≈ 1.25 x FS (t/h) with Fresh steam output FS = 12,000 kg/h Fresh steam pressure pB = 13 bar Condensate return feed CON = 6000 kg/h at Condensate pressure pCON = 5 bar and Condensate temperature TCON = 158 °C Raw, softened water temperature T RW = 15 °C Speciﬁc heat/water cP = 0.001163 kWh/KgK Feedwater temperature Tfw = 104 °C deaeration Raw, softened water cost kRW ≈ €3.5/t Natural gas (E) cost kE ≈ €0.414/Nm³ Natural gas (E) lower net caloriﬁc value Hi ≈ 10.35 kWh/Nm³ Full-load hours run b = 6000 h/a a) See Fig. D.5.2.1-3. b) With reference to steam enthalpy 0.75 kWh/kg in atmospheric conditions. pB - operating pressure of the steam boiler(s) and FS - fresh steam output of the steam boiler(s) With an expected doubling of additional costs compared with selecting an open vented system, payback periods of between six months and 2 years can nevertheless be achieved by utilising the speciﬁed "potential savings", depending on annual full-load hours run (see example calculation). 146/147 Potential savings (E) over the open vented system: E1 - Savings in raw, softened water (ΔkRW(E1)) due to omission of re-evaporation in the case of condensate expansion from pCON = 5 bar to ambient atmospheric pressure. path = 0 bara) from: ෙN5:( NJVWHDPNJFRQGHQVDWH[&21[E[N5:D ΔkRW(E1) = 0.11 x 6000 x 6000 x 3.5 x 10-3 t/kg ΔkRW(E1) = €13,860/a E2 - Savings in fuel (ΔkB(E2)) due to omission of heating the additional amount of raw, softened water (RW) from E1 with: RW = (11 kg steam / 100 kg condensate) x CON RW = 0.11 x 6000 RW = 660 kg/h and an efﬁciency ŠK for the steam boiler ≈ 89 %b), the following savings would result: ෙN [F [7 7 5: 3 %( IZ + [ǹ L 5: [E[N [[ ( [ . [[ D E3 - Savings in fuel (ΔkB(E3)) due to already elevated feedwater inlet temperature into the steam boiler resulting from mixing of additional feedwater (tfw = 104 °C) into the sealed unvented condensate tank (tCON = 158 °C) with a feedwater mix temperature (tfw/M) being arrived at in the condensate tank of: 7 [ 7 [ &21 7 &21 IZ0 IZ &21 IZ LQr& assuming fw = FS - CON [kg/h] IZ Note: Desalination rate (A) = set to zero! This results in a mixed temperature of 7 [ 7 [ 7 &21 IZ0 &21 IZ &21 [[ IZ IZ r& and therefore: ෙN [F [7 7 IZ &21 S + [ǹ %( L ෙN %( IZ0 IZ [E[N ( . [[ [[ D [ On observing all aforementioned values, an annual cost saving of E = ΔkRW(E1) + ΔkB(E2) + ΔkB(E3) = 13,860 + 18,422 + 101,612 = €133,894 results. Based on the approximate current cost for a sealed vented condensate system of ≈ €80,000 to €110,000c) and an annual cost saving ≈ €130,000, this results in a payback period A ≈ 0.62 to 0.84 years. a) See [Tb. 8]. b) From Vitomax 200-HS datasheet without ECO operation. c) Major proportion of additional costs over open vented systems (estimated costs) for: - High pressure condensate tank - High pressure condensate pumps - More control equipment required - Higher expenditure on pipework and valves approx. €80,000 to €110,000. D.5 Condensate management Sealed unvented system Open vented system 5340 kg/h EG EG Soft water 6660 kg/h 6660 kg/h; 15 °C 15 °C; raw soft water 0.2 bar (h) 0.2 bar (h) SB 10 m3; 104 °C SB 6 m3; 104 °C TWA - thermal water treatment with: EG deaerator SB feedwater tank Feedwater pumps Feedwater pumps High pressure condensate Low pressure (LP) condensate pumps High pressure (HP) condensate tank LP condensate pumps )'= 12,000 kg/h; 13 bar (ü) DE ND-KG Hm3 3 - 8 bar ǹ. ~ 89 % સ; Hi )'= Feedwater pumps 12,000 kg/h; 13 bar (ü) 12,000 kg/h Condensate pumps 12,000 kg/h approx. €80,000 to €100,000 Diagram open vented / sealed unvented system Expansion steam (E) E=660 kg/h Major proportion of additional costs over open vented systems (estimated costs) for: High pressure condensate tank High pressure condensate pumps More control equipment required Higher expenditure for pipework and valves Fig. D.5.3–1 )'=6000 kg/h: 9 bar (ü); 158 °C Note DE ǹ. ~ 89 % સ; Hi 148/149 Fig. D.5.3–2 Thermal total deaeration system D.6 Pumps Pumps Sizing the feedwater pumps taking account of the control versions described in chapter C.7. On the one hand, the provisions of the relevant regulations must be observed. On the other, the speciﬁc circumstances of the actual system must also be taken into consideration. For this reason, various versions are presented here. 150/151 D.6.1 Feed pumps - criteria for design and operation Fig. D.6.1–1 Suction head or required inlet pressure (source: Grundfos) H (m) The task(s) of the feed pump(s) (also referred to as boiler feedwater pump(s)) consist(s) of feeding the steam boiler(s) with an amount of feedwater corresponding to the amount of steam generated. The pumps normally used for this purpose are centrifugal pumps, taking account of and complying with NPSH valuesa) speciﬁc to the pumps; see following diagram (Fig. D.6.1-1). Minimum positive pressure 14 12 10 8 6 4 2 1.3 NPSH [m] 0 Maximum suction head NPSH at standard atmospheric pressure At a standard atmospheric pressure of 1013 mbar, the necessary inlet head or maximum possible suction head can be determined using the accompanying diagram. Example NPSH pump = 4.0 mWC (manufacturer speciﬁcation) at media temperature = 90 °C A minimum inlet pressure of 1.3 mWC must be available at the pump suction port. This includes a safety margin of 0.5 mWC. The majority of pressure losses arising in the pump suction line should be compensated for with the speciﬁed safety margin of 0.5 mWC. This assumes that the suction line is designed to be as short as possible, i.e. ≤ 10 m in the case of moderate ﬂow velocities ≤ 0.5 m/s in the suction line. In special cases, a precise determination of pressure losses that may arise must be performed for the suction line; see chapter 8.3.3. -2 7 6 -4 5 4 -6 3 2 -8 1 0 -10 80 60 40 20 Media temperature 90 100 120 t (°C) Note The minimum necessary inlet pressure (pMIN) with reference to the pump suction ports and standard atmospheric pressure can also be estimated from the following: S0,1 S6( 136+SXPS[̖IZ >[email protected] with values for: pS/E NPSHpump ̖fw Steam pressure in feedwater tank (in bar) NPSH value at 20 °C media temperature (according to pump supplier) (in mWC) Feedwater density at operating temperature (see Appendix Tb. 2.2) (in kg/m³) As orienting standard values, literature reference L2 speciﬁes: Fig. D.6.1–2 Table Feedwater temperature [°C]: 90 100 110 Required inlet head [mWC]: 2 4 6 a) Net positive suction head (see diagram) - suction head and/or inlet pressure, as a function of the media temperature. D.6 Pumps Note The NPSHavail value is the available pressure differential between the total pressure in the centre of the pump inlet connection and the evaporation pressure pD (also referred to as saturation pressure), measured as a pressure level differential in m. To a certain extent, it is an indication of the evaporation risk at this point and is only determined by data relating to the system and the pumped ﬂuid. According to DIN EN 12953-6 Clause 5.5, sufﬁcient feedwater must be made available at maximum operating pressure (safety pressure). According to TRD 401 Clause 3, the following criteria must also (either/or) be met. (In the following sample calculation, both criteria are used.) Feed pump head ≈ 1.1 x pBa) [bar] With the selected supplement of 10 % in addition to the head, the arising pressure losses for connecting pipes, built-in pipe components and economisers, if applicable, can near enough be compensated for and therefore disregarded in practice. This is conditional, however, on maintenance of ﬂow velocities in the connecting pipes and built-in components of ≤ 2.5 m/s throughout. In special cases, a precise determination of arising pressure losses must be carried out for the pressure line; the calculated losses are then added to the required head; see also chapter D.8.3. In the case of expected losses of A > 5 %, with reference to the steam boiler output, a supplement of 25 % + ΔA % would have to be considered. On determination of the pump head and pump rate, the necessary pumps and/or associated pump motor rating (N) can be calculated from: 1.ป [)6[[S% [[Š3 >N:@ the pump shaft output (NK) and a commonly used output supplement as an compensation for any ﬂuctuations in the pump operating point, which can lead to an increased pump rate requirement (NK) in certain circumstances, with a supplement (ZEL) in accordance with (L7) according to the following Fig. D.6.1-2. Permissible steam boiler operating pressure ฬ safety pressure ฬ safety valve discharge pressure. Required pump rate and supplement NK (kW) up to 7.5 7.5 to 40 from 40 ZEL (%) 20 15 10 The pump motor rating from: 1ป Pump rate ≈ 1.25 x FS in t/h With the selected supplement of 25 % in addition to the pump rate, the pressure losses on the water side (blow-down and desalination losses at A ≤ 5 %) are completely compensated for. a) Fig. D.6.1–2 1.[ =(/ >N:[email protected] Note on the determination of (NK): The following equation applies in general for the determination: ̖[J[+[9ɘ 1 . >:@ ŠS with ̖ – Density of the delivery medium in kg/m³ g – Gravitational acceleration in m/s² H – Pump head in mWC V̇ – Pump delivery amount in m³/s and – Pump efﬁciency of > 0 to < 1 ŠP Taking account of conversion factors from Watt to kW, mWC to bar and m³/h to m³/s or kg/h to kg/s from the relationship 9 ɘ )6 ̖ the necessary "dimensionless" factor in the denominator of the equation is calculated to be 0.36 x 105. In the further course of derivation, gravitational acceleration and density are divided, yielding the equation for determining the pump coupling rating (NK), as speciﬁed, with the previously described multiplication factors for the required pump rate (of 1.25) and head (of 1.1). 152/153 Pump selection example Notes Amount of fresh steam - FS = 12,000 kg/h 1. Note With inlet heads found in practice here of between 2.0 and 4.0 mWC, pumps are only recommended, in principle, at NPSH-pump ≤ 4.0 mWC. During the process of pump selection, consideration need only be given, in principle, to an associated ﬂat curve for the NPSH value, as a function of the pump rate (see Fig. D.6.1-3), for the necessary operating range (between minimum and maximum pump rate). Permissible steam boiler operating pressure - pzul = 16 bar (safety valve discharge pressure), Operating temperature in feedwater tank - T B/E = 105 °C Steam pressure in feedwater tank - p D/E = Ł T B/E from (Appendix Tb. 2) = 0.21 bar Feedwater density - ̖ FW = Ł T B/E from (Appendix Tb. 2.2) = 954.5 kg/m³ Design case 100 % Required pump volumetric ﬂow rate (V̇ P) with reference to operating temperature 1.25 x 12,000 1.25 x FS V̇ V˙ P = = = 15.72 m³/h 2. Note The pump efﬁciencies should achieve their optimum values as far as possible in the range of the curve for lower NPSH values. An electric limiter on the pump motor for higher than permissible pump rates is also recommended here. 954.5 ̖ FW Required head (delivery pressure p D) = 1.1 x 16 = 17.6 bar Required pump or drive output (N) at an assumed average pump Fig. D.6.1–3 Pump curves (schematic diagram) Operating range efﬁciency (pump manufacturer speciﬁcation) of Š p ≈ 75 % to be selected 1 . [ [ N: and with ZEL~15 % Delivery head (H) Hmax [[[ (H (1.1 x pB) (H) - )- (V̇ ) - line at n * (V̇ )- lin ea min t n* ma x Pump efﬁciency ŠP N = 9.77 x ( 15 1+ 100 H ) ≥ 11.24 kW NPSH - pump With a required assurance of NPSH values for the pump in the ** V̇ MIN range between NPSHPUMP ≥ 0 and ≤ 7 mWC, this would result in a required minimum inlet pressure (PMIN) for the respective borderline of between Pump rate (V̇ ) *Assumptions: pump speed regulation between n*MAX./ n*MIN. pMIN(NPSH=0) = 0.21 + 0.5 x 954.5 10 ≈ 0.258 bar **Difﬁcult to measure in practice, but NPSH does not remain constantly min! and for pMIN(NPSH=7) = 0.21 + 9 ɘ MAX with limitation (7 + 0.5) x 954.5 10 ≈ 0.926 bar with a resulting geodetic inlet head (H geo) that can be generated of: Hgeo(NPSH=0) ~ (pMIN(NPSH=0) - p D/E) x 10.2 mWC/ bar Hgeo(NPSH=0) ~ (0.258 - 0.21) x 10.2 ≈ 0.49 mWC Hgeo(NPSH=7) ~ (0.926 - 0.21) x 10.2 ≈ 7.30 mWC with limitation 1.25 x FS ˮ D.6 Pumps Regular operation - technical boundary conditions for practical operation, curve characteristics, load cases, etc. Supplementary to the speciﬁcations in chapter C.7.1, the following provides further detailed notes and recommended versions for "practitioners". A summary of the most common versions for operation as single boiler systems is provided for this purpose, with features, depending on the control range, of the Steam boiler (load proﬁle) Combustion system (burner) Pump (curve characteristic, minimum pump volume) for versions 2, 3 and 4 1. Intermittent level control for boiler systems without ECO up to max. 3 t/h boiler steam output This can be regarded as the simplest solution for steam boilers without an economiser and an output of up to 3 t/h. This version is not recommended for steam output above 3 t/h or when using an economiser. Reason On controlled shutdown of the boiler feedwater pump (pump OFF, boiler water demand lower than pump rate, minimum burner load lower than the minimum pump ﬂow), the economiser does not receive any ﬂow on the water side. Therefore, there would be no increase in efﬁciency due to the ECO and/or superheating. Control function The water level is regulated between two adjustable ﬁxed switching points, i.e. "pump ON" and "pump OFF". The level electrode signal has a corresponding effect on the pump. Furthermore, steam hammer may occur in the economiser. 2. Continuous level control by means of a feedwater control valve for all sizes of steam boiler with/without economiser Can be regarded as a simple solution for steam boilers with or without an economiser. Here, the feedwater control valve is regulated as a function of the boiler level. The feedwater pump shuts down if the ﬂow rate falls below a minimum level speciﬁed by the pump manufacturer. This version is not recommended if the combustion output can be regulated to less than the minimum amount of feedwater, and an economiser is used. In this case, the economiser would likewise receive no ﬂow on the water side. Control function The aim of the controller is to maintain the level in the boiler at a ﬁxed set value. The actual value is continuously monitored by a level probe and compared with the set value in a controller. Opening and closing the feedwater control valve regulates the level to the required set value in the case of load ﬂuctuations. When the minimum pump rate is reached, the pump shuts down and the feedwater control valve closes (signal via limit switch in the feedwater control valve and/or pump load proﬁle with minimum/maximum limitation). This version is not recommended if the burner control range is greater than the feedwater pump control range. 3. Continuous level control by means of a feedwater control valve/bypass valve for all sizes of steam boiler with an economiser Here, the feedwater valve is regulated as a function of the boiler level. If the ﬂow rate to the boiler falls below the minimum level, the bypass valve is opened by increasing pressure and lets the minimum volume required for pump protection return to the feedwater tank. Control function The aim of the controller is to maintain the level in the boiler at a ﬁxed set value. The actual value is continuously monitored by a level probe and compared with the set value in a controller. Opening and closing the feedwater control valve regulates the level to the required set value in the case of load ﬂuctuations. 154/155 A partial volume is returned to the feedwater tank via an adjustable minimum ﬂow line. This valve can be designed as a coneshaped butterﬂy valve or a control valve. This so-called bypass line is designed to protect the pump from falling below a speciﬁed minimum pump rate. It ensures that the economiser receives ﬂow when the burner control range > pump control range. A PLC controller is a basic requirement for switching purposes. The ﬂow rate is adjusted via the speed of the pump motor. This means the feedwater volume can be regulated down to a partial load that corresponds to the minimum ﬂow rate required for the pump. The minimum ﬂow rate depends on the type of pump. Please note! The version shown here is one control option. However, the preferred version is that depicted under point 4 with feedwater control valve with spillback. Bypass valves must be sized hydraulically for each individual application. Control function The aim of the controller is to maintain the level in the boiler at a ﬁxed set value. The actual value is continuously monitored by a level probe (4-20 mA signal, e.g. NRGT 26-1 Gestra) and compared with the set value in a controller. 4. Continuous level control by means of a feedwater control valve with spillback for all sizes of steam boiler with an economiser A change in the level results in variable speed adjustment of the pump rate (in this case by a mounted inverter, FU) to match the changing demand, until the set level has been achieved. This can be regarded as the preferred option for steam boilers with or without economisers. Here, the feedwater control valve with spillback is regulated as a function of the boiler level. If the ﬂow rate falls below the minimum level, the spillback valve opens and lets the minimum volume required for pump protection return to the feedwater tank. An additional butterﬂy valve is not necessary in the bypass line. The reduction in speed is limited by two parameters: 1. Flow rate 2. Required pressure The back pressure of the system (system curve) must be overcome. For this reason, only limited use can be made of the possible speed range of the pump. Control function The feedwater control valve continuously regulates the volume of feedwater depending on the level. As soon as the main ﬂow falls below a certain feedwater ﬂow rate (e.g. 30 %), the spillback connection (bypass) opens wide enough to ensure that the required minimum pump rate (e.g. 30 %) can always be drawn off. 5. Continuous level control by means of pump speed regulation for all sizes of steam boiler with/without economiser Inverter-controlled boiler feedwater pumps can be employed in the case of steam boilers with or without economisers. Note Use of an inverter pump is not recommended if the burner control range is greater than that of the pump, i.e. the pump control range is < 1:4. Power can be saved by means of this demanddependent speed optimisation. It also saves on installation of control valves upstream of the boiler. 6. Continuous level control by means of pump speed regulation and bypass for all sizes of steam boiler with/without economiser The determinations described under point 5 apply. Furthermore, depending on the project in question, it can be necessary to use a bypass line as an overﬂow line. This is the case if, due to the system, the control range of the pump needs to be choked so far that the partial load of the burner is lower than the partial load of the pump. Note Taking account of the pump curve and the load reduction, a bypass cannot always be omitted. One third of the nominal ﬂow rate can be assumed as a standard value for the minimum ﬂow rate of the pump. However, a bypass does not always represent a loss of energy. Depending on the load proﬁle (how long the pump runs in bypass mode), speed regulation may be more practical. D.6 Pumps Fig. D.6.1–4 Grundfos pump (example 1) Operating range Whether and to what extent an invertercontrolled pump is worthwhile is shown in Fig. D.6.1-4. Curve ﬁeld Pump data: Rated speed: Nominal pump rate: Minimum pump rate: Rated head: Maximum head: Pump Curve ﬁeld System Assumptions: Boiler output: Permissible operating pressure: Ø positive operating pressure: Motor rating in operating range: Curve ﬁelds Power consumption Motor Fig. D.6.1–5 360 - 2789 rpm 3 m³/h 0.9 m³/h 66.6 m 97 m 2.3 t/h 6 bar 4.5 bar 0.5 to 0.95 kW Pump diagram for a pump without inverter control Operating range The ﬁgure opposite (Fig. D.6.1-5) is the pump diagram for a pump without inverter control. At this load, the conventional pump has a power consumption of 1.14 kW. Assuming that the boiler runs for a total of 8000 h/a and half the time at a load of 70 %, the following power savings are possible: Power requirement 100 % load (with inverter): 0.95 kW Inverter internal power requirement: 0.05 kW (approx. 5 %) Conventional power requirement at 100 %: 1.14 kW Difference over 4000 h: 560 kW Power requirement 70 % load (with inverter): 0.78 kW Inverter internal power requirement: 0.02 kW (approx. 5 %) Conventional power requirement at 70 %: 0.95 kW Difference over 4000 h: 600 kW At an electricity price of €0.06/kWh, this yields a saving of €70 p.a. At this output, the investment outlay of versions 4 and 5 is almost identical. Further beneﬁts of pumps with inverter control: Longer service life due to lower load. 156/157 Pump data: Rated speed: Nominal pump rate: Minimum pump rate: Rated head: Maximum head: Assumptions: Boiler output: Permissible operating pressure: Ø positive operating pressure: Control range: Fig. D.6.1–6 2947 rpm 30 m³/h 9 m³/h 180 m 230 m 20 t/h Grundfos pump (example 2) Curve ﬁeld Pump Curve ﬁeld System 16 bar 13.5 bar Between 7.5 and 14 kW electrical motor power The ﬁgure opposite (Fig. D.6.1-7) is the pump diagram for a pump without inverter control. At this load, the conventional pump has a power consumption of 16.7 kW. Assuming that the boiler runs for a total of 8000 h/a and half the time at a load of 70 %, the following power savings are possible: Power requirement 100 % load (with inverter): 14 kW Inverter internal power requirement: 0.7 kW (approx. 5 %) Conventional power requirement at 100 %: 18 kW Difference over 4000 h: 13,200 kW Power requirement 70 % load (with inverter): 11.5 kW Inverter internal power requirement: 0.6 kW (approx. 5 %) Conventional power requirement at 70 %: 16 kW Difference over 4000 h: 15,600 kW Fig. D.6.1–7 Pump diagram for a pump without inverter control H (m) 200 160 120 80 40 0 0 5 10 15 20 25 30 35 Q (m3/h) P2 (kW) 20 16 12 8 4 At an electricity price of €0.06/kWh, this yields a saving of €1728 p.a. The additional investment outlay compared with version 4 are approx. €3000 with a payback period of ≈ 1.74 years. D.6 Pumps Note Continuous control by means of an inverter on the pump is recommended if there are frequent or severe ﬂuctuations in the steam demand and/or only partial load up to a deﬁned pump ﬂow rate is required over a prolonged period. The inverter adjusts the pump speed (and thus the pump rate) to the steam demand. Consideration must be given to the fact that some pumps equipped with inverters have a higher connected load and the motor transitions are not as ﬁnely tuned, hence putting the savings into perspective. Basic contexts: Ratio of throughput to speed Q 4 4[ Q Ratio of pressure to speed + +[ Q Q curves of every pump. The potential savings are, among other factors, also subject to the structural design of the pump. Q Index 1 = known point Index 2 = required new point at new speed n2 Fig. D.6.1–8 120 100 80 As soon as the pump rate falls below a deﬁned "minimum ﬂow rate", a so-called valve bypass opens and hence always guarantees the required minimum ﬂow rate of the pump. Pressure ˜ n2 Size As an alternative to the described versions 4, 5 and 6 for "bypass operation", the use of socalled automatic recirculation non-return valves should also be mentioned. Automatic recirculation non-return valves are self-acting safety valves that protect centrifugal pumps from damage that can arise during pump operation in low-load situations due to partial evaporation and accompanying cavitation. Constant control by inverter Output ˜ n3 60 40 Throughput ˜ n 20 0 If, however, the system load only changes infrequently or within a small range, it can also be practical, from the point of view of investment and electricity costs (see version 4), to use a continuous control valve. The continuous control valve acts as a throttle. At constant pump speed, the choking generates a higher back pressure so the pump can only deliver a lower ﬂow rate. The output requirement for the pump motor also drops, albeit in a much lower proportion. This correlation can be seen in the head/ ﬂow rate and power consumption/ﬂow rate Q Ratio of motor rating to speed 3 3[ over a particular period and the local costs of electricity. 0 20 40 60 80 100 120 Speed This means that, for example, at a change in speed n from 100 % to 50 % (which also corresponds to a change in ﬂow rate V from 100 % to 50 %), the motor power consumption P drops to 1/8. This value is theoretical because the inverter itself is also a consumer of electrical power. The demand of the inverter can be taken as approximately 5 % of the total output. The payback period depends on the actual system load curve The automatic recirculation non-return valve is installed in the feedwater pressure line as directly as possible on the pressure port of the pump to be protected. A clearance should be selected between the pump pressure port and the valve inlet of no more than 1.5 m for the purpose of minimising ﬂow pulsations. In order to safeguard the valve, an additional so-called "manual start auxiliary outlet" (option) can be opened in the event of prolonged minimum discharge rates. The auxiliary outlet is not, however, likely to be regarded as essential in practice (in the case of hydraulically coordinated designs combined with load characteristics of the pumps to be employed). 158/159 Straight-through internal diameter and nominal pressure of the automatic recirculation nonreturn valves must be selected appropriately for the pump pressure ports and are commercially available for pressure levels from PN10 to PN40. Valve main throughput and minimum ﬂow rates are speciﬁed as a function of the straight-through internal diameter (see Fig. D.6.1-9). Fig. D.6.1–9 Valve main throughput and minimum ﬂow rates Straight-through internal diameter (mm) 25 32 40 50 65 80 100 125 150 Main ﬂow ratea) (m³/h) 17 28 45 68 114 178 270 400 530 Minimum ﬂow rateb) - standard - (m³/h) 6 10 18 18 40 40 65 65 116 Spillback internal diameterb) (mm) 25 25 25 25 40 40 50 50 65 One advantage of these automatic recirculation non-return valves is valve operation without auxiliary power, while guaranteeing "low-wear" operation for the bypass in the case of required system operation always being greater than the "zero pump rate" of the selected feed pump. Notes regarding multi-boiler operation For system operation with several steam boilers, a wide selection of hydraulic control options can be combined, with reference to the actual operating case in question. For example: Similar to the above, but with provision of a separate inverter-controlled feedwater pump for each steam boiler, with reference to versions 5/6 Three feed pumps (one of which a back-up pump) for two steam boilers with ﬁxed allocation of pump to boiler, each with a separate feedwater control valve as an output for each steam boiler and common bypass operation analogous to versions 3/4 from the distributor back to the feedwater tank. This version can generate cost savings due to omission of pumps, but it also reduces the system availability Twin-pump units for each boiler, identical to single boiler systems a) With reference to a maximum permissible ﬂow velocity in the pressure line, appropriately modiﬁed ﬂow rates can also be applied here. b) Depending on demand according to pump selection. D.6 Pumps Reference to: Datasheets - accessories for high pressure steam boilers Variable speed pump drives similar in design to versions 5/6 in chapter D.6.1 are only conceivable, however, for sealed unvented systems. Viessmann offers a matching feedwater pump (Grundfos / KSB / Lowara / Speck / Wilo) with or without speed control for all of its steam boilers. Variable speed pumps are not recommended on account of the expected low motor rating of condensate pumps in open vented systems. Please address your enquiries to: [email protected] Sample calculation D.6.2 Condensate pumps - criteria for sizing and operation 1.ป Reference is made here to the versions described previously in chapters D.5.1 and D.5.2 (open vented/sealed unvented condensate systems - standard values), but with additional information on the need for any applicable modulation of feed ﬂow rates into the feedwater tank and/or the steam boiler directly by means of regulated bypass operation using motorised control valves (see Fig. D.6.2-1). Condensate pumps with CON ≥ 1.25 FS standard for open vented and sealed unvented systems pS"open" = 1.0 barabs < pG/fwTank ≈ 1.5 barabs pS"sealed" = 3.0 to 6.0 barabs < pG/SteamBoiler ≈ 7.0 to 26.0 barabs [)6[[S% [[Š3 >N:@ 160/161 Fig. D.6.2–1 Bypass operation Directly to the feedwater tank and/or steam boiler with backpressure – PG Open vented and sealed unvented condensate tank at system pressure – pS Bypass Condensate pumps D.7 Thermal equipment Sizing the thermal equipment With reference to the previous statements in sections C.5.4 Sampling cooler, C.8.1 Mixing cooler, C.8.2 T.D.S. expander, C.8.3 Exhaust vapour condenser and C.8.4 Feedwater cooler the individual pieces of thermal equipment are discussed in the following in terms of their function and their "approximate" sizing. System assignment can be taken here to a limited extent from Viessmann standard components with reference to the speciﬁc data for steam boiler output > 14 t/h to ≤ 75 t/h (see tables in Fig. D.7.1.1-2, Fig. D.7.2.1-2, Fig. D.7.2.1-3 and Fig. D.7.2.1-4). In case of deviation from the selected standard values and initial values, enquiries should be addressed to: [email protected] 162/163 D.7.1 D.7.1.1 Mixing cooler Function description, standard values, sizing assumptions The mixing cooler does not require any special foundations for its installation; the ﬂoor on site needs only be level and capable of bearing the relevant load. The tank is equipped with the necessary connectors for: Blowing down the steam boiler Desalinating the steam boiler Thermostatic control of the cooling water inlet regulator Mixed water drain outlet Ventilation (vapour extraction) Draining (clearing residues) Inspection port Standard values T.D.S. rate T.D.S. mass ﬂow rate Blow-down capacity Blow-down time Blow-down mass ﬂow rate Cooling water temperature Waste water temperature Waste water mass ﬂow rate Boiler water blow-down temperature A = 5 % A = FS x A/100 (kg/h) a = 7.5 kg/s Ta = 4 s/8h a = a x Ta = 7.5 kg/s x 4 s/8h = 3.75 kg/h TCW = 15 °C TWW = 30 °C WW = A + a + CW (kg/h) Ta (°C), Ta ≈ Ts Ł(pB) with Ts the saturated steam temperature as a function of the operating pressure (pB) from [Tb.2]. Boiler water blow-down temperature (cooler inlet) T.D.S. water temperature Ta/C ≈ (pE/C = 0 bar) ≈ 100 °C TA (°C); TA = Ł(pE/D) as a function of the deaerator steam pressure pE/D from [Appendix Tb.2]. Assumptions: TA = 105 °C for pE/D ≈ 0.21 bar The mixing cooler is designed to accept all pressurised and hot waste water that occurs in the boiler system. This water is depressurised to atmospheric pressure in the mixing cooler. The mixing cooler is vented to atmosphere. By adding cooling water from the untreated water or softened water network via an inbuilt lance, the expanded waste water is cooled to a drain temperature of 30 to 35 °C. For this purpose, the mixing cooler is equipped with an electrical cooling water controller. Depending on the hardness of the raw water, blending of the raw water with softened water is recommended to minimise scale formation in the mixing cooler. However, the blow-down volume entering the mixing cooler (a/C) is reduced by the waste steam volume (expansion amount of steam a/DE): D& DD'( DQGZLWK D'( Ł'( [D WKHLQFRPLQJEORZGRZQYROXPHLVGHULYHGIURP D& D[ Ł'( with ŁDE, the percentage proportion of re-evaporation from [Appendix Tb. 8] as a function of the difference between the operating pressure (pB) and the atmospheric expansion operating pressure (pE/C = 0). Fig. D.7.1.1–1 Mixing cooler Note During each shift (8 h), a spontaneous blow-down amount occurs brieﬂy (4 s) of approx. 7.5 kg/s x 4 s = 30 kg. Assuming an operating pressure of PB = 13 bar, the amount is reduced to: Venting via the roof Cooling water connection Desalination/ blow-down inlet Cleaning aperture Discharge (waste water) < 35 °C Drain PD& [ ปNJ Cooling of this intermittently occurring amount takes place using the constantly adequately calculated "cold" 30 °C water seal (mW/V) in the mixing cooler according to the following rough calculation: P:9ุ PD&[7D&7:: 7::7&: ุ [ ุ OLWUHV D.7 Thermal equipment Conclusion As a consequence, in order to determine the necessary hourly amount of cold water and the incoming total waste water volume, only the balance amounts resulting from the continuous processes need to be determined. Intermittent blow-down, 2 x per shift (8 h operation), each with 2 s blow-down time, is recommended to minimise the cooling water requirement and necessary tank volume for ensuring an adequate water seal. Sample determination of tank volumes for mixing coolers Determination of tank volumes as an indicative approximation, with assumptions for: Fresh steam output FS = 12,000 kg/h Fresh steam pressure pB = 13 bar Saturated steam temperature Ts = 195 °C [7 7 [7 7 $ $ &: :: :: Observe the information speciﬁed in chapter D.8.5 concerning essential straight-through nominal diameters (DN) for ventilation (vapour line, waste water, cooling water). D D& :: [kg/h] 7 7 &: [[ &: [kg/h] CW = 3017.50 kg/h and the total amount of waste water Standard values Required amount of cooling water CW (kg/h), as a balance variable (heat and volume balance) for the mixing cooler, neglecting the amount of expansion steam a/DE &: K ::K &: (with cpi = constant boiler lye and cooling water) becomes: $[7$7::D7D&7:: 7::7&: and the additional input data: &: )6[[[ and the total amount of waste water WW (kg/h) from: :: $D&: )6[&: A = 3621.25 kg/h derived from standard systems, according to the following tabular overview, a tank volume of ≈ 600 litres results. $[K $K ::DK D&K :: and the general relationship for calculating the media enthalpy for hi = cpi x ti &: A = 3017.50 + 12,000 x 0.05 +3.75 [kg/h] >[email protected] 164/165 Fig. D.7.1.1–2 Container volumes - standard systems System 1 2 3 4 5 6 type FS ≤ 4.0 > 4 to ≤ 7 > 7 to ≤ 14 > 14 to ≤ 20 > 20 to ≤ 40 > 40 to ≤ 75 WK 6.0 8.0 10.0 13.0 16.0 18.0 20.0 22.0 25.0 FS pB 125/ 125/ 125/ 125/ 325/ 600/ 400 x1450 400 x1450 400 x1450 400 x1450 600x1580 800x1690 325/ 325/ 325/ 600/ 1000/ 1500/ 600x1580 600x1580 600x1580 800x1690 1000x1810 1200x2100 325/ 325/ 325/ 600/ 1000/ 1500/ 600x1580 600x1580 600x1580 800x1690 1000x1810 1200x2100 600/ 600/ 600/ 600/ 2000/ 1500/ 800x1690 800x1690 800x1690 800x1690 1500x2100 1200x2100 600/ 600/ 600/ 600/ 2000/ 1500/ 800x1690 800x1690 800x1690 800x1690 1500x2100 1200x2100 600/ 800/ 800/ 1000/ 2000/ 2000/ 800x1690 900x1750 900x1750 1000x1810 1500x2100 1500x2100 600/ 800/ 800/ 1000/ 2000/ 2000/ 800x1690 900x1750 900x1750 1000x1810 1500x2100 1500x2100 1000/ 1000/ 1000/ 1400/ 2400/ 2600/ 1000x1810 1000x1810 1000x1810 1150x1870 1500x2200 1600x2100 1000/ 1000/ 1400/ 1400/ 2400/ 2600/ 1000x1810 1000x1810 1400x1870 1150x1870 1500x2200 1600x2100 – Fresh steam output – Fresh steam pressure Numeric speciﬁcations, e.g. xxx/yyy x zzz xxx = Capacity (litres) yyy = Container diameter (mm) zzz = Total height (mm) D.7 Thermal equipment Note For multi-boiler operation, provision must be made for the corresponding selections similar to single boiler operation, but with parallel feed into the mixing cooler. D.7.1.2 Lye cooler - function description, standard values, design assumptions Lye, in this instance, refers to the T.D.S. amount. Or: Lye = T.D.S. amount Example: System type 3 Feeding of (n+1) steam boilers with a total output ≤ 14 t/h, etc.; The following rule of thumb applies: (n+1) always ≤ FS For system concepts with boiler output FS > 20 t/h, consideration would have to be given, in principle, to the use of an indirect lye cooling system (for the purpose of heat recovery) upstream of the mixing cooler inlet. This would be conditional, however, on a consistently (continuously) available amount of top-up feedwater (softened water quantity) as a so-called heat sink. The cooling water demand (cooling water costs) could be minimised A cost-beneﬁt analysis would deliver appropriate veriﬁcation in this instance. Balance sheet approach The required lye cooling capacity Q̇L/C (see also Fig. D.7.1.1-3) 4 ɘ /& $[FS[7$(7$$ ::[FS[7::$7::(LQN: 4 ɘ /& )6[[FS[7$(7$$ [[[ 4 ɘ /& N: and cooling water savings (Δ CW) from: ෙ&: $[7$(7$$ 7::7&: [[ NJK plus an expected payback period (Amo) of: $PR &RROHUFRVWVN/& &RROLQJZDWHUFRVWVෙN&: LQ\HDUV with: Cooler costs kL/C ≈ €3500 (plate heat exchanger including pipework and valves) Cooling water costs ΔkCW = €3.50/t and 3000 kg/h ฬ 3t (ΔcW ) plus annual hours run b = 1760 h (8 h/day x 220 days/year) $PR [D K[WK[W Dฬ\HDUV Note In terms of procedure, however, continuous throughput of softened water through the cooler and/or an alternative available "heat sink" on the customer side (e.g. domestic heating water) must be assured here. 166/167 Fig. D.7.1.1–3 Schematic diagram of lye cooler a) Soft water outlet Lye cooler 7::$ Lye outlet 7$$ปr& $ 7$(ปr& Lye inlet ::ปNJK 7::(ปr& Soft water inlet Lye cooler System System lye cooler mixing cooler cp - speciﬁc heat for lye and softened water ~ 0.001163 kWh/kgK a) An additional check must be made in the actual application case as to whether any temperature limiting measures (temperature control with limiter as a watchdog function) are required for the softened water leaving the cooler. D.7 Thermal equipment Fig. D.7.2.1–1 T.D.S. expander D.7.2 T.D.S. expander Expansion steam outlet (if applicable, feed into thermal deaerator) T.D.S. lye T.D.S. lye outlet (mixing cooler feed) The amount of heat . (Qiye) "withdrawn" as part of the boiler desalination is recovered by feeding the expansion steam into the thermal feedwater deaeration system. With the heat balance assumption: . . Qlye = Qexpansion steam Function description, standard values, sizing assumptions The T.D.S. expander is designed to accept the boiler desalination ﬂuid and to depressurise it to a level of 0.5 bar. The expansion steam is utilised as heating steam in the deaeration system. The residual lye is fed into the mixing cooler. Inlet Note D.7.2.1 No separate foundations are required for installing the expander. The ﬂoor on site needs only to be level and capable of bearing the relevant load. The expander (tank) is equipped with the necessary connectors for: T.D.S. inlet, originating from the steam boiler T.D.S. outlet, to the mixing cooler connection Expanded steam outlet, to the thermal deaeration connection Connection for safety valve (optional), only when feeding expanded steam into unprotected systems Draining (removing residues) T.D.S. expander - standard values: T.D.S. rate A = 5 % T.D.S. mass ﬂow rate A = FS x A/100 [kg/h] T.D.S. water temperature TA (°C) where TA = Ł(pE/D) is a function of the expansion steam positive pressure from (Tb. 2), TA = 105 °C in this case for pE/D ≈ 0.21 bar Expansion steam output - D/E [kg/h], as a balance variable (heat and volume balance) for the lye expander from the enthalpy values (as a function of temperature and pressure according to Tb. 2) for: T.D.S. inlet h'A/E = Ł(Ts - saturated steam temperature) [kWh/kg] T.D.S. outlet h'A/A = Ł(pE/D) Feedwater enthalpy h' fw [kWh/kg] Expansion steam h''D/E = Ł(pE/D) [kWh/kg] a) '( $[K $(K $$ K '(K $$ NJK 168/169 and b) )6[$[K $(K $$ '( K '(K $$ and the amount of lye L/A from the expander /$ )6[$'( >[email protected] Sample calculation Fresh steam output FS = 12,000 kg/h Fresh steam pressure pB = 13 bar Saturated steam temperature from [Tb. 2] Ts = 195 °C Deaerator steam positive pressure as expansion steam pressure pE/D ≈ 0.21 bar Enthalpy values as f = pB, pE/D from [Tb. 2] h'A/E = Ł(pB) = 0.230 kWh/kg ฬ830 kJ/kg h'A/A = Ł(pE/D) = 0.122 kWh/kg ฬ439 kJ/kg h''D/E = Ł(pE/D) = 0.745 kWh/kg ฬ 2683 kJ/kg '( )6[$[K $(K $$ NJK[[N:KNJ K '(K $$ N:KNJ ปNJK and /$ )6[$'( NJK[NJK /$ ปNJK a) = An estimation is also possible here from the enclosed diagram Tb.6 with approx. 17.5 % of A. D.7 Thermal equipment For output ranges ≤ 14 t/h, a similar selection is possible from the Viessmann datasheets Container volumes As an indicative approximation (derived from conventional Viessmann systems) according to tabular overview for steam boiler outputs > 14 t/h to ≤ 75 t/h Fig. D.7.2.1–2 FS - steam boiler output > 14,000 kg/h to ื 20,000 kg/h Note For multi-boiler operation, provision should be made for the corresponding selections similar to single boiler operation, but with parallel feed into the expander, as stated previously for the mixing cooler. pB- Lye Steam Steam operating Aa) DNlye DNsteam L xW H ØD Capacitya) pressure D/Ea) Connections Dimensions kg/h kg/h inlet/outlet outlet mm mm mm litres 6.0 1000 116 20/25 65 950 x 750 1700 500 100 8.0 1000 135 20/25 65 1050 x 850 1800 600 320 10.0 1000 153 20/25 80 1050 x 850 1800 600 320 13.0 1000 173 20/25 80 1050 x 850 1800 600 320 16.0 1000 193 20/25 80 1050 x 850 2400 600 450 18.0 1000 204 20/25 80 1050 x 850 2400 600 450 20.0 1000 214 20/25 100 1050 x 850 2400 600 450 22.0 1000 223 20/25 100 1050 x 850 2400 600 450 25.0 1000 238 20/25 100 1050 x 850 2400 600 450 Fig. D.7.2.1–3 FS - steam boiler output > 20,000 kg/h to ื 40,000 kg/h pB- Lye Steam Steam operating Ab) DNlye DNsteam L xW H ØD Capacityb) pressure D/Eb) Connections Dimensions kg/h kg/h Inlet/Outlet Outlet mm mm mm litres 6.0 2000 231 20/32 100 1050 x 850 2400 600 450 8.0 2000 270 20/32 100 1050 x 850 2400 600 450 10.0 2000 306 20/32 100 1050 x 850 2400 600 450 13.0 2000 347 20/32 100 1050 x 850 2400 600 450 16.0 2000 386 20/32 125 1250 x 900 2600 750 800 18.0 2000 408 20/32 125 1250 x 900 2600 750 800 20.0 2000 427 20/32 125 1250 x 900 2600 750 800 22.0 2000 446 20/32 125 1250 x 900 2600 750 800 25.0 2000 475 20/32 125 1250 x 900 2600 750 800 Fig. D.7.2.1–4 FS - steam boiler output > 40,000 kg/h to ื 75,000 kg/h a) With reference to FS(max) = 20,000 kg/h b) With reference to FS(max) = 40,000 kg/h c) With reference to FS(max) = 75,000 kg/h pB- Lye Steam Steam operating Ac) DNlye DNsteam L xW H ØD Capacityc) pressure D/Ec) Connections Dimensions kg/h kg/h Inlet/Outlet Outlet mm mm mm litres 6.0 3750 433 32/50 125 1250 x 900 2600 750 800 8.0 3750 506 32/50 150 1250 x 900 2600 750 800 10.0 3750 572 32/50 150 1250 x 900 2600 750 800 13.0 3750 650 32/50 150 1250 x 900 2600 750 800 16.0 3750 723 32/50 150 1500 x 1250 2400 1000 1200 18.0 3750 766 32/50 200 1500 x 1250 2400 1000 1200 20.0 3750 801 32/50 200 1500 x 1250 2400 1000 1200 22.0 3750 837 32/50 200 1500 x 1250 2600 1000 1400 25.0 3750 891 32/50 200 1500 x 1250 2600 1000 1400 170/171 D.7.3 D.7.3.1 Exhaust vapour condenser The extracted gases (O2, CO2) are removed into the open air via the ventilation duct that must terminate outside the building (on the roof). The condensate, on the other hand, is discarded. In the case of multi-boiler systems with a common thermal water treatment system (TWT), installation of a motorised control valve in the exhaust vapour pipe upstream of the condenser inlet is recommended to further minimise the amount of exhaust vapour. Function description, standard values, sizing assumptions With reference to the speciﬁcations in chapter C.8.3, the following section provides more detailed information on function and sizing. By condensing the exhaust vapours, in conjunction with subsequent further cooling of the vapour condensate, the "exhaust vapour waste heat" energy can be returned to the system. A partial feedwater ﬂow upstream of the deaerator inlet would be employed in this instance as the required heat sink, with appropriate process switching (see Appendix A1). The energy-speciﬁc context is illustrated in the following temperature/heating surface diagram (Fig. D.7.3.1-1). The control valve would have to be controlled as a function of the operational loada) (see Fig. D.7.3.1-2) by the control equipment of the steam boiler system (in this case, the PLC programmable logic controller). 0HGLDWHPSHUDWXUHr& Fig. D.7.3.1–1 Temperature/heating surface diagram Exhaust vapour Exhaust vapour condensation supercooling Q̇V/C Q̇V/U Δ7ODUJH TS/V TU/V Tfw/A Partia l ﬂow Feedw ater p ΔT(small) Q̇V rehea ter Tfw/E +HDWLQJVXUIDFHPt ([KDXVWYDSRXUFRQGHQVHU TS/V Tfw/E Tfw/A TU/V Saturated steam temperature, exhaust vapours Feedwater inlet temperature Feedwater outlet temperature Exhaust vapour condensate outlet temperature a) In addition to the operational load, continuous hooking up of arising O2 values (O2 test in the feedwater line) would be optimal (see also chapter D.4.5 Water analysis). D.7 Thermal equipment Fig. D.7.3.1–2 Schematic diagram of exhaust vapour condenser operation Vent (O2 / CO2) 9& fw સCON Exhaust vapour condenser Motorised control valve Exhaust vapour steam Feedwater partial ﬂow Vapour condensate Sight glass Steam trap Ventilation to the outside (via roof) Deaerator dome SG S/V M-CVb) VC M-CV S/V fw સCON SG ST Vent D M ST D &RQGHQVDWHGUDLQLQJLQWRWKHFRROLQJ DQGH[SDQVLRQSLWWREHSURYLGHGRQ VLWHRQWKHZDVWHZDWHUVLGH Further standard values and information to be considered for sizing: Amount of exhaust vapour steam S/V calculated from: 69ปŁ9P[&21DGGIZ Ł%P)6[$>[email protected] with the variables: CON Condensate return feed into the deaerator add/fw Additional amount of feedwater as amount let into the deaerator Fresh steam output FS A T.D.S. rate in (%) ŁV/m Average factor for calculating the minimum amount of exhaust vapour steam b) A 5 to 10 % "open" position for the M-CV must be ensured by means of control technology via an appropriate end position locking mechanism. Note In practice, sufﬁcient accuracy is provided by ŁV/m = 0.005 to 0.01 [-], whereby "higher" values must be assumed for "lower" amounts of return condensate (< 40 %). For reasons of energy management, temperature differentials across the condenser (heat exchanger) should be selected: ෙ7VPDOO 7Q97IZ(ปWR. ෙ7ODUJH 7V97IZ$ปุ. Pressure losses (steam side) condenser ≤ pV/E Pressure losses (water side) condenser ≤ 0.5 bar Heat output - Q̇V of the exhaust vapour condenser from the condenser heat balance 4 ɘ 9 4 ɘ 9&4 ɘ 98 IZ[F3[7IZ$7IZ( RU 4 ɘ 9 69U9F3[769789 where cP - Speciﬁc heat for condensate and feedwater ~ 4.19 kJ/kg K and/or 0.001163 kWh/kg K rV - Latent heat of condensation - exhaust vapour steam rV = (h''S/V - h'C/V) as a function of deaerator pressure (pV/E) from [Tb. 2] and/or determined with: h''S/V - exhaust vapour steam enthalpy = Ł(pV/E) and h'C/V - exhaust vapour condensate enthalpy = Ł(pV/E) 172/173 1st sample calculation 3rd sample calculation Calculation of Q̇V in (kW): Potential savings - payback period T.D.S. rate A = 5 % Fuel - natural gas (E) with Hi = 10.35 kWh/Nm³ Fresh steam output FS = 12,000 kg/h Mean boiler efﬁciency Š K(M) ≈ 94.75 % Factor for minimum amount of vapour (according to datasheet and ECO operation) V/M ≈ 0.0075 (selected) S/V = 0.0075 x [12,000 (1+5/100)]= 94.5 kg/h Composite fuel price k FP = € 0.414/Nm³ Annual full-load hours b = 6000 h (assumption) Deaerator positive pressure p B/D = 0.21 bar T S/V = Ł(pB/D) from (Tb. 2) = 105 °C r V = Ł(pB/D) from (Tb. 2) = 0.623 kWh/kg .) ɘ 9[N)[E 4 +L[Š .0 N:[[K 1P N:K[ 1P cp = 0.001163 kWh/kgK Annual cost savings K F = €17,335/a Feedwater temperature - Tfw/E = 15 °C Temperature differential - ΔTsmall = 3 K (selected) (T U/V = 15 + 3 = 18 °C) Q̇V = 94.5 [0.623 + 0.001163 (105 - 18)] = 68.44 kW 2nd sample calculation Calculation of the required feedwater partial ﬂow - With estimateda) additional expenditure (Kcon) for the condenser of €11,500, including pipework, valves and exhaust vapour steam output controller, amortisation can be expected within a period (AK) of AK = Kcon / KF = €11,500/a / €17,335/a = 0.66 years. fw in (kg/h) Temperature differential - ΔT large = 20 K (selected) Tfw/A = 105 - 20 = 85 °C IZ N:[NJ[. NJK N:K[. a) Required speciﬁcation by obtaining speciﬁc quotations. D.7 Thermal equipment D.7.4 D.7.4.1 Feedwater cooler Function description, standard values, sizing assumptions With the feedwater cooler, the feedwater entering the economiser (ECO) can be cooled down to feedwater temperatures (Tfw/C-O) below the deaerator saturation temperature (TS/D). The feedwater outlet temperature from the feedwater cooler would have to be selected accordingly (see Fig. D.2.3.3-1), however, taking account of a permissible further cooling of the ﬂue gases leaving the ECO close to the ﬂue gas dew-point temperature. In the following text, reference is made to ECO types 100/200, while observing the thermodynamic data speciﬁed in the Vitomax 200-HS datasheets. Soldered plate heat exchangers made of stainless steel are recommended for the feedwater cooler. Process-related integration (circuit) into the overall system concept is illustrated in the enclosed schematic process diagram (see Appendix A1). Calculation of Tfw/C-O and the associated additional ECO output Q̇ECO in terms of heat recovered: Assumptions: The feedwater outlet temperature Tfw/O-ECO remains the same for each load case considered (see Fig. D.7.4.1-2 Temperature/ heating surface diagram). With reference to the notes for calculating the ECO heating output Q̇ECO (see chapter D.2.3.1), the additional output ΔQ̇ECO due to reduction of the feedwater inlet temperature into the ECO is determined similarly from the statement equation: 174/175 Statement equation With assumptions and values for: Fresh steam output Operating pressure Factor RECO = ŁSB) for FS = 12,000 kg/h pB = 12 bar RECO/200 = 1.044; RECO/100 = 1.067 Tfw/ECO-Standard = 102 °C Feedwater inlet temperature into the ECO (standard design temperature) Flue gas density Speciﬁc heat - feedwater T.D.S. rate Flue gas outlet temperature for (design temperature = Ł(PB) and 100 % boiler load) Permissible ﬂue gas temperature reduction for HEL operation for natural gas (E) operation ෙ4 ɘ (&2 ̖FG = 1.345 kg/Nm³ cP = 0.001163 kWh/KgK A = 5 % TFG/ECO-200 ≈ 132 °C TFG/ECO-100 ≈ 177 °C TFG/ECO-reduced = 125 °C TFG/ECO-reduced = 115 °C 7)*(&2VWDQGDUG7)*(&2UHGXFHG ෙ4 ɘ (&2 )6[ $ [ )6[5 ̖)* [F3[7IZ(&2VWDQGDUG7IZ2& >N:@ where: ΔT FG = T FG/ECO-standard - T FG/ECO-reduced [°C], and: fw = FS x (1 + A/100) [kg/h] and the equation for the reduced feedwater temperature: 7)*(&2VWDQGDUG7)*(&2UHGXFHG 7IZ2& 7IZ(&2VWDQGDUG [ 5(&2 ̖)* $[F3 ෙ4 ɘ (&2 ෙ7)* [ )6[5 ̖)* IZ[F3[7IZ(&2VWDQGDUG7IZ2&>N:@ the following results are yielded, summarised in the form of a table of values (see Fig. D.7.4.1-1). D.7 Thermal equipment Fig. D.7.4.1–1 Table of values Value table: Type ECO-200 TFG/ECO-standard (°C) TFG/ECO-reduced (°C) Tfw/ECO (ECO design) (°C) Type ECO-100 132 132 177 177 HEL Natural gas (E) 132 HEL Natural gas (E) 177 125 115 100 125 115 100 102 102 102 102 102 102 Permissible Tfw/O-C (°C) 100.22 97.68 93.87 88.79 86.25 82.44 Temperature differentiala) (TFG/ECO-reduced - Tfw/O-C) (K) 24.78 17.32 6.131a) 36.21 28.75 17.56 ΔQ̇ 26.08 63.30 119.14 193.57 230.79 286.63 132.2 132.5 132.5 121.5 121.5 121.5 ECO (kW) Tfw/O-ECO (for standard design) (°C) In the following temperature/heating surface diagram, the results from the table of values are presented by the ECO-200‘ as an example: Note Fig. D.7.4.1–2 Temperature/heating surface diagram The ﬁgures in [ ], apply in addition to the ECO 100. 0HGLDWHPSHUDWXUHr& (&2ᚐXHJDVLQOHW >@ VWDQGDUG Δ7ODUJH  >@ (&2IHHGZDWHU  +(/ )OXHJDV QDWXUDOJDV RXWOHW RXWOHW Δ7VPDOO 7IZ2(&2 VWDQGDUG   102 (standard) 100.27 (HEL) [88.79] )HHGZDWHU LQOHW 97.68 (natural gas) [86.25] +HDWLQJVXUIDFHPt(&2 $(&2 ΔT(large) ΔT(small) 1) ΔQ̇ECO 2) ΔQ̇ECO a) The temperature differentials should not fall below ≤ 10 K (in respect of an optimum ECO heating surface size). Temperature differential between ﬂue gas inlet and water outlet Temperature differential between ﬂue gas outlet and water inlet HEL operation Natural gas (E) operation 176/177 Cost of natural gas (E)a) kF(E) ≈ €0.414/Nm³ Feedwater cooler sizing The required cooling capacity - Q̇fw/C (in kW) and the ensuing additional feedwater outlet temperature/cooler - Tadd/fw/O-C are calculated from the statement equations: Cost of fuel oil (HEL)a) kF(HEL) ≈ €0.65/kg 4 ɘ IZ& DGGIZ[F3[7DGGIZ2&7DGGIZ,& Annual full-load hours b ≈ 6000 h/a Costs saved - potential savings (kF): With values for: IZ[F3[7V,7IZ2&LQ>N:@ the equation: .) where ɘ Δ4 [N)[E (&2 IZ )6[ +L[ǹ .0 $ LQNJK yields the expected minimum annual savings for HEL operation: and [[ .)(/ [ DGGIZ )6[ ปD $ &21LQNJK and for natural gas operation: the required cooling capacity [in kW] from: [[ .)( [ 4 ɘ IZ& )6[$[F3[7V,7IZ2&LQ>N:@ ปD and the expected additional feedwater outlet temperature/cooler from: 4 ɘ IZ& 7DGGIZ2& Fig. D.7.4.1–3 [)6[$&21] 7DGGIZ2& [F3 Schematic diagram of feedwater cooler Additional feedwater outlet temp./cooler Tadd/fw/O-C Feedwater Feedwater outlet temp./ fw cooler Tfw/O-C Feedwater inlet temp. TS/D (as a function of the deaerator pressure pB/D) Additional Additional feedwater feedwater inlet temp./cooler add/fw Tadd/fw/I-C a) Current prices must be determined here in each case (e.g. www.heizoelboerse.de; www.carmen-ev.de). D.7 Thermal equipment 2nd sample calculation 1st sample calculation With the results from the table of values and the Ktot = ΔK ECO + Kcooler (€) additional assumptions for: = 23.94 x ΔQ̇ECO + 2.86 x Q̇fw/C + €13,258 T S/D = Ł(pB/D = 0.2 bar) and: = 105 °C A = Ktot /K B [a] Amount of condensate CON ≈ 0.5 x FS = 6000 kg/h Additional feedwater inlet temperature/cooler - Tadd/fw/I-C for HEL operation: Ktot = 23.94 x 26.08 + 2.86 x 70.04 + 13,258 ≈ = 15 °C €14,083 A = 14,083/9021 ≈ 1.56 years the required cooling capacities for HEL operation: for natural gas (E) operation: Q̇fw/C = 12,000 x (1+ 5/100) x 0.001163 x (105 - 100.22) = 70.04 kW Ktot = 23.94 x 63.30 + 2.86 x 108.51 + 13,258 ≈ €15,084 Natural gas operation A = 15,084/16,034 ≈ 0.94 years Q̇fw/K = 12,000 x (1+ 5/100) x 0.001163 x (105 - 97.68) = 108.51 kW and the respective expected additional feedwater outlet temperature/cooler of: Note for HEL operation: Tadd/fw/O-C = 70.04 [(1200 x (1 + 5/100) - 6000)] x 0.001163 + 15 = 24.10 °C for natural gas (E) operation: Tadd/fw/O-C = 108.51 (1200 x (1 + 5/100) - 6000) x 0.001163 + 15 = 29.13 °C Payback periods In principle, the total expected costs (Ktot) for the feedwater cooler, including pipework and valves, but excluding the expected costs for any necessary enlargement of ECO heating surfaces, must be prepared via a speciﬁc manufacturer's quotation, as a function of each calculated ECO "additional output" - ΔQ̇ECO. For the time being, the previously cited ECO cost function could be helpful with ΔKECOa) ≈ 11,500 + 23.94 x ΔQ̇ECO (€) and for the feedwater cooler with Kcooler ≈ 1758 + 2.86 x Q̇fw/C (€) (value range Q̇fw/C ≥ 50 to ≤ 900 kW). Regarding a) The assumption of rising costs can be dismissed if the manufacturer ensures an increased mean logarithmic temperature differential ΔTm = (ΔTlarge - ΔTsmall) / (ᔉΔTlarge / ΔTsmall) in [K] over the ECO heating surface that then remains constant. The feedwater temperatures for ECO inlet and outlet would have to change in line with requirements compared with the data in the table of values. However, the feedwater inlet temperatures into the ECO should here not fall below 85 °C if at all possible. In line with the modiﬁed selection, the feedwater outlet temperature would also be subject to a downward correction. However, a precise determination can only be made in conjunction with the respective thermodynamic ECO sizing and construction on request at: [email protected] 178/179 Conclusion - recommendations Most effective use of a feedwater cooler is made with the selected ECO type 200 and natural gas (E) operation The available "utilisation potential" is much greater with ECO type 100 than type 200 and therefore also retains considerable reserve capacity, preferably for HEL operation The thermodynamically balanced feedwater cooler outlet temperatures between 83 and 89 °C for the ECO 100 and 94 to 100°C for the ECO 200 (see table of values Fig. D.7.4.1-1) should be selected approx. 10 K higher for HEL operation, to ensure that the temperature does not fall below the dew point. The standard feedwater outlet temperature from the ECO 100 would also rise in line with this increase System concepts should focus on maximised heat recovery from the ﬂue gas, for example with ECO types 200/100 Additional use of feedwater coolers should therefore only be regarded as an supplementary optimisation version in the case of justiﬁable expenditure and payback periods ≤ 1 year. Check the application case as to whether any temperature limiting measures (temperature control with limiter as a watchdog function) are required for the softened water leaving the cooler. D.7 Thermal equipment Fig. D.7.5.1–1 Workplace for evaluating water samples taken from feedwater and boiler water D.7.5 D.7.5.1 Sampling cooler Notes on installation and taking samples According to regulations (TD 611 Clause 5 and EN 12953 Part 10), feedwater and boiler water must be monitored continuously. The samples described here are taken intermittently and subjected to an appropriate laboratory test (on site in the boiler installation room and/or externally in company laboratories assigned to the steam boiler system). Before they are taken, however, samples must be cooled down to ≤ 30 °C. The Viessmann sampling cooler can be employed, in the case of an appropriately designed circuit combination, both for the cooling of boiler water and the cooling of feedwater. The necessary cooling water must be taken from the corporate drinking water supply according to the rules of good engineering practice (see proposed installation in the installation instructions). 180/181 Key BW FW DW WD Fig. D.7.5.1–1 Boiler water (if applicable, taken from the discharge pipe - reﬂection water level in the steam boiler) Feedwater (taken from the feedwater tank and/or feedwater pipe) Drinking water (cold water) - water supply, customer side (R 1/8 to R 1/2 = PN6) Water drain, customer side (R 3/4 to R 1) discharge into main system Schematic diagram of sampling cooler 2 BW FW 1.2 1 1 Sample cooler with 1.1 Drain outlet 1.2 Temperature display (planned, recommended on site) 2 Shut-off valve 3 Non-return valve 4 Shut-off valve (with drain connector) 1.1 2 WD 3 4 WD Document the results of the determined analysis values in the boiler book. Monitoring takes place intermittently at a frequency of no less than 1x per 8 h operating time. However, for system operation according to TRD 604 Sheet 1 (operation without constant supervision - BosB - here speciﬁcally for BosB 72 h), continuous monitoring (see chapter D.4.5 - Water analysis) is recommended. Install the cooler as close as possible to the sampling point. Suitable sampling tanks are: Erlenmeyer ﬂasks (e.g. in the case of immediate laboratory examination) and/or glass-stoppered glass bottles with a capacity of approx. 1 litre each. Analyses values to be documented: pH value Residual hardness p value (for determining the free alkalinity) m value (for determining the total alkalinity) Phosphate and Sulphide For boiler water and boiler feedwater requirements, see Appendix A.3. DW D.8 Pipework Pipework Within the scope of this manual, the intention is to provide information for selected main pipes (see chapter C.9) for planning purposes. Note National regulations and relevant standards must be observed. The engineering process requires close collaboration between the pipework manufacturer and the responsible monitoring/ approval authority in conjunction with the subsequent operator. A range of information and calculations provided can also be applied analogously to pipes not mentioned here for transportation of liquid and gaseous ﬂow media. The pipework considered here is restricted to the steam boiler room and a perimeter extending 1 m beyond. 182/183 D.8.1 Note Pipework D.8.1.1 Dimensions and weights for seamless and welded steel pipes are speciﬁed in DIN EN 10220 for pipe series 1 to 3. In principle, the pipe dimensions of pipe series 1 are recommended. All accessories (ﬁttings, ﬂanges etc.) required for building a pipeline are available for pipe series 1. Not all standard components are available for pipe series 2 and there are hardly any standard accessories for pipe series 3. Nominal diameters - DN The nominal diameter (abbreviation: DN) is an index used in pipework systems as an identifying parameter for parts that are suited to one another. In accordance with the following table, nominal diameters have no units and must not not be used as dimensions, since they only correspond in part to the internal diameter of pipework components. The internal diameters can exhibit differences compared with the indices for nominal diameter depending on the wall-thickness used in a particular design, as the external diameters are generally speciﬁed out of consideration for the manufacturing process. Extract from nominal diameter (DN) classiﬁcation of pipes, based on DIN EN 1092-1 Fig. D.8.1.1–1 Nominal diameters (DN) - extract DN 10 (17.2) DN 40 (48.3) DN 125 (139.7) DN 350 (355.6) DN 700 (711) DN 1400 (1420) DN 15 (21.3) DN 50 (60.3) DN 150 (168.3) DN 400 (406.4) DN 800 (813) DN 1600 (1620) DN 20 (26.9) DN 65 (76.1) DN 200 (219.1) DN 450 (457) DN 900 (914) DN 1800 (1820) DN 25 (33.7) DN 80 (88.9) DN 250 (273) DN 500 (508) DN 1000 (1016) DN 2000 (2020) DN 32 (42.4) DN 100 (114.3) DN 300 (323.9) DN 600 (610) DN 1200 (1220) --- Note: Values in brackets are the outer pipe connection diameters (mm) D.8 Pipework D.8.1.2 Pressure ratings - PN The nominal pressure of pipelines and components (pipes, ﬂanges, ﬁttings, valves etc.) is the identiﬁer for a pressure rating that classiﬁes parts of a similar design and identical connection dimensions. The pressure ratings are classiﬁed according to standard numbers and listed in the following table. Extract from pressure rating (PN) of pipes, based on DIN EN 1092-1 Fig. D.8.1.2–1 Nominal diameters (DN) - extract PN 2.5 PN 25 PN 160 PN 250 PN 6 PN 40 PN 10 PN 63 PN 320 PN 16 PN 100 PN 400 The nominal pressure (PN) = maximum permissible positive pressure (in bar) at the reference temperature T = 20 °C. a) Minimum yield strengths can be taken from standards DIN EN 10216-2/10217-2 for pipes and DIN EN 1092-1 in addition for castings, forgings and hot-rolled products. Notes In accordance with DIN EN 1092-1, the selected nominal pressure must always satisfy the condition PN ≥ PD x (RP0.2(20°C) / RP0.2(Toper.)) where PD design pressure (calculation pressure = secure operating pressure) of the component (pipes, ﬂanges etc.) in [bar] and Ra)P0.2 the minimum yield strength at room temperatures (RP0.2 (20°)) and at calculation temperature or operating temperature (RP0.2 (Toper.)) respectively. The maximum permissible pressure (pD) calculated at the operating temperature (Toper.) must not exceed a maximum permissible pressure assigned to the PN rating. For calculation or operating temperatures (Toper.) of -10 °C to 120 °C, the speciﬁed condition can be approximated for ferrous materials with PN ≈ PD. 184/185 D.8.1.3 Test pressure (Pp) with reference to Pressure Equipment Directive The pipes, valves and assemblies (hereinafter referred to as pressure equipment) must correspond to the test pressures according to the Pressure Equipment Directive 97/23/EC. If the test pressures according to the Pressure Equipment Directive are higher than the permissible test pressures for the valves, valves must be selected from the next higher nominal pressure rating (see chapter D.8.1.2). Pressure equipment is subject to a ﬁnal inspection. For this purpose, the acceptance process for pressure equipment must include a pressure strength test in the form of a hydrostatic pressure test with a minimum test pressure of Pp ≈ 1.43 x PD. Notes If the hydrostatic test is detrimental or impracticable, alternative non-destructive tests must be coordinated in consultation with the customer and the local approved monitoring body, depending on established categories I, II and III. Assigning the pipework systems to the individual categories is carried out subject to product of (PD x DN) according to diagrams 6 and 7 (Appendix II) of the Pressure Equipment Directive, whereby natural gas (E) is assigned to ﬂuid group 1 and the remaining media to ﬂuid group 2. The selection and assignment of modules must be made in agreement between the system installer, the customer and the designated body. Exceptions are pipelines (pressure equipment) that can be classiﬁed below Category I. This type of pressure equipment need only meet the requirement of good engineering practice in respect of design and production. Conventions regarding inspection obligations and recurring inspections of the pipework must be speciﬁed accordingly, in conjunction with overall system acceptance, on the basis of the [German] Health & Safety at Work Act (BetrSichV), between the installer of the pipework, the customer and the designated body. The quality of the pipework system and system documentation must be designed in such a way that the maximum intervals (5 years) are easily complied with. The Roman numerals for the categories correspond to the module categories to be selected accordingly for the pipelines, such as: Category I Module A Category II Modules A1, D1 and/or E1 Category III Modules B1+D, B1+F, B+E, B+C1 and/or H Fig. D.8.1.1–1 Module categories Modules A, A1 Internal production control for A, supplemented with monitoring by the designated body for A1 Module B EC type examination by the designated body, with examination of qualiﬁcations of the assembly and NDT personnel Module B1 Similar to module B, but without testing of a prototype Module C1 Conformity to type; the designated body monitors production and inspection at the manufacturer on a random sample basis Module F EC individual examination by the designated body as a basis for issuing conformity Modules D,E,H Aside from the classic product tests for verifying conformity, additional introduction of QA systems and their appraisal by the designated body D.8 Pipework D.8.1.4 Operating temperatures (Td) and operating pressures (PD) For the "hot-running" pipe complex, the following must be expected and/or selected in reality subject to media: Fig. D.8.1.4–1 PN6 Pipe operating temperatures PD (bar) Steam1 Lye2 Lye3 Exhaust steam Condensate5 Condensate Feedwater (°C) Blow-down Blow-down vapours4 (sealed unvented) (open) (°C) (°C) (°C) (°C) (°C) (°C) 95 110 16 0.5 111 111 111 16 1.0 120 120 120 16 2.0 134 134 134 16 3.0 148 148 148 16 4.0 152 152 152 16 5.0 159 159 159 16 6.0 165 165 -- 16 8.0 175 175 16 10.0 184 184 -- 25 13.0 195 195 -- 25 16.0 204 204 -- 25 18.0 210 210 -- 40 20.0 215 215 -- 40 22.0 220 220 -- 40 25.0 226 226 -- Key 1 Required supplement (ΔTü) for superheating with Δtü ≈ 50 K (as standard) 2 Temperatures before expansion 3 Temperatures after expansion to pD ~ 0.5 bar 4 Expanded to around atmospheric pressure 5 Assuming pDmax ~ 5.0 bar 6 Nominal pressure ratings based on the steam boiler used in the initial analysis. An additional check in accordance with chapter D.8.1.2 is nevertheless recommended 110 110 -- 186/187 D.8.1.5 Identiﬁcation of pipes D.8.1.6 Pipelines are identiﬁed according to the ﬂuid conveyed according to DIN 2403. This includes pipes and their connections, valves and ﬁttings, as well as thermal insulation. The ﬂuids are divided into 10 groups based on their general properties; the colours for the groups being deﬁned (according to RAL colour register) in the following table. As a separate identiﬁcation of ﬂammability, the tops of signs for groups 4 and 8 are coloured red (RAL 3000). Flow diagrams, graphic symbols for pipe and equipment design, and identiﬁcation systems The ﬂow diagram (system scheme, ﬂow scheme, heat ﬂow chart, pipework diagram etc.) should render, with the help of pictorial symbols and graphic characters, a simpliﬁed graphic representation of the structure and function of the system. It is designed to provide all those involved with the system, e.g. customer, manufacturer, authority, designated body etc. with a clear understanding. The layout and representation must be adapted liberally to ﬁt the intended purpose (steam boiler system). The basis is provided by the relevant graphic characters and pictorial symbols according to DIN 2481, 2429, 19227 and DIN 28004 (see also design and representation in Appendix [A1]). The components indicated in the ﬂow diagram (steam boiler with ancillary systems, pipes with add-on and built-in parts, including indicated control components) should additionally be provided with a consistent identiﬁcation system throughout. A consistent identiﬁcation system allows the aforementioned parties involved to address each individual part of the steam generation system in a clear and consistent manner. Fig. D.8.1.5–1 Identiﬁcation of pipes Fluid Group Colour Water 1 green RAL 6018 Steam (water vapour) 2 red RAL 3000 Air 3 grey RAL 7001 Flammable gases 4 yellow or RAL 1021 yellow with additional red RAL 3000 yellow with additional black RAL 1021 or black RAL 9005 6 orange RAL 2003 Lyes 7 violet RAL 4001 Flammable liquids 8 brown or RAL 8001 brown with additional red RAL 3000 Non-ﬂammable gases Acids Non-ﬂammable liquids 5 9 brown with additional black or black RAL colour register RAL 8001 RAL 9005 Oxygen 0 blue RAL 5015 D.8 Pipework Note Determination and assignment of categories depends on the type of ﬂuid employed (group 1 and/or group 2); see following diagrams taken from the Pressure Equipment Directive 97/23/EC. D.8.2 Speciﬁcations - materials, welding work Within the scope of this manual, the intention is to provide information for selected main pipes (see chapter C.9) for planning purposes. In principle, the regulations TRD 100 materials, AD 2000 - datasheets (W4 - pipes made of non-alloy and alloy steels, W9 - nuts and bolts made of ferritic steels, W9 - steel ﬂanges) and material - DIN EN 13480 and TRD 201 - welding steel components must be observed. According to the Pressure Equipment Directive 97/23/EC, corresponding veriﬁcation of conﬁrmation of the materials used must be kept in the project. For category I parts subjected to pressure (see chapter D.8.1.3), the provision of a company certiﬁcate according to DIN EN 10204 type 2.2 (conﬁrmation of certiﬁcation by the manufacturer) is required. For parts subjected to pressure in categories II and III, an acceptance test certiﬁcate is required in line with type 3.1 and/or type 3.2, depending on the selected and/or required product testing. 188/189 Assignment for media in ﬂuid group 1 (natural gas - E) Pipe according to Pressure Equipment Directive 97/23/EC DN = 25 PS (bar) DN = 100 II 1000 Article 3, Paragraph 3 100 PS ·D N =1 00 ·D N 0 = 35 0 I DN = 100 10 PS III 1 0.5 0 DN = 350 Fig. D.8.2–1 Pipes according to Article 3, number 1.3, letter a), ﬁrst dash PS = 0.5 ..."The exception here are pipes intended for use with unstable 1 0.1 10 25 100 350 1000 10,000 DN gases that fall into categories I and II according to diagram 6, but need to be classiﬁed as category III."... Assignment for media in ﬂuid group 2 (steam, condensate, water, fuel oil etc.) 1000 I 100 II III 0 00 =5 N 3500 ·D = PS N ·D 00 10 = PS PS N ·D 10 DN = 250 DN = 32 PS (bar) DN = 100 Pipe according to Pressure Equipment Directive 97/23/EC Article 3, Paragraph 3 Fig. D.8.2–2 1 PS = 0.5 0.5 Pipes according to Article 3, number 1.3, letter a), second dash 0.1 1 10 32 100 1000 250 10,000 DN ..."The exception here are pipes that contain ﬂuids at temperatures greater than 350 °C and fall into category II according to diagram 7, but need to be classiﬁed as category III."... D.8 Pipework With reference to the aforementioned standards, the following are recommended for use: D.8.2.1 Materials for the pipework identiﬁed in chapter D.8.5 Fig. D.8.2.1–1 Pipes Ferritic steels: Material Material no. Temperature (°C) P235TR1 1.02551 ≤ 50 P235TR2 P265TR2 Standards DIN EN 10216-1 DIN EN 10217-1 1.02591 ≤ 50 or DIN EN 10224 P235GH 1.03454 ≤ 450 DIN EN 10217-23,7 P265GH 1.04255 ≤ 450 DIN EN 10217-23,7 16Mo3 1.5415 ≤ 500 DIN EN 10217-23,7 13CrMo4/5 1.7335 ≤ 500 DIN EN 10217-23,7 10CrMo9/10 1.7380 ≤ 500 DIN EN 10217-23,7 14MoV6/3 1.7715 ≤ 550 DIN EN 10217-23,7 X10CrMoVNb9/1 1.4903 ≤ 600 DIN EN 10217-23,7 P265TR1 DIN EN 10216-2 DIN EN 10216-2 DIN EN 10216-2 DIN EN 10216-2 DIN EN 10216-2 DIN EN 10216-2 DIN EN 10216-2 Austenitic steels6: X6CrNiMoTI17-12-2 1.45712 ≤ 550 Notes X6CrNiTi18-10 Note 1 Where welded tubes according to DIN EN 10217 are used, a welding factor to be observed of 0.85 is recommended for the strength calculation. Note 2 The following documents must also be observed in the project, as mentioned previously (DIN EN 10204), for the preparation of acceptance test certiﬁcates: For ferritic steels: AD 2000 datasheet W4 and TRD 102, plus For austenitic steels: AD 2000 datasheet W2 and TRD 102 DIN EN 10217-7 DIN EN 10216-5 1.45412 ≤ 550 DIN EN 10217-7 DIN EN 10216-5 Notes 1 Tubes for pressure purposes (seamless and/or welded) or steel tubes and ﬁttings for preferred use in the pipework (DHW system) described in chapter D.8.5.4-C) and galvanised 2 Stainless steel tube (previous designation "V4-A") for preferred use in the pipework (softened water pipework) described in chapter D.8.5.4-E), seamless and/or welded 3 For ﬂue systems, here with preferred use according to DIN EN 10217-2 (as welded steel tubes) 4 5 6 7 Preferred use also for fuel oil (HEL) systems (previous designation St 37) Preferred use also for natural gas (E) systems (previous designation St 35.0) Austenitic tubes are employed according to DIN EN 10216-5 (seamless tubes) and/ or according to DIN EN 10217-7 (welded tubes) For "hot-running" pipework (> 100 °C) preference should be given to the selection of steel tubes according to DIN EN 10216-2 190/191 D.8.2.2 Sheet metal materials Only insofar as is applicable for ferritic materials according to DIN EN 10028-2, for example: Fig. D.8.2.2–1 Materials D.8.2.3 Flange materials With reference to and observance of DIN EN 1092-1 on the project side - ﬂanges and their joints (steel ﬂanges) - as well as DIN EN 102222 - steel forgings for pressure purposes - and DIN EN 10025 - technical delivery conditions the following recommendations are made: Material Material no. Temperature (°C) S235JR 1.0037 ≤ 100 S235JRG2 1.0038 ≤ 300 P235GH 1.0345 ≤ 400 Temperature range (°C) PN16 PN25 to PN40 ≥ PN63 ≤ 450 ≤ 120 S235JRG2 (1.0038) S235JRG2 (1.0038) P250GH (1.0460) P250GH (1.0460) P250GH (1.0460) 16Mo3 (1.5415) P250GH (1.0460) P250GH (1.0460) P265GH 1.0425 16Mo3 1.5415 ≤ 500 13CrMo4/5 1.7335 ≤ 530 Fig. D.8.2.3–1 Materials > 120 to ≤ 400 > 400 to ≤ 500 With acceptance test certiﬁcate according to DIN EN 10024 and AD 2000 datasheet W1, as well as TRD 101, with information on any necessary austenitic materials according to DIN EN 10028-7, such as where a requirement exists for condensing technologies, and acceptance test certiﬁcate according to DIN EN 10204 and AD 2000 datasheet W2, as well as TRD 101. Fig. D.8.2.2–2 Materials Material Temperature (°C) Temperature (°C) X6CrNiMoTI 17-12-2 1.4571 ≤ 550 X6CrNiTI18-10 1.4541 ≤ 550 P250GH (1.0460) 16Mo3 (1.5415) 16Mo3 (1.5415) 16Mo3 (1.5415) 13CrMo4-5 (1.7335) 13CrMo4-5 (1.7335) 10CrMo9-10 (1.7380) > 500 to ≤ 550 Notes Acceptance test certiﬁcates according to DIN EN 10204, speciﬁcally with additional reference to AD 2000 datasheet W9 and TRD 100 As standard, ﬂange types 11 (welding neck ﬂanges) and 05 (blank ﬂanges) should be selected According to the standard, Form B2 is recommended for the design of sealing strips of steam and hot water pipework and Form B1 for cold water pipework (≤ 50 °C) Welding ends of welding neck ﬂanges must comply with the subsequent pipe diameters, taking into account a permissible edge offset (± 8 % to ± 10 % of the wall thickness (T) to be joined according to DIN EN 10216-2/10217 -2, but with ≤ 2 mm recommended); see Fig. D.8.2.3-2 and Fig. D.8.2.3-3 DIN EN ISO 5817 - quality categories for imperfections - must also be observed here. Note Respectively observing a permissible operating pressure due to "decay" of the temperaturedependent material yield point. 10CrMo9-10 (1.7380) D.8 Pipework Fig. D.8.2.3–2 Pipe/pipe connection Key Di DNP 60° X 1 s‘P/sP sPF Δx Swg ˞ 2 °a 15 tX ≥ 3 Fig. D.8.2.3–3 Pipe/ﬂange connection 60° 0-3 Pipe/ﬂange internal diameter Pipe straight-through nominal diameter (external diameter) Pipe wall thickness Flange wall thickness Edge offset (max. ≤ 2 mm) Weld gap 15° adjustment to Di at Δx > 2 mm ° 15 192/193 D.8.2.4 Nuts and bolts With reference to and observance of DIN EN 20898 on the project side unalloyed fasteners - and DIN EN 10268 - alloyed fasteners - and DIN EN 1515 selection of nuts and bolts, the following recommendations are made: Fig. D.8.2.4–1 Nuts and bolts Temperature range (°C) Components PN16 PN25 to PN40 ≥ PN63 to ≤ 100 ≤ 100 Bolt 5.6 -- -- Nut 5 > 100 to ≤ 300 > 300 to ≤ 350 Bolt 5.6 5.6 25CrMo4 (1.7218) Nut 5 5 C35E (1.1181) Bolt -- Nut > 350 to ≤ 400 Bolt -- Nut > 400 to ≤ 450 Bolt -- Nut > 450 to ≤ 540 Bolt -- Nut 25CrMo4 (1.7218) 25CrMo4 (1.7218) C35E (1.1181) C35E (1.1181) 25CrMo4 (1.7218) 21CrMoV5-7 (1.7709) C35E (1.1181) 25CrMo4 (1.7218) 21CrMoV5-7 (1.7709) 21CrMoV5-7 (1.7709) 25CrMo4 (1.7218) 25CrMo4 (1.7218) 21CrMoV5-7 (1.7709) 21CrMoV5-7 (1.7709) 21CrMoV5-7 (1.7709) 21CrMoV5-7 (1.7709) -- Austenite Bolta) A4-70 (A4-50) A4-70 (A4-50) ≤ 400 Nuta) A4-70 (A4-50) A4-70 (A4-50) Notes Acceptance test certiﬁcate according to DIN EN 10204 type 2.2 for fasteners according to DIN EN 20898 (bolts 5.6 / nuts 5), speciﬁcally with additional reference to AD 2000 datasheet W7 and TRD 106, recommending - Type 3.1 - for nuts according to DIN EN 10269 and - Type 3.2 - for bolts according to DIN EN 10269 For temperature ranges > 300 °C, exclusive use of bolted connections with reduced shank is recommended according to DIN 2510 a) Note: A4-70 to M20 and > M20 (A4-50) D.8 Pipework Note D.8.2.5 Gasket materials must be completely free of asbestos. With reference to and observance of DIN EN 1514 on the project side - ﬂanges and their joints - dimensions, type and materials, the following recommendations are made in accordance with DIN EN 28091: Gasket materials D.8.2.6 Valve body materials With reference to and observance of DIN EN 1503 and DIN EN 12516 on the project side - valve body materials - speciﬁcally with additional reference to TRD 110, Clause 2 and 3, the following recommendations are made: As speciﬁed in chapter D.8.3.2, but with additional supplements for ferritic and austenitic castings, such as: Temperature range > 100 °C to ≤ 200 °C, ﬂat gaskets made from ﬁbrous materials and/or from graphite with stainless steel foil insert Temperature range > 200 °C, ﬂat gaskets made from graphite with stainless steel foil insert and/or chamber proﬁle gaskets with graphite seat and centring Fig. D.8.2.6–1 Materials Material Material no. Temperature range (°C) Nominal pressure range (PN)a) 0.7043 ≤ 350 16 to ≤ 40 GP 240 GH 1.0619 > 350 to ≤ 400 16 to > 63 G20Mo5 1.5419 > 400 to ≤ 490 16 to > 63 G17CrMo5-5 1.7357 > 490 to ≤ 570 16 to > 63 GX5CrNiTi19-10 1.4308 > 570 to ≤ 600 16 to > 63 GX5CrNiMo19-11-2 1.4408 > 570 to ≤ 600 16 to > 63 Nodular cast iron Ferritic casting: Austenitic casting: Notes In principle, use of cast iron valve body with material no. 0.6025 is not recommended Exclusive use of corrosion-resistant materials is recommended for valve spindles Use of nodular cast iron valve bodies with material no. 07043 according to TRD 108 only up to straight-through nominal diameters ≤ 150 (DN 175) Acceptance test certiﬁcates according to DIN EN 10204, speciﬁcally with additional reference to TRD 110, Clause 6 for: - Valve group 1 (DN x operating pressure in bar ≥ 20,000) with test certiﬁcate type 3.2 - Valve group 2 (DN x operating pressure in bar < 20,000) with test certiﬁcate type 3.1 a)Nominal pressure (PN) selection as a function of a permissible operating pressure due to "decay" of the temperature-dependent material yield point. 194/195 D.8.2.7 Welding, weld seams etc. In principle, necessary welding must be carried out by registered and qualiﬁed welding professionals (welders). These welders must submit welding certiﬁcates relating to qualiﬁcation tests according to DIN EN 287-1. For welding work, the AD 2000 HPO and TRD 201 approvals are required, along with the comprehensive qualiﬁcation certiﬁcate according to DIN 18800 and procedure tests according to DIN EN ISO 15614. Welded joints (weld seam preparations) must be formed according to DIN EN ISO 9692, in compliance with the following aspects speciﬁed in Appendix [A7]: Welding processes Additional welding materials Welding shielding gases The following should be available from and/or provided by the specialist welding company undertaking the work: List of welders and valid welder test certiﬁcates Applicable procedure test (AD2000 HP2/1; DIN EN ISO 15614) Welding instructions (WPS) Non-destructive weld seam tests must be coordinated with the customer's QA department, on the basis of and in compliance with the AD 2000 worksheets and TRD 201, for circumferential, ﬁllet and connector joints, on the basis of the aforementioned welding plans. Certiﬁed personnel must be provided for radiographic and ultrasonic testing, in accordance with DIN EN 473. Note Depending on the material and the weld seam design, testing scopes of between 10 %, 25 % and 100 % may be necessary, with a recommendation (unless otherwise speciﬁed) for category II and category III pressure-bearing pipework components according to the Pressure Equipment Directive of at least 25 % and 100 % for austenitic materials. D.8 Pipework D.8.3 Pipework calculations and sizing In the following, suggestions are provided for necessary calculations. However, any detailed discourse on physical processes is omitted. In individual cases, precise calculations must be carried out again by the implementers (engineers) with the help of speciﬁc calculation programs. During the layout and sizing process, the following standards and regulations must be observed by engineers: AD 2000 - worksheets (focussing on W4 - pipes, W7 - nuts and bolts, and W9 ﬂanges, along with HP100R - pipework and HP512R - testing of pipework) TRDs (focussing on the TRDs for materials, fabrication, calculation and testing) In addition to DIN EN 13480, Part 1 to Part 7 (focussing on Part 2 - materials, Part 3 design and calculation, Part 4 - fabrication and installation, and Part 5 - inspection and testing) D.8.3.1 Calculation of the internal pipe diameter For calculation purposes, a ﬂow velocity used in common-practice and determined as cost-effectively based on experience forms the basis for the "initial" approach and the arising pressure and/or temperature losses are recalculated accordingly. At the same time, the losses must comply with permissible limits (speciﬁcation by the system operator/customer). The values listed in the following table are recommended as standard values for the ﬂow velocities to be selected. 196/197 Fig. D.8.3.1–1 Standard values for ﬂow velocity (w): Type of pipe Pressure range P (bar)* Flow velocity w (m/s) Steam pipes: Wet steam ≤ 10 10 - 20 Saturated steam ≤1 10 - 15 > 1 to ≤ 5 15 - 25 > 5 to ≤ 10 25 - 35 > 10 to ≤ 40 35 - 40 > 40 to ≤ 100 40 to ≤ 60 Superheated steam: as for saturated steam, but with selection of the respective "higher" velocity Safety valve discharge pipes and start-up pipe Around atmospheric (also mixing cooler air vent pipe)a) pressure ≤ 70 Exhaust vapour and waste steam pipes, expansion steam Around atmospheric in condensate pipes (open system) pressure Long-distance steam pipes < 40 ≤ 20 Suction line ≥ 0.5 to ≤ 1 10 - 25 Water pipes: Condensate pipes Feedwater pipes Pressure line ≥ 1 to ≤ 3 Suction line ≥ 0.5 to ≤ 1 Pressure line Boiler lye and blow-down pipe ≥ 2 to ≤ 3.5 ≥ 1 to ≤ 2 (without expansion steam) Boiler lye and blow-down pipe ≤1 10 - 15 (with expansion steam) > 1 to ≤ 5 15 - 20 Suction line ≥ 0.5 to ≤ 1.5 Pressure line ≥ 1.0 to ≤ 3.5 Drinking water and DHW pipes Cooling water ≥ 1 to ≤ 2 Other pipes and ducts: Compressed air lines Natural gas pipes Fuel oil pipes ≥ 10 to ≤ 20 up to ≤ 0,05 ≥ 3 to ≤ 8 > 0.05 to ≤ 1 ≥ 5 to ≤ 10 > 1 to ≤ 6 > 10 to ≤ 25 Suction line ≥ 0.2 to ≤ 1 Pressure line ≥ 0.5 to ≤ 1.5 Combustion air ducts Suction line ≥ 8 to ≤ 20 Pressure line ≥ 15 to ≤ 30 Flue ducts up to chimney connection ≥ 8 to ≤ 15 Note With reference to none but "short" pipe lengths to be expected in the steam boiler room, ﬂow velocities could be selected here close to the speciﬁed upper limits. a) For the mixing cooler ventilation duct, ﬂow velocities can be selected according to speciﬁed details due to the short-term nature of loads from boiler blow-down. * The pressures referred to in this manual are exclusively positive pressures, unless explicitly stated otherwise. D.8 Pipework D.8.3.2 Flow rate in pipes, calculation of the internal pipe diameter In the following, equations are presented for calculating volumetric ﬂow rate, mass ﬂow rate, ﬂow velocity and internal pipe diameter. Notes regarding case 1 Calculation for the operational state based on the equation for conversion of an air or gas ﬂow from the standard state to the operational state with: 9 ɘ Pu 9 ɘ 1[ From the general equation for volumetric ﬂow rate V̇ = w x A, with A being the ﬂow cross-section (in m²), the following can be determined: S Volumetric ﬂow rate GL[˭ ˮ GL[˭ [ˮ[Z Flow velocity 9ɘ Z GL [˭ ˮ[9ɘ >[email protected] GL[˭[ˮ Internal pipe diameter 9ɘ GL [ [ ˭[Z ෭ Note >[email protected] ˭[ˮ[Z >[email protected] with calculation variables for: ˮ, Y (see [Tb. 2]) for steam and water) and properties for air, ﬂue gas, natural gas, fuel oil according to overview (approximately) Fig. D.8.3.2-1. Fig. D.8.3.2–1 ෭ w Flow velocity (see standard values from table in chapter D.8.3.1, Fig. D.8.3.1-1) ˮ Density of the medium (in kg/m³) (ˮ = 1/Y) Y Speciﬁc volume of the medium in [m3/kg] = where p=1/Y Density (kg/m³) overview for various media Medium ˮ [T = (15 °C) 20 °C] ˮ [T = 50 °C] ˮ [T = 100 °C] ˮ [T = 0 °C (standard state)] Air1 1.207 1.095 0.948 1.293 1.251 1.135 0.983 1.34 0.732 -- -- 0.784 Flue gas1 Natural gas1 Fuel oil1 (E) (LL) 0.774 (EL) (840) 815 -- -- 0.829 (S) (960) 940 910 -- >[email protected] [S 7 >[email protected] although with each neglecting the "operating pressures" (p in bar) [Z >[email protected] Mass ﬂow rate 7 and/or the density directly with: ˮNJPu ˮNJ1Pu[ 9 ɘ [ 198/199 Sample calculation 1 - steam pipe Sample calculation 2 - natural gas pipework Saturated steam/fresh steam output Saturated steam parameters as in 1st sample calculation, plus: FS = 12,000 kg/h Saturated steam enthalpy (from [Tb. 2]) Saturated steam/fresh steam pressure Feedwater enthalpy (from [Tb. 2]) pB = 13 bar (assuming feedwater temperatures Tfw ≈ 104 °C) Speciﬁc steam volume (from [Tb. 2]) with ECO type 200 (from Vitomax 200-HS datasheet) Selected ﬂow velocity from [ ෭ ෭ ≈ 94.6 % Lower net caloriﬁc value Hi-natural gas w ≈ 35 m/s = 10.35 kWh/Nm³ Fuel demand સ F (see chapter D.4.3.1) from: Required internal pipe diameter GL [ = 0.1213 kWh/kg Steam boiler efﬁciency Š K(M)) Y''B = 0.1414 m³/kg Fig. D.8.3.1-1 = 0.7744 kWh/kg સ)ป 9ɘ NJK[N:KNJN:KNJ[ ป1PuK N:K1Puy ˭[Z NJKyPuNJ ˭[PV K [ P Natural gas ﬂow pressure (assumption) ≈ 4.0 bar V Conversion of fuel demand (સ F ) into operational state (સ*F ) at 20 °C ambient temperature Selected: DN 125 according to DIN EN 10216-2 સ)ป [ ปPuK For standard wall thickness s= 4.0 mm External diameter da = 139.7 mm Internal diameter di = 131.7 mm Selected ﬂow velocity from Fig. D.8.3.1-1 ≈ 17 m/s Required internal pipe diameter GL [ [NJK[PuNJ[K ZDYDLO Ptt[˭[V >[email protected] ෭ PuK P ˭[VK[PV Selected: DN 65 according to DIN EN 10216-2 thus yielding a maximum ﬂow velocity (wavail) of 34,62 m/s < w selected For standard wall thickness s = 2.9 mm External diameter da= 76.1 mm Internal diameter di = 70.3 mm 4 x 173.59 m³ x h wavail = 0.07032 m2 x 3600 s/h x = 12.43 m/s ˭ thus available ﬂow velocity wavail < wselected D.8 Pipework D.8.3.3 v- Pressure losses The pressure loss in a pipeline results from the sum of individual losses from all pipeline components, such as pipes, ﬁttings, valves, changes in cross-section and other inbuilt parts. In the case of gaseous media, the change in volume of the ﬂowing medium due to expansion must be considered. However, this parameter is omitted in the following calculations due to its negligible impact on the result. The pressure loss calculations for liquids and gases are therefore the same in this context. Š- the kinematic viscosity of the medium (in [m²/s]) and/or the dynamic viscosity from Š Y[ˮLQ > NJ P[V 3D[V 1V Pt @ (see following tabular overview for several selected media) and di - the internal pipe diameter (in [m]) and/or dgl - the equivalent diameter in the case of an angular cross-section (in [m]) (see description in D.3.4-B) and therefore the drag coefﬁcient - ˨R from the If the pipeline has different diameters (changes in cross-section), the associated pressure losses must be determined accordingly in sections. equations for According to [L8] and [L9], the "total pressure losses" Δˮtot to be expected are calculated from: ˨Rb) = 64 / Re [-] ෙSWRW ˮ [Zt ˨5 / GL ːˣ ( [ >[email protected] D.8.3.2) in (m/s) Drag coefﬁcient (coefﬁcient of friction) of the pipeline, dimensionless, determined as a function of available ﬂow types (laminar and/or turbulent). The ﬂow type is based on the dimensionless index (Re), the so-called Reynolds' number, calculated from: 5H and a) Speciﬁc information from the valve manufacturer, if applicable, should also be observed here. b) c) ˨R - depends only on the Re number. ˨R - depends only on the relative roughness - kR/di. Z[GLGJO ˮ[Z[GL ˪ Š turbulent ﬂow - assuming a "smooth pipe" for ranges Re ≤ 105 ˨5E with the individual calculation variables for: ː ˣE - Sum of all individual resistancesa) dimensionless (see [Tb. 4]) and/or [L5/L9] LPipeline length in [m] di - Internal pipe diameter in [m] ˮ= 1/v (density of medium, see chapter D.8.3.2) in [kg/m³] w - Selected and/or available ﬂow velocity [wavail] (see chapter D.8.3.1 and/or ˨R - laminar ﬂow Re ≤ 2300 >@ ෭5 >@ H turbulent ﬂow - assuming a "smooth pipe" for ranges Re ≥ 105 to ≤ 108 ˨5E  5H and for the "completely rough pipe" ˨5F OJ[ N5 GL >@ 200/201 with wall roughness values (kR) to be assumed here according to table: Fig. D.8.3.3–1 Wall roughness Material Steel pipes Steel pipes Cast iron Cast iron pipes Concrete Concrete Sheet metal condition (new) (rusty) pipes (new) (rusty) (smooth) (rough) ducts (seamed) pipes PVC/PE kR (mm) 0.04 - 0.1 0.4 - 0.6 0.5 - 1.0 1.0 - 1.5 0.3 - 0.8 1.0 - 3.0 0.15 0.007 See also speciﬁcations in chapter G [Tb. 3] Notes 1. Values for ˨R can be determined reliably as a function of the Re number and the quotient di/kR from the enclosed diagram in chapter G [Tb.3.1]. 2. An estimate of ˨R ≈ 0.02 to 0.04 can be selected with sufﬁcient accuracy for rough calculations. Extra assistance for calculating pressure losses in a straight pipeline for the media steam and water can also be provided with sufﬁcient accuracy by the enclosed diagrams in [Tb. 4; 4.1.8]. d) In the diagram in chapter G, Tb.4.0, ˨R values of 0.0206 (according to Eberle) have been used and therefore contain corresponding reserves compared with the depicted calculations. D.8 Pipework Overview of kinematic viscosity (Y) for selected media [L9] [L11] Fig. D.8.3.3–2 Saturated steam ts (°C) 100 120 150 180 200 230 250 280 300 Y (m²/s) y 10-6 20.013 11.463 5.469 2.929 2.033 1.241 0.913 0.6 0.461 Note for superheated steam: see diagram according to Timroth; the values for saturated steam can also be selected here with sufﬁcient accuracy. Fig. D.8.3.3–3 Sample calculation 1 - Steam line pressure loss (ΔpR) Values corresponding to chapter D.8.3.2 (for 1st sample calculation) plus Steam density Superheated steam – diagram according to Timroth 1 ˮ'' = Y $EVROXWH SUHVVXUHLQEDU 1 kg = Internal pipe diameter di = 0.1317 m 300 250 Available ﬂow velocity '\QDPLFYLVFRVLW\ǹLQ3DyV 200 = 7.072 kg/m3 0.1414 m³ wavail = 34.62 m/s 150 Pipe length (assumed) 100 L = 20 m 80 60 Saturated steam temperature (Ts from Tb. 2) ≈ 195 °C 40 20 Viscosity at Ts (approximated) ≈ 2.257 · 10-6 m²/s 6WHDPWHPSHUDWXUH7LQr& Reynolds' number Re R e Fig. D.8.3.3–4 34.62 m/s x 0.1317 m 2.257 x 10 -6 m2 /s Fuel oil – air – water – ﬂue gas = 2.02 x 10 6 > 10 5 [-] Drag coefﬁcient for "smooth pipe" T (°C) 20 50 100 Oil Y (m²/s) x 10-6 Y (m²/s) x 10-6 Y (m²/s) x 10-6 Fuel oil (S) 1520 300 30 Fuel oil (EL) 5.0 2.6 / Air a) at 1.013 bar absolute ˨R = 0.0032 + = 0.0032 + 15.11 17.94 23.06 at 5 bar absolute 3.105 3.657 4.712 Water 1.004 0.553 0.295 0.221 (2.02 · 10 6) 0.237 0.221 31.215 = 0.0103 [-] yielding ΔpR = 7.072 kg/m3 2 ( x (34.62 m/s)2 x 0.0103 x 20 m 0.1317 m ) x = 0.0663 bar or 0.003315 bar/m Normal practice and acceptable pressure losses of ΔpR ≈ 0.003 bar/m of pipe can be used. a) Also applies approximately to natural gas. b) (Source: Weishaupt) on combustion of fuel oil with an excess of air (˨L) between 1.1 to 1.2. 1 10 5 202/203 Ex. 2 - Pressure loss in the feedwater suction line (ΔpR/S) Cont. - Pressure loss in the feedwater suction line (ΔpR/S) Feedwater suction line: Standard practice and acceptable pressure losses of Amount of feedwater fw = 12,000 kg/h Feedwater temperature Tfw = 104 °C Feedwater density (according to [Tb. 2]) ˮfw = 955 kg/m³ Selected ﬂow velocity (see standard values in table in chapter D.8.3.1) recommended. Wit additional assumptions for: Ltot = 5 m Individual ﬁlter resistance (1x) (clean) w = 1.0 m/s Pipe length (assumed) L=1m ˣ F ≈ 3.0 Individual valve resistance (2x) Required internal pipe diameter di erf = 2 x √ In light of the information speciﬁed in chapter D.6.1, sizing of the suction line for values of Δptot/s ≤ 500 mmWC is recommended. ΔpR/S ≈ 10 to 20 mmWC per metre of pipe can be Suction line length - total ˣV ≈ 2 x 3.7 = 7.4 Individual 90° bend resistance (3x) 12,000 kg/h x s xh ˭ x 955 kg/m 3 x 1 m x 3600 s = 0.0668 m selected: DN 65 according to DIN EN 10216-2 For standard wall thickness s = 2.9 mm ˣ B ≈ 3 x 0.2 = 0.6 Sum of individual resistances: ːˣE = 3.0 + 7.4 + 0.6 = 11 Total suction line pressure loss External diameter da = 76.1 mm Internal diameter di = 70.3 mm ෙSWRWV NJP EDUP[P[ resulting in an available ﬂow velocity of wavail = 4 x 12,000 kg/h x h 0.07032 m2 x 3.14 x 955 kg/m3 x 3600 s = 0.89 m/s [PV[ EDU DQG [EDU[PP:& Viscosity at Tfw ≈ 0.295 x 10-6 m²/s ෙSWRWV Reynolds' number 0.89 m/s x 0.0703 m Re = = 2.21 x 10 5 > 10 5 [-] 0.295 m2 /s x 10 -6 Drag coefﬁcient for "smooth pipe" 0.221 ˨ R = 0.0032 + = 0.0032 + ΔpR/S = 922 2 (2.12 x 10 5) 0,237 0.221 18.29 ( = 0.0153 [-] x 0.89 2 x 0.0153 x 1 0.0703 ) x 1 10 5 = 0.000823 bar/m and ΔpR/S = 0.000823 x bar x mmWC 9.81 x 10 -5 x bar x m = 8.39 mmWC/m [[EDU PP:& Note D.8 Pipework D.8.3.4 Heat and temperature losses Heat losses can arise due to conduction, convection and radiation. Two or even all three types frequently occur together as a thermal transfer. Conduction, convection and radiation of heat are different processes subject to different physical laws, which need not be described in any greater detail in the following. Thermal insulation has the task of economically minimising these losses to the greatest extent possible. With reference to and in compliance with the following speciﬁed standards and directives, losses of ≤ 100 W/m² surface area and maintenance of average thermal conductivity coefﬁcients (see Fig. D.8.3.4-1) must be ensured. Fig. D.8.3.4–1 Coefﬁcients of thermal conductivity Mean temperature in °C Thermal conductivity coefﬁcient 50 100 150 200 250 350 0.04 0.045 0.055 0.065 0.075 0.09 (W/mK) for: Mineral ﬁbre shells Thermal conductivity coefﬁcient (W/mK) for: Mineral ﬁbre mats 0.035 0.039 0.046 0.055 0.066 0.081 In the case of "normal" air movement (wind speeds < 5 m/s), maintaining a surface temperature on the exterior of the sheet metal jacket no higher than 20 K above ambient temperature is recommended. The following fundamental standards should be observed: DIN 4102-T1 - (building material category A1) DIN 4140 - Insulation work on industrial installations and building equipment; execution of thermal and cold insulations Technical datasheets from the Arbeitsgemeinschaft Industriebau e. V. (AGI worksheets) VDI Guideline 2055 - Thermal insulation for heated and refrigerated industrial and domestic installations EnEV - [German] Energy Saving Ordinance (minimum requirement according to paragraph 12) In the enclosed tables (see Appendix [A2]), typical values are provided with sufﬁcient accuracy for determining cost-effective thermal insulation of pipes and contact protection insulation. Insofar as is dictated by processrelated issues, the insulation thickness should be determined independently from economic principles. Notes regarding A) Contact protection insulation Contact protection is recommended in cases where, at normal operating temperature, object surface temperatures > 60 °C can occur "temporarily", e.g. discharge pipes and objects partially accessible for inspection of certain surfaces (platforms, walkways, etc.). In individual cases, perforated sheet steel covers (without insulation material) can be provided instead of thermal insulation, e.g. drainage systems, ventilation facilities or as large-area contact protection on steam boiler components etc., in accessible areas. B) Low temperature insulation or insulation for the prevention of condensation In this case, the insulation is designed according to criteria for the prevention of condensation forming on "cold-running" pipework systems (e.g. untreated and softened water pipes). The speciﬁc circumstances must be taken into consideration here on a system-related basis. Use can be made with sufﬁcient accuracy of the typical values in the following table in accordance with Appendix [L10]; see Fig. D.8.3.4-3. C) Protection against moisture Insulating materials must be protected with appropriate measures against moisture, such as ingress of rainwater. The insulating materials must be stored and laid in an absolutely dry environment. Reuse of insulation that has become "damp" is not recommended. Additional installation of suitable monitoring systems is recommended for pipework in the open air, such as longdistance pipeline systems. D) Heat loss and temperature drop in "hotrunning" pipes With reference to the speciﬁcations in [L5] and [L10], the arising losses can be calculated in simpliﬁed terms as follows: 204/205 +HDWORVV Calculation example ˭[707$[/3 4 ɘ /3 ˨ ᔉ 'D 'L >:@ ˞D['D Note With data according to 1st sample calculation - Steam output M = 12,000 kg/h ฬ 3.33 kg/s Steam temperature With calculation variables for: Media temperature - TM [°C] Ambient temperature - TA [°C] Insulating material coefﬁcient of thermal conductivity - ˨[W/mK] (with reference to TM) External/internal diameter of the insulation Da/Di in [m] Heat transfer coefﬁcient at the insulation surface - ˞a in [W/m²K] with typical values for - ˞a: It is assumed that ﬂanges and valves are installed throughout with thermal insulation and can therefore be included in the calculation as continuous pipes. Heat losses caused by pipe brackets should also be considered, if applicable, with a proportionate loss of 15 % (for interiors) to 25 % (for arrangements in the open air). Exceptions to this rule are valves with electronic sensors or actuators. Due to their heat sensitivity, such valves must not be enclosed in insulating material, e.g. steam output meter. steam pipework, as in chapter D.8.3.2: T M = 195 °C Ambient temperature TA (assumed) = 20 °C Pipe length L P (assumed) = 1 m Insulation internal diameter Di = 139.7 mm (External pipe diameter) Insulation external diameter Da = 279.7 mm (assumed in accordance with selected insulation thickness of 70 mm from [A5]) Insulating material coefﬁcient ˨ ≈ 0.055 W/mk of thermal conductivity (assuming mineral ﬁbre mats) Heat transfer coefﬁcient ˞a ≈ 3.5 W/m² K (assumed) Q̇L/P ≈ Fig. D.8.3.4–2 Heat transfer coefﬁcient Vertical pipes Horizontal pipes 2˨ ˞ a≈ 5.6 W/m²K in buildings ˭ x (T M - TA ) x L P 1 ᔉ ˞ a≈ 3.5 to 5.6 W/m²K Di + 1 ˞a x Da Z˭[[ :P in buildings with Da [ ᔉ [ Da ≤ 1000 mm Pipes in open air ˞ a≈ 20 to 40 W/m²K up to Da ≤ 700 mm and with reference to a 1 m² surface: Q̇L/P ≈ 74.94 W/m x 1/(0.2797 x 3.14 x m/m²) ≈ 85.33 W/m2 Temperature drop (ΔTM) In general the following applies with reference to the ﬂowing medium (in M): 4 ɘ /3 0[FS0[ෙ70: or ෙ70 4 ɘ /30[FS0 With calculation variables for: Heat loss Q̇L/P - in [W and/or W/m] Medium mass ﬂow rate - M in [kg/s] Speciﬁc thermal capacity - cpM of the ﬂowing medium at constant pressure in [Ws/kg K] where: cpWater ≈ 4200 Ws/kgK and cpSteam - [Tb. 2] diagram for saturated steam and [Tb. 2.3] diagram for superheated steam and with speciﬁc thermal capacity (cpM - for steam from [Tb2]) ≈ 2939 Ws/kgK results in ΔT M = Q̇L/P/ ( M x cpM) = 74.94/(3.33 x 2939) W/m kg K s / (Ws kg m) = 0.00766 K/m Fig. D.8.3.4–3 Insulation thickness as a function of relative humidity Air temperature (°C): 20 25 30 35 80 % 16.5 21.4 26.3 31.0 85 % 17.5 22.4 27.3 32.2 Dew point temperature (°C): Air at relative humidity: 90 % 18.5 23.5 28.4 33.3 Economical insulation Inside buildings 40 65 90 110 thickness (in mm): Outside buildings 10 20 25 30 D.8 Pipework Notes Fig. D.8.3.4–4 Diagram for determining heat transfer coefﬁcient ke Flanges and pipe brackets cause additional heat losses. Insulated ﬂanges are included in calculations as continuous pipes, while insulated ﬂanges with ﬂange caps must be considered by adding 1 m to the pipe length. Pipe brackets increase heat losses in the interior by ≈ 15 % and in the open air by ≈ 25 % Detailed calculations - see VDI Guideline 2055 Although documented sufﬁciently for practitioners in chapter D.8.3.4 Fig. D.8.3.4–5 Source: GESTRA Diagram for determining diameter factor fd ! Fig. D.8.3.4–6 Source: GESTRA Diagram for determining wind factor fW ˨ - Coefﬁcient of thermal conductivity for selected insulating material (see also table Fig. 8.3.4-1) Source: GESTRA 206/207 E) Heat loss and temperature drop in "hotrunning" pipes With the help of empirical equations and layout diagrams (source: Gestra), the following can be determined on the basis of the cited calculation examples: Heat loss (Q̇i) for 1 m pipe length in the building: Q̇i = ke x fd x (T M - TA ) in [W/m] and Heat loss (Qf) for 1 m pipe length in the open air: Q̇f = ke x fd x f w x (T M - TA ) in [W/m] With calculation variables for: Media temperature - T M (°C) Ambient temperature - TA (°C) and the reading (see Fig. D.8.3.4-4 to Fig. D.8.3.4-6) for: Heat transfer coefﬁcient for a - ke (W/m² K) for an even wall Diameter correction factor - fd (m²/m) Wind factor - f w Sample calculation 1 Insulating layer thickness s = 40 mm Coefﬁcient of thermal conductivity ˨ = 0.058 W/m K External pipe diameter da = 48.3 mm Temperature of the medium T M = 160 °C Ambient temperature TA = 20 °C Reading: ke = 1.25 W/m² K fd = 0.27 m²/m fw = 1.068 Result for the interior: Q̇i = ke x fd x (T M - TA ) = 1.25 W/m² K x 0.27 m²/m x (160 - 20) °C = 47.3 W/m Result for open air: Q̇f = ke x fd x f w x (T M - TA ) = 1.25 W/m² K x 0.27 m²/m x 1.068 x (160 - 20) °C = 50.5 W/m D.8 Pipework Temperature drop (ΔTM) in "hot-running" pipes (water-bearing): The following rule of thumb applies: ΔTM = Q̇i(f) / (cpw x w) [K/m] With calculation variables for: Heat loss - Q̇i and/or Q̇f - [W/m] see calculation example 1 under E) Speciﬁc thermal capacity - [Ws/kg K] cpWater ≈ 4200 Ws/kg K and Water mass ﬂow rate W [kg/s] Temperature drop (ΔTS) in "hot-running" pipes (steam-bearing): As for water-bearing, but with the assistance of and readings from Fig. D.8.3.4-5 Sample calculation 2 Steam temperature = 220 °C Steam pressure = 10 bar (abs) Steam mass ﬂow rate = 30 x 10 3 kg/h Heat loss Q̇f (see sample calculation 1) = 50.5 W/m Result from Fig. D.8.3.4-5 ΔT S ≈ 0.0028 K/m 208/209 Diagram for determining temperature drop as a function of steam temperature, steam pressure and steam mass ﬂow rate ! Source: GESTRA Fig. D.8.3.4–5 D.8 Pipework D.8.4 Strength, expansion, support spans, clearances, routing / mountings The major applicable calculation and sizing principles to be taken into consideration during engineering were described by way of introduction in chapter D.8.3. The materials ﬂowing through a pipeline subject the pipe walls to loads due to positive or negative pressure. In addition to these loads, thermal stresses due to the arising temperature gradient in the pipe wall must also be considered in the case of hot-running pipes. This temperature gradient is of particular signiﬁcance when starting up and shutting down the system, especially with "thick-walled" pipes. Further loads arise due to prevented changes in length of the pipework system between the ﬁxed points and restrictions resulting from deﬂection between the individual supports. A) Strength For the purpose of ensuring an "adequate" pipe wall thickness, the pipes must be sized accordingly, with reference to cited standards and regulations, for the arising operating conditions (static loads up to 120 °C and/or > 120 °C as well as varying loads). In the ﬁnal analysis, the selected pipe wall thickness to be implemented (sselected) must satisfy the conditions: sselected ≥ SV + C1 + C2. Where: SV - The calculated required wall thickness C1 - Supplement taking account of the permissible shortfall in wall thickness C2 - Supplement for corrosion and wear 210/211 In order to avoid excessively high forces at the ﬁxed points, provision must be made for appropriately designed expansion joints. Prestressing of the pipe can compensate for the stresses caused by thermal expansion during operation. Where this is not possible naturally, appropriate expansion joints (compensators) must be included in the design in the form of pipe-leg and horseshoe-bend expansion joints, lyra expansion loops, or axial, restrained, and angular expansion joints. Precise calculation of the reaction forces occurring at the respective ﬁxed points is difﬁcult and should be carried out with the help of conventional computer programs, such as "ROHR-2". The determination of permissible reaction forces (lateral forces) and torques is carried out on the basis of and in compliance with relevant manufacturer's speciﬁcations. This applies primarily to: Valves and connectors on steam boilers Note: In this context, Viessmann requires "stress-free" connection Valves and connectors on pumps in the system Valves and connectors on the thermal devices in the system With the commencement of engineering the installation of individual components, the possibility must be investigated at this early stage of a "structurally soft" mounting of the pipework system, by means of routing options and incorporating appropriate "natural" pipe deviations for the purpose of expansion compensation. One good option is the inclusion of so-called pipe-leg expansion joints (see diagram for pipes according to DIN EN 10220). Pipe-leg and U-bend expansion joints are manufactured from the same material as the pipe in question. The pipe legs are pre-stressed during installation with 50 % of the expected expansion (ΔL). Fig. D.8.4–1 Expansion compensator diagram m Required pipe leg length in m B) Expansion Pipes bearing "hot-running" ﬂow media undergo a change in length (ΔL) during operation. Calculated from ΔL = Lo x ˞ x ΔT in [mm], where Lo - Rectilinear distance between two ﬁxed points in the pipework system in [m] ˞ - Expansion coefﬁcient for ferrous materials ˞ ≈ 12 x 10 -6 [m/mK] ΔT - Temperature increase [K], for example: ΔT = (120 °C - 20 °C) = 100 K Lo = 1 m ΔL = 1 m x 12 x 10 -6 m/mK x 100 K = 1.2 x 10 -3 m = 1.2 mm/m nf 0 =4 0m tio a ns pe m o nc sio an p Ex Fixed point . I = Expansion in mm Da = Ext. pipe dia. in mm l = pipe leg length in m Nominal diameter D.8 Pipework C) Support span The effects of inertia forces (line stress due to insulation, pipe ﬁlling and pipe weight) on the permissible deﬂection and/or permissible stress are limited by the deﬁnition of suitable support spans. Proof of permissibility is considered to have been furnished if the support spans according to AD 2000 - datasheet HP100R - are observed for the steel pipeline. Fig. D.8.4–2 Extract: permissible support span in (m) for steel pipes Nominal diameter Pipe wall thickness (s in mm) DN 25 DN 40 2.0 DN 50 DN 80 DN 100 DN 150 4.0 2.0 4.0 2.0 4.5 2.3 5.6 2.6 6.3 2.6 7.1 2.9 2.9 3.5 3.5 4.5 4.4 5.5 5.4 6.3 6.2 7.6 7.5 2.7 2.8 3.1 3.3 3.9 4.1 4.6 5.0 5.1 5.6 5.8 6.6 2.0 2.2 2.5 2.3 3.2 3.6 4.0 4.5 4.6 5.2 5.4 6.3 1.8 2.0 2.8 3.2 2.9 3.3 3.7 4.3 4.4 5.0 5.2 6.1 Permissible support span, L1 in m Empty pipe (uninsulated) Water-ﬁlled pipe (uninsulated) Water-ﬁlled pipe (insulated) Dda) 40 Water-ﬁlled pipe (insulated) Dda) 80 Fig. D.8.4–3 Extract: permissible support span in (m) for steel pipes Nominal diameter Pipe wall thickness (s in mm) DN 200 DN 250 DN 300 DN 350 DN 400 DN 500 2.9 7.1 2.9 7.1 2.9 8.0 3.2 8.8 3.2 10.0 4.0 11.0 8.7 8.7 9.7 9.7 10.6 10.6 11.1 11.1 11.9 11.8 13.3 13.2 6.5 7.4 6.9 8.0 7.3 8.7 7.7 9.1 8.0 9.7 8.9 10.7 6.1 7.1 6.6 7.7 7.0 8.4 7.4 8.8 7.7 9.5 8.7 10.5 5.9 6.9 6.5 7.6 6.9 8.3 7.3 8.7 7.6 9.4 8.6 10.4 Permissible support span, L1 in m Empty pipe (uninsulated) Water-ﬁlled pipe (uninsulated) Water-ﬁlled pipe (insulated) Dda) 40 Water-ﬁlled pipe (insulated) Dda) 80 a) Dd = Insulation thickness in [mm]. 212/213 Based on empirical values and applicable in practice, the following information summarised in tables a) to e) is of use in initial design considerations: Fig. D.8.4–4 a) Support span (b) in (m) for PVC pipes, hard PVC up to 20 °C (source: Gestra) Nominal diameter DN 25 DN 32 DN 40 DN 50 DN 65 DN 80 DN 100 DN 125 DN 200 Support span (m) 1.0 1.1 1.25 1.4 1.5 1.65 1.85 2.15 2.6 For steel pipes (source: Mannesmann) with a permissible deﬂection (fperm = 5 mm) and permissible stress (˰perm = 40 N/mm²) Fig. D.8.4–5 d mm b) Support spans in (m) - seamless steel pipe (d x s) - with water and insulation thickness (Dd) s mm qM kg/m Dd = 50 mm 100 mm 150 mm 200 mm 250 mm 300 mm 0 mm 60.3 2.9 6.4 4.1 3.4 3.0 2.8 2.4 2.1 1.9 63.5 2.9 6.9 4.2 3.5 3.1 2.9 2.5 2.2 1.9 70.0 2.9 8.0 4.3 3.7 3.3 3.1 2.7 2.4 2.1 76.1 3.2 9.6 4.5 3.9 3.6 3.3 3.0 2.7 2.4 88.9 3.2 12.1 4.8 4.2 3.9 3.6 3.4 3.0 2.7 101.6 3.6 15.7 5.1 4.6 4.3 4.0 3.8 3.6 3.2 108.0 3.6 17.2 5.3 4.7 4.4 4.1 3.9 3.7 3.4 114.3 3.6 18.8 5.4 4.8 4.6 4.3 4.0 3.8 3.5 127.0 4.0 23.3 5.7 5.2 4.9 4.6 4.4 4.2 4.0 133.0 4.0 25.0 5.8 5.3 5.0 4.7 4.5 4.3 4.1 139.7 4.0 27.0 5.9 5.4 5.1 4.9 4.6 4.4 4.2 159.0 4.5 34.8 6.3 5.8 5.6 5.3 5.1 4.9 4.7 168.3 4.5 38.1 6.4 6.0 5.7 5.5 5.3 5.0 4.9 193.7 5.6 52.1 6.9 6.5 6.3 6.1 5.9 5.7 5.5 219.1 6.3 66.6 7.4 7.0 6.8 6.6 6.4 6.2 6.0 244.5 6.3 79.2 7.7 7.3 7.1 6.9 6.7 6.6 6.4 273.0 6.3 94.7 8.0 7.7 7.5 7.3 7.1 6.9 6.7 323.9 7.1 130.8 8.6 8.3 8.2 8.0 7.8 7.7 7.5 355.6 8.0 159.2 9.1 8.8 8.7 8.5 8.3 8.2 8.0 406.4 8.8 205.0 9.7 9.4 9.3 9.1 9.0 8.8 8.7 457.0 10.0 260.2 10.3 10 9.9 9.8 9.6 9.5 9.3 508.0 11.0 320.3 10.8 10.6 10.5 10.3 10.2 10.1 9.9 610.0 12.5 453.0 11.7 11.5 11.4 11.3 11.2 11.1 11.0 D.8 Pipework Fig. D.8.4–6 d mm c) Support spans in (m) - welded steel pipe (d x s) - with water and insulation thickness (Dd) s mm qM kg/m Dd = 50 mm 100 mm 150 mm 200 mm 250 mm 300 mm 0 mm 60.3 2.9 6.4 4.1 3.4 3.0 2.8 2.4 2.1 1.9 63.5 2.9 6.9 4.2 3.5 3.1 2.9 2.5 2.2 1.9 70.0 2.9 8.0 4.3 3.7 3.3 3.1 2.7 2.4 2.1 76.1 2.9 9.1 4.5 3.8 3.5 3.2 2.9 2.6 2.3 88.9 2.9 11.6 4.8 4.1 3.8 3.6 3.3 2.9 2.6 101.6 2.9 14.3 5.0 4.4 4.1 3.8 3.6 3.3 2.9 108.0 2.9 15.7 5.1 4.6 4.3 4.0 3.8 3.4 3.1 114.3 2.9 17.2 5.2 4.7 4.4 4.1 3.9 3.6 3.2 127.0 3.2 21.2 5.5 5.0 4.7 4.4 4.2 4.0 3.6 133.0 3.2 22.8 5.6 5.1 4.8 4.6 4.3 4.1 3.8 139.7 3.2 24.7 5.7 5.2 4.9 4.7 4.4 4.2 3.9 159.0 3.2 30.6 6.0 5.5 5.2 5.0 4.8 4.6 4.3 168.3 3.6 35.0 6.2 5.7 5.5 5.3 5.0 4.8 4.6 193.7 3.6 44.2 6.5 6.1 5.9 5.6 5.4 5.2 5.0 219.1 4.0 56.2 6.9 6.5 6.3 6.1 5.9 5.7 5.5 244.5 4.0 67.7 7.2 6.8 6.6 6.4 6.2 6.0 5.8 273.0 4.0 81.7 7.4 7.1 6.9 6.7 6.5 6.3 6.2 323.9 4.0 109.9 7.9 7.5 7.4 7.2 7.0 6.9 6.7 355.6 4.0 129.6 8.1 7.8 7.6 7.5 7.3 7.2 7.0 406.4 5.0 172.9 8.8 8.5 8.4 8.2 8.1 7.9 7.8 457.0 5.0 212.7 9.2 8.9 8.7 8.6 8.5 8.3 8.2 508.0 5.0 256.8 9.5 9.2 9.1 9.0 8.8 8.7 8.6 559.0 6.0 316.8 10.1 9.8 9.7 9.6 9.5 9.4 9.2 610.0 6.0 370.2 10.4 10.1 10.0 9.9 9.8 9.7 9.6 660.0 6.0 426.6 10.6 10.4 10.3 10.2 10.1 10.0 9.9 711.0 6.0 488.1 10.9 10.6 10.6 10.5 10.3 10.2 10.1 762.0 6.0 553.7 11.1 10.9 10.8 10.7 10.6 10.5 10.4 813.0 6.0 623.3 11.3 11.1 11.0 10.9 10.8 10.7 10.6 864.0 6.0 697.1 11.5 11.3 11.2 11.2 11.1 11.0 10.9 914.0 6.0 773.4 11.7 11.5 11.4 11.4 11.3 11.2 11.1 1016.0 6.0 941.1 12.1 11.9 11.8 11.7 11.7 11.6 11.5 214/215 Fig. D.8.4–7 d mm d) Support spans in (m) - seamless steel pipe (d x s) - empty pipe and insulation thickness (Dd) s mm qM kg/m Dd = 50 mm 100 mm 150 mm 200 mm 250 mm 300 mm 0 mm 60.3 2.9 4.1 4.6 3.5 3.1 2.8 2.5 2.1 1.9 63.5 2.9 4.3 4.7 3.7 3.2 2.9 2.6 2.2 2.0 70.0 2.9 4.8 4.9 3.9 3.5 3.1 2.7 2.5 2.2 76.1 3.2 5.8 5.1 4.1 3.7 3.4 3.1 2.8 2.5 88.9 3.2 6.8 5.6 4.5 4.1 3.8 3.5 3.2 2.8 101.6 3.6 8.7 6.0 5.0 4.5 4.2 3.9 3.7 3.4 108.0 3.6 9.3 6.1 5.2 4.7 4.4 4.1 3.8 3.5 114.3 3.6 9.8 6.3 5.3 4.9 4.5 4.2 4.0 3.7 127.0 4.0 12.1 6.7 5.7 5.3 4.9 4.6 4.3 4.1 133.0 4.0 12.7 6.8 5.9 5.4 5.1 4.7 4.5 4.3 139.7 4.0 13.4 7.0 6.0 5.6 5.2 4.9 4.6 4.4 159.0 4.5 17.1 7.5 6.5 6.1 5.8 5.4 5.1 4.9 168.3 4.5 18.2 7.7 6.8 6.3 6.0 5.6 5.3 5.1 193.7 5.6 26.0 8.3 7.4 7.0 6.7 6.3 6.1 5.8 219.1 6.3 33.1 8.8 8.0 7.6 7.3 6.9 6.7 6.4 244.5 6.3 37.0 9.3 8.5 8.1 7.7 7.4 7.1 6.8 273.0 6.3 41.4 9.8 9.0 8.6 8.2 7.9 7.6 7.3 323.9 7.1 55.5 10.7 9.9 9.5 9.2 8.9 8.6 8.3 355.6 8.0 68.6 11.2 10.5 10.1 9.8 9.5 9.2 8.9 406.4 8.8 86.3 12.0 11.3 10.9 10.6 10.3 10.0 9.7 457.0 10.0 110.2 12.7 12.0 11.7 11.4 11.1 10.9 10.6 508.0 11.0 134.8 13.4 12.8 12.5 12.2 11.9 11.6 11.4 610.0 12.5 184.2 14.7 14.1 13.8 13.5 13.3 13.0 12.8 D.8 Pipework Fig. D.8.4–8 d mm e) Support spans in (m) - welded steel pipe (d x s) - empty pipe and insulation thickness (Dd) s mm qM kg/m Dd = 50 mm 100 mm 150 mm 200 mm 250 mm 300 mm 0 mm 60.3 2.9 4.1 4.6 3.5 3.1 2.8 2.5 2.1 1.9 63.5 2.9 4.3 4.7 3.7 3.2 2.9 2.6 2.2 2.0 70.0 2.9 4.8 4.9 3.9 3.5 3.1 2.8 2.5 2.2 76.1 2.9 5.2 5.1 4.1 3.7 3.3 3.1 2.7 2.4 88.9 2.9 6.2 5.6 4.5 4.0 3.7 3.4 3.1 2.7 101.6 2.9 7.1 6.0 4.9 4.4 4.0 3.7 3.5 3.1 108.0 2.9 7.5 6.2 5.0 4.6 4.2 3.9 3.6 3.2 114.3 2.9 8.0 6.3 5.2 4.7 4.4 4.1 3.8 3.4 127.0 3.2 9.8 6.7 5.6 5.1 4.7 4.4 4.2 3.9 133.0 3.2 10.2 6.9 5.7 5.3 4.9 4.6 4.3 4.0 139.7 3.2 10.8 7.0 5.9 5.4 5.0 4.7 4.4 4.2 159.0 3.2 12.3 7.5 6.3 5.9 5.5 5.1 4.8 4.6 168.3 3.6 14.6 7.7 6.6 6.2 5.8 5.4 5.1 4.9 193.7 3.6 16.9 8.3 7.1 6.7 6.3 5.9 5.6 5.3 219.1 4.0 21.2 8.8 7.7 7.3 6.8 6.5 6.2 5.9 244.5 4.0 23.7 9.3 8.2 7.7 7.3 6.9 6.6 6.3 273.0 4.0 26.5 9.9 8.7 8.2 7.8 7.4 7.1 6.8 323.9 4.0 31.6 10.8 9.5 9.0 8.6 8.2 7.8 7.5 355.6 4.0 34.7 11.3 10.0 9.5 9.0 8.6 8.3 8.0 406.4 5.0 49.5 12.1 10.9 10.4 10.0 9.6 9.3 9.0 457.0 5.0 55.7 12.8 11.6 11.1 10.7 10.3 9.9 9.6 508.0 5.0 62.0 13.5 12.2 11.8 11.3 10.9 10.6 10.2 559.0 6.0 81.8 14.1 13.0 12.6 12.2 11.8 11.4 11.1 610.0 6.0 89.4 14.8 13.6 13.2 12.8 12.4 12.0 11.7 660.0 6.0 96.8 15.4 14.2 13.7 13.3 12.9 12.5 12.2 711.0 6.0 104.3 16.0 14.7 14.3 13.8 13.4 13.1 12.7 762.0 6.0 111.9 16.5 15.3 14.8 14.4 14.0 13.6 13.2 813.0 6.0 119.4 17.1 15.8 15.3 14.9 14.4 14.1 13.7 864.0 6.0 127.0 17.6 16.3 15.8 15.3 14.9 14.5 14.2 914.0 6.0 134.4 18.1 16.7 16.3 15.8 15.4 15.0 14.6 1016.0 6.0 149.4 19.1 17.7 17.2 16.7 16.3 15.8 15.5 216/217 D) Clearances When routing pipes, attention should be paid to adequate average spacing between pipe centres and the building wall, as well as centre clearances between pipes laid parallel to one another. Insulation and built-in pipeline components (ﬂanges, valves etc.) must remain accessible at all times. Based on empirical values and applicable in practice, the following are recommended for initial design considerations: Fig. D.8.4–9 Initial design considerations Note Wall clearance (mm) with ﬂange and/or valve Nominal diameter (DN) 25 32 50 65 80 100 125 150 200 250 300 400 500 Without insulation 150 150 150 150 150 200 200 200 250 300 300 400 450 With insulation 200 200 200 200 200 250 250 300 350 400 450 450 600 Minimum clearance between insulation and wall approx. 50 mm. Wall clearance (mm) without ﬂange and/or valve Without insulation 150 150 150 150 150 200 200 200 250 300 300 350 400 With insulation 200 200 200 200 200 250 250 250 300 350 400 400 450 (Source: Mannesmann) Fig. D.8.4–9 Initial design considerations Note Centre clearances between uninsulated pipes DN DN 25 40 50 80 100 150 200 250 300 350 400 450 500 500 380 380 430 430 465 505 530 555 580 610 635 660 685 180 25 450 355 355 405 405 430 455 505 530 555 580 610 635 200 185 40 400 330 335 380 380 405 430 480 505 530 555 580 215 210 190 50 350 330 330 355 355 380 405 455 480 480 505 265 240 230 215 80 300 305 305 330 355 355 380 405 455 480 305 285 260 255 235 100 250 280 280 305 305 330 355 380 405 360 335 310 290 280 265 150 200 250 250 280 280 305 330 355 435 395 370 350 325 315 300 200 150 225 225 225 250 250 280 485 460 425 395 375 360 345 325 250 100 200 220 220 225 225 555 520 495 460 430 410 385 380 365 300 80 175 175 175 200 590 575 540 510 475 450 425 400 395 380 350 50 150 150 175 680 645 630 595 565 530 505 480 455 450 435 400 40 150 150 730 695 660 645 610 580 545 520 495 475 465 460 450 25 150 790 765 730 695 680 645 615 580 555 530 510 500 460 500 500 450 400 350 300 250 200 150 100 80 50 40 25 DN DN Centre clearances between insulated pipes (Source: Mannesmann) Minimum clearance between insulation and pipe surface respectively approx. 50 mm Flanges are assumed as being offset to one another For media temperatures > 300 °C, centre clearances must be increased by 40 to 50 mm as of DN 50 D.8 Pipework E) Routing - mountings In the building and the steam boiler room respectively: Here, pipes should be routed as rectilinearly as possible (in the case of natural bends), close to supports and transverse beams. This facilitates the installation of necessary supports, mountings or brackets. According to the relevant regulations (see chapter E.1 - installation), attention must be paid to optimum accessibility, operation, maintenance and repair of individual components On a pipe bridge: Outside the building and the steam boiler room respectively, individual routing is preferred along the existing external building wall. When routing several pipelines (e.g. steam condensate, raw water and fuel pipes) from building to building over a "larger" distance, so-called pipe bridges should be employed Mountings: Taking account of necessary support spans, with reference to the expansion compensation that must be ensured, a diverse range of mounting designs are implemented in practice. Depending on the forces and torques to be supported, a demand-dependent decision is made between: Friction bearing designs, such as pipe clamps and pipe bearings clamped with bearing slides Friction bearing designs, force-guideda), as above, but "blocked" in one direction of motion (x and/or y direction) Fixed-point bearing designsb), for example clamped with bearing slide and/or welded together with bearing slide ("blocked" in x, y and z directions) Sprung mountings, implemented in the form of support and/or suspension mountings as an alternative version of friction bearing design for the purpose of absorbing a structurally veriﬁed vertical movement (+/- z direction) at the mounting point Fig. D.8.4–10 a) Friction bearing - positively guided, guide spacing (LSBG) according to empirical formula: LSBG ≈ 0.08 x DN (in m); for example, nominal pipe diameter DN 125; provision of a positively guided bearing design every LSBG ≈ 0.08 x 125 = 10 m for the purpose of preventing pipe "deﬂection" in the y direction. b) Maximum distance between ﬁxed points in [m] (rectilinear standard value) in the case of angular and U-bend expansion joints. See Fig. D.8.4-10. Mounting components DN ≤ [m] for: Angular ≤ [m] for: U-bend expansion joint expansion joint 50 to 80 50 100 100 to 150 70 140 200 to 250 80 160 300 to 350 90 180 ≥ 400 100 200 218/219 D.8.5 Notes on design engineering of selected pipework systems In the following, only pipework within the steam boiler room is considered. Statements and information provided are equally applicable to pipework systems outside the installation room, especially to those bearing steam and condensate. With particular reference to compliance with requirements according to AD 2000 regulations - datasheet HPOR Clause 7.4 A) Routing of pipework in the areas of operating and maintenance gangways must ensure unrestricted access in terms of compliance with headroom (according to TRD 403 ≥ 2000 mm) and passage height requirements. Routing of pipes directly above top edge ﬂoor (in the form of so-called "trip pipes") must be avoided. A conceivable alternative would be to lay or route the pipes in ducts. B) Regarding appropriate material selection with reference to the respectively expected operating temperatures, operating pressures (see chapter D.8.1.4) and rated pressure stages, the speciﬁcations and recommendations detailed in chapter D.8.2 must also be observed. D.8.5.1 Steam pipes / steam distributors Aside from suitability, one of the most important aspects in designing steam pipework systems and routing steam pipework is the operational reliability. Hence, the following recommendations are made on the basis of available empirical values: A) In principle, steam pipes must be routed sloping downwards in the ﬂow direction towards the required permanent drainage point (see below in B). This applies equally to heating steam and saturated steam pipes with a slope of no less than 1:200 to 1:100 or 0.5 to 1 %. The steam pipes of a single or multi boiler system are normally routed to a (common) steam distributor. The consumer pipes on the customer side should be connected here, in line with requirements, along with those for internal system demands (thermal deaeration system, space heating etc.) including spare connections, a connection for plant metrology and connection to a permanent drainage point (see steam distributor diagram for a recommended design). Note Do not select a lesser slope, otherwise drainage of the pipe sections would be hardly, if at all, possible due to the permissible pipe deﬂection (fperm) In principle, steam branch lines must be connected at the top of the main steam pipe in order to prevent ingress of draining pipe condensate D.8 Pipework Proposed steam distributor design ≥ ØF 2 D3 D4 D5 *) *) *) Hmin ØF Ø Fi V ØF 2 +275 E *) TI R *) Ø Fn Ø Fi PI ØF K1 D11) 2) D2 ~150 K1 ≥ Lmin D1 +150 2 Fig. D.8.5.1–1 K24) DN1 DN2 DN1 KH KT DN3 EL Key to Fig. D.8.5.1-1: D11) Steam distributor diameter in (mm) (see Fig. 8.5.1-2) D22) Condensate/sludge collector diameter in (mm) (see Fig. 8.5.1-2) D3 to D5 Connection internal diameters - steam boiler feed pipe in (mm) DN1 Residue drain nominal diameter, sludge and contamination removal (see Fig. 8.5.1-2) DN2 Permanent drainage and start-up drainage nominal diameter (selected: DN 20) DN3 Condensate drain pipe nominal diameter (selected: DN 25) TI/PI Temperature and pressure test port (local and remote display) V Consumer connections (customer) E Consumer connections (internal demands) R Spare connections (blank ﬂange) (normally approx. 0.25 x V) KOA K1 / K2 Basket and/or dished ends KH KT KOA Ball valve Steam trap (normally bimetal controller or ball ﬂoat) Condensate drain pipe (feed) into the existing condensate system Discharge into central drain network and/or system mixing cooler Flange external diameter in (mm) Flange external diameter "neighbouring" ﬂanges in (mm) Insulation thickness in (mm) EL ØF ØFi - Fn Dd Hmin3) Minimum ﬂange connection height in (mm) ≥ Lmin Minimum centre clearances in (mm) ≥ D1 2 ØF 2 + Dd + 100 + Ø Fi/n 2 + 100 220/221 Notes regarding 1) Pipe cross-sectional area ˭ 4 [ D12 ≈ 1.5 [ pipe cross-sectional area ˭ x (D32 + D42 + D52) 4 2) Central arrangement of the manifold below the consumer connections (V) 3) Design observing same spindle axle positions for the shut-off valves for *) 4) Alternative blank ﬂange connection for K2 Fig. D.8.5.1–2 Diameter and internal diameter for residue drainage D1 (mm) 125 150 200 250 300 350 400 450 500 600 D2 (mm) 80 100 100 100 150 150 200 200 200 250 DN 1 25 25 25 25 32 32 32 32 32 40 Fig. D.8.5.1–3 Steam distributor D.8 Pipework B) Drainage points (manual and/or automatic) are recommended before every change of direction upwards, at low points, at pipe ends and approx. every > 25 m to ≤ 100 m of straight pipe length. The drainage points are normally connected to the relevant condensate manifold and/or condensate collector taking into consideration the available pressure levels. The condensate arising from the steam pipeline drainage point is normally discharged into the open air due to the remoteness of the drainage point. superheated steam (≤ 50 K above saturated steam temperature), standard drains are just as suitable as those mentioned above. Special versions must be selected for superheating temperatures > 50 K. A standard drain could still be used if required, so long as the drain is situated approx. 1 to 2 m from the condensate connection and the pipe is left uninsulated. In order to ensure optimum condensate collection or drainage, the condensate collector connections are designed to be nearly as large as the straight-through internal diameter of the steam-bearing pipe. The speciﬁcations in Fig. D.8.5.1-4 and Fig. D.8.5.1-5 serve as a engineering aid here. Preferential use is made here of thermodynamic steam traps. Float and thermostatic traps would be better, but they are much more expensive. For slightly Fig. D.8.5.1–4 Nominal diameters of the steam and dewatering lines D1 50 65 80 100 125 150 200 250 300 350 400 450 500 600 D2 50 65 80 80 80 100 150 150 200 200 200 200 200 200 DN 1 20 20 20 20 20 20 20 20 20 20 20 20 20 20 DN 2 20 25 25 40 40 40 40 50 50 50 50 50 50 50 KON EW2 Fig. D.8.5.1–5 Diagram of dewatering line connection Steam pipe slope direction 1:100 (1:50) ~75 ≥ 250 D1 DN1 D2 DN2 EW1 a) Impairment to visibility due to expansion steam and risk of scalding must be prevented. Key: EW1 EW2 KOA Drain, blow-down into the open Start-up drainage Discharge to condensate collector 222/223 C) Ventilation of steam-bearing systems is normally provided at the end of the steambearing pipe and/or directly upstream of the consumption connection. Automatic air vent valves are preferred in this instance over manual ventilation. Makes, such as Gestra, and designs, such as bimetal controllers, diaphragm controllers and/or ﬂoat and thermostatic traps are recommended. For steam pipes in steam boiler rooms, no additional venting is necessary since it is part of the commissioning of the steam boiler. Note An air layer only 1/10 mm thick provides about the same resistance to heat transfer as a 10 mm thick layer of dirt on the heating surface. Furthermore, the entrained air (or rather its O2 content) fosters the corrosion of pipe and heating surfaces. D.8 Pipework D.8.5.2 Condensate pipes and systems In principle, condensate pipes must be routed sloping downwards in the ﬂow direction (due to possible expansion steam content) towards the condensate collector station (condensate collector pipe, condensate tank - open vented or sealed unvented). A minimum slope of 1:100 (1 %) is mandatory. In the case of supercooled condensate ≤ 95 °C (no re-evaporation), similar approaches apply with regard to necessary ﬂow cross-section sizing as for feedwater and other "hot-running" liquid media ≤ the respective boiling point (see chapter D.8.3.2). Sample calculation 2 Note Condensate as in sample calculation 1, but with: With the help of Fig. 8.1.1-1, this results in an TCON/E ≈ 158 °C before expansion internal pipe diameter di ≈ 70 mm. p CON/E ≈ 5.0 bar before expansion h'C/E ≈ 0.186 kWh/kg before expansion TCON/A ≈ 133 °C after expansion p CON/A ≈ 2.0 bar after expansion h'C/A ≈ 0.156 kWh/kg after expansion h''C ≈ 0.758 kWh/kg Enthalpy of expansion steam following expansion DE = 6000kg/h x The following variables are used in the equation speciﬁed in chapter D.7.2 for determining the expansion steam ﬂow rate (DE) instead of those used previously: A = CON Condensate mass ﬂow rate [kg/h] h'A/E = h'C/E Condensate enthalpy before expansion [kWh/kg] from [Tb. 2]a) h'A/A = h'C/A Condensate enthalpy after expansion [kWh/kg] from [Tb. 2]a) h''D/E = h''C Enthalpy of the expansion steam in [kWh/kg] from [Tb. 2]a) (0.186 kWh/kg - 0.156 kWh/kg) (0.758 kWh/kg - 0.156 kWh/kg) = 299 kg/h ≈ 15 m/s selected (according to wDE D.188.8.131.52 - standard values for ﬂow velocity) ≈ 0.606 m³/kg (from [Tb.2], Y''DE spec. volume) di = 2 x √ 299 kg/h x 0.606 m3/kg x 1 h ˭ x 15 m/s x 3600 s = 0.0654 m (selected: DN 65 > DN 40 with the following calculation results for: K &(K &$ '( &21[ K &K &$ >[email protected] Sample calculation 1 Condensate where TCON ≈ 95 °C CON ≈ 6000 kg/h w CON ≈ 1.5 m/s (selected according to D.8.3.1-1 standard values for ﬂow velocity) ˮ CON ≈ 962 kg/m³ (according to [Tb. 2]) GL [ a) Each as a function of the given condensate operating pressures. ෭ NJK[K ˭[NJP[PV[V PVHOHFWHG'1 sample calculation 1) 224/225 For the section of pipework between a consumer (e.g. heat exchanger) and the steam trap, standard practice is to select the internal diameter of the steam trap. Downstream from the steam trap, the decisive design variable (due to pressure reduction) for pipe crosssection sizing is the expansion steam ﬂow rate (DE) (see chapter D.7.2, plus Fig. D.8.1.1-1 and sample calculation 2 in chapter D.8.5.2). The aforementioned slope in the pipework should ensure that the condensate pipe drains in the event of system standstill. For the same reasons, inlet pipes into the collector should be inserted from above, if possible in the ﬂow direction. The additional provision of non-return valves is recommended here for the hydraulic separation of sections of pipework. Note Condensates from widely differing pressure stages should only be brought together following prior expansion of the hot condensate. Low points (so-called water traps) must be avoided at all costs in the routing of pipework due to an increased risk of water and frost damage. System-dependent low points must therefore be drained completely. All equipment and valves must be capable of "running dry". The use of so-called "expansion trap" condensate drains is recommended, particularly in external system areas. An expansion trap condensate drain, which is set for example to an opening temperature of around + 10 °C, opens automatically following system shutdown, as soon as the temperature drops to close to freezing point. If elevation of the condensate is required as a result of the system implementation (for example, routing of the main condensate collection pipe above the point where condensation occurs), the use of socalled condensate lifts and/or condensate compensators is recommended depending on the amounts of condensate involved. Elevating the condensate results approximately in a notable additional back pressure (PG) that must be overcome downstream from the trap of: pG ≈ 0.15 bar/m + pCON bar, where PCON positive pressure (bar) in the condensate collector pipe itself. Note The function of the condensate drainage system should be checked at least every six months (for ineffective steam blow through). The employment of electronic monitoring systems is recommended for this purpose, especially in the case of process-related large scale consumers on the customer side (example: Gestra type VKE 26 with NRG 16-27 electrode and NRA 1-3 inspection station with separate alarm). Speciﬁc additional reference is made to appropriate manufacturer's engineering materials for speciﬁc applications, in respect of selecting suitable condensate drain, lifting and transport systems. D.8 Pipework D.8.5.3 Boiler lye and blow-down lines Pipe routing each from steam boiler connecting ﬂange to connection and inlet to lye expander and mixing cooler respectively (see chapters C.8.1, D.7.1 and D.7.2). If, in the case of multi boiler systems, the pipes are routed to a common collector before feeding into the aforementioned thermal equipment, attention must be paid to a hydraulic separating mechanism at the feed-in point (installation of a non-return valve on each pipe). Where pipes are connected to a common collector, attention should also be paid to implementing the connections from above. The pipes must be routed with constant adequate slope in the ﬂow direction. As described in chapter D.8.5.2, a minimum slope of 1/100 (1 %) must also be ensured in this instance; the same applies to speciﬁcations regarding pipe cross-section sizing. In order to minimise hydraulic low-noise media discharge (particularly for the blow-down line), the level of the feed-in points on the mixing cooler should be provided as far as possible below the feed lines (mixing cooler positioning sunk below upper edge of the ﬂoor). Due to expected slight vibration and water hammer during operation, the pipes must be held in place securely by means of positive guides (force-guided friction bearing - see chapter D.8.4). Particular attention should be paid to unrestricted thermal expansion (structurally "soft" routing with an adequate number of natural pipe bends), whereby the connectors on the steam boiler and the thermal equipment must not be excessively stressed. Note With reference to only relatively short pipe lengths, pipe cross-section sizing under consideration of actual expansion steam is not recommended. Draining therefore takes place in the pipe in the form of a twin-phase ﬂow with speciﬁc phase separation (steam/water) in the lye expander or mixing cooler. Straightthrough internal diameters for the respective pipe must be selected in accordance with the connecting valve on the steam boiler. If the blow-down line needs to be routed more than 1 m vertically upwards in order to minimise water hammer, draining of the line at the lowest point is always recommended before every blow-down process. 226/227 D.8.5.4 Feedwater - softened water drinking water Necessary routing for: A) Feedwater - suction line From feedwater tank to connecting ﬂange (suction side) of the boiler feedwater pumps On routing, a constant downwards slope and the necessary feed pump inlet height (see chapter D.6) must be observed Taking account of adequate expansion compensation as a function of the permissible stresses (lateral forces and moments) for the pump inlet manifold in accordance with manufacturer speciﬁcations, if applicable, veriﬁcation necessary during engineering Provision of a drainage option at the pipe low point of at least DN 20 Pipe cross-section sizing according to chapter D.8.3.1 taking account of any applicable permissible total pressure loss of ≤ 0.5 mWC B) Feedwater - pressure line From boiler feedwater pump pressure port to feedwater inlet connector on the steam boiler and/or to the ECO connector in the case of ECO operation Provision of ventilation points at the pipe high points and residual water drainage options at the pipe low points of at least DN 20 Taking account of expansion compensation, as in A), but with reference to the pressure ports of the boiler feedwater pumps Pipe cross-section sizing, as in A), but with reference to a total pipe pressure loss up to steam boiler inlet of ≤ 0.1 x pB (with pB = steam boiler operating pressure), whereby the boiler feedwater pump pressure at zero head (maximum possible pump delivery pressure according to pump curve), which can be higher than the operating pressure (operating pressure ≈ 1.1 x pB, see chapter D.6), should be used as the basis for the wall thickness calculation C) Raw water - drinking water line From the customer-side connection point up to connection to the selected project-side CWT system (chemical water treatment system), in compliance with the necessary nominal pipe connection diameter (see also information in chapter D.8.3.1 - standard velocities) Pump-side implementation of a non-return device with respect to the customerside connection point in accordance with DIN 1988 by means of a non-return valve Assurance of necessary water ﬂow rate according to CWT type (see chapter D.4.3.1) at a minimum ﬂow pressure of 3.0 a) bar and a maximum pressure of 6.0 bar that must not be exceeded Provision of residue draining points (dewatering) of at least DN 15 to DN 20 at applicable pipe low points Expansion compensation considerations are irrelevant due to media temperature < 20 °C D) as in C), but with mixing cooler connection As a branch line from C) with branch connection point downstream from the non-return device in the ﬂow direction, guaranteeing the necessary cooling water ﬂow rate according to chapter D.7.1 a) Not including the back pressure from the thermal water treatment system. D.8 Pipework E) Softened water line From CWT system to connector on the deaerator Provision of an additional non-return valve in the ﬂow direction at the end of the line, directly upstream of the deaerator inlet Pipe connection nominal diameters (crosssection sizing), minimum ﬂow pressure and expansion compensation as in C) Fig. D.8.5.4–1 Ventilation/drainage line routing Slope Venting F) Ventilation/drainage line routing In order to entrain an air bubble in the ﬂow, a minimum ﬂow velocity ≥ 0.3 m/s is required for horizontal pipes Lines to ventilation equipment must be routed with an incline 1 : 200 Drain pipe routing: The minimum internal diameter for drain valves should be selected in such a way that "dirt" (mechanical contamination) can also be discharged. In practice, nominal diameters of at least DN 20 and selfcleaning valve seats have therefore proven to be effective. If need be, it should be possible to break through the valve (ball valve). Lines to drainage facilities must be routed with a fall Drainage and ventilation lines should be visible by routing them via a common tundish, with central discharge into the existing customer-side ﬂoor drainage system Slope 1 : 100 Drain (dewatering) 228/229 D.8.5.5 Exhaust vapour, waste steam and discharge pipes Necessary routing for: A) Exhaust vapour line From thermal deaeration system in the case of routing outside the building (via roof) Line routing with constant incline in ﬂow direction Line routing as short and straight as possible with sufﬁcient expansion compensation Pipe cross-section sizing with a recommended nominal diameter expansion above than the speciﬁed nominal deaerator connection diameter, but taking account of total pressure losses that must not be exceeded of ≤ 0.5 x pB/E (where pB/E is the available deaerator positive pressure) and maximum exhaust vapour output ( S/V ) according to chapter D.7.3 (see also chapters D.7.1 and D.8.3.1) from: di(req) ≥ 2 x √ a/DE x Y''S ZS(MAX) x ˭ [m] with calculation variables for: Maximum blow-down amount a ≈ 7.5 kg/s Operating pressure (pB) ≈ 13 bar Expansion to atmosphere ≈ 0 bar Proportion of re-evaporation (fDE) from [G2 Tb.6] of 17 %, corresponding to ฬ 0.17 kg steam /kgblow-down amount Expansion steam output - a/DE = a x fDE = 7.5 kg/s x 0.17 kg steam/kgblow-down amount = 1.275 kgsteam/s Speciﬁc volume Y''S of the expansion steam at atmospheric pressure from [Tb. 2] = 1.694 m³/kg Maximum selected ﬂow velocity limit w S(MAX) B) Ventilation - steam vapour - lines For condensate tank (open unvented), partial deaeration system and mixing cooler, the lines must be routed with a constant incline (via roof, outside building) from the connecting ﬂange on each device Line routing also as short and straight as possible with sufﬁcient expansion compensation Pipe cross-section sizing respectively in accordance with the connectors (nominal ﬂange connection diameters) speciﬁed here on the manufacturer side Note Sample calculation 1 ≈ 70 m/s (see note regarding 1) in chapter D.8.3.1) the required internal diameter for the ventilation line is: di(req) ≥ 2 x √ 1.275 kg/s x 1.694 m3/kg 70 m/s x ˭ ≥ 0.198 m Note With reference to a permissible positive pressure of 0.5 bar for the mixing cooler, this results in di(req)(0.5 bar) where Y''S(0.5 bar) ≈ 1.159 m³/kg of: GLUHTEDU ุ[ ෭ NJV[PNJ PV[˭ ุP and corresponds to the Viessmann factory speciﬁcations of DN 150. The cross-section sizing for the mixing cooler ventilation line must reliably cope with the discharge of the actual expansion steam from the steam boiler blowdown process "without" any appreciable back pressure to be expected. D.8 Pipework C) Safety valve (SV) - discharge pipes for: SV steam boiler SV thermal deaeration system SV economiser (if available and ﬁtted with shut-off devices) SV steam superheater (if available and ﬁtted with shut-off devices) each routed from SV connecting ﬂange with constant incline (via roof, outside building) Discharge pipes must be routed as short and straight as possible with sufﬁcient expansion compensation Discharge pipes must terminate without risk to bystanders No liquid (condensate, rainwater etc.) may accumulate in the discharge system, which must therefore be equipped with a dewatering line at the pipe low point (see drawing) that cannot be shut off Fig. D.8.5.5–1 Discharge system DNL Note SV blow-off silencer When blowing off safety valves (particularly steam boiler SV), unacceptable noise emissions may occur at the outlet points, depending on the blow-off pressure and discharge amount. Short-lived sound pressure levels in the range 120 to 132 dB(A) can be expected. According to regulatory requirements (TA-Lärm), employment of steam blow-off silencers with attenuation values (ΔdB(A)) of 30 to 50 dB(A) is recommended. EXR On the outlet side, it is recommended that the discharge pipe is increased in size by at least one nominal diameter (see drawing), although the following notes must also be considered: - Discharge of the steam mass ﬂow ( FS), without the respective permissible operating pressure increasing at the same time by more than 10 % - Safety valve => saturated steam boiler ≥ FS (as boiler output) - Safety valve => superheater ≥ 0.25 x FS - Safety valve => thermal deaeration ≥ FS (as required amount of heating steam see chapter D.10.2) Diameter DNL and length of pipe, existing bends and other inbuilt parts (silencer maybe), should also be sized in such a way that the back pressures speciﬁed by the manufacturer for the respective SVs are not exceeded and the required steam mass ﬂow can therefore be discharged safely Back pressure > 0.15 x pA (where pA is the set SV discharge pressure) should therefore not be exceeded DNA Distance from connector to weld seam must be Together with the previously mentioned noise emission from the valve, the expected noise load is largely determined by the outlet velocity. Hence, the maximum velocity speciﬁed in chapter D.8.3.1 should not be exceeded. approx. 50 mm Key: DNA SV outlet nominal diameter DNL Discharge pipe SV nominal diameter (recommended: DNA + 1 x increase in nominal diameter) DNE Drainage nominal diameter (recommended.: DN 15 to DN 25) EXR Eccentric reduction in nominal diameter The discharge pipes must be sized and routed, taking into consideration the given operating conditions, in such a way that the static, dynamic (reaction and/or repulsive forces) and thermal loads are absorbed safely. Corresponding documentation must be maintained here on the engineering side. It is recommended that the safety valve(s) is/ are mounted accordingly as (a) ﬁxed point(s). Appropriately designed sprung supports (see also chapter D.8.4) should be used to compensate for any vertical movement in the pipes. The installation and assembly instructions from the respective safety valve manufacturer must also be observed. 230/231 Information regarding routing via the roof Roof outlet with thermally insulated, silenced slide coupling (vertical friction bearing) and protection against precipitation (rain collar). Single and/or double-sided obtuse-angled outlet terminal (see Fig. D.8.5.5-2/3/4): Fig. D.8.5.5–2 Version A Note regarding regulations that must also be observed TRD 421, particularly Clause 6, and DIN EN 12953-8, particularly Clause 4.2. Fig. D.8.5.5–3 Version B '1/ '1/ ~ 120 ° ~ 120 ° )5 '1/ '1/ Fig. D.8.5.5–4 Version C With version B preferred If version A is selected, the bending moment arising due to the power of repulsion FR at the roof outlet must be considered. Version C Wall outlet with thermally insulated, silenced slide coupling (horizontal friction bearing). FR DNL Disadvantages: Provision must be made for installation and/or retroﬁtting of a silencer. Increases the bending moment to be absorbed by the vertical pipe leg. External wall DNL D.8 Pipework D.8.5.6 Fuel lines A) General information Pipes are considered from each point of entry into the building up to connection to the combustion system valve train for extra light fuel oil and natural gas (E) Design of the respective connection sizes according to speciﬁcations for the combustion system to be implemented (gas and/or fuel oil combustion) as a function of the required combustion output according to chapter D.3.3.1 Sizing the feed pipes with reference to the recommended standard values for ﬂow velocity according to chapters D.8.3.1 and D.8.3.2 Design of the fuel oil line from the customer-side fuel oil tank to the combustion system and back to the fuel oil tank as a so-called ring pipeline. The fuel oil circulating through the ring pipeline is maintained at a constant pressure of between 1.0 and 2.5 bar by appropriately sized pressure control valves Recommended sizing of the ring pipeline for approx. 1.5 to 2.5 times (depending on system size) fuel demand સ B, with the higher supply rate (including spare capacity) being the design basis for the feed pump to be provided on the customer (project) side Combustion-side (burner) connection to the ring pipeline via so-called gas/air separator that must be sized accordingly on the project-side Ventilation and drain lines (recommended: DN 15 to DN 20) must be discharged into sealed unvented tanks (such as slop tanks) in a controlled manner (in accordance with [German] Water Resources Act) and supplied to a form of reuse (via pump return feed) The ventilation and discharge pipes from the gas valve section(s) must be routed separately, in accordance with manufacturer speciﬁcations, with a constant incline to the building exterior (exterior wall outlet preferred) If dewatering devices are necessary on the gas line (due to expected gas condensate, if applicable), any escaping gas must also be dissipated safely Pipe supports and the spacing thereof must be designed in accordance with chapter D.8.4 Expansion compensation must be ensured by the expected natural pipe bends in the system and for unexpected ambient temperatures > 40 °C B) Speciﬁc information for extra light fuel oil (HEL) lines With reference to the Pressure Equipment Directive 97/23/EC, the ﬂuid (HEL) is assigned to Group 2 With expected pressures ≤ 3.0 bar and expected straight-through nominal diameters signiﬁcantly < DN 100, the pipework system (assignment) is executed according to Article 3 Paragraph 3, which states: "In the case of good engineering practice..." (see also notes in chapter D.8.1.3) "Good" engineering practice is considered to have been delivered subject to compliance with and implementation of regulation TRD 411 - Oil combustion systems on steam boilers, in particular Clauses 6.1, 6.2, 6.3 and 7.1 - safety shutoff devices, as well as: DIN EN 12953-7, particularly Clauses 4.2 and 4.3 with reference to DIN EN 267 Pressure-jet oil burners C) Speciﬁc information on gas lines With reference to the Pressure Equipment Directive 97/23/EC, the ﬂuid (natural gas E) is assigned to Group 1 With expected pressures ≤ 4.0 bar and expected straight-through nominal diameters signiﬁcantly > DN 25 to ≤ DN 350, the pipework system (assignment) is implemented according to Categories I to II, or Category III for straight-through nominal diameters > DN 350 (see also notes in chapter D.8.1.3) The regulations TRD 412 - Gas combustion systems on steam boilers, in particular Clauses 4 and 5.1 - shut-off devices outside the boiler installation room, must also be observed, as well as DIN EN 12953-7, particularly Clauses 4.2 and 4.3 with reference to DIN EN 676 Pressure-jet burners for gaseous fuels 232/233 D.8.5.7 Waste water and ﬂoor drainage systems It must be possible to drain the technological waste water arising in the system safely via an on-site (customer-side), centrally implemented drain network, according to the rules of good engineering practice. Suitable drainage facilities (ﬂoor traps) must be provided for this purpose on the project side at the locations described in the following. The fall of the pipes (ground pipes) should be selected to be no less than 1:50 (2 cm/m) in the ﬂow direction. A) Steam boiler Positioning at the end of the steam boiler approx. 500 mm to the right (from burner viewpoint), next to the base frame, with a recommended inlet of DN 100 for feeding in: Incoming ﬂue gas condensate (short-lived from the steam boiler system start-up phase) Note: (see also chapter D.2.3.3), Flue gas condensates with a pH value < 6.5 must always be routed through a neutralising system (to be provided on the project side) before entry Incoming condensates from the discharge pipe safety valve Ventilation facilities, feedwater line drains Steam boiler ventilation Blow-off and dewatering line from manostats, distributors and reﬂection water level Drainage, waste water from sampling cooler (intermittent, maximum once per 8 h shift at ≤ 0.25 l/s) Economiser ventilation/drainage Note B) Feedwater tank - condensate tank Positioning subject to the selected location (installation plan) directly at the overﬂow pipe exit with a recommended point of entry ≥ DN 100 to ≤ DN 125, depending on system size, for feeding in: Incoming overﬂow outputa) Any necessary containerb) and/or tank contents in the event of repair and maintenance Incoming condensates from the discharge pipe safety valve Blow-off and dewatering lines from level displays Drainage (draining residue) from feedwater suction line Drainage from boiler feedwater pumps The points of entry must also be capable of accepting any waste water from the sanitation area (e.g. spray water from ﬂoor cleaning). a) Maximum expected overﬂow rate in kg/h ≤ 0.5 x FS (where FS is the steam boiler output in kg/h). b) See Fig. D.4.1.2-1. D.8 Pipework C) Mixing cooler - lye expander Positioning subject to the selected location (installation plan) directly at the mixing cooler outlet pipe exit with a recommended point of entry ≥ DN 100 to ≤ DN 150, depending on system size, for feeding in: Any necessary residual drainage of tank content (mixing coolera) and/or lye expander) Any necessary residual drainage from the steam boiler The continuously incoming waste water output ( A in kg/h) from the mixing cooler (see also chapter D.7.1) depending on steam boiler output ( FS in kg/h), the necessary T.D.S. rate (A in %), the T.D.S. water temperature (TA in °C) as inlet temperature into mixing cooler, the selected waste water outlet temperature (T WW/A in °C) from the mixing cooler and the actual cooling water temperature (TCW in °C) as inlet temperature into mixing cooler, from: a) Container capacity, see chapters D.7.1/D.7.2. $ )6[ $ 7$7::& 7::&7&: NJK (disregarding the only intermittent blow-down output (a), for example: FS = 25,000 kg/h; A = 5 % TA = 105 °C TWW/C = 30 °C TCW = 15 °C => A ≈ 7500 kg/h as before, however, with: FS = 4000 kg/h; => A ≈ 1200 kg/h as before, however, with maximum 3 x 25,000 kg/h ≈ 22,500 kg/h A Notes regarding the sample calculations: This should be subjected to a repeated plausibility check for the recommended inlet DN range. At a T.D.S. rate of A > 3 % to ≤ 6 %, the size of the point of entry must be increased, in the case of maximum boiler output (FS ≥ 25 to ≤ 75 t/h), to DN150 and/or an additional lye cooler (waste heat utilisation) is advisable according to the amortisation calculation in chapter D.7.1, with the objective of minimising the necessary cooling water requirement. 234/235 D) Chemical water treatment system (CWT) Positioning subject to the selected location (installation plan) directly (approx. 500 mm) in ﬂow direction upstream of the "open air" waste water connection with a recommended point of entry, depending on CWT size, ≥ DN100 to ≤ DN125 for expected intermittent amounts, once per system regeneration and full-load operation once per shift (7 to 8 h), in accordance with the following tabular speciﬁcations (approximate): Fig. D.8.5.7–1 Size of the CWT in case of incoming waste water Size (see also Viessmann datasheet) Amount of ﬂushing water per regeneration (m³) Flushing water throughput (m³/h) Fig. D.8.5.7–2 60 120 200 320 400 500 0.11 0.22 0.375 0.6 0.75 0.9 0.3 0.5 0.5 0.9 0.9 1.2 Size of the CWT in case of incoming waste water Size (see also Viessmann datasheet) Ventilation drainage lines (residual(m³) Amount ofand ﬂushing water per regeneration drainage) must also be fed into the design Flushing water throughput (m³/h) point of entry. 600 800 1000 1400 3000 4500 1.1 1.42 1.82 2.55 5.5 8.0 1.6 1.6 2.7 2.7 5.8 7.5 E) Reference to regulations During the engineering of the central drain network, appropriate preventive measures must be taken, with respect to possible use of "fuel oil" as the fuel, against discharge of fuel oil (in case of accident, leakage etc.) into the drain network (for example, use of ﬂoor inlets with fuel oil traps). In principle, standard works, such as: DIN 1986 - Drainage systems on private ground - Part 100: Speciﬁcations in relation to DIN EN 752 and DIN EN 12056 DIN 1999 - Installations for separation of fuel oil, in conjunction with DIN EN 858 DIN 4043 - Traps for light liquids (fuel oil traps) must be observed D.9 Flue system Flue system The ﬂue system, with connection to the ﬂue outlet of the steam boiler, usually consists of the continuously rising ﬂue pipe with built-in parts up to the system chimney connection (stack). Built-in parts, in this instance, are considered to be the necessary deﬂections (bends), expansion joints, silencers and ﬂue gas dampers with actuators for isolating the steam boiler on the ﬂue gas side and/or controlling ﬂue gas pressure (combustion chamber pressure regulation). Flue systems must be designed in accordance with national and local regulations, as well as the relevant standards. General requirements for ﬂue systems in and on buildings are speciﬁed in DIN EN 1443. The design must comply with the applicable national building regulations, DIN 18160 and TRD 403 Clause 7. Apart from the building regulations, DIN 1056, DIN 4133 and DIN EN 13084-1 apply in the case of freestanding chimneys. Hydraulic measurements must be carried out in compliance with the standards DIN EN 13384 and DIN EN 13084 (for freestanding chimneys). The following sections contain general recommendations for the design of ﬂue systems, which guarantee uninterrupted operation of the combustion system employed. Non-observance of these rules could lead to the occurrence of, in part, substantial operational problems. Frequently, these are acoustic faults and/or impairments of combustion stability or excessive vibration of parts and/or their components. 236/237 D.9.1 Deﬂections in the connection pieces must be designed for optimum ﬂow with appropriate pipe bends (≤ 90° pipe bends) Connection pieces with several deﬂections should be avoided, since they have a negative impact on air and structure-borne noise, as well as the "start-up pressure surge" (combustion back pressure) A transition angle of ≤ 30° is recommended for any necessary transitions (reductions/expansions) from round to angular connection, e.g. silencer connection and/or chimney The material used for the connection pieces (including built-in parts) must be suitable for a ﬂue gas temperature of up to 350 °C Planning and design information for connection pieces The ﬂue gas from the combustion system must be routed directly to the chimney with as little pressure and heat loss as possible. The connection pieces to the chimney must therefore be designed for optimum ﬂow (rectilinear, short and rising with a minimum number of deﬂections) and with appropriate thermal insulation (see [A2]). Any arising thermal expansion and reaction forces on the chimney must be compensated by the installation of expansion joints (here with the preferred use of fabric expansion joints due to the unreliable reaction forces to be expected) or slide couplings. Due to their excellent vibration and pressure resistance, the use in principle of pipes (welded pipe according to DIN EN 10217-2 and/or rolled as cylinder jacket pipe) in the wall thickness range ≥ 4.0 to ≤ 8.0 mm is recommended. The internal diameters (straight-through nominal diameters) of the ﬂue pipe (connection pieces) must be selected in accordance with the ﬂue gas connection diameter of the respective steam boiler (see Fig. D.9.1-1). Fig. D.9.1–1 Flue outlet diameter of the Vitomax steam boilers Steam boiler output (FS) (t/h) Flue gas connection internal diameter (mm) 0.7 1.15 1.75 2.9 4.0 6.0 8.0 11.0 14.0 18.0 22.0 to to to to to to to to to to to 0.9 1.4 2.3 3.8 5.0 7.0 10.0 12.0 16.0 20.0 25.0 240 290 340 440 600 700 800 900 1000 1100 1200 D.9 Flue system Note In the case of intended falling below the dew point (utilisation of condensing technology see speciﬁcations in chapter D.2.3.3), expected mediaa) temperatures "permanently" < 90 °C and a sulphur content in the fuel > 0.2 percent by weight, the use of corrosion-resistant materials (stainless steels) is absolutely essential (DIN 51603). supports" for straight-through nominal diameters > DN 800) are the preferred design here and/or friction bearings with spring supports (see also chapter D.8.4) Test ports (emission test points) must be provided at suitable locations. The gas sampling deﬁned in VDI guidelines (VDI 4200) must be implemented, taking account of any applicable statutory speciﬁcations On installation of a ﬂue gas damper (as described in the introduction to chapter D.9), a safety-oriented "OPEN" limit switch must be integrated into the steam boiler control system During the engineering process, attention should be paid to allowing the unrestricted drainage of ﬂue gas condensate along the whole length of the connection pieces (also in the chimney itself), as dealt with in ATV datasheet 251, ensuring its disposal subject to relevant local provisions In order to prevent ﬂue gas discharge at the dewatering connectors provided for this purpose, installation of an approx. 100 mm so-called "water trap pipe" is recommended In the event of steam boiler system standstill and outside temperatures below freezing, the risk of frost damage must be prevented Cleaning apertures must be provided in accordance with DIN 18160-1, DIN 18160-5 and IVS Guideline 105, and their installation positions speciﬁed in cooperation with the responsible ﬂue gas inspector Pipe supports (compliance with necessary support spans) must be provided in accordance with the required structural documentation. Friction bearings (if applicable, in the form of so-called "saddle Fig. D.9.1–2 Note Locking of the damper with combustion. An opened damper is a prerequisite for commissioning the steam boiler. After shutting down the system, if applicable, the end position "damper CLOSED" should be set in such a way that the damper does not close tightly (approx. 5 % in "open" position), so that short-lived residual heat is allowed to escape from the combustion chamber via the ﬂue system. Wall outlets must be thermally insulated and protected from the elements in the form of a sliding mount through a wall sleeve and skid support (see Fig. D.9.1-2) Sliding shoe mounting a) Assumption, expected media temperatures ฬ feedwater inlet temperatures in the unalloyed economiser (ECO type 100 and/or type 200). Key: WH - Wall sleeve with wall anchor at x) DNV - Connection piece (pipe) straight-through nominal diameter DD WS ΔL GLK - Required insulation thickness Weather protection Pipe sliding movement Skid (3 x 120°) 238/239 D.9.2 Sizing the ﬂue system The basis for ﬂow-related sizing is provided by standards DIN EN 13384 and/or DIN EN 13084-1 In order to prevent ﬂow noises in the ﬂue system, ﬂow velocities with reference to the operating volume [in m³/h] and full-load operation should not exceed 12 to 15 m/s in practice The combustion system is designed in such a way that the resistances of the steam boiler on the ﬂue gas side, including economiser (ECO) plus the expected resistances for ﬂue pipe and silencer, can be overcome (see chapter D.9.2-1 and D.9.2-2 resistance values for steam Note For a freestanding chimney according to DIN EN 13084-1, appropriate structural documentation must be furnished by the manufacturer. In the ﬁnal analysis, the resulting lateral forces and moments at the chimney base are fundamental for chimney stability, which must be veriﬁed (on-site) on the projectside (sizing the necessary anchor cage and foundations; provision of a ground survey with reference to the installation location on the customer side) The anchor cage is designed to provide a structurally stable support for the chimney on the base foundations via a threaded fastening, with connection of the necessary chimney earthing (lightening protection) to the conductor system to be provided on the customer side. boilers), so that a manometric pressure of ± 0 mbar (up to a recommended slight positive pressure of 1 mbar) is present at the chimney ﬂue gas inlet connector Pressure drop on the hot gas side (ΔpHG) as a function of the steam boiler output (FS) with and/or without economiser operation for the boiler type: Fig. D.9.2–1 Boiler type M237 / M73A ΔpHGa) [mbar] M73A FS [t/h] with ECO 200 without ECO 0.5 5 4.5 0.7 6 5 1.0 8 6.5 1.3 9.5 7.5 1.65 11 9.5 2.0 12 10.5 2.5 13.5 11 3.2 4.0 14 16 12 13 Guide values; see datasheet for precise details Fig. D.9.2–2 Boiler type M 75A ΔpHGa) [mbar] M 75A FS [t/h] with ECO 200 without ECO 5 10 17 6 11 16 7 11 15 9 12 17 10 13 18 12 15 17 14 15 17 17 17 18 22 18 15 25 18 14 20.0 18.5 14.5 22.0 18.5 14.0 25.0 18.5 14.0 Guide values; see datasheet for precise details a) Assumption, each plus approx. 1.5 to 5.0 mbar for built-in parts, including silencer, at ﬂow velocities between 10.0 and 15 m/s as a practical guide value. D.9 Flue system D.9.3 Chimney connection and design Freestanding chimneys must be designed with a structurally supportive outer pipe (made from unalloyed sheet steel) and a thermally insulated inner ﬂue (made from alloyed stainless steel). Connection pieces must be inserted into or connected with the chimney with an incline in the ﬂow direction at an angle of ≥ 30° to ≤ 45° In the case of a design with multiple connections (see below in chapter D.9.4), chimney connections opposite one another or at the same height must be avoided Any attachments present at the stack opening must guarantee unrestricted emission of the ﬂue gases into the open air A separate ﬂue must be included in the design for each steam boiler Notes For chimneys with multiple ﬂues comprising one supporting pipe and several thermally insulated inner ﬂues, the height is determined in principle on the basis of the applicable TA-Luft for: Systems not requiring ofﬁcial approval (1st German Immissions Order - BImSchV) by the district ﬂue gas inspector, and for Systems requiring ofﬁcial approval (4/13 BimSchV) by the responsible [German] Regional Ofﬁce for Health Protection and Technical Safety (LAGetSi) or the responsible factory inspectorate on the basis of an air/climatological report that must be prepared a) Bracketed expression, conversion of standard volumetric ﬂow rate into operational volumetric ﬂow rate, disregarding the operating pressures. The chimney and ﬂue system are designed on the basis of system-speciﬁc ﬂue gas parameters, such as operational volumetric ﬂow rate (V̇ FG in m³/h), ﬂue gas temperature (in °C) and the pressure conditions (positive pressure) in mbar inside the ﬂue, as well as the required negative pressure in mbar at the chimney-ﬂue connector on determination of the operational volumetric ﬂow rate (V̇ FG) as follows: 9 ɘ )* )6[5 ˮ)* [[7)*D[PK] with the calculation variables: FS Nominal fresh steam output from the steam boiler (kg/h) ˮFG Mean ﬂue gas density according to [L4] ≈ 1.345 kg/Nm³ R Dimensionless factor for determining the amount of ﬂue gas according to Vitomax 200 HS datasheet (see table Fig. D.9.4-1 and Fig. D.9.4-2) 7FG Flue gas temperature in [°C] (see table Fig. D.9.4-1 and Fig. D.9.4-2) as a function of the operating steam pressure with and/or without ECO operation 240/241 Fig. D.9.4–1 Vitomax 200-HS, type M237 / M73A Operating Vitomax 200-HS, type M237 / M73A pressure [pB] R [-]a) in bar TFG in [°C]b) without ECO with ECO 100 with ECO 200 without ECO with ECO 100 with ECO 200 6.0 1.094 1.053 1.032 246 168 126 8.0 1.105 1.060 1.038 256 172 127 10.0 1.1135 1.065 1.042 265 174 129 13.0 1.1235 1.070 1.0475 276 178 132 16.0 1.132 1.075 1.052 284 182 135 18.0 1.137 1.078 1.0535 290 184 137 20.0 1.141 1.081 1.0565 295 187 139 22.0 1.144 1.083 1.058 299 190 141 25.0 1.148 1.086 1.061 308 194 145 Fig. D.9.4–2 Vitomax 200-HS, type M75A Operating Vitomax 200-HS, type M75A pressure [pB] R [-]a) in bar TFG in [°C]b) without ECO with ECO 100 with ECO 200 without ECO with ECO 100 with ECO 200 6.0 1.083 1.0525 1.030 226 168 126 8.0 1.094 1.058 1.037 235 172 128 10.0 1.100 1.063 1.0415 246 174 131 13.0 1.109 1.068 1.045 254 177 133 16.0 1.1175 1.073 1.0485 264 182 136 18.0 1.1235 1.076 1.0525 272 184 138 20.0 1.1265 1.078 1.053 275 187 140 22.0 1.130 1.081 1.054 278 190 142 25.0 1.134 1.084 1.056 287 194 145 Note: Intermediate values linearly interpolated a) Mean values for designing the ﬂue system according to DIN EN 13384. b) At full load (100 %), 3 % O2 in ﬂue gas and feedwater temperature 102 °C. D.9 Flue system D.9.4 Note The following must not be connected to multiboiler ﬂue systems: Steam boilers with ﬂue gas temperatures > 400 °C Liquid gas combustion systems Combustion systems equipped with fans, if all the steam boilers are not installed in the same room Common ﬂue system, merging of ﬂue gas ﬂows Several steam boilers (combustion equipment) may only be connected to a common ﬂue system, in accordance with DIN EN 12953-7, if the combustion system in conjunction with the steam boiler is suitable for such an operating mode and the following requirements can also be complied with: Sizing of the system for guaranteed discharge of the ﬂue gases in every operating state and load case Prevention of ﬂue gas inﬂow into offline steam boilers in the case of positive pressure operation, e.g. using tightly closing ﬂue gas dampers Constant combustion chamber pressure conditions in each of the connected steam boilers and in every operating state Minimum ﬂue gas velocities according to DIN EN 13084-1 (wmin ≈ 0.5 m/s) Merging of ﬂue gas ﬂows should however be avoided, since the creation of negative pressure in the chimney can be impeded in the event of large reductions in load, e.g. ≤ 30 %. Flue gases would then no longer completely ﬁll the chimney and "cold" air could "fall" into the stack. If a decision is nevertheless made in favour of merging, it must be ensured that the ﬂue gas ﬂows (connection pipes) are merged unidirectionally in a so-called Y piece (Fig. D.9.4-1). The chimney system ﬁnally employed for the project must guarantee reliably stable system operation, on the basis of the air/ climatological conditions to be expected at the location, in conjunction with speciﬁed ﬂue gas parameters and system load characteristics. Documentation (control calculation) of the draught calculation for the selected chimney system must be prepared on the project side in accordance with DIN 13384 and/or DIN 4705. The following technical data must be observed on the project side for the (if applicable) already selected chimney system, focussing here on ofﬁcial speciﬁcations regarding: Compliance with noise emission levels Chimney height above ground level Immissions forecasts according to TA-Luft 242/243 Fig. D.9.4–1 Y piece Fig. D.9.4–4 Chimney Chimney (dia. internal chimney ﬂue ≥ DN) Fabric compensator (DN ฺ DN2 + DN1) Key: Chimney stack inner ﬂue ≥ DND ཱ Fabric expansion joint ི Y piece DE1 Steam boiler connection 1 DE2 Steam boiler connection 2 Y piece DN2 Flue gas connection, steam boiler 2 DN1 a60˚ to 90˚ Flue gas connection, steam boiler 1 Source: SES Fig. D.9.4–2 Y piece Source: SES Fig. D.9.4–5 Chimney base Source: SES Fig. D.9.4–3 Chimney connection Source: SES a) DN >/= DE1 + DE2 D.10 Internal system demand Internal system demand With reference to the speciﬁcations in chapter C.11, the necessary internal system demand for electrical and thermal energy must be considered in the project. In the following, appropriate speciﬁcations are recommended as standard values and information is provided for a possible calculation. D.10.1 The need for a redundant power supply, as a function of necessary uninterrupted steam provision (for example, in a hospital), must be identiﬁed by the customer at an early stage during the project preparations. Internal electrical system demand The power supply on the customer side is generally rated at a voltage level of 0.4 kV to 0.6 kV and a frequency of 50 Hz with connection to the central system control panel provided by the manufacturer. Voltage-related provision of power to all consumers in the steam generation system is governed on the manufacturer side from the aforementioned central system control panel. For the purpose of ensuring provision from the steam generation system in line with demand, a corresponding list must be prepared within the project (see following tabular overview Fig. D.10.1-1). 244/245 Fig. D.10.1–1 List of electrical consumers Consecu- Consumer No. of Voltage Output Control tive no. (components) (pce) (Volt) (VA) signal Comments 1.0 Componentsa) 1.1 Burner With and/or without Type: inverterb) 4 - 20 mA 1.2 1.3 Combustion air fan With and/or without Type: inverterb) Flue gas recirc. fan With and/or without Type: 1.4 Boiler feed pump inverterb) With and/or without c) Type: 1.5 Condensate pump (open vented system) inverterb) c) Type: 1.6 Condensate pump (sealed unvented system) With and/or without c) Type: 1.7 inverterb) HEL pumps Type: 1.8 Fuel oil preheating Only if heavy oil used Make: 1.9 CWT incl. dosing system (I&C technology) 4 - 20 mA Type: 1.10 TWT (I&C technology) 4 - 20 mA Type: 1.11 Mixing cooler (I&C technology) 4 - 20 mA Type: etc. (the list can be extended as necessary at any time) 2.0 Actuatorsa) 2.1 Flue gas damper 2.2 Feedwater control valve(s) 2.3 4 - 20 mA 4 - 20 mA Superheater mixing valve Type: Make: Type: Make: Type: 4 - 20 mA Make: (if installed) 2.4 Heating steam valve/slider 4 - 20 mA Type: Make: 2.5 Blow-down valve 4 - 20 mA Type: Make: etc. (the list can be extended as necessary at any time) a) All equipment (motors, sliders, valves etc.) and automatic systems (automatic switching, controllers and control voltage activators) must be designed with "on" and "off" or "open" and "closed" feedback signals. b) In the case of inverter operation, disruptive circuit feedback in the form of harmonics must be prevented. c) Prior determination of the necessary drive output as a function of the respective pump rate is required (see chapter D.6.1 - boiler feedwater pumps and D.6.2 - condensate pumps) - see also chapter D.10.1.-3. D.10 Internal system demand Fig. D.10.1–2 List of electrical consumers Consecu- Consumer No. of Voltage Output Control tive no. (components) (pce) (Volt) (VA) signal Comments 3.0 I&C systems 3.1 Steam boiler 3.2 Condensate system 4 - 20 mA Type: (open) 3.3 Condensate system (closed) 3.4 External: Emergency stop button Entrance area installation room 3.5 External: Leak detector - oil Fuel depot - customer 3.6 External: Before entry to Quick-acting safety valve - gas installation room External: Fuel depot - customer 3.7 Quick-acting safety valve - oil 3.8 etc. External: Flue gas Chimney system emission measurements (if installed) (the list can be extended as necessary at any time) 4.0 Lighting and TGA systems 4.1 Installation room lightingd) 4.2 Installation room emergency lightingd) 4.3 Installation room ventilation facilities etc. (the list can be extended as necessary at any time) 5.0 Lightening protection systeme) etc. d) According to TRD 403 Clause 10, with particular reference to accident prevention regulations "electrical systems and operating equipment" (VBG4). e) According to TRD 403 Clause 11.2 (DIN 57 185, VDE 0185). Implementation on the customer side from supply sub-distribution unit If required Customer-side implementation if required (the list can be extended as necessary at any time) 246/247 Overview of expected electrical output (kW) pump motor as a function of steam boiler output (FS) and operating pressure (pB) Fig. D.10.1–3 Expected electrical output - overview pB FS in [t/h] bar 0.7 0.8 1.0 1.3 1.65 2.3 2.9 3.8 4.0 5.0 6 0.25 0.32 0.40 0.50 0.60 0.80 1.00 1.40 1.40 1.80 8 0.33 0.42 0.54 0.66 0.82 1.10 1.36 1.80 1.90 2.30 10 0.41 0.53 0.57 0.82 1.10 1.35 1.70 2.20 1.30 2.90 13 0.53 0.70 0.87 1.10 1.33 1.75 2.20 2.90 3.00 3.80 16 0.66 0.84 1.10 1.30 1.64 2.20 2.70 3.60 3.75 4.70 18 0.74 0.95 1.20 1.50 1.85 2.40 3.00 4.00 4.20 5.30 20 0.82 1.05 1.35 1.65 2.05 2.70 3.40 4.50 4.70 6.00 22 0.90 1.20 1.50 1.80 2.30 3.0 3.70 4.90 5.20 6.40 25 1.03 1.30 1.70 2.10 2.60 3.40 4.30 5.60 6.00 7.30 8.0 10.0 12.0 14.0 16.0 18.0 20.0 22.0 pB FS in [t/h] bar 6.0 7.0 25.0 6 2.00 2.50 2.80 3.50 4.00 5.00 6.00 6.00 7.00 8.00 9.00 8 2.80 3.20 3.80 4.70 5.60 6.60 7.50 8.00 9.00 10.00 12.00 10 3.50 4.10 4.70 5.80 7.00 8.20 9.40 11.00 12.00 13.00 15.00 13 4.60 5.30 6.10 7.60 9.00 10.70 12.20 14.00 15.00 17.00 19.00 16 5.60 6.60 7.50 9.40 11.00 13.00 15.00 17.00 19.00 21.00 23.00 18 6.30 7.40 8.40 10.50 12.70 15.00 17.00 19.00 21.00 23.00 26.00 20 7.00 8.20 9.40 12.00 14.00 16.00 19.00 21.00 23.00 26.00 29.00 22 7.70 9.00 10.30 13.00 15.50 18.00 21.00 23.00 26.00 28.00 32.00 25 9.00 10.00 12.00 15.00 18.00 20.00 23.00 26.00 29.00 32.00 37.00 Assumptions Pump efﬁciency 75 % Supplement for pump shaft output 15 % Output values rounded D.10 Internal system demand Fig. D.10.2–1 System diagram D.10.2 TWT Steam boiler CWT Internal thermal system demand From the heat and mass statement, around the thermal deaeration system, with the assumptions: Operation without exhaust vapour condenser Operation without feedwater or lye cooler Operation with lye expander and waste steam utilisation Speciﬁc thermal capacity (cp) of condensate = feedwater = - constant ≈ 4.19 kJ/kgK - or 1.163 x 10 -3 kWh/kgK a value results for the required amount of heating steam (FS/E) as an internal thermal demand (Q̇FS/E) from: 4 ɘ )6( 4 ɘ &214 ɘ DGGIZ4 ɘ 94 ɘ 65>N:@ where Q̇CON Heat required for heating up the return condensate in [kW] based on feedwater temperature (Tfw) Q̇CON = CON x cp (Tfw - TCON) Q̇ADD/FW As for Q̇CON but for heating up the additional feedwater (softened water from the CWT) Q̇add/fw = add/fw x cp (Tfw - Tadd/fw) Q̇V Amount of exhaust vapour heat in [kW] as lost heat (deaerator exhaust vapour outlet (S/V) Q̇V = S/V x (h''V - cp x Tfw) Q̇SR Amount of heat recovered in [kW] from the T.D.S. expander Q̇SR = S/V x (h''SR - cp x Tfw) 248/249 therefore: )6([K )6FS[7IZ &21[FS[7IZ7&21DGGIZ[FS[7IZ7DGGIZ69[K 9FS[7IZ65[K 65FS[7IZ and: )6( FS[>&21[7IZ7&21DGGIZ[[email protected]69[K 9FS[7IZ65[K 65FS[7IZ K )6FS[7IZ with the individual calculation variables for: Condensate return rate [kg/h] CON TCON Condensate temperature in [°C] Tfw Feedwater temperature in the deaerator as saturation temperature as a function of deaerator positive pressure [see Tb 2] ADD/FW Required additional amount of feedwater (softened water) in [kg/h] calculated from: DGGIZ )6[ $ &21 where - FS is the required total fresh steam output and - A - the required T.D.S. rate in [%] Tadd/fw Available temperature of additional feedwater in [°C] S/V Amount of exhaust vapour as an amount of steam lost (deaerator outlet) in [kg/h] calculated from: 69 Ł90[ > )6[ $ @ where ŁV/M is a factor for determining the minimum amount of exhaust vapour (see chapter D.7.3), dimensionless [-]; ≈ 0.005 to 0.01 h''S/E, h'' V Expansion steam and exhaust vapour steam enthalpy each as function of the deaerator positive pressure (pE/D) according to [Tb 2] S/R Amount of expansion steam from the T.D.S. expander in [kg/h] calculated from: D.10 Internal system demand 65 )6[$[K $(FS[7IZ K '65FS[7IZ where h'A/E is the enthalpy of T.D.S. lye at saturated steam temperature (Ts) as a function of steam operating pressure (pB) from [Tb 2]; (see also chapter D.7.2) and h''F/S Available fresh steam enthalpy of the heating steam Sample calculation 1 With assumed values for: Fresh steam output FS = 12,000 kg/h Fresh steam pressure pB = 13 bar Saturated steam temperature Ts = 195 °C (from [Tb 2]) Enthalpy of T.D.S. lye =f(pB) - h‘A/E ≈ 0.230 kWh/kg Feedwater temperature Tfw ≈ 105 °C =Ł(Tfw) - pE/D ≈ 0.25 bar Deaerator positive pressure Expansion steam and = Ł (pE/D) exhaust vapour enthalpy =h''D/R ≈ h''EV ≈ 0.7457 kWh/ kg Enthalpy of fresh steam f(pB) h''FS ≈ 0.7743 kWh/kg temperature Tadd/fw ≈ 15 °C Condensate ﬂow rate CON = 6000 kg/h Additional feedwater Condensate temperature TCON = 85 °C T.D.S. rate A = 5 % ŁV/m ≈ 0.0075 [-] Factor for minimum exhaust vapour output 250/251 DGGIZ )6[ NJK[ > 69 Ł90[ [ '( 65 > )6[ $ NJK[ &21 NJK NJK $ @ @ NJK )6[$[K $(FS[7IZ K 65FS[7IZ [[N:KNJ[[ [[ NJK and the resulting amount of heating steam (FS/E) as the necessary internal steam demand for the selected sample calculation: )6( )6( FS[>&21y7IZ7&21DGGIZ[[email protected]69[K 9FS[7IZ65[K 65FS[7IZ K )6FS[7IZ [>[[[[[[[[ FS/E ≈ 1269 kg/h ฬ 10.6 % of FS Note Where CON =0 (no condensate return) the necessary amount of heating steam in the sample calculation increases to FS/E = 2018 kg/h ฬ 16.8% of FS. [[ System with 2 Vitomax 200-HS, each with an output of 10 t/h, 16 bar with regulated steam superheaters and downstream ﬂue gas heat exchangers. Klaipeda (Lithuania), district heating plant, Klaipedos energija, construction year 2007. 252/253 E Requirements and regulations The following chapter addresses relevant requirements and regulations. We refer here explicitly to land-based steam boilers. The boiler installation conditions, together with general requirements for the system, the installation room and the building are explained here in detail. Furthermore, we refer to noise emissions, transportation, handling and the basic principles of earthquake protection. 253 E Requirements and regulations 254 Basic requirements and regulations for the licensing procedure 254 E.1.1 265 268 E.1.2 E.1.3 271 E.1.4 272 Principle requirements and regulations for the installation of steam boilers 273 273 274 277 278 279 E.2.1 Installation of category IV land-based steam boilers E.2.2 Installation of category III land-based steam boilers (TRD 802) E.2.3 Steam boiler system installation room E.2.4 Acoustic emissions E.2.5 Transportation and handling E.2.6 Earthquake protection Licensing procedure according to Section 13 of the [German] Health & Safety at Work Act Overview of German licensing procedures Overviews and summary of application documents and their compilation Overviews for compiling the application documents E.1 Requirements and regulations Basic requirements and regulations for the licensing procedure E.1.1 Licensing procedure according to Section 13 of the [German] Health & Safety at Work Act E.1.1.1. General information Depending on the size and/or capacity (and therefore the potential risk), the [German] Health and Safety at Work Act (BetrSichVa)) speciﬁes a reservation of permission for some of the systems subject to mandatory monitoring referred to in paragraph 1 section 2 of the BetrSichV. The system types covered by the reservation of permission are subsequently listed in paragraph 13 section 1 Items 1 to 4 of the BetrSichV. Assembly, installation, operation, signiﬁcant modiﬁcations and changes to the design or operating mode that affect the safety of the system require permission. The reservation of permission therefore applies to both new and existing systems. A system in the sense of the regulation is composed of several function units that interact with one another, the safe operation thereof being largely determined by these interactions. Facilities required for safe operation of the system subject to mandatory monitoring are also covered. Hence the whole system must be considered in the licensing process, i.e. not only the part of the system that determines the purpose of the system, for example the pressure vessel of a steam boiler system, but all parts, devices and equipment that have an effect on the safe operation of the system. a) Regulations concerning health and safety protection in the provision of equipment and its use in the work environment, concerning safety in the operation of systems requiring supervision and those concerning organisation of operational industrial safety ([German] Health & Safety at Work Act – BetrSichV) dated 27 September 2002 (Federal Law Gazette BGBl. I p. 3777; 25/11/2003 p. 2304; 6/1/2004 p.2; 23/11/2004 p.3758; 25/6/2005 p.1866). A whole system can also consist of several (sub-)systems, i.e. an actual system can be a system subject to mandatory monitoring both in terms of the pressure risk and risk of explosion or in respect of the risk associated with the storage and ﬁlling of inﬂammable or highly ﬂammable liquids. A signiﬁcant change according to paragraph 2 section 6 of the BetrSichV to a system subject to mandatory monitoring is characterised by the system being modiﬁed to the extent that it represents a new system in terms of safety features. In the case of a signiﬁcant change, the whole system must be considered in the licensing process in the same way as new systems. If a modiﬁcation (BetrSichV paragraph 2 section 5) to the design or operating mode is carried out that affects the safety of the system, the licensing procedure only extents to the modiﬁed part. However, it must be ensured that the safety of the whole system is still guaranteed. Assembly and installation encompasses all activities required to prepare the system on site for the commissioning process. This also includes testing prior to initial commissioning. Operation of a system subject to mandatory monitoring also includes testing by third parties. Steam boiler systems are ﬁred or otherwise heated pressure vessels at risk of overheating for the generation of steam or heated water with a temperature greater than 110°C that, according to Article 9 in conjunction with Appendix II Diagram 5 of EU Directive 97/23/EC, must be be classiﬁed as Category IV Exceptions are systems in which steam or heated water arise in a manufacturing process by means of heat recovery, except where ﬂue gases are cooled and the steam or heated water produced is not fed predominantly into the processing plant (process-related waste heat boiler). For the purposes of the licensing requirement, it is irrelevant whether the pressure vessel has been brought into service as a single component or as an assembly according to the Pressure Equipment Directive. The permit covers the whole steam boiler system. Apart from the steam boiler itself, the steam boiler system includes the following parts and equipment, if available: Boiler supporting structure, thermal insulation and/or refractory lining and casing Combustion equipment 254/255 Steam and heated water pipes and their valves serving the purpose of steam boiler operation, insofar as they form a functional unit in conjunction with the steam boiler, up to the interfaces deﬁned in the risk analysis/safety evaluation Facilities within the boiler room for storage, preparation and supply of fuels, as well as facilities outside the boiler room for the storage, preparation and supply of highly ﬂammable and all powdered, liquid and gaseous fuels Facilities for the provision of air to the steam boiler, including the fan and the air preheater heated with ﬂue gas Superheaters and intermediate superheaters heated with ﬂue gas and ﬁtted with shut-off devices, as well as the steam cooler and associated connection lines located in the boiler room Feedwater preheater ﬁtted with shutoff devices, insofar as it is located in the combustion ﬂue gas ﬂow, as well as the feed equipment and the feed lines leading to the steam boiler Facilities for discharging ﬂue gas, including the induced draught systems, the chimney and/or the ﬂue gas line routed via a cooling tower, as well as the systems built into the ﬂue gas discharge equipment for reducing air contamination Facilities for pressure maintenance and volume compensation (pressure expansion vessels, expansion tanks) in heated water generation systems, including associated connection lines All other facilities that serve the purpose of steam boiler system operation Equipment in which the generated steam is superheated or cooled and which is located wholly or partially within a steam boiler, where steam boilers are deﬁned as an arrangement of vessels or pipes that are subject to a pressure higher than atmospheric pressure All steam boiler monitoring and safety equipment Boiler installation room E.1.1.2 Requirements for the application documents 1.—Standard requirements All documents required for assessing the system must be enclosed with the application. If any relevant speciﬁcations are omitted, additional demands from the authorities or the approved monitoring body (ZÜS) may lead to delays in the licensing process. Application documents that are incomplete and/or expert opinions that do not comply with the accreditation conditions of the ZÜS shall be returned to the applicant. Systems subject to mandatory monitoring in the sense of the BetrSichV are mainly systems subject to EU directives offered for sale or systems that at least contain components to which these regulations apply. See also [German] Equipment and Product Safety Act (GPSG) section 1, paragraph 2(7). The certiﬁcate of conformity, however, needs not have been issued until directly before commissioning and does not constitute a mandatory element of the application documents. The scope of application documentation to be submitted differs depending on whether a certiﬁcate of conformity has already been issued for the complete system or only the general conditions are known. If only system components and not the whole system have been subjected to a conformity assessment procedure, the compatibility of the individual components with each other must be described in the application. The actual manufacturer of the system need not yet be speciﬁed in the application. In this case, however, the system must be described in detail with reference to the design data (e.g. output, fuel, operating mode and construction), so that the system can be assessed in respect of safe operation. Requirements that have already been tested in the conformity assessment procedure need not be tested again as part of the licensing process. E.1 Requirements and regulations Insofar as compliance with quality requirements is veriﬁed by certiﬁcates of conformity issued to the initial vendor, the licensing procedure focuses on correct siting and safe operation of the system. For example: The precise location of installation either in the open air or in a building Potential risks to the system (collision protection, ﬁre protection etc.) and the respective precautions, taking into consideration the requirements that the manufacturer makes of the installation site in the operating instructions as a result of the risk analysis Translation of the manufacturer's speciﬁcations to the actual local conditions, for example on the "Ex zone" plan Mode of operation, for example, the special safety and organisational precautions to be taken in the case of intermittent supervision Veriﬁcation of compatibility of the individual components with each other, in the event that no proof of conformity is provided for the whole system The application must include all the information that the ZÜS requires for the expert opinion and/or the test before commissioning (see sections 4 and 6). Attention must also be paid to the fact that the expert opinion of the ZÜS is a formal part of the application (BetrSichV paragraph 13 section 2 BetrSichV). With acceptance of the expert opinion as an application document, any applicable deﬁciencies, supplementary requirements and proposed measures described in the document automatically become an integral part of the application. The necessary coordination process between the applicant and the ZÜS is described in greater detail in section C.14.2.4. As a rule, the subsequent system operator and the applicant are one and the same. If the application is submitted by a third party, such as an engineering consultancy as a service for the subsequent system operator, then the appropriate authorisations must be enclosed with the application. Insofar as the applicant, by way of exception, is not the subsequent system operator, it must be ensured that the operator satisﬁes all the requirements detailed in the licence. If application documents are returned to the applicant for the purpose of completion, this does not constitute a formal decision; the process is solely interrupted, whereby no administration costs are charged. 2. Submission of an explosion protectionconcept If the required risk analysis in accordance with the [German] Hazardous Substances Ordinance (GefahrstoffV), taking account of Appendix III Item 1, establishes that the occurrence of a hazardous substance of an explosive amount in the atmosphere cannot be avoided in the system applied for, then a check must be carried out in the licensing procedure as to whether the necessary structural ﬁre protection and structural conditions for explosion protection exist, even if the explosion protection document required by the BetrSichV need only be prepared by the time of commissioning. The term "explosion protection concept" has established itself for the concept to be presented in the application. The statements required in the explosion protection concept are listed in the Appendix. 3.—Documents required The documents required for each individual system type are to be found in the checklist in the Appendix. Depending on the case in question, additional documentation may be necessary. 256/257 E.1.1.3. Requirements for the expert opinion from an approved monitoring body (ZÜS) With reference to siting and safe operation, the expert opinion forms the fundamental basis for the licensing procedure. It must therefore be resilient. According to the regulatory text, it must be evident from the expert opinion that siting design and operating mode of the system comply with the regulation. The information that the expert opinion from the approved monitoring body must contain as a minimum requirement according to AKK-RL  is reproduced in the Appendix. Furthermore, the ofﬁcial justiﬁcation of the BetrSichV states that: "Before issuing a licence, the expertise of a ZÜS must be called upon and this shall check whether the interaction between parts of the system under actual operational conditions allows safe operation of the system." When preparing an application, a differentiation must be made between three case situations: Case 1: A declaration of conformity is available for the whole system Case 2: There are some subsections with a declaration of conformity and some without, but all components are subject to harmonised regulations Case 3: (Sub)sections do not fall within the harmonised regime (such as storage tanks in the case of ﬂammable liquids) Depending on the case in question, the ZÜS test scope in the expert opinion differs from that applicable to testing before commissioning. Everything that is not veriﬁed on the part of the manufacturer must be proven during testing, at the latest prior to commissioning. If, in the case of pressure equipment, an assembly is assembled under the responsibility of the operator, a certiﬁcate of conformity must be available for each individual piece of pressure equipment at the time of the acceptance test. The ZÜS checks the correct selection and installation of the individual pressure devices during testing at the latest prior to commissioning. It must be evident from the ZÜS expert opinion that all of the following issues have been checked – insofar as no relevant measures have been proposed – and complied with: Completeness of information with reference to safety issues, also including, for example: Statements regarding the intended materials to be used and Speciﬁcations concerning special safety measures for employees and third parties. Requirements with reference to the installation site (taking account of neighbouring plots of land), including checking of: Compliance with the necessary distances to neighbouring systems due to potential reciprocal risk, particularly in the event of a ﬁre Compliance with the installation requirements regarding explosion protection, i.e. particularly in terms of checking the "explosion protection concept" insofar as safety zones are required for explosion protection according to Appendix 3 of the BetrSichV, and compliance with the structural requirements (e.g. no openings in walls or ﬂoor drains in the safety zones) Guarantee of the necessary protection from damage depending on the situation at the installation location, with particular reference to vehicular trafﬁc taking account of the vehicle type and the speeds travelled Exclusion of any other potential reciprocal effects with regard to neighbouring systems, such as the risk of undergrate ﬁring due to leaking ﬂammable liquids or fuel oil/diesel Suitability of the system and/or system components for the intended operating modes and for the intended form of supervision Insofar as the whole system is not subject to only one conformity assessment procedure, a check should be conducted at this stage regarding the suitability and mutual compatibility of the individual intended components. The following statement is necessary as the result of a positive expert opinion: Note A statement such as "there are no concerns preventing conferral of a licence" does not comply with BetrSichV speciﬁcations and is therefore insufﬁcient. E.1 Requirements and regulations Inspection of the application documentation by ...… has established that the siting, design and operating mode of the …..system complies with the requirements of the BetrSichV, provided that the following measures are implemented together with the speciﬁcations in the application: ... The intended project therefore complies with the requirements of the [German] Health & Safety at Work Act (BetrSichV). The following aspects must be considered in drafting the expert opinion: The ZÜS must ﬁrstly pay particular attention to maintaining its necessary independence as an adjudicator, which implies that its advisory role is subject to very strict limitations. This is dealt with and deﬁned in detail in  and , also with regard to auditing activities. In drafting the expert opinion, the ZÜS must not have a formative inﬂuence on the concept, i.e. it must not act in the same way as an engineering consultancy; rather, it should specify as precisely as possible which target requirements of the BetrSichV and the technical regulations are taken into account inadequately. If important points are not taken into account, the ZÜS must ﬁrstly prompt the applicant to provide supplementary information prior to publishing its opinion. Only afterwards can the ZÜS check whether the measures taken are adequate and comply, for example, with the technical regulations of the BetrSichV. If there are several alternatives for achieving a particular safety-related objective (e.g. with reference to the design of adequate collision protection), the ZÜS need only assess whether the solution proposed by the applicant is sufﬁcient. At the same time, the applicant can propose several solutions and then decide at a later stage which of the solutions is implemented No demands may be made of the quality of the system or system components, insofar as these have been subjected to a conformity assessment procedure; the quality is assessed subsequently by an approved body The ZÜS shall list each of the submitted application documents that it has audited (see ). Stamping of the application documents by the inspector as in the past is no longer necessary Insofar as requirements are still outstanding, the ZÜS must stipulate them in concrete form with speciﬁcation of the reason, but without undertaking any planning activity. Repetition of texts from technical regulations is not sufﬁcient. Rather, it must be speciﬁed how the regulatory requirement is actually to be applied to the assessed system. For example: "The discharge pipe must be routed 3 m above the roof of the neighbouring warehouse." A long list of requirements in the form of pre-formulated texts tailored to the speciﬁc system type that practically repeat the application speciﬁcations make the inspection appear at least very superﬁcial Legal obligations may at most be included as notes in the expert opinion, but not as proposals for any incidental provisions A description of the approach taken during the inspection or explicit reference to the information in the application that has been audited is possible, but this must be clearly separated from the additional requirements made On principle, information provided in the application must be checked on site by the ZÜS in accordance with . The ZÜS must assess beyond any doubt whether the installation location is suitable. A site inspection is therefore an inherent part of the expert opinion In the expert opinion, the ZÜS must cover all the risk areas touched on by the system. If it is unable to do so comprehensively, for example due to the limited extent of its approval, this must be pointed out to the applicant explicitly. In this case, another ZÜS may need to be called upon, whereby one of the approval bodies must play the coordinating role so that the intersections between both aspects (e.g. pressure hazards and explosion protection) can also be considered 258/259 If special requirements are made of the equipment in individual cases (such as the extension of a discharge pipe), this must be substantiated, for example with the circumstances at the installation location (which must be described) 1. General information The application must be submitted in triplicate with the required documentation, including the expert opinion from the approved monitoring body (if necessary) to the regional administration. Only if planning permission is to be granted at the same time, do the extra copies required for the planning permission process also need to be enclosed. If possible, preliminary discussions should be held with the applicant to clarify which documents are necessary. If the documentation is complete, the applicant receives an acknowledgement of receipt from the authorities. The 3-month deadline is calculated from the date of receipt of the complete application documentation. If the check for completeness reveals that documents essential for evaluating the application are missing, the applicant is requested to (re)submit these documents with a note that the 3-month period has not yet started. The period only begins on receipt of all (additionally) required documents. The applicant also receives an acknowledgement of receipt for the additional documents. If applicants intend to implement a large project in several stages and each application only covers a part of the whole system, then the respective licence must be restricted to the assembly and installation of that part of the system applied for. In this case, the licence for operation of the whole system can only be combined with the licence for assembly and installation of the ﬁnal part of the overall system. 2. Scope and depth of auditing by the — licensing authority The licensing authority is not assigned the role of "chief adjudicator", i.e. it can particularly depend on the fact that the ZÜS – insofar as an expert opinion is included in the application – has audited the application documentation thoroughly and competently. However, the licensing authority must still check the application for completeness and plausibility. Knowledge speciﬁc to the technology in question must also be available for this purpose. Lack of due diligence by the applicant and/or the ZÜS is evident in particular from the fact that Information is inconsistent Information on the installation location is missing or imprecise The ZÜS proposes unspeciﬁc measures Potential risks (ﬁre loads, mechanical hazards due to vehicles) are inadequately described and evaluated It remains unsettled how the deﬁciencies indicated in the expert opinion from the ZÜS are to be rectiﬁed If the licensing authority has any enquiries regarding the form or content of the expert opinion or the ZÜS, for example, has proposed any measures that are incompatible with the information in the application, then the licensing authority turns ﬁrstly to the applicant. With the consent of the applicant, individual issues can then also be clariﬁed directly between the licensing authority and the ZÜS. If the issues can be clariﬁed amicably and unequivocally, the ﬁnal version selected must arise unambiguously and in concrete terms from the licence and/or from the accepted incidental provisions. Should applicants decide on another solution for achieving the intended objective after approval has been granted, then they can apply informally at any time for replacement of the means, i.e. for an amendment to an incidental provision. If this is taken into account, the letter of conﬁrmation of the licence should be reattached. A formal change permit is not necessary for a modiﬁcation to requirements. E.1 Requirements and regulations If differences still exist following discussion thereof, with reference to statements in the application and/or the expert opinion, then the application shall be returned to the applicant with a relevant explanation and a request for supplementary information and/or clariﬁcation. A separate consultation with the applicant is not necessary prior to issuing a decision if the application has been accepted in its entirety. Otherwise a consultation must take place. If applicants do not agree with any of the incidental provisions, they can apply for replacement of the means. If the solution is acceptable, this is conﬁrmed in a letter to which the licence is attached. 3. Involvement of other agencies The licensing procedure is established as a lean process and does not display any bundling effects. It deals solely with the safety issues relevant to the system on the basis of the BetrSichV. In North Rhine-Westphalia, however, there is a special situation that includes the licence with the building permit according to paragraph 63 of the [NRW] Building Regulations (BauO). Outwardly, therefore, only one licensing authority makes an appearance; the one that issues the licence and planning permission in one legal document. Hence, the overall decision includes the intrinsically independent part of the building permit. This is also expressed within the administrative decision by means of a clear delimitation. Regarding the involvement of other agencies, a differentiation can be made between two cases: 1) No other legal sectors (such as building, planning, water or environmental law) are involved with the modiﬁcation or construction of a system; in other words, it only has to do with technological questions and matters of system safety. In this case, the licensing authority issues the licence without the involvement of other agencies. 2) Inspection of the application on the basis of BauO paragraph 63ff reveals that a building permit is required. The requirement for planning permission can be justiﬁed by the system exceeding a particular order of magnitude (e.g. in the storage of gases as part of a ﬁlling system, if the storage tank has a volume > 5 m³). It can, however, also be founded on planning permission solely being required due to the change in usage of the property. If it cannot be established without doubt whether or not planning permission is required, then the planning authority must be involved. If the BauOA (planning department) conﬁrms the need for a building permit, this decision is binding for the licensing authority. In this case, the applicant must also include documents required for inspection by the BauOA with the application. The responsible planning department is requested to deliver a judgement within a speciﬁed period (normally 4 weeks) from submission of the necessary documentation. Other public legal issues that could be affected by erection and operation (i.e. subsequent use of the system), must be checked during the course of the planning application process. Whether and to what extent this is the case is the responsibility of the BauOA. Within the scope of its auditing obligation, the BauOA must also check for compliance with emission control legislation. The licensing authority is not obliged to involve any other agencies directly. The wording and incidental provisions of the licence and building permit should be speciﬁed separately. In the licence section, only incidental provisions concerning technical requirements (design, equipment or operation) are permissible. The proposed incidental provisions from the BauOA cannot be embodied in what is the direct responsibility of the licensing authority; they can only be included in the section of the administrative decision relating to building regulations. 260/261 According to building law, it is perfectly permissible to restrict the use of a building or a system permanently, especially by limiting the operating times (e.g. to daytime), if this appears to be called for in light of the designation of the property (e.g. as a mixed use area). The licensing authority does not check the incidental provisions deemed necessary by the BauOA for the section of the administrative decision dealing with building legislation. In the case of obvious serious errors, feedback should be provided to the BauOA. Should it prove necessary in exceptional circumstances to directly involve other agencies for the purpose of speeding up the process, the submissions must be returned via the planning department, because it is the only body capable of checking the admissibility and correctness of the incidental provisions proposed by them. The proposed incidental provisions cannot be embodied in what is the direct responsibility of the licensing authority; they can only be included in the section of the administrative decision relating to building regulations. If it is established during the course of the process that a statutory requirement from another legal area has been omitted, the process is suspended until the requirements with respect to the applicant have been fulﬁlled. For this purpose, the applicant is notiﬁed of the circumstances and referred to the fact that the process will only be resumed once the procedural requirements have been satisﬁed. The three-month deadline is extended accordingly. One such legal requirement is to be found, for example, in paragraph 25 section 1 of the [NRW] Highways and Bye-ways Act. The licensing authority checks the issues of occupational and operational safety. Incidental provisions are formulated as necessary. The incoming statements and expert opinions are examined to see whether they relate to requirements speciﬁc to the building or the system technology. Proposed incidental provisions that represent pure reproductions of legal texts must not be adopted. An extension of the 3-month deadline is only possible in justiﬁable circumstances. This could be the case if the BauOA requests additional documents. The applicant is notiﬁed in writing that the deadline is being extended by an appropriate period. If inspection of the documents yields that the system is not licensable, a negative administrative decision is issued. Assembly and installation of the system must be explicitly prohibited in that decision. In the case of a request for change, if applicable, the non-licensable amendment must be prohibited. The operator and, if applicable, the BauOA each receive one copy of the licensing decision. 4. Consequences of issuing the license and planning permission in one decision If problems are to be expected due to inclusion of the building permit, for example with reference to admissibility of use of the property in the planned form, several options are available: The applicant can be requested to present certain requirements in the application itself, for example a restriction of the operating times. Then the permit can be granted without restrictions The applicant is requested to have the other statutory issues affected by a building permit examined in a preceding process. In this way, the admissibility of a change in use or an access road from a public highway (see paragraph 9 of the [German] Federal Trunk Road Act) can be examined and decided upon in advance If the future use of the system at the intended location is clearly not at all permissible (for example in the outdoor area) for other statutory reasons, then the application can also be declined with the substantiation that no decision-making interest exists. The applicant is at liberty to appeal against such a decision E.1 Requirements and regulations In general, other statutory issues must not be based on the BetrSichV; rather, only on building law, for which the BauOA bears sole responsibility. 5. Licence within a BImSch process If a system requiring a licence is part of a system subject to authorisation according to the German Immissions Act (BImSchG), then the licensing authority is not responsible for the licence; rather, the ofﬁce managing the BImSch process. Process regulations according to the BImSchG and the 9th German Immissions Ordinance (BImSchV) are relevant here. The 3-month deadline does not apply. It is the time limit set by the ofﬁce managing the BImSch process that has to be complied with. The requirements for documents that need to be submitted in the licensing procedure according to the BetrSichV also apply to documents within the scope of the BImSch process (including the expert opinion from the ZÜS). Following inspection of the documentation, a statement is made to the responsible approval agency, if necessary, with proposals for incidental provisions. E.1.1.4 Inspection before commissioning The extent of inspections (and therefore also the one before commissioning) is speciﬁed in paragraph 15 section 2 of the BetrSichV. The inspection certiﬁcate required in accordance with paragraph 19 section 1 of the BetrSichV must include a minimum of the following information according to AKK-RL : Legal basis Initial inspection, inspection following modiﬁcation, following a major change or after corrective maintenance according to paragraph 14, BetrSichV Recurring inspection according to paragraph 15, BetrSichV Extraordinary inspection according to paragraph 16, BetrSichV and speciﬁcation, if applicable, of whether a whole system or a partial system has been inspected Master data of the ofﬁce (name, postal address, identiﬁcation as an approved monitoring body) Operator data (name, postal address) Speciﬁcation of the maintenance contractor (if necessary) System location (system identiﬁcation, in-house designation and system ID, plus, if necessary, precise description of the system interfaces, for example with slide gate number, pipe number and/or speciﬁcation that it is a partial system) Inspection date and inspection period, if applicable Clear indication of the relevant inspector Signature of the inspector Unique identiﬁcation of the inspection certiﬁcate Inspection result, if applicable with information on defects Release for commissioning or continued operation Inspection interval In addition to the scope of inspection before commissioning and the relevant documentation, the following is expected of the ZÜS inspector: Inspection of the whole system, including siting and required safety clearances 262/263 Insofar as the system has only been certiﬁed in parts, the supplementary statement that the components and assemblies used are compatible with each other and that the required reciprocal safety equipment is available and its integration complies with the state of technology (quality) Explicit conﬁrmation that the requirements relating to assembly, siting and operation have been complied with in accordance with the state of technology (operation) Conﬁrmation that the speciﬁcations in the licence application have been complied with, including the expert opinion from the ZÜS and any applicable special incidental provisions in the licensing decision Reference to the inspection certiﬁcate from the qualiﬁed person concerning testing for explosion protection before commissioning (if necessary), insofar as explosion protection is not checked by the ZÜS itself A positive inspection certiﬁcate includes the following inspection contents, even if they are not dealt with explicitly in the certiﬁcate: The statement that the supervision method (including possible indirect supervision) complies with information in the application and whether any applicable alternative measures for supervision have been taken The statement that the selected protection against possible mechanical effects is adequately sized to meet the actual installation conditions, insofar as no relevant precise speciﬁcations were made in the application The statement that the selected measures for preventing access by unauthorised personnel are sufﬁcient (enclosure etc.) The statement that the necessary clearance with respect to potential ﬁre hazards and any other hazards has been complied with, particularly with respect to the risk of undergrate combustion, for example, installation at a sufﬁcient distance from a petrol station where a liquid gas storage tank is sited above ground The fundamental statement that the necessary documents, for example the explosion protection document and a system-speciﬁc "Ex-zone" plan, are available to employees, along with the operating instructions In the system-speciﬁc technical regulations that are still largely based on former individual pieces of [German] legislation (DruckBehV, DampfKV, VbF, AcetV) and hence can only be applied to a limited extent, further speciﬁc aspects of the inspections are addressed, which must be observed. The evaluation of identiﬁed deﬁciencies is absolutely essential, i.e. an unequivocal statement regarding the admissibility of commissioning, specifying any applicable restrictions. In any event, the ZÜS must always issue a certiﬁcate regarding the result of the inspection without delay and hand this over to the operator, so that an indication of the permissibility of operation is available on-site at the operating location. This must take place within one week. On no account is it permissible for the ZÜS to issue a satisfactory inspection certiﬁcate weeks or even months later, after the operator has corrected all the faults identiﬁed during the inspection and explained during the meeting. Missing pieces of evidence must be noted as defects in the inspection certiﬁcate and qualiﬁed accordingly (minor, hazardous, serious). Resulting consequences must also be speciﬁed. Implementation of the system begins with the licence application. Hence, the state of the art at this time applies. Should new, completely up-to-date ﬁndings be made during the course of the licensing process, the licensing authority can impose supplementary requirements in the licensing decision. The ZÜS is bound to the application documents and the requirements in the licensing decision during the inspection before commissioning. E.1 Requirements and regulations If the state of the art has made advances in the period between issuance of the administrative decision and performance of the inspection prior to commissioning and the ZÜS therefore establishes during the inspection and prior to commissioning that variance exists with respect to the state of the art, the ZÜS can report this to the monitoring and/or licensing authorities, who themselves must then check whether supplementary requirements need to be applied in accordance with paragraph 13 section 5 Clause 2 of the BetrSichV. The ZÜS may not declare deﬁcits due to advances in the state of the art as defects. Insofar as the operator has already determined the necessary inspection intervals at the time of the inspection, the ZÜS can carry out the necessary examination of the determined interval, according to BetrSichV paragraph 15 section 4, in conjunction with the acceptance test. In so doing, a differentiation must be made between the individual components and between the various hazardous features of the system. If the ZÜS has already recommended an inspection interval in the expert opinion, the operator can use this information in its safety assessment for determining the inspection interval. In principle, the ZÜS only states anything after the operator's safety assessment, which is normally only practical following the inspection prior to commissioning. In the case of recurring inspections, the ZÜS need not explicitly conﬁrm the inspection interval deﬁned initially. However, if the monitoring body has any indication that the interval should be reduced, then it reports this to the operator. The operator itself must then undertake another safety assessment, which is subject to examination by the ZÜS. 264/265 Fig. C.14.3–1 E.1.2 Reservation of permission Overview of German licensing procedures The necessary licensing procedure or approval process can exhibit differences from one federal state to another. Before initiating the licensing or application process, it is therefore always advisable to coordinate [steps] in advance on an individual basis with the local approval agency, at the same time presenting the boiler system to be approved. Overviews of the standard licensing procedure according to BImSchG (BImSchV 1/4/13, state: Berlin/Brandenburg, see also Fig. C.14.3-2 and C.14.3-3) E.1 Requirements and regulations Fig. E.1.2-1 Overview of licensing procedures Steam boiler system to BImSchG (1st German Immissions Order) [see also appendix A4] Application to permit granting authority (for example competent commerce authority) Details to planning authority Details to environment authority Asking for comments Permit-granting authority grants permit System is installed Expert checks system System may be operated Final acceptance by the authority => system not subject to permits according to the Federal Immissions Act (BImSchG) [Germany] Overview of the standard sequence of events in the licensing procedure according to BImschG (State of Berlin) Source: TÜV Rheinland 266/267 Fig. E.1.2-2 Overview of licensing procedures Steam boiler system to BImSchG (4th/13th German Immissions Order) [see also appendix A4] Expert statement Application to environment authority Details to environment authority Details to planning authority - Publication of intended project - Public participation Documents to permit-granting authority (for example competent commerce authority) Environment authority grants permit Other authorities - Aviation - Federation - etc. System is installed Expert checks system System may be operated Final acceptance by the authority => system subject to permits according to the Federal Immissions Act (BImSchG) [Germany] Overview of the standard sequence of events in the licensing procedure according to BImschG (State of Berlin) Source: TÜV Rheinland E.1 Requirements and regulations E.1.3 Overviews and summary of application documents and their compilation Checklist for the compilation of application documents for the approval process according to the German Immissions Act (source: Federal Environmental Agency, Krefeld, 08/2005) General preamble: The following brief checklist should provide applicants with assistance in preparing application documentation for approval processes in accordance with the German Immissions Act. Documents and information are speciﬁed in this checklist, which must normally be submitted. Depending on actual speciﬁcations, it can however arise that the submission of certain documents can be dispensed with or that additional documents are indispensable for an audit. In cases of doubt, it is therefore recommended that contact be established with the approval agency in order to discuss the ﬁner details. The following general requirements must be observed: Document formats and document folding must comply with DIN regulations (particularly DIN 28004). Each additional copy of the application must be bound in a separate ﬁle. As a rule, 6 copies of the application must be submitted for carrying out ofﬁcial tasks All application documents must be signed by the applicant or an authorised representative, with the design documentation also being signed by the system architect and the expert opinion by the expert involved The application and the table of contents must be signed on all events by the applicant or an authorised representative Trade secrets must be indicated and the corresponding documents submitted separately 268/269 a) Checklist for steam boiler systems Name or company name and address of the operator Name or company name and address of the manufacturer (if known) Intended operating location and address (except for mobile steam boilers) Description of the steam boiler system and the intended operating mode, including schematic drawings that reveal the design, dimensions and mounting of the relevant safety equipment For the system components that must be brought into service according to an EU directive, details of the corresponding conformity assessment procedures (Machinery Directive 98/37/EC; Pressure Equipment Directive 97/23/EC; ATEX 94/9/EC for operating equipment, insofar as hazardous explosive atmospheres can form), declaration of conformity for the assembly (including a list of components to which it applies) or, if conformity assessment procedures have not yet been carried out, speciﬁcation of the category from which devices are selected and a description of the interfaces Drawings (layout and section, escape routes, pressure relief areas) Boiler installation room Facilities for the storage of fuels Facilities for discharging ﬂue gases, including chimney (plus the associated structural calculations and height calculation) Site plan containing the following information: Location of the installation room N eighbouring areas on the property and their intended purpose Adjacent plots of land, buildings, thoroughfares and spaces Information on building design Ventilation facilities Escape routes Structural ﬁre protection Expert opinion from an approved monitoring body from which it is evident that siting, design and operating mode of the systems comply with the requirements of the Act Speciﬁcation of total costs including VAT Special procedures and deviations from the technical regulations must be described separately. Design documents for pressure equipment and assemblies according to the Pressure Equipment Directive need not be enclosed. According to LASI (Committee of the States for Occupational Safety and Health) guidelines for BetrSichV Section C.14.1, the old forms can still be used. However, it must be noted that these need only be partially completed and that additional information is required. E.1 Requirements and regulations b) Checklist for the expert opinion In accordance with AKKRL , the expert opinion from the approved monitoring body must contain at least the following information: Legal basis (e.g. paragraph 13 section 2 BetrSichV) Reason for the expert opinion Master data of the ofﬁce (name, postal address, identiﬁcation as an approved monitoring body) Operator data (name, postal address) System location (system identiﬁcation, in-house designation and any system ID) Description of the project with designation of the main components Date report created, date of site inspection and scope of system inspected Basis for testing Test documents viewed Unique identiﬁcation for the expert opinion Assessment of the system components and/or the system or systems Result of the assessment with any applicable conditions and recommendations Clear speciﬁcation of the expert involved, signature of the expert c)—Necessary statements in the explosion protection concept In the case of areas at risk of explosion in enclosed spaces (rooms): Designation of the enclosed spaces Classiﬁcation of enclosed spaces into zones according to BetrSichV Appendix 3 The statement that electrical and other installations in the building comply with requirements according to BetrSichV Appendix 4 The statement that any applicable structural measures deemed necessary in accordance with GefStoffV Appendix III No. 1 have been taken, for example prevention of ﬁre transference In the case of areas at risk of explosion in the open air: Classiﬁcation of areas into zones according to BetrSichV Appendix 3 The statement that the requirements for zones in the open air (such as the omission of openings to lower lying areas) have been complied with A statement regarding the quality of any walls that enclose the open air areas The statement that electrical and other installations comply with requirements according to BetrSichV Appendix 4 270/271 E.1.4 Overviews for compiling the application documents Application documents Boiler assembly Number of application Operator Design Viessmann2b) engineer documentsa) III IV Steam boiler system description 3 3 X X Steam boiler system operating mode 3 3 X X Steam boiler system drawings 3 3 X X Boiler house ﬂoor plan 4 4 X X Layout of the fuel storage facility 4 4 X Layout of the ﬂue gas discharge equipment 4 4 X Layout of the chimney 4 4 X Sectional drawing of the boiler house 4 4 X Sectional drawing of the fuel storage facility 4 4 X Sectional drawing of the ﬂue gas discharge equipment 4 4 X Sectional drawing of the chimney 4 4 X Static chimney calculations 3 3 X 4 4 X 4 4 X Steam boiler system wiring diagrams - 3 X2b) Burner description/combustion system 3 3 X2b) X For drawings: scale 1:100; for site plans: scale 1:1000 to 1:5000 Site plan of the installation room + neighbouring rooms with intended purpose Site plan of the adjacent plots of land, buildings, thoroughfares and spaces (Source: TÜV Rheinland, issue: 11/2007) a) Minimum scope that can be submitted in agreement with the authorities partially except for 6 (8) copies. b) Insofar as Viessmann is the supplier of these system components. E.2 Requirements and regulations Note Steam boiler group assignment, see also section C.14. Principle requirements and regulations for the installation of steam boilers General requirements Boiler systems should always be installed in buildings that are free from the risk of frost, dust and dripping water. The temperature in the installation room should be between 5 and 40 °C. Provision must be made for adequate ventilation (combustion air supply). In so doing, attention must be paid to ensuring that no corrosive elements (e.g. chlorine or halogenated compounds) are drawn in with the combustion air. The ﬂoor must be level and offer sufﬁcient load-bearing capacity. For the load-bearing capacity, the maximum operating weight, i.e. the wet weight together with all ﬁtted components, must be taken into consideration. Boilers can be installed without special foundations. However, foundations are advisable for better cleaning of the installation room. Regulations DDA information, issue 2.2002 [Germany], describes the "installation and operation of land-based steam boiler systems with CE designation". These rules are largely drawn from TRD 403 or, depending on water capacity and permissible operating pressure for easier installation, from TRD 702. Furthermore, the respective state building regulations and combustion ordinance must be observed. Alongside minimum requirements for clearances for operation and maintenance, escape routes, ﬂue gas routing, fuel storage and electrical equipment, these regulations stipulate the type of room where steam boilers may be installed. High pressure steam boilers (category IV according to TRD) must not be installed in the following areas: in, below, above or next to living spaces, in, below or above social spaces (e.g. washrooms, changing rooms and rest areas) and working areas The regulations also list less strict installation conditions, depending on the product of water content and permissible operating pressure, taking into consideration the maximum steam output. However, the regulations stipulate different requirements, so speciﬁc clariﬁcation in advance with the locally responsible authorities is recommended. The respective state building regulations must be observed for the installation of steam boilers. In general, siting of boilers in working areas is not out of the question. In principle, the requirements speciﬁed in TRD 403 (Group IV Steam Boilers) and TRD 802 (Group III Steam Boilers, Clause 11 in particular) must be observed. 272/273 E.2.1 Installation of category IV land-based steam boilers In the following, partial reference is made solely to the installation of land-based steam boilers (indicated accordingly with an "L" in TRD 403), for example: Clause 3.1 - structural requirements Clause 3.2 - installation requirements Clause 3.3 - clearances for operation and maintenance Clause 3.3.1 - minimum height/width of the accessible area 2 m/1 m; restriction of the minimum width to 0.8 m by valves Clause 3.3.2/3.3.3 - minimum width in areas that need not be accessed for operation or maintenance 0.5 m; 0.3 m in the case of cylindrical boiler bodies (at one side) Clause 3.3.4 - minimum clearance between boiler top edge and ceiling lower edge 0.75 m Clause 3.4 - access to boiler rooms Clause 4 - installation in enclosed spaces, with speciﬁc reference to: Clause 4.1 - deﬁnition of the enclosed spaces in which group IV boilers may be installed (neither in, above, below nor next to living spaces; neither in, above nor below social spaces and working areas) Clause 4.2./4.3 - exceptions for the permissible installation of so-called product-pressure boilers Note regarding Clause 4.3 An area of at least 10 % of the ﬂoor area of the installation room must give way much more easily on the outer walls or ceiling surfaces than the rest of the enclosing walls. Clause 4.4 - escape routes and emergency exits Clause 4.41 - it must always be possible to leave and access the boiler room quickly and freely via the escape routes Clause 4.4.2 - for land-based steam boilers, linear distance of no more than 35 m to the exit Clause 4.4.3/4.4.4 - boiler rooms with at least two exits, if possible on opposite sides Clause 4.4.5 - exit clear width at least 0.6 m, minimum height 2 m Clause 4.4.6 - escape doors opening in escape direction and able to be opened from the outside without a key during boiler operation Clause 4.5/4.6 - connecting paths from installation room to other rooms; separating walls and ceilings between installation room and other rooms Clause 4.7/4.8 - ventilation of boiler rooms in such a way that negative pressure of no more than 0.5 mbar results Clause 5 - open air installation Clause 6 - walkways and railings Clause 7 - ﬂue gas discharge Clause 8 - fuel storage and supply Clause 9 - contact protection Clause 10 - lighting Clause 11 - electrical equipment and lightning protection systems E.2.2 Installation of category III landbased steam boilers (TRD 802) Partial reference solely to Clause 11 installation: In this context the respective state building regulations must be observed. In general, siting of boilers in working areas is not out of the question. E.2 Requirements and regulations Note See chapter G1, Appendix 4 for an example sketch of an installation room (container facility). E.2.3 Steam boiler system installation room E.2.3.1 General requirements for building/geometric data and structural physics Architectural and design aspects are not considered here and must be clariﬁed on site in individual cases. The speciﬁc requirements for ﬁre resistance levels to be complied with for building components according to DIN 4102 and/or DIN 13501 must be observed on the basis of the respective applicable state building regulations. The same applies to equipment of smoke extraction systems and escape routes. Subsoil and foundations According to details speciﬁed in an expert's report to be prepared on site for subsoil assessment and recommendation of foundations. Assumed loads According to DIN 1055 and/or according to speciﬁcation of the technological building guidelines derived from unit loads, transport and assembly loads. Live loads According to DIN 1055 and/or according to VGB guideline VGB-R 602 U "Speciﬁcation and handling of effects on building structures in power stations", 2005 edition. Within a range of ﬁve metres from installation openings, the live loads must be designed accordingly for the expected installation loads. Building structures Reinforced concrete structures or steelframed structures, made from uprights, beams and ties with threaded assembly joints, are preferred. Ceilings According to operational requirements; reinforced concrete ceilings, steel/concrete composite ceilings on permanent sheet steel shuttering, for example grating platforms. Roof ceilings Concrete roof ceilings in the form of in-situ concrete or prefabricated ceilings. For subordinate buildings, trapezoidal panels can be integrated in consultation with the developer and according to static requirements. Emergency staircases Insofar as these are necessary due to the building dimensions and/or building use; solid, ﬁre-resistant, brickwork or reinforced concrete structures with facing brickwork or facing concrete on the inside. Thermal/sound insulation According to DIN 4108/4109 for walls and roofs and/or according to noise impact assessment. External walls If no higher level requirements apply for design reasons: External wall surfaces in the form of a double-skin, thermally insulated and soundproof wall covering comprising horizontally arranged self-supporting 60 cm high sheet steel caissons - galvanised and coated in standard colours. Perforated design in areas where sound-absorption measures are required Thermal insulation and/or soundprooﬁng made from mineral ﬁbre panels inlaid into the sheet steel caissons. Vertically arranged trapezoidal sheet covering on the outside, made from aluminium, coilcoated in RAL colour; proﬁle and colour as required by building owner For subordinate buildings without any soundprooﬁng requirements, sandwich elements consisting of sheet aluminium on both sides with a rigid PUR foam core can be employed in consultation with the building owner Internal walls Made from lime-sand brick, thickness according to structural requirements, skimmed on both sides, if no higher level demands are made of the wall surface 274/275 Roof sealing For solid roofs, for example reinforced concrete ceilings, aerated concrete ceilings etc., the following roof structure is conceivable: Primer (bituminous) Vapour barrier V 60 S4 AI 01 Non-ﬂammable thermal insulation, thickness according to requirements, with slope One layer KSA cold glue ﬁlm One layer 200 PYE PV S5 One layer PYP PV 200 S5 EN Separating layer of ﬁbrous web or PE ﬁlm Mechanical fastenings according to structural requirements 6 to 8 cm gravel ballast layer of washed round gravel 16/32 mm Surfaces and walkways that are walked on for operational or maintenance purposes must be covered with 50/50/5 cm paving slabs on protective building mats For light roofs: (subordinate buildings) Trapezoidal panel roofs Thermal insulation made of foam glass; thickness according to requirements 1 layer Evalon-V To provide fall protection, external walls must be extended to at least 0.3 m above the upper edge of the ﬁnished roof to form a parapet. Stairs, platforms, railings, ladders Design engineers must take account of all potential damage and faults considered possible based on their knowledge and experience in the layout of stairs and platforms. In particular, endangering of the operating personnel must be minimised by providing adequate means of escape. It must be ensured that the distance of the escape routes from rooms at risk to an emergency exit does not exceed that demanded by the building regulations. At the same time, the emergency exit must open either directly into the open air or directly into an safety stairwell. On principle, there must always be two escape options, if possible diagonally opposite one another. The stairs, platforms and ladders should permit easy and safe access: to all access openings, inspection ports and cleaning apertures, to parts of the system that require regular checks or maintenance, to the equipment that must be actuated manually, either normally or in the event of a fault. Ladders should only be provided in exceptional circumstances. The vertical clearance above all platforms and stairs must be at least 2.10 m. The layout of stairs and platforms must be coordinated with the building owner. Walkways, stairs Frequently used walkways and stairs, as well as escape routes, should have a minimum width of 1.20 m; narrower widths are possible in consultation with the building owner. Step ratios for stairs required by building legislation: h/a ≤ 19/26 cm ≤ 36° Other stairs: h/a ≤ 20/23 cm ≤ 40° (see also DIN 18065 and DIN 31003) Stairs must be implemented in the form of solid, pre-cast concrete steps with slip-proof edge protection proﬁles embedded in the concrete and/or grating steps according to DIN 24531 with slip-proof leading edges. Gratings According to DIN 24531, type SP, 40 mm high, mesh side 30 mm, supporting bar 40 x 3 mm. The gratings are provided with an outer border, even in recesses for pipes etc. The gratings must be secured against displacement by positive clamps at the 4 corners of each individual element. Railings and ladders Made of round tubing according to DIN 24533, but with rungs made of square steel bars. E.2 Requirements and regulations E.2.3.2 Building services equipment Heating Buildings must normally be equipped with a domestic hot water heating system. The exceptions are all electrical, instrumentation and control rooms, IT systems, transformer and switchgear rooms. In principle, these spaces are heated with electric radiators or wall mounted or ceiling mounted electric fan heaters. In areas for boiler and machine houses, as well as district heating stations, where low pressure steam is available, this steam could be used for heating. The heating system is designed in such a way that a room temperature of +5 °C can be maintained at a minimum outside temperature of -25 °C. In this design, it is ensured that water-bearing parts cannot freeze up. Furthermore, the heating system is designed in such a way that at a standard outside temperature according to DIN 4701 of 12 °C, the following temperatures can be maintained: System rooms +18 °C Operations rooms +18 °C Ofﬁces and common rooms +20 °C Changing, wash and shower rooms +24 °C Pure trafﬁc areas, such as stairwells and passageways, and rooms in which no water-bearing system parts are situated +15 °C Ventilation Part of the exterior glazing must be equipped with opening windows (with storm protection) for the purpose of ventilating existing ofﬁces and common rooms. Cross ventilation must be possible. If window airing is not possible, natural ventilation must be provided with forced or mechanical ventilation. Mechanical operations rooms, such as turbine, boiler, pump and similar rooms, must be ventilated. Ventilation systems are designed on the basis of the following criteria: the required temperatures; the amount of heat released in the room; the amount of combustion air; depending on which of these criteria makes the greatest demands on the ventilation systems. Otherwise, the ventilation systems must be designed according to DIN 1946. The necessary unrestricted air intake and exhaust vents for the steam boiler room must be provided here on the basis of the formula in section D.3.4. Technical operations rooms, such as transformer, switchgear and electrical systems rooms, must be equipped with their own ventilation systems. The design of these systems is governed by the respective technical requirements and relevant ofﬁcial regulations, DIN, VDI and other guidelines. If cooling by outdoor air is dispensed with in electrical operations rooms due to the temperatures being too high and they are cooled instead by circulating air coolers, a minimum outdoor air content must be provided by means of simple air change. Areas with permanent workplaces, such as ofﬁces and workshops, must be ventilated in accordance with [German] workplace regulations (ArbStättV) and DIN 1946. Common rooms, changing, shower and washrooms must be ventilated in accordance with the ArbStättV and/or DIN 18228 and DIN 1946. Interior WC rooms without windows must be ventilated according to DIN 18017. 276/277 Smoke and heat extraction systems must be provided for all areas with relevant ﬁre hazards. The smoke and heat extraction system is dimensioned according to DIN 18230 (structural ﬁre protection in industrial buildings). Sanitary installations Sanitary installations may only be installed by registered contractors. Town water pipes Made of copper. Otherwise according to guidelines from the responsible water supply utility; cross sections and routing according to DIN 1988. Domestic hot water systems are coupled according to DIN 1988 with the drinking water and designed in compliance with AD datasheet A3. Hot water pipes and DHW circulation pipes must be insulated. The insulation thickness is governed by DIN 18421 and must be designed according to VDI 2055. Pipes laid beneath plaster must be fully insulated and must not come into contact with the brickwork. All insulating materials may only be provided in ﬂame-resistant or incombustible versions. Drain pipes must be designed according to DIN 1986. Collector pipes and downpipes must be made from socketless drain pipes (SML) with pipe connection up to DN 100 by means of AKO rapid connectors and from DN 125 with CV connectors. The connection lines to pieces of equipment must be laid beneath plaster in HT piping. Sizing according to DIN 1986. Fire extinguishing equipment Insofar as the local authorities have no other requirements, preference should normally be given to the provision of hand-held ﬁre extinguishers. These should however be provided in adequate numbers in coordination with the local ﬁre department and the building owner. E.2.4 Acoustic emissions Sources of noise Sound is understood as mechanical vibrations and waves in elastic media, such as solid bodies (structure-borne noise), air (airborne noise) and liquids. These vibrations occur at certain frequencies (= number of vibrations per second). The human ear perceives vibration from approx. 16 Hz (low notes) to approx. 16,000 Hz (high notes). Any type of sound perceived as annoying or irritating by the human ear is described as "noise". To prevent noise creating a nuisance, the legislator [in most countries] has issued regulations for protection against noise. These include the German Immissions Act (BImSchG), DIN 4109, DIN 45 680 and VDI Guideline 2058. Limits, testing and evaluating processes are deﬁned here as a function of the different environments and times of day. The noise emanating from boiler systems is mainly caused by the following: Combustion Burner fan Structure-borne vibrations Pump motors Airborne noise is predominantly created by the combustion process and transmitted by emissions from the burner, boiler and ﬂue. Structure-borne noise is generated by mechanical vibration in the boiler system and is generally transmitted through the foundations, walls and sides of the ﬂue system. Depending on the frequency, sound pressure levels of between 50 and 140 dB(A) can arise. E.2 Requirements and regulations Selected noise protection measures Sound-insulating bases can only be supplied up to a limited load-bearing capacity. Furthermore, separation can only be achieved by structural means, such as anti-vibration foundations. A) Structure-borne noise insulation Sound-insulating boiler supports minimise the transmission of structure-borne noise to the ﬂoor surface. B) Flue gas silencers Flue gas silencers are used for the attenuation of combustion noises. To ensure effectiveness, their design must be carefully coordinated with the boiler/burner combination, the ﬂue system and the chimney. When planning the size of the installation room, attention must be paid to the fact that the ﬂue gas silencer requires a considerable amount of space. C) Flue expansion joints Flue expansion joints prevent the transmission of structure-borne noise from the boiler/burner unit via the ﬂue path to the building structure. In addition, they can absorb the thermal expansion of the ﬂue pipes. D) Burner fan – silencer hoods Silencer hoods are used to attenuate burner fan noises. Their main purpose is therefore to reduce the amount of noise within the installation room. E) Air intake and exhaust Balanced ﬂue systems with silencers supply the burner with speciﬁc amounts of combustion air and prevent the outward transmission of noise generated in the boiler room via vents. We recommend that provision be made for noise prevention measures as early as the planning phase to avoid costly retroﬁtting. One prerequisite for an optimum solution is close collaboration between architects, developers, design engineers and contractors. The contact point for clarifying emission requirements is the local factory inspectorate. E.2.5 Transportation and handling A) Transportation Shell boilers can be transported by road, rail or water. Packaging must be designed appropriately for the means of transport; where necessary, the particularly fragile thermal insulation is shipped separately. Accessories such as burners, control equipment and valves are packed and shipped separately to protect them from damage in transit. A further beneﬁt of this approach is minimum possible transport dimensions. Accessories are ﬁtted only after the steam boiler has been installed on site. The higher the steam output, the more expensive the transportation. In certain circumstances, forwarding agents take account of appropriate transport routes (e.g. consideration of narrow roads and low bridges, the load-bearing capacity of transport routes) and police escorts (special transports). The developer must ensure that there is adequate access to the installation location on site. The access route must provide sufﬁcient load-bearing capacity (no underground tanks or underground car parks). In addition, sufﬁcient space for manoeuvring must be available. Suitable lifting equipment for unloading the boiler and accessories and for handling heavy equipment (e.g. burner, pumps, valves, control panel etc.) must be provided in the boiler house. B) Moving into the building An adequately sized opening must be provided for bringing the boiler and the additional components into the building. This opening may also be in the boiler house roof or take the form of a shaft. To reduce costs, the handling paths should be as short as possible and not restricted by obstructing elements. Sufﬁcient load-bearing capacity must also be ensured in this area. Lifting gear should be able to be sited as close to the installation location as possible. It must be adequately sized for the loads to be lifted and the heights and/or reach to be covered. Lifting equipment requires a sufﬁciently solid ﬂoor area. In certain circumstances, it may be necessary for access roads or sections of road to be closed temporarily. 278/279 E.2.6 E.2.6.1 Earthquake protection Basic principles When designing boiler houses in earthquake zones, it is essential that certain requirements for producing an earthquake-proof supporting structure are considered at an early stage. The basic task of earthquake protection is, by means of modelling, design and sizing, to direct and distribute the vibration energy transferred to the boiler house by earth movements and convert it into other forms of energy in such a way that major damage is prevented. Attention must therefore be paid to a clearly designed supporting structure with extensive regularity both in the ﬂoor plan and extending above the height of the boiler house. Aside from the vertical load-bearing elements, the shearing action of the ﬂoors is very important with regard to spatial load-bearing capacity and rigidity. The engineering design of the foundations and their connection to the boiler house that sits on them must ensure that large relative displacements of the foundation structures among themselves is prevented and the entire building structure is loaded uniformly by the movement of the earthquake. The stresses applied by an earthquake can be better appreciated and considered more accurately in the design due to the required regularity of the boiler house ﬂoor plan and elevation. Aside from the regularity of the structure, other important features must be examined, such as natural frequencies and damping of the structure. This should take place above all with reference to the constraints of the earthquake loads to be assessed. If necessary, appropriate measures must be provided to modify the natural frequencies and/or damping action. Such products as "protective elements" and/or "spring/VISCO® damping elements" can be used for this purpose. E.2.6.2 Steam boilers For boilers installed within an earthquakeproof boiler house, the earthquake impact on the boiler must be examined. This may require limitation of the acting forces and/or accelerations. However, the basic requirement is that the boiler(s) is/are installed on a foundation that has been included in the calculations for earthquake protection. E.184.108.40.206 Boiler accessories The speciﬁcations in item E.2.6.2 apply equally to ancillary components, such as pumps and thermal/chemical tanks. Calculationbased veriﬁcation of ability to withstand the respective loads (structural analysis) must be furnished for feedwater tanks, which are normally mounted on a frame. Chimneys must be designed for buckling prevention, even if they are installed in the building. Wind loads must be considered due to the construction height and the geodetic altitude of the installation location. E.2 Requirements and regulations E.2.6.3 Pipes In addition to static and dynamic operational loads, pipes in the boiler house must be designed to withstand the dynamic loads induced by an earthquake. Pipes only have insigniﬁcant inherent damping properties. Dynamic excitation due to operational or abnormal occurrences, such as an earthquake, is therefore always particularly critical if the excitation frequency corresponds to the natural frequency of the pipework. In order to restrict pipe movements to a permissible level, it may be necessary to provide for measures that increase damping here. Pipes that penetrate the boiler house wall, i.e. fuel, blow-off, steam, electrical and water inlet and outlet lines, must be routed in such a way that deformation of the body to be penetrated, as well as the pipes themselves, is prevented. Irrespective of the correctly and and safely implemented pipework design, pipes bearing hazardous materials (steam, oil, gas etc.) must be protected against earthquakes with a quickclosing system that reliably inhibits leakage of the medium. E.2.6.4 Earthquake-proof planning of openings and slits in walls In principle, earthquake walls with openings or slits must be regarded as individual walls that have a lower shearing resistance independently of one another than a single homogeneous wall. Electrical lines and piping must be planned in such a way that they impair the shearing resistance of a wall to the lowest extent possible. E.2.6.5 Earthquake standards Applicable building standards for earthquake safety must be considered in the project on a country-speciﬁc basis. In Germany, for example, DIN 4149 "Earthquake protection of solid structures" must be observed. 280/281 Vitomax 200-HS, type M237 2 Vitomax 200-HS, type M237, mirrored design SSAO Servolux, Lithuania, 3 x Vitomax 200-HS 4 t/h; 13 bar. 282/283 F Operation The following chapter deals with the operating modes and regulations for operation in Germany. Different regulations may apply in other countries. If applicable, the country-speciﬁc legislation must therefore be considered. The basis for operation in Germany is the [German] Health & Safety at Work Act (BetrSichV) and the associated technical regulations for operational safety (TRBS). 283 F Operation 284 Operating modes 284 286 287 F.1.1 F.1.2 F.1.3 Operating modes Standards and regulations governing operation Inspection intervals for boilers according to the Pressure Equipment Directive F.1 Operation Operating modes Depending on the respective equipment level, the TRD differentiates between several operating modes for high pressure steam systems. F.1.1 Operating modes 1. Operation with constant direct supervision In this operating mode, the boiler must be subject to constant supervision by an operator. Automatic equipment for regulating the water and pressure levels are therefore superﬂuous in this mode. Such functions can be carried out by the operators. 2. Operation with limited supervision The operator must personally verify the correct state of the boiler system every two hours. The boiler must be equipped with control equipment for water and pressure levels. 3. Temporary unattended operation with reduced operating pressure In the unattended operating mode, the steam boiler is operated with a safety pressure of 1 bar. This operating mode requires that additional equipment (safety valve, pressure regulator, pressure limiter, pressure gauge) are installed on the boiler. 4. Operation without constant supervision for a period of 24 hours (BosB 24h) The steam boiler must operate fully automatically and be equipped with two selfmonitoring pieces of safety equipment for limiting the water level at the lowest possible water level. Combustion with additional safety equipment must also be approved for unattended operation. 284/285 5. Operation without constant supervision for a period of 72 hours (BosB 72h) In addition to the requirements for 24-hour unattended operation, the high water level must also be limited in this mode using a separate switching ampliﬁer. Furthermore, limiters for the maximum conductivity of the boiler water and equipment for monitoring the water quality (top-up water, condensate) are required and additional control panel requirements must be met. The operating modes described in points 1 to 3 are practically irrelevant today. Due to the current standard of safety technology and equipment reliability, new boiler systems are equipped for unattended operation for a period of 24 or 72 hours. The present trend is towards unattended operation for 72 hours (BosB 72h). The following aspects must be observed as a condition for unattended operation: The operator must carry out the test procedures speciﬁed in the operational requirements, record their completion in the operator's log and conﬁrm such entries with his/her signature. A time switch for complying with the test intervals is not compulsory. In addition, a contractor, such as Viessmann Industrieservice, must conduct an inspection every six months of control and limiting equipment that is not subject to the regular checks by the operator. With this type of equipment, the operator's responsibilities are extended to include maintenance, therefore demanding a greater in-depth knowledge than is necessary for the operation of simpler systems. In conjunction with advanced control systems (e.g. PLC), it is possible to transfer boiler data to a control centre. Control functions can also be triggered from this control centre. Furthermore, automatic fuel changeover is also possible for dual-fuel combustion systems. The boiler must always be manually reset on the boiler itself after a safety shutdown has taken place. Note (for Germany) The amendment to the BetrSichV dated 18 December 2008 stipulates that, with effect from 31 December 2012, all technical regulations (TRD), which are no longer maintained following introduction of the Pressure Equipment Directive, will lose their validity, i.e. by this date, all the old technical regulations must have been superseded by the new TRBS. Quality requirements will be governed by the EN regulations. F.1 Operation F.1.2 Standards and regulations governing operation In Germany, the principle regulation for operation is the BetrSichV ([German] Health & Safety at Work Act). Paragraph 12 thereof stipulates that systems must be operated in accordance with the rules formulated by the Commission for Health & Safety at Work at the Federal Ministry for Labour (BMA) (Technical Regulations for Operational Safety – TRBS). However, these regulations are not yet completely available at the moment. Consequently, the TRD still apply to steam boilers in accordance with the transitional regulations. New systems may only be operated after the "Inspection prior to commissioning" has been carried out. For boilers in category III and IV, this inspection must be conducted by the approved monitoring body (ZÜS), which certiﬁes the correct condition of the system. Personnel trained in operating the system must be available during commissioning. For high pressure systems, these are qualiﬁed boiler operators who have completed an approved training course [in most cases, at the German Technical Inspectorate [TÜV]). Individuals who have the relevant technical knowledge on account of their training are considered to be of equal status. Correct operation also requires the use of operating instructions. These instructions must contain all information required by the operator for operation, maintenance and inspection work. This also includes a list of the actions operators must take on each individual piece of boiler equipment and at what intervals (see operating and service instructions for the Vitomax 200-HS). An operator's log must be available for each boiler where all inspections are recorded, and each entry is conﬁrmed by the signature of the person carrying out the inspection. The log serves the purpose of verifying correct operation and maintenance of the boiler system and must be submitted as and when required to the authorised inspector and the relevant regulatory authority. Paragraph 3 of the BetrSichV stipulates the compulsory requirement for employers to prepare a risk assessment. In preparing the assessment, all risks must be identiﬁed that could arise in the area of the steam boiler system, with the aim of ensuring provision and evaluation of the equipment without risk. Category III high pressure steam boilers (for a product of volume in litres and maximum permissible pressure in bar exceeding 1000) and those in category IV are subject to regular inspections by the approved monitoring body (ZÜS). According to paragraph 15 of the BetrSichV, operators are obliged to notify the relevant authority of the inspection intervals they have determined within six months of commissioning. The approved monitoring body must verify the determined inspection intervals. In the event of disagreement between operator and approved monitoring body regarding these intervals, the authority's decision is ﬁnal and binding. The inspection intervals are based on speciﬁcations issued by the boiler manufacturer, who makes relevant recommendations in the Declaration of Conformity. According to the [German] Health & Safety at Work Act (BetrSichV), the maximum intervals are as follows: External inspection 12 months Internal inspection 3 years Strength test 9 years These intervals must not be exceeded. 286/287 F.1.3 Inspection intervals for boilers according to the Pressure Equipment Directive The design work carried out by Viessmann in accordance with current regulations leads to the longest possible inspection intervals during operation. Viessmann prepares designs in accordance with TRD in conjunction with the trade association agreements and under consideration of the DIN/DIN EN standards. As a manufacturer, we recommend the following inspection intervals a) for our products: An expert inspection every six months. This can also be conducted by Viessmann Industrieservice (same scope as the annual inspection) After one year, external inspection by the approved monitoring body (ZÜS). All safety equipment (safety valve, control and limiting equipment, condition of threaded ﬁttings, state of the system, expertise of boiler operator, inspection of the operating log). The boiler may be operational After 3 years in operation, internal inspection by the approved monitoring body (ZÜS). At the same time, the boiler is inspected and all components examined on the water and gas sides After nine years, a strength test (water pressure test) by the approved monitoring body (ZÜS) F.1.3.1 Requirements for regular inspection according to TRD 505 – external inspection – A) Scope This guideline applies to the external inspection of all Vitomax high pressure steam and high pressure hot water boilers with the following parameters: TS > 120 °C, PS > 1 bar, which are employed as land-based steam boilers for generating high pressure hot water and steam. B) Inspection intervals See Declaration of Conformity (e.g. Vitomax 200-HS type M75A, Fig. C14.1-3) for the respective boiler type. The intervals begin after the system has been commissioned. Insofar as internal inspections are due at the same time, the external inspection must take place on conclusion of the internal tests. C) Extent of the external inspection The regular external inspection of the steam boiler system extends to the steam boiler and the components of the steam boiler system, i.e. every piece of equipment required for operating the boiler system. Based on our Declaration of Conformity, the operator recommends the aforementioned inspection intervals to the relevant authority. The authorised inspector from the approved monitoring body either agrees or demands a shorter inspection interval. Until now, neither Viessmann Werke nor Viessmann customers have experienced any difﬁculties with this procedure. a) see also Appendix. G, Tb.10. F.1 Operation D) Execution of the regular external inspection On carrying out the inspection, e.g. function test, the operation will be interrupted. No hazardous conditions may arise in the system due to testing. The system operator is responsible for identifying any defect, damage or unusual occurrence that comes to light during the observation period. Compliance of the system with the permit and the system condition are generally checked in accordance with the following points, whereby the system is inspected together with the operator or a person authorised by the operator. D1) Assessment of the general system condition, namely: the boiler components and hot water expansion vessels that are accessible during operation, the spot check of the combustion chamber through inspection ports, the sheet metal casing, the thermal insulation, the closures, the inspection ports, the determination of leaks, signs of condensation, discolouration and vibration. Combustion and the fuel supply/charging, storage and treatment equipment, air lines, air pre-heaters, ﬂue ducts and ﬂue silencers Feedwater, steam, hot water, drain and dewatering lines D 2) Safety-related equipment on the water and steam side, namely: devices for limiting water level, pressure and temperature with regard to their function; controllers only insofar as they fulﬁl a safety function Feed pump operational availability Network circulation pump operational availability Safety equipment to prevent excess pressure: response pressure, function: safeguarding against unintentional adjustment Pressure maintaining equipment in hot water systems with external pressure maintenance; determination of the switching points and changeover testing, if applicable Flue gas non-return devices, shut-off and drainage equipment D 3) Safety-related combustion equipment with regard to function: Equipment on fuel tanks Safety equipment on fuel oil pre-heaters Fuel supply lines and equipment, including valves for easily ﬂammable, liquid and gaseous fuels Safety shut-off equipment, also checking for tightness and tightness/leak testing equipment Burner, shut-off and actuating equipment for combustion air, air shortage prevention devices, ignition equipment, ﬂame monitoring equipment, fuel/air control equipment, safety equipment leading to a shutdown, giving due consideration to the possible operating modes, safety, maintenance, ﬂushing and ignition times Observation apertures for the combustion chamber, the burner lining and the ﬂame appearance Devices for combustion chamber pressure regulation 288/289 D 4) Safety power circuit The safety power circuit of the steam boiler system is tested for such possible faults that cannot be established as part of the function test on individual pieces of equipment. D 5) Operating mode Visual inspection of the operating records regarding the quality of the feedwater and boiler water as well as inspection of the additional equipment for operation with limited supervision or without constant supervision. D 6) Operation A check is made with regard to the availability of suitable operating instructions and the familiarity of operating personnel with the operation of the boiler system. E) Test certiﬁcate The tester must produce a report of the inspection (see EN 12953-6, Appendix C) and suitable measures must be initiated if defects are discovered. F.1.3.2 Requirements for regular inspection according to TRD 506 – internal inspection – A) Scope This guideline applies to the internal inspection of all Vitomax high pressure steam and high pressure hot water boilers with the following parameters: TS > 120 °C, PS > 1 bar, which are employed as land-based steam boilers for generating high pressure hot water and steam. B) Inspection intervals The interval for the recurring internal inspection is three years1). The intervals begin after the system has been commissioned. An internal inspection must be conducted prior to re-commissioning if the steam boiler has been non-operational for more than two years. C) Extent of the internal inspection The recurring internal inspection extends to the steam boiler and the feedwater pre-heater located in the ﬂue gas ﬂow of the combustion chamber. The steam boiler includes all the equipment and lines associated with the boiler, including the shut-off equipment. This does not apply to parts connected with the inlet, outlet and drain lines that can be shut off from the boiler and those parts in which the generated steam is superheated that can be shut off from the boiler, unless these are located wholly or partially inside a container that is part of the steam boiler. Fig. F.1.3.2-1 Inspection intervals for recurring internal testing in selected member states D F B I L NL GB S Pressure vessel 5 1.5 - 3 1-3 1-2 5 4 2.17 3 Steam boiler 3 1.5 1 2 1.5 2 1.17 1 1) = country-speciﬁc. F.1 Operation D) Execution of the recurring internal inspection The recurring internal inspection is generally conﬁned to a visual inspection that may be carried out, if necessary, using suitable auxiliary means, such as inspection devices (endoscopy), or by additional simple testing, such as measuring the wall thickness or checking for surface cracks. If there is other cause (operating mode) to assume the existence of damage that cannot be detected with the means mentioned in the previous section, additional inspection actions are required that extend beyond the general scope. Normally, these are test methods such as supplementary water pressure checks, ultrasound testing, material tests, surface crack inspections and chemical analysis of deposits. D1) The recurring internal inspection is carried out as follows: boiler jackets and ﬂoors, ﬂame tubes, reversing chambers and similar are inspected, insofar as they are accessible, taking into consideration the welded and threaded connections, the ﬂanges, the anchors (end anchor, tensioning anchor and similar), the connectors, the pipe connections, the attachment and condition of built-in parts, the manhole covers and the inspection ports. Deposits are assessed. The walls on the ﬂue gas and combustion side and the external walls are inspected, insofar as they are accessible, in particular the ﬂame tubes, ﬂanges, connectors, manhole covers, inspection ports and boiler supports. The boiler body insulation need not be removed for conducting these inspections. Proﬁles and ﬁttings are inspected externally, whereby particular attention is paid to welding seams, ﬂange collars, brackets and supports. Casings for water level controllers and limiters are also inspected internally. For other ﬁttings, the following section applies. Flue gas feedwater pre-heaters are visually inspected on the ﬂue gas side; on the water side, only insofar as detachable closures are available. The inspection includes checking for corrosion, particularly as a result of temperatures falling below the dew point. E) Test certiﬁcate The tester must produce a report of the inspection (see DIN EN 12953-6, Appendix C) and suitable measures must be initiated if defects are discovered. 290/291 F.1.3.3 Requirements for regular inspection according to TRD 507 – water pressure testing – A) Scope This guideline applies to the external inspection of all Vitomax high pressure steam and high pressure hot water boilers with the following parameters: TS > 120 °C, PS > 1 bar, which are employed as land-based steam boilers for generating high pressure hot water or steam. B) Inspection intervals The interval for the recurring water pressure test is normally nine years1). The intervals begin after the system has been commissioned. B1) Extent of the water pressure test The recurring water pressure test extends to the steam boiler and the feedwater pre-heater located in the ﬂue gas ﬂow of the combustion chamber. C) Execution of the recurring water pressure test C1) Test pressure level Test pressures must not exceed those applied during the ﬁrst water pressure test. For Vitomax: see type plate2) For Turbomat: see approbation drawing For ﬂue gas water pre-heaters, the test pressure is equal to the test pressure level of the associated steam boiler. C2) Applying and maintaining the test pressure The test pressure must be applied in the presence of the authorised inspector, after the components to be tested have previously been subjected to operating pressure. Where no alternative values are stated by the manufacturer, the rate of pressure change must not exceed 10 bar per minute up to approx. 75 % of the test pressure and thereafter approx. 1-2 bar per minute. The test pressure must be applied for approx. 30 minutes before the authorised inspector begins testing the pressurised components. The test pressure must be checked with a test pressure gauge. For steam boilers and system components with test pressures of up to 42 bar, test pressure must be maintained for the entire duration of the test. In the case of test pressures in excess of 42 bar, the pressure prior to ramping to the level of the permissible operating pressure must not fall below 42 bar. When reducing the pressure, the rate of pressure change should correspond to that when the pressure was applied. C3) Water requirements Water used for ﬁlling the system must not contain any coarse contaminants. Under consideration of the operating conditions, the water must not contain any constituents that would attack or contaminate the walls. During inspection, the ﬁlling water temperature should not exceed 50 °C. C4) Visual inspection of the walls Pressurised components must be checked visually for the presence of cracks, impermissible deformation and leaks. Visual spot checks are permissible if the authorised inspector can assess the safety-relevant condition of the system components to be tested on the basis of these checks. The thermal insulation is removed as far as is appropriate if there is good reason to assume that damage has occurred. D) Test certiﬁcation The tester must produce a report of the inspection (see DIN EN 12953-6, Appendix C) and suitable measures must be initiated if defects are discovered. 1) Country-speciﬁc requirements must 2) This ensures compliance with the be observed. requirements of TRBS 1201. Vitomax 200-HS, 26 t/h, Austria 292/293 G Appendix Technical data collection and tables 293 G Appendix Technical data collection and tables 294 [A 1] 296 297 298 302 304 305 306 309 313 314 315 316 317 318 319 320 311 322 323 324 325 Standard circuit diagram; other diagrams can be found in the cover inside pocket [A 2.1] Thermal insulation of pipes [A 2.2] Contact protection insulation [A 3] Technical Guide on water quality – extract [A 4] Sketch of steam boiler container system [Tb. 1.0] SI units / conversion table [Tb. 1.1] 1. Conversion table – BTU / BHP / KW / t/h [Tb. 2.0] Steam table (saturation state) [Tb. 2.1] Properties of superheated steam [Tb. 2.2] Properties of saturated steam [Tb. 2.3] Enthalpy/Entropy [Tb. 3.0] Internal pipe roughness [Tb. 3.1] Pipe friction factor / Reynolds number [Tb. 4.0] Pressure drop in steam pipes [Tb. 4.1] Pressure drop in steam pipes – example [Tb. 5] Conversion for the units of water hardness [Tb. 6] Re-evaporation in condensate expansion [Tb. 7] Pipe cross section for given steam parameters – example [Tb. 8] Pressure drop in water pipes for a particular ﬂow rate – example [Tb. 9] Flow velocities (standard values) [Tb. 10] Steam boiler inspection checklist Literature references G.1 Appendices [A 1] Standard circuit diagram 294/295 G.1 Appendices [A 2.1] Thermal insulation of pipes Ambient temperature: 9 °C Wind speed: 5 m/s Number of hours run: 8000 h/a Cost-effective thermal insulation for pipes °C 80 100 120 140 160 180 200 220 240 260 280 300 320 340 360 380 400 420 440 460 480 500 DN 10 40 40 40 40 40 40 40 40 40 40 40 40 40 50 50 50 50 50 60 60 60 60 15 40 40 40 40 40 40 40 40 40 40 40 50 50 50 50 50 50 50 60 60 60 60 20 40 40 40 40 40 40 40 40 40 50 50 50 50 50 60 60 60 60 60 70 70 70 25 40 40 40 40 40 40 40 40 50 50 50 50 50 50 60 60 60 60 70 70 80 80 32 40 40 40 40 40 40 40 40 50 50 60 60 60 60 60 60 70 70 70 80 80 80 40 40 40 40 40 40 40 40 50 50 60 60 60 60 70 70 70 70 70 80 80 80 80 50 40 40 40 40 40 50 50 50 60 60 60 70 70 70 70 70 80 80 80 90 90 90 65 40 40 40 40 50 50 50 60 60 70 70 70 70 80 80 80 80 90 90 90 90 100 80 40 40 40 50 50 60 60 60 70 70 70 70 80 80 80 90 90 90 90 100 100 100 100 40 40 50 50 50 60 70 70 70 80 80 80 80 90 90 90 100 100 100 100 110 110 125 40 40 50 50 60 60 70 80 80 80 90 90 90 90 100 100 100 110 110 110 110 110 150 40 50 50 60 60 80 80 80 90 90 90 100 100 100 100 110 110 110 120 120 120 120 200 40 50 50 60 80 80 80 90 90 100 100 100 110 110 110 110 120 120 120 150 150 150 250 50 50 60 60 80 90 90 90 100 100 100 110 110 120 120 120 120 150 150 150 160 160 300 50 50 60 80 80 90 90 100 100 100 110 110 110 120 150 150 150 150 150 160 160 170 350 60 60 60 80 90 90 100 100 100 110 110 120 120 120 150 160 160 160 160 160 170 170 400 60 60 80 80 90 100 100 100 110 110 120 120 150 150 150 160 170 170 170 170 170 190 500 60 80 80 90 90 100 100 100 110 110 120 150 150 160 160 160 170 190 190 190 190 190 600 60 80 90 90 100 100 100 110 110 120 120 150 160 160 170 170 170 190 190 190 200 200 700 60 80 90 100 100 100 110 110 120 120 150 150 160 170 170 180 180 190 190 200 200 200 800 80 80 90 100 100 100 110 110 120 150 150 160 160 170 180 180 190 190 200 200 200 210 900 80 90 90 100 100 110 110 120 120 150 160 160 170 170 180 190 190 200 200 200 210 210 1000 80 90 100 100 100 110 110 120 150 150 160 170 170 180 180 190 200 200 200 210 210 220 1100 90 90 100 100 100 110 110 120 150 160 160 170 170 180 190 190 200 200 210 210 220 220 1200 90 90 100 100 100 110 120 120 150 160 170 170 180 180 190 190 200 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210 210 220 230 230 240 240 240 240 240 wall 296/297 [A 2.2] Contact protection insulation Contact protection insulation [A 2.2] Contact protection insulation on pipes and containers/cylinders Design data: Surface temperature on the weather jacket: 60 °C Ambient air temperature: 20 °C Wind speed: 3 m/s Insulating material: mineral mat DN/t 100 150 200 250 300 350 400 450 500 550 600 700 800 (°C) 10 40 40 40 40 40 40 40 40 40 40 40 50 70 15 40 40 40 40 40 40 40 40 40 40 40 60 80 20 40 40 40 40 40 40 40 40 40 40 50 60 80 25 40 40 40 40 40 40 40 40 40 40 50 70 90 32 40 40 40 40 40 40 40 40 40 50 50 70 90 40 40 40 40 40 40 40 40 40 40 50 50 70 100 50 40 40 40 40 40 40 40 40 40 50 60 80 100 65 30 30 30 30 30 30 30 30 40 50 60 80 120 80 30 30 30 30 30 30 30 30 50 50 60 90 120 100 30 30 30 30 30 30 30 40 50 60 70 90 120 125 30 30 30 30 30 30 40 40 50 60 70 100 130 150 30 30 30 30 30 30 40 40 50 60 80 100 130 200 30 30 30 30 30 30 40 50 60 70 80 120 140 250 30 30 30 30 30 30 40 50 60 70 80 120 150 300 30 30 30 30 30 30 40 50 60 70 90 120 160 350 30 30 30 30 30 30 40 50 60 80 90 120 160 400 30 30 30 30 30 40 40 50 70 80 90 130 170 500 30 30 30 30 30 40 50 60 70 80 100 130 180 600 30 30 30 30 30 40 50 60 70 80 100 140 190 700 30 30 30 30 30 40 50 60 70 90 100 140 190 800 30 30 30 30 30 40 50 60 70 90 120 150 200 900 30 30 30 30 30 40 50 60 80 90 120 150 210 1000 30 30 30 30 30 40 50 60 80 90 120 160 210 1100 30 30 30 30 30 40 50 60 80 100 120 160 210 1200 30 30 30 30 30 40 50 70 80 100 120 160 220 1400 30 30 30 30 30 40 50 70 80 100 120 170 240 240 1500 30 30 30 30 30 40 60 70 80 100 120 170 1600 30 30 30 30 40 50 60 70 90 100 120 170 240 1800 30 30 30 30 40 50 60 70 90 120 130 180 240 2000 30 30 30 30 40 50 60 70 90 120 130 180 250 2400 30 30 30 30 40 50 60 80 90 120 130 190 260 2800 30 30 30 30 40 50 60 80 90 120 140 190 270 3200 30 30 30 30 40 50 60 80 100 120 140 200 270 4000 30 30 30 30 40 50 60 80 100 120 140 200 280 30 30 30 30 30 30 30 40 50 60 70 100 140 Hori. + vert. wall G.1 Appendices [A 3] Technical Guide on water quality - extract 7HFKQLFDOJXLGH±ZDWHUTXDOLW\IRUVWHDPERLOHUV\VWHPV 8VHRIWKLVWHFKQLFDOJXLGH The specified limits apply to steam generators made from unalloyed or low-alloyed steel. They are based on many years' experience gained by Viessmann in the steam boiler sector as well as the minimum requirements specified by the EN 12953-10. $LP Maintaining the aforementioned water parameters enables system operators ■ to reduce the risk of corrosion, ■ to reduce the formation of deposits, ■ and to safeguard the separation of sludge. This facilitates safe, economical system operation over a long service life. 6WHDPERLOHU In its natural state, most untreated water will be unsuitable as boiler feedwater. The type of boiler feedwater treatment should be matched to the raw water quality. As its quality may change, regular checks are required. The water feed pipe downstream of the boiler feedwater treatment should be equipped with a suitable water meter to record the volume of top-up water added to the return condensate; this also provides an indirect check on the steam draw-off volume. In all circumstances, it is advisable to return as much condensate as possible to the feedwater tank. The condensate may also have to be treated so it conforms to the requirements of the boiler feedwater (according to table 1). These requirements, plus those appertaining to the boiler water (according to table 2), mean that – depending on the condition of the untreated water and the amount of top-up water – at the very least a suitable chemical or thermal water treatment system should be installed and there should be a facility for adding oxygen binders (possibly alkalines and phosphates) into the feedwater tank supply line. The requirements are monitored by measurements made by suitable, preferably uncomplicated devices (either every 24 h or 72 h or in line with national requirements, subject to the mode of operation). These test values, the volume of top-up water, the chemical consumption and the required maintenance should be entered into a boiler log to enable the operating conditions to be checked at any time. 7DEOH6DOLQHERLOHUIHHGZDWHUUHTXLUHPHQWV 3HUPLVVRSHUDWLQJSUHVVXUH General requirements pH value at 25 °C Conductivity at 25 °C Total alkaline earths (Ca2+ + Mg2+) Oxygen (O2) Bound carbon dioxide (CO2) Iron, total (Fe) Copper, total (Cu) Oxidability (Mn VII ඎ Mn II) as KMnO4 Oil, grease Organic substances EDU µS/cm mmol/litre mg/litre mg/litre mg/litre mg/litre mg/litre mg/litre — XSWR ! Colourless, clear and free of undissolved substances >9 Only standard values applicable to boiler water < 0.01 0.05 < 25 < 0.2 < 0.05 < 10 < 1 see footnote >9 < 0.01 < 0.02 < 25 < 0.1 < 0.01 < 10 <1 7DEOH%RLOHUZDWHUUHTXLUHPHQWV Silicic acid (SiO2) 2 EDU )HHGZDWHUFRQGXFWLYLW\!6FP XSWR ! 10.5 to 12 mmol/litre µS/cm mg/litre mg/litre 1 to 12 < 6000 10 to 20 )HHGZDWHUFRQGXFWLYLW\싨6FP ! Colourless, clear and free of undissolved substances 10.5 to 11.8 1 to 10 see Fig. 1, page 3 10 to 20 Subject to pressure; see Fig. 1 (page 3) and 2 (page 3) 10 to 11 0.1 to 1.0 < 1500 6 to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싩DQGERLOHUZDWHUS+YDOXH싩PD\EHXVHG,QVXFKFDVHV WKHFRQGXFWLYLW\GRZQVWUHDPRIDVHYHUHO\DFLGLFFDWLRQH[FKDQJHUPXVWEH6FP %DVHOHYHODGMXVWPHQWRIWKHS+YDOXHWKURXJKLQMHFWLRQRI1D32DGGLWLRQDO1D2+LQMHFWLRQRQO\LIWKHS+YDOXHLV :LWKVXSHUKHDWHUVRIWKHVSHFLILHGXSSHUYDOXHVKRXOGEHWUHDWHGDVPD[LPXPYDOXH ,ISKRVSKDWHLVXVHGKLJKHU32FRQFHQWUDWLRQVDUHSHUPLVVLEOHVXEMHFWWRFRQVLGHUDWLRQRIDOORWKHUYDOXHVHJZLWKEDODQFHGRUFRRUGLQDWHG SKRVSKDWHWUHDWPHQW6HHVHFWLRQ³&RQGLWLRQLQJ´ WATER QUALITY FOR STEAM BOILER SYSTEMS 5822 454 GB 3HUPLVVRSHUDWLQJSUHV VXUH General requirements pH value at 25 °C Acid capacity (KS 8.2) Conductivity at 25 °C Phosphate (PO4) 298/299 Technical guide – Water quality for steam boiler systems (continuation) Note The addition of phosphate is recommended, but not always essential. Conversion: 1 mol/m3 = 5.6 °dH; 1 °dH = 0.179 mol/m3; 1 mval/kg = 2.8 °dH Operation with salt-free boiler feedwater is also possible as an alternative to operation with saline boiler feedwater. Maximum permissible direct boiler water conductivity as a function of pressure Feedwater conductivity > 30 ˩S/cm 'LUHFWFRQGXFWLYLW\LQw6FP 2SHUDWLQJSUHVVXUHLQEDU Figure 1 Maximum permissible silicic acid content (SiO2) of the boiler water as a function of pressure B 6LOLFLFDFLGFRQWHQW6L2LQPJO A B B B 2SHUDWLQJSUHVVXUHLQEDU Figure 2 A This level of alkalinity is no longer permissible > 20 bar KS 8.2 value in mmol/l 5811 454 B Water quality for steam boiler systems 3 G.1 Appendices Technical guide – Water quality for steam boiler systems (continuation) Conditioning Certain feedwater and boiler water properties must be improved by means of chemical treatment. This conditioning can contribute to: ŶSupporting the formation of magnetic layers or other protective oxide layers, Ŷ5HGXFLQJFRUURVLRQE\RSWLPLVLQJWKHS+YDOXH ŶStabilising the hardness and preventing or minimising boiler scale and deposits, Ŷ Achieving chemical bonding of residual oxygen Conventional conditioning agents may, for example, contain sodium and potassium hydroxide, sodium phosphate, sodium sulphite, ammonia and diamide. Note Use of some of these chemicals may be restricted in certain countries or processes. General information regarding conditioning ŶConductivity – Saline This refers to feedwater with an electrical conductivity of > 30 μS/cm (e.g. downstream from a softening system). – Low-salt This refers to feedwater with an electrical conductivity of 0.2 - 30 μS/cm (e.g. downstream from a T.D.S. system). – Salt-free This refers to feedwater with an electrical conductivity of < 0.2 μS/cm and a silicic acid concentration < 0.02 mg/l , as well as condensate with an electrical conductivity of < 5 μS/cm (e.g. downstream from full T.D.S. systems with mixed bed quality). ŶAcid capacity KS 4.3 Elevated alkalinity (m value) in raw/soft water implies too much bonded carbon dioxide. This results in an increased alkalinisation of the boiler water, which in turn leads to an increased risk of corrosion in the steam boiler and also in the steam network downstream from the boiler due to separation of vapour-volatile carbon dioxide. ŶSetting the alkalinity The selection of the alkalising agent depends, amongst other things, on the use of the steam, the steam pressure and the type of water treatment. There are solid and volatile alkalising agents. Balanced conditioning with phosphate or its derivatives can also be ŶOxygen and carbon dioxide or oxygen binders Carbon dioxide and oxygen are expelled from the feedwater by total thermal deaeration. Should it prove to be impossible to keep the oxygen content of the feedwater below the permissible values in practical operation, e.g. due to repeated idle periods, then the use of oxygen binders is necessary. This "correction chemical" is admixed to the feedwater via the dosing equipment. Note Note Evaporation of the boiler water leads to concentration of the solute non-volatile boiler constituents in the remaining boiler water (salts, solid conditioning agents). This is referred to as "thickening" of the boiler water. Such conditions can lead to local alkali concentrations that result in stress fracture corrosion. Therefore, with only mildly buffered feedwater (feedwater with low salt content) with a conductivity of < 30 μS/cm, sodium hydroxide is only permissible as an alkalising agent if the recommended pH range cannot be achieved with sodium phosphate alone. At the same time, low pH value. organic conditioning agents have also been in use for years. If organic conditioning agents are used, the amounts and processes the supplier of the chemical products. Deviation during conditioning If actual values deviate during continuous operation from those The chemical composition of the boiler water can be monitored Ŷ,QDGHTXDWHWUHDWPHQWRIWKHWRSXSZDWHU blow-down of a part of the water volume. This must be carried out in such a way that both solute and suspended contaminants can be eliminated. Ŷ Advanced corrosion of certain system components ŶContamination of the water due to ingress of contaminants from other systems, e.g. condensate tank, heat exchangers. Appropriate changes must be carried out immediately to reinstate correct operation. For example, returned condensate must not affect the feedwater quality and may have to be treated. Conditioning/Warranty Note The warranty becomes void: 5811 454 ŶLIGRVLQJDJHQWVDUHXVHGWKDWDUHQRWOLVWHGLQWKHJXLGHOLQHVRUKDYHQRWEHHQDJUHHGZLWK9iessmann. 4 Water quality for steam boiler systems 300/301 Technical guide – Water quality for steam boiler systems (continuation) Sampling Sampling of water and steam from the boiler system must be conducted in compliance with ISO 5667-1; the treatment and handling of samples in compliance with ISO 5667-3. Samples are taken by means of a sampling cooler. This cools down the water sample to a temperature of approx. 25 °C. In order to take a usable sample, the sampling line must be ﬂushed for an appropriate period. The sample should be analysed immediately after it has been taken, since values may change as a result of prolonged settling. Opaque or contaminated sample water must be ﬁltered prior to testing. See also "Sampling cooler operating instructions" Sampling points Provision must be made for sampling points at representative locations in the system. Typical sampling points are: ŶBoiler feedwater inlet valve ŶBoiler water from a downpipe or a continuous T.D.S. line ŶTop-up water downstream from the top-up water treatment system or the storage tanks ŶCondensate at the outlet from the condensate tank, if installed Otherwise, the sample must be taken from as close as possible to the feedwater tank. Analysis General information Veriﬁcation of compliance with the values speciﬁed in Table 1 (page 2) and Table 2 (page 2) must be provided by means of analysis. If the analyses are conducted according to other standards or by means of indirect methods, those methods must be calibrated. A clean work surface with water supply and drainage must be available for carrying out the analyses. The required equipment must also be stored at this workplace in a cabinet. Note For some types of water, the amount of solute matter can be estimated based on its conductivity. Furthermore, a correlation exists between the pH value and both conductivities. For continuous monitoring of the O2 and pH values as well as water hardness, Viessmann supplies water analysis components. Analysis method/Test equipment Boiler values can be measured adequately with the test equipment during ongoing boiler operation. In the event of severe deviation in values, the actual values must be conﬁrmed by means of the corresponding standardised analysis methods and corrective measures identiﬁed. Parameters must be checked in accordance with the following standards: Acid capacity Conductivity Copper Iron Oxygen pH value Phosphate Potassium Silicic acid*6 EN ISO 9963-1 ISO 7888 ISO 8288 ISO 6332 ISO 5814 ISO 10523 ISO 6878–1 ISO 9964–2 Sodium TOC*7 Total harness as Ca + Mg ISO 9964–1 ISO 8245 ISO 6059 The acid conductivity in the form of the hydrogen ion concentration must be measured continuously in the same way as the conductivity in hydrogen form, after the sample has passed through a severely acidic cation exchanger with a volume of 1.5 l. The exchanger is inserted into a cylinder with a diameter: height ratio of 1:3 or less, whereby the exchanger medium takes up at least three quarters of the cylinder volume. The ion exchanger must be regenerated once it has been exhausted by two thirds ; this can be recognised when using an exchanger with colour indicator and transparent cylinder. Shutdown periods/frost protection 5811 454 If boiler systems are shut down for longer periods, it is recommended that the systems are completely ﬁlled with water and that the water is enriched with oxygen binders to bind the oxygen in the water. The boiler must be kept under pressure for this purpose. Another option is that of dry preservation, which is recommended for shutdown periods exceeding 4 weeks. For detailed relevant information, see manual "Preservation on the water & hot gas side" *6 There is currently no European or international standard; see for example DIN 38405-21 Standardised German procedure for water, waste water and sludge examination; anions (group D); photometric determination of dissolved silicic acid (D 21). *7 As an alternative, the permanganate index can be measured in accordance with ISO 8467, if these values are speciﬁed. Water quality for steam boiler systems 5 G.1 Appendices [A 4] Sketch of steam boiler container system 302/303 Container system with Vitomax 200-HS 2.9 t/h, 10 bar RT-Group LLC Ukraine G.2 Technical data collection and tables [Tb. 1.0] SI units / conversion table Pressures bar mbar mm WC 1 kp/cm2 = 1 at 1 1000 10200 1.02 750 0.001 1 10.20 0.00102 0.750 0.0000981 0.0981 1 0.0001 0.07355 0.981 981 10000 1 735.5 1 torr 0.001333 1.333 13.6 0.00136 1 1 Pa 0.00001 0.01 0.1020 0.000012 0.0075 1 bar 1 mbar 1 mm WC 1 kp/cm2 torr Energy, work, heat kcal Mcal 1 kcal 1 0.001 1 Mcal 1000 1 0.000239 0.000000239 1 1 kJ 0.2388 0.000239 1 MJ 238.8 0.2388 860 0.860 3600000 1 J = 1 Ws 1 kWh J Ws kJ MJ kWh 4186.8 4.1868 0.00418 0.001163 4186800 4186.8 4.1868 1.163 0.001 0.000001 0.0000002778 1000 1 0.001 0.0002778 1000000 1000 1 0.2778 3600 3.6 1 Output and heat ﬂux kcal kcal/min 1 kcal/h 1 1 kcal/min 60 1 J/s = 1 W 1 kW J/s W kW MJ/h 0.01667 1.163 0.001163 0.0041868 1 69.768 0.69768 0.2512 0.860 0.01433 1 0.001 0.0036 860 0.01433 1 0.001 0.0036 Temperature °C degrees Celsius °C degrees Fahrenheit °C degrees Kelvin °C degrees Rankine °C °F K °R 1 1.8 x °C + 32 °C + 273 1.8 x °C + 492 0.56 x (°F - 32) 1 0.56 x °F - 460 °F + 460 K - 273 1.8 x K - 460 1 1.8 K 0.56 x (°R - 492) °R - 460 0.56 x °R 1 The conversion values are rounded Kelvin - Temperature on the absolute temperature scale, whereby 1 degree Kelvin = 1 degree Celsius Rankine - Temperature on the absolute temperature scale, whereby 1 degree Rankine = 1 degree Fahrenheit Temperature differential in Celsius division: 1 in gr. Temperature differential in Fahrenheit division: t in degF. 304/305 [Tb. 1.1] 1. Conversion table - BTU / BHP / KW / t/h 1. Conversion table - BTU / BHP / KW / t/h [Tb. 1.1] kCal/hr kW BTU BHP t/ha) 562,500 675 2,250,000 68 1 1.5 841,667 1,010 3,366,667 101 1,125,000 1,350 4,500,000 135 2 1,395,833 1,675 5,583,333 168 2.5 1,687,500 2,025 6,750,000 203 3 1,970,833 2,365 7,883,333 237 3.5 2,250,000 2,700 9,000,000 270 4 2,812,500 3,375 11,250,000 338 5 3,375,000 4,050 13,500,000 405 6 3,937,500 4,725 15,750,000 473 7 4,500,000 5,400 18,000,000 540 8 5,062,500 6,075 20,250,000 608 9 5,625,000 6,750 22,500,000 675 10 6,750,000 8,100 27,000,000 810 12 7,875,000 9,450 31,500,000 945 14 a) 12 bar, 102 °C feedwater temperature. G.2 Technical data collection and tables [Tb. 2.0] Steam table (saturation state) Absolute pressure Temp. Specific volume, boiling water Q’ m3/kg Steam volume Q” 3 m /kg Steam density U” kg/m3 Water enthalpy K¶ kJ/kg K´ kJ/kg U kJ/kg Steam enthalpy Evaporation heat S bar ts °C 0.010 0.015 0.020 0.025 0.030 0.035 6.98 13.04 17.51 21.10 24.10 26.69 0.0010001 0.0010006 0.0010012 0.0010020 0.0010027 0.0010033 129.20 87.98 67.01 54.26 45.67 39.48 0.00774 0.01137 0.01492 0.01843 0.02190 0.02533 29.34 54.71 73.46 88.45 101.00 111.85 2514.4 2525.5 2533.6 2540.2 2545.6 2550.4 2485.0 2470.7 2460.2 2451.7 2444.6 2438.5 0.040 0.045 0.050 0.055 0.060 0.065 28.98 31.04 32.90 34.61 36.18 37.65 0.0010040 0.0010046 0.0010052 0.0010058 0.0010064 0.0010069 34.80 31.14 28.19 25.77 23.74 22.02 0.02873 0.03211 0.03547 0.03880 0.04212 0.04542 121.41 129.99 137.77 144.91 151.50 157.64 2554.5 2558.2 2561.6 2564.7 2567.5 2570.2 2433.1 2428.2 2423.8 2419.8 2416.0 2412.5 0.070 0.075 0.080 0.085 0.090 0.095 39.03 40.32 41.53 42.69 43.79 44.83 0.0010074 0.0010079 0.0010084 0.0010089 0.0010094 0.0010098 20.53 19.24 18.10 17.10 16.20 15.40 0.04871 0.05198 0.05523 0.05848 0.06171 0.06493 163.38 168.77 173.86 178.69 183.28 187.65 2572.6 2574.9 2577.1 2579.2 2581.1 2583.0 2409.2 2406.2 2403.2 2400.5 2397.9 2395.3 0.10 0.15 0.20 0.25 0.30 0.40 45.83 54.00 60.09 64.99 69.12 75.89 0.0010102 0.0010140 0.0010172 0.0010199 0.0010223 0.0010265 14.67 10.02 7.650 6.204 5.229 3.993 0.06814 0.09977 0.1307 0.1612 0.1912 0.2504 191.83 225.97 251.45 271.99 289.30 317.65 2584.8 2599.2 2609.9 2618.3 2625.4 2636.9 2392.9 2373.2 2358.4 2346.4 2336.1 2319.2 0.45 0.50 0.55 0.60 0.65 0.70 78.74 81.35 83.74 85.95 88.02 89.96 0.0010284 0.0010301 0.0010317 0.0010333 0.0010347 0.0010361 3.576 3.240 2.964 2.732 2.535 2.365 0.2796 0.3086 0.3374 0.3661 0.3945 0.4229 329.64 340.56 350.61 359.93 368.62 376.77 2641.7 2646.0 2649.9 2653.6 2656.9 2660.1 2312.0 2305.4 2299.3 2293.6 2288.3 2283.3 0.75 0.80 0.85 0.90 0.95 1.00 91.79 93.51 95.15 96.71 98.20 99.63 0.0010375 0.0010387 0.0010400 0.0010412 0.0010423 0.0010434 2.217 2.087 1.972 1.869 1.777 1.694 0.4511 0.4792 0.5071 0.5350 0.5627 0.5904 384.45 391.72 398.63 405.21 411.49 417.51 2663.0 2665.8 2668.4 2670.9 2673.2 2675.4 2278.6 2274.0 2269.8 2265.6 2261.7 2257.9 306/307 [Tb. 2.1] Steam table (saturation state) Absolute pressure Temp. Specific volume, boiling water Q’ m3/kg Steam volume Q” 3 m /kg Steam table (saturation state) [Tb. 2.0] Steam density U” kg/m3 Water enthalpy Steam enthalpy Evaporation heat K¶ kJ/kg K´ kJ/kg U kJ/kg 467.13 504.70 535.34 561.43 584.27 604.67 2693.4 2706.3 2716.4 2724.7 2731.6 2737.6 2226.2 2201.6 2181.0 2163.2 2147.4 2133.0 2.417 2.669 2.920 3.170 3.419 3.667 623.16 640.12 655.78 670.42 684.12 697.06 2742.9 2747.5 2751.7 2755.5 2758.8 2762.0 2119.7 2107.4 2095.9 2085.0 2074.0 2064.9 0.2554 0.2403 0.2268 0.2148 0.2040 0.1943 3.915 4.162 4.409 4.655 4.901 5.147 709.29 720.94 732.02 742.64 752.81 762.61 2764.8 2767.5 2769.9 2772.1 2774.2 2776.2 2055.5 2046.5 2037.9 2029.5 2021.4 2013.6 0.0011331 0.0011386 0.0011438 0.0011489 0.0011539 0.0011586 0.1747 0.1632 0.1511 0.1407 0.1317 0.1237 5.637 6.127 6.617 7.106 7.596 8.085 781.13 798.43 814.70 830.08 844.67 858.56 2779.7 2782.7 2785.4 2787.8 2789.9 2791.7 1998.5 1984.3 1970.7 1957.7 1945.2 1933.2 204.31 207.11 209.80 212.37 214.85 217.24 0.0011633 0.0011678 0.0011723 0.0011766 0.0011809 0.0011850 0.1166 0.1103 0.1047 0.09954 0.09489 0.09065 8.575 9.065 9.555 10.05 10.54 11.03 871.84 884.58 896.81 908.59 919.96 930.95 2793.4 2794.8 2796.1 2797.2 2798.2 2799.1 1921.5 1910.3 1899.3 1886.6 1878.2 1868.1 219.55 221.78 223.94 226.04 228.07 230.05 0.0011892 0.0011932 0.0011972 0.0012011 0.0012050 0.0012088 0.08677 0.08320 0.07991 0.07686 0.07402 0.07139 11.52 12.02 12.51 13.01 13.51 14.01 941.60 951.93 961.96 971.72 981.22 990.48 2799.8 2800.4 2800.9 2801.4 2801.7 2802.0 1858.2 1848.5 1839.0 1829.6 1820.5 1811.5 S bar ts °C 1.5 2.0 2.5 3.0 3.5 4.0 111.37 120.23 127.43 133.54 138.87 143.62 0.0010530 0.0010608 0.0010675 0.0010735 0.0010789 0.0010839 1.159 0.8854 0.7184 0.6056 0.5240 0.4622 0.8628 1.129 1.392 1.651 1.908 2.163 4.5 5.0 5.5 6.0 6.5 7.0 147.92 151.84 155.46 158.84 161.99 164.96 0.0010885 0.0010928 – 0.0011009 – 0.0011082 0.4138 0.3747 0.3426 0.3155 0.2925 0.2727 7.5 8.0 8.5 9.0 9.5 10.0 167.75 170.41 172.94 175.36 177.66 179.88 – 0.0011150 – 0.0011213 – 0.0011274 11 12 13 14 15 16 184.07 187.96 191.61 195.04 198.29 201.37 17 18 19 20 21 22 23 24 25 26 27 28 G.2 Technical data collection and tables [Tb. 2.0] Steam table (saturation state) Absolute Temp. pressure Specific volume, boiling water Steam volume Steam density Water enthalpy Steam Evaporation enthalpy heat 308/309 [Tb. 2.1] Properties of superheated steam 3UHVVXUH S EDU Properties of superheated steam [Tb. 2.1] 6SHFLILFHQWKDOS\LQN-NJDWDVWHDPWHPSHUDWXUHLQ& ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± G.2 Technical data collection and tables [Tb. 2.1] Properties of superheated steam 6SHFLILFHQWKDOS\LQN-NJDWDVWHDPWHPSHUDWXUHLQ& 3UHVVXUH S EDU ± ± ± 310/311 Properties of superheated steam [Tb. 2.1] 3UHVVXUH S EDU 6SHFLILFYROXPHLQPNJDWDVWHDPWHPSHUDWXUHLQ& ± – ± – ± ± ± ± – ± – ± ± ± ± – ± ± – ± – ± ± – ± ± ± ± ± ± – ± ± – ± ± ± ± – ± – ± ± ± ± – ± ± – ± – ± ± – ± ± – ± – ± ± ± ± – ± ± – ± – ± – – ± ± ± ± ± – ± ± – ± ± – ± ± ± ± ± ± – ± – ± ± – ± ± ± ± ± ± – ± – ± ± – ± ± ± ± ± ± – ± ± ± – ± ± ± ± ± ± – ± ± ± ± ± ± ± – ± ± ± ± – ± G.2 Technical data collection and tables [Tb. 2.1] Properties of superheated steam 6SHFLILFYROXPHLQPNJDWDVWHDPWHPSHUDWXUHLQ& – ± ± 3UHVVXUH S EDU 312/313 [Tb. 2.2] Properties of saturated steam Properties of saturated steam [Tb. 2.2] Properties of saturated steam Saturated steam Absolute pressure Speciﬁc thermal capacity temperature ts [°C] p [bar] Cp [kJ/kgK] Dynamic viscosity 106 x ǹ [kg/ms] 100 1.01 2.135 11.968 110 1.43 2.177 12.459 120 1.98 2.207 12.851 130 2.69 2.257 13.243 140 3.62 2.315 13.538 150 4.76 2.395 13.930 160 6.18 2.479 14.323 170 7.93 2.583 14.715 180 10.04 2.709 15.107 190 12.56 2.856 15.598 200 15.56 3.023 15.990 210 19.10 3.199 16.383 220 23.21 3.408 16.873 230 27.97 3.634 17.364 240 33.49 3.881 17.756 250 39.79 4.158 18.247 260 46.96 4.468 18.835 270 55.07 4.815 19.326 280 64.22 5.234 19.914 290 74.48 5.694 20.601 300 85.94 6.281 21.288 Speciﬁc thermal capacity and dynamic viscosity of saturated steam as a function of saturated steam temperature (ts) Notes: Absolute pressure = operating pressure + 1 [bar] Conversion factor kJ/kg to kWh/kg 1 kJ/kg = 1/3600 kWh/kg Density (p) = for: Kinematic viscosity 1 Specific volume (Ŷ) For: Kinematic viscosity (v) = [kg/m2] Dynamic viscosity (ǹ) Density (S) [m2/s] G.2 Technical data collection and tables [Tb. 2.3] Enthalpy/Entropy 4000 2 ,0 3 ,0 2,6 2,2 5 4 10 20 30 26 22 40 100 50 700°C 3800 C 0° 400 600 500 3600 600 220 30 260 0 200 70 500 500 r 3400 100 0ba 400 400 3200 300 3000 200 20 0 3, 4 5 40 10 0 50 2800 3 26 0 22 200 10 enthalpi kJ/kg 300 0 , 6 2, 2,2 2 100 0 1, 5 0, 0,4 2600 3 0, 2 0, 1 0, 05 4 0, 0,0 ,03 0 2400 2 0,0 x =1 1 0,0 0,95 0,90 2200 r 0,85 ba 08 61 0 0 ,0, C 0° 0,80 2000 0, 70 h-s diagram 0,7 5 -1 -1 entropi kJ kg K 314/315 Internal pipe roughness [Tb. 3.0] Internal pipe roughness k in mm for various pipes and pipe materials Pipes Absolute Material Description Condition Copper Drawn or pressed New roughness k in mm Brass (also steel pipes Bronze with speciﬁed Alloys material coating 0.0013 ÷ 0.0015 Glass Rubber Pressure hose New 0.002 not embrittled Plastic Steel New 0.0015 ÷ 0.0070 Seamless New 0.02 ÷ 0.06 (commercially available) - Rolling skin 0.03 ÷ 0.04 - Pickled 0.07 ÷ 0.10 - Galvanised Longitudinally seam-welded New 0.04 ÷ 0.10 - Rolling skin 0.01 ÷ 0.05 - Tarred 0.008 - Galvanised Seamless and longitudinally Used seam-welded - Moderately 0.1 ÷ 0.2 rusted or lightly encrusted Cast iron New 0.2 ÷ 0.6 - With casting skin 0.1 ÷ 0.2 - Tarred Asbestos cement Used 0.5 ÷ 1.5 New 0.03 ÷ 0.1 New 0.1 ÷ 0.2 - Carefully smoothed 0.3 ÷ 0.8 - Sleek 1÷2 - Medium rough 2÷3 (e.g. Eternit) Concrete - Rough Pipe friction factor˨ as a function of Re and relative roughness di/k. G.2 Technical data collection and tables [Tb. 3.1] Pipe friction factor / Reynolds number 316/317 Pressure drop in steam pipes [Tb. 4.0] Fittings and profiles : C=] Pipes: C = O l/d with O = 0.0206 acc. to Eberle 'p in Pa For given pipework components of the same nominal diameter, the flow resistance coefficients C are determined from Fig. 4. From the total of all individual values 6 C and the operating data, the total pressure drop 'p in bar results from Fig. 5. pe Pi w k or 0 10 m valve ough aight-thr r t s d r a d n Sta l Ang ev e alv Pressure drop value C Tee pipe Sp ec ial v comp ensator alv e . . . . Corr ugat ed . Bend . . ff ut-o e gat Sh . Fig. 4 Source: GESTRA e valv Nominal diameter DN G.2 Technical data collection and tables [Tb. 4.1] Pressure drop in steam pipes – example Example: Pipework sections DN 50 20 m pipe C = 8.11 1 angle valve C = 3.32 2 special valves C = 5.60 1 tee C = 3.10 2 pipe bends 90° C = 1.00 C = 21.10 Operating data: Temperature Steam pressure Speed t = 300 °C p = 16 bar w = 40 m/s Result p = 1.1 bar Absolute pressure p Speed w . . Temperature . Flow resistance coefficient C . . . . . . . . Fig. 80 Source: GESTRA Pressure drop . 318/319 [Tb. 9.0] Strömungsgeschwindigkeiten (Richtwerte) Conversion for the units of water hardness [Tb. 5] Conversion for the units of water hardness ºdH ºe ºTH ppm mMol/l Deutsche Grad 1º dH= 1 1,253 1,78 17,8 0,179 Englische Grad 1º e= 0,798 1 1,43 14,3 0,142 Französische Grad 1º TH= 0,560 0,702 1 10 0,1 CaCo3 (USA) 1º ppm= 0,056 0,07 0,1 1 0,01 mMol/l 1º mMol/l= 5,6 7,02 10,00 100,0 1 % Source: Spirax Sarco kg re-evaporation steam per 100 kg condensate or re-evaporation in % 1 2 3 4 6 8 10 15 20 30 40 50 60 50 0.1 p2= 60 0.2 0.1 70 0.4 0.2 80 100 1 0.4 0.5 90 0.7 0.3 P2 = Pressure of condensate and re-evaporation steam after expansion (in bar abs) 2 1.5 3 2 4 5 3 4 0.1 10 5 6 7 8 9 10 140 160 180 All speciﬁed pressures in bar Condensate temperature before expansion (in °C) 120 Pressure before expansion (in bar abs) 1 p 2= 200 20 15 1 220 20 240 40 30 260 70 70 350 200 ˚C bar (abs) 100 bar (abs) 100 bar (abs) 100 280 300 40 50 10 G.2 Technical data collection and tables [Tb. 6] Re-evaporation on condensate expansion Steam pressure (bar absolute) 1.1 1.2 1.3 1.4 1.6 1.8 2 3 4 6 8 10 15 20 30 40 60 80 100 4 10 15 8 10 20 20 30 40 40 70 50 100 200 80 100 500 150 120 700 1.000 250 200 2.000 3.000 350 5.000 10.000 25 10 13.6 Nominal diameter DN Internal diameter mm 15 17.3 60 20 22.3 500 300 25 28.5 32 37.2 40 43.1 50 54.5 65 70.3 80 82.5 107 100 Steam throughput (in kg/h) (at 25 m/s steam velocity) 300 400 Internal diameter of seamless steel pipes according to EN 10220 "ISO TUBES" in standard wall thickness 6 132 125 20.000 150 159 207 200 50.000 260 250 100.000 Steam pressure Saturated steam throughput Ergebnis Next larger DN Example 310 300 200.000 340 350 500.000 550 kg/h 50 mm DN 50 (54.5 mm) 5 barO (6 bar abs.) 389 400 1.000.000 320/321 Pipe cross section for given steam parameters - example [Tb. 7] [Tb. 7] Pipe cross section for given steam parameters (example) G.2 Technical data collection and tables [Tb. 8] Pressure drop in water pipes for a particular ﬂow rate - example Flow resistance head Hv in m for 100 m straight pipe run Water ﬂow rate . . . . . w Flo cit lo ve . yW 0.4 /s m . . . . . . Fig. 6 Source: GESTRA Nominal diameter DN 322/323 [Tb. 9.0] Flow velocities (standard values) Flow velocities (standard values) [Tb. 9] Standard values for ﬂow velocity (w): Type of pipe Pressure range P (bar) Flow velocity w (m/s) Steam pipes: Wet steam ≤ 10 10 - 20 Saturated steam ≤1 10 - 15 > 1 to ≤ 5 15 - 25 > 5 to ≤ 10 25 - 35 > 10 to ≤ 40 35 - 40 > 40 to ≤ 100 40 to ≤ 60 Superheated steam: as for saturated steam, but with selection of the respective "higher" velocity Safety valve discharge pipes and start-up pipe Against atmospheric (also mixing cooler air vent pipe)a) pressure ≤ 70 Exhaust vapour and waste steam pipes, expansion steam Against atmospheric in condensate pipes (open vented system) pressure Long-distance steam lines < 40 ≤ 20 Suction line ≥ 0.5 to ≤ 1 10 - 25 Water pipes: Condensate pipes Feedwater pipes Pressure line ≥ 1 to ≤ 3 Suction line ≥ 0.5 to ≤ 1 Pressure line Boiler alkali and blow-down pipe ≥ 2 to ≤ 3.5 ≥ 1 to ≤ 2 (without expansion steam) Boiler alkali and blow-down pipe ≤1 10 - 15 (with expansion steam) > 1 to ≤ 5 15 - 20 DHW and service water pipes Cooling water ≥ 1 to ≤ 2 Suction line Pressure line Compressed air pipes Natural gas pipes Fuel oil pipes Combustion air ducts Flue ducts ≥ 0.5 to ≤ 1.5 ≥ 1.0 to ≤ 3.5 ≥ 10 to ≤ 20 Up to ≤ 0,05 ≥ 3 to ≤ 8 > 0.05 to ≤ 1 ≥ 5 to ≤ 10 > 1 to ≤ 6 > 10 to ≤ 25 Suction line ≥ 0.2 to ≤ 1 Pressure line ≥ 0.5 to ≤ 1.5 Suction line ≥ 8 to ≤ 20 Pressure line ≥ 15 to ≤ 30 Up to chimney connection ≥ 8 to ≤ 15 G.2 Technical data collection and tables [Tb. 10] Steam boiler inspection checklist Operation of steam boiler systems Part I - General instructions for operators of steam boiler systems For category IV steam boilers June 1983 edition (unchanged 8/93) TRD 601 OperationAppendix 1, / EN 12953 T6, Appendix C (see also Section 18.3) S 3.2.2 Water level - display equipment F F* F* F* 12 months 6 months Safety valves** Month 3.2.1 Week Operation, maintenance and inspection tasks per: 24h / 72h BosB See Section TRD 601 Sheet 2 Checklist for a steam boiler system (steam and hot water boiler) (S = Visual inspection, monitoring for unusual noises; F = Function test) Type of tests (examples) Venting Blow through and for boilers with p < 32 bar 3.2.3 Remote water levels S Comparison of display with directly indicated water level 3.2.4 Filling/sampling facility F Functionality and continuity 3.2.5 Water level controller S 3.2.6 Water level limiter 3.2.7 Flow limiter 3.2.9/12 Temperature or pressure controller S F* 3.2.10/13 Temperature or pressure limiter S F* F* Blow through and functionality F* Blow through or reduction to switching point Flow reduction 3.2.8/11 Temperature or pressure indicators (pressure gauges) S 3.2.14 Drain and T.D.S. equipment F 3.2.15 Boiler - ﬁttings/valves S 3.3.1 Feedwater and circulation equipment S Carry out comparative test Change in set value/test keys Checking with precision thermometer / zero-point check F* By activation By activation F By alternate operation By analytical monitoring in accordance with TRD 611 3.3.2 Feedwater and boiler water examination X 3.3.3 Devices for monitoring boiler water for ingress of contaminants S 3.4.1 Flue gas damper limit switch F* Closing and re-opening of the damper 3.4.2 Burner control (servomotors for air and fuel) F* Functionality 3.4.3 Combustion air fan, ignition and/or cooling air fan F* Quiet operation, power transmission (e.g. V-belt) 3.4.4 Air pressure volume display and air pressure limiter 3.4.5 Fuel shut-off facility S 3.4.6 Fuel tank and lines/valves S 3.4.7 Fuel pressure display S F 3.4.8 Safety shut-off facility upstream of the burner (for 72-hour operation also in the return line) S F 3.4.9 Tightness checking facility or intermediate ventilation S F 3.4.10 Burner limit switch 3.4.11 Emergency stop switch 3.4.12 Ignition S 03/04/2013 Ventilation S 3.4.14 Flame monitor S 3.4.15 Assessment of combustion S 3.4.16 Assessment of combustion chambers and hot gas ﬂues 3.4.17 Emergency stop switch F S Activation of test key F* Interruption of the pulse line F Functionality Functionality, tightness Functionality, tightness Pivoting the burner, pulling the burner lance F F* Activation F* F By covering the sensor F* F F* - during the six-monthly inspection (according to TRD or EN 12953 Part 6 Appendix C). ** A regular check for easy action of the safety valves is required at least every 6 months in systems with fully demineralised water and in hot water generators. The interval should not exceed 4 weeks for other types of steam boiler. 324/325 Literature references (L1) (L2) (L3) (L4) - TRD Technical Regulations for Steam Boilers, 2002 edition - Boiler Operating Manual / 11th edition, Publishing house: Dr. Ingo Resch, 2005 - Steam boiler legislation / Pressure Equipment Directive - 97/23/EC, 2004 - Thermodynamic Calculations for Combustion and Steam Boiler Systems, Friedrich & Karl Nüber, R. Oldenburg Munich, 1967 (L5) - Heating Notebook, Air Conditioning, R. Oldenburg Munich, 1995 (L6) - Technical Manual for Water Treatment Systems, Publishing house: Technik Berlin, 1968 (L7) - Centrifugal Pumps and Centrifugal Pump Systems, Vogel Buchverlag, 1994 (L7.1) - Pipe Technology, Vogel Buchverlag, 1993 (L8) - Examples and Exercises: Chemical Processing Technology, Publishing house for the primary materials industry, Leipzig 1963 (L9) - VDI Heat Atlas, VDI Verlag, 1994 (L10) - Heat manual, Resch Verlag, 1991 (L11) - Gestra Guide, Bremen, 2005 (L12) - Codes of Practice - Spirax/Sarco Keyword index 277 125 19 Acoustic emissions Acoustic emissions from monoblock / duoblock burners Application areas 254 32 226 Basic requirements and regulations for the licensing procedure Boiler equipment Boiler lye and blow-down lines 58 132 240 49 122 242 118 48 93 21 142 64 224 73 160 66 297 86 305 Chemical water treatment (CWT) Chemical water treatment system (CWT softening system) Chimney connection and design Combustion air Combustion air, supply air ducts Common ﬂue system, merging of ﬂue gas ﬂows Combustion systems Combustion system Component layout Components of a steam boiler system Condensate management Condensate management / treatment Condensate pipes and systems Condensate pumps Condensate pumps - criteria for sizing and operation Condensate treatment Contact protection insulation Control system Conversion table - BTU / BHP / KW / t/h 51 Dual fuel burner 44 279 106 105 75, 171 229 Economiser (ECO) Earthquake protection ECO output Economiser (ECO) operation Exhaust vapour condenser Exhaust vapour, waste steam and discharge pipes 76, 174 151 76 Feedwater cooler Feed pumps - criteria for design and operation Feedwater preheater 326/327 71 227 104 321 80, 236 232 136 143 Feedwater pumps & control Feedwater - softened water - drinking water Flame tube temperature monitoring (FTTM) Flow velocities (standard values) Fuel system Fuel lines Function description - reverse osmosis system (RO) Function description of open vented condensate systems 144 Function description of sealed unvented condensate systems 50 Gaseous fuels 65 12 High pressure condensate History of steam generation 287 273 273 84 244 314 83 82, 244 83, 248 9 Inspection intervals for boilers according to the Pressure Equipment Directive Installation of category III land-based steam boilers (TRD 802) Installation of category IV land-based steam boilers Insulation of pipes, tanks etc. Internal electrical system demand Internal pipe roughness Internal power demand Internal system demand Internal thermal power demand Introduction 324 Keyword index 88 254 49 323 65 Legal framework Licensing procedure according to Section 13 of the [German] Health & Safety at Work Act Liquid fuels Literature references Low pressure condensate 87 75, 163 38 Main functions Mixing cooler Multi-boiler system 219 Notes on design engineering of selected pipework systems 283 284 59 265 268 271 Operation Operating modes Osmosis systems Overview of German licensing procedures Overviews and summary of application documents and their compilation Overviews for compiling the application documents 130 196 319 315 182, 183 78 237 317 316 320 116 272 334 102 313 309 85 70, 150 Partial deaeration system Pipework calculations and sizing Pipe cross section for given steam parameters - example Pipe friction factor / Reynolds number Pipework Pipework system Planning and design information for connection pieces Pressure drop in steam pipes - example Pressure drop in steam pipes Pressure drop in water pipes for a particular ﬂow rate - example Pressure / heat maintenance - steam boiler Principle requirements and regulations for the installation of steam boilers Production Product range Properties of saturated steam Properties of superheated steam Protection against the formation of condensate Pumps 253 88 Requirements and regulations Rules and regulations 67, 180 304 98 239 162 302 188 294 286 24, 26, 103 Sampling cooler SI units / conversion table Selection of the boiler pressure level Sizing the ﬂue system Sizing the thermal equipment Sketch of steam boiler container system Speciﬁcations - materials, welding work Standard circuit diagram Standards and regulations governing operation Steam boilers 328/329 41 322 96 274 219 46 306 307 Steam boiler in standby mode Steam boiler inspection checklist Steam boiler selection Steam boiler system installation room Steam pipes / steam distributors Steam superheaters (SH) Steam table (saturation state) Steam table (saturation state) 210 113 74 Strength, expansion, support spans, clearances, routing / mountings Superheater (SH) operation System-dependent thermal equipment 168 75 293 298 18 85 296 60 129 278 T.D.S. expander T.D.S. expander and lye cooler Technical data collection and tables Technical Guide on water quality - extract Thermal capacity Thermal insulation Thermal insulation of pipes Thermal water treatment (TWT) Total deaeration system Transportation and handling 11 110 Utilising steam Utilising condensing technology 119 Variable-speed combustion air fan 42, 99 233 139 54, 128 16 15 52 Waste heat boilers Waste water and ﬂoor drainage systems Water analysis, general explanations Water treatment Wet steam, saturated steam, superheated steam What is steam? Wood combustion The comprehensive range of products and services from Viessmann Oil low temperature and Gas low temperature and Solar thermal and condensing technology condensing technology photovoltaics 13 – 20,000 kW 4 – 20,000 kW Detached houses Apartment buildings Commerce / Industry Local heating networks Individual solutions with efficient systems The comprehensive range of products and services from Viessmann The comprehensive range of products and services from Viessmann offers individual solutions with efficient systems for all applications and all energy sources. As environmental pioneers, the company has, for decades, been supplying particularly efficient and clean heating systems for oil and gas, as well as solar thermal systems along with heat generators for sustainable fuels and heat pumps. The comprehensive range of products and services from Viessmann offers top technology and sets new benchmarks. With its high energy efficiency, this range helps to save heating costs and is always the right choice where ecology is concerned. Individual and efficient Viessmann offers the right heating system for any demand – wall mounted or ﬂoorstanding, in individual combinations – all are futureproof and economical. And whether for detached houses or two-family homes, large residential buildings, commercial/industrial use or for local heating networks; for modernising existing properties or new build – they are always the right choice. 330/331 Wood combustion technology, Heat pumps for CHP and biogas production brine, water and air 4 – 13,000 kW 1.5 – 2000 kW Air conditioning technology System components The comprehensive range of products and services from Viessmann: Individual solutions with efficient systems for all energy sources and applications Key performers The Viessmann Group sets the technological pace for the heating industry. This is what the Viessmann name represents, and also what the names of the subsidiaries in the Group represent, as they are founded on the same pioneering spirit and power of innovation. The company offers the following: Condensing technology for oil and gas Solar thermal systems Heat pumps Wood combustion systems CHP modules Biogas plants Services Viessmann is extremely highly specialised in all these market segments, yet at the same time the company has a crucial advantage over specialist suppliers: Viessmann understands heating technology as a systematic whole and offers unbiased advice on technology and fuel type. This guarantees the best solution for every application. The comprehensive range of products and services from Viessmann Detached houses Apartment buildings Commerce / Industry Local heating networks Architect's own home, Bad Füssing, Residential development Zi Wei Ameco A380 Hangar Beijing, European Parliament, Strasbourg, Germany Garden Xi'an, China China France Detached house, Kevelaer, "Wohnoase" residential park in Porsche Leipzig, European Parliament, Brussels, Germany Regensburg, Germany Germany Belgium Heliotrop Freiburg, HafenCity Hamburg, City of Tomorrow, Malmö, The Palm Jumeirah, Germany Germany Sweden Dubai Detached house, Wiesloch, Hotel Lagorai Cavalese, Congressional Centre, Brunstad, Monastery St. Ottilien, Germany Italy Norway Germany Loftcube Regional Garden Show, Studio ﬂats, Brandenburg, University library, Bamberg, Germany Residential estate, Pfäffikon, Neu-Ulm, Germany Germany Oil low temperature and condensing technology 13 – 20,000 kW Gas low temperature and condensing technology 4 – 20,000 kW Solar thermal and photovoltaics Wood combustion technology, CHP and biogas production 4 – 13,000 kW Heat pumps for brine, water and air 1.5 – 2,000 kW The comprehensive range of products and services from Viessmann: Individual solutions with efficient systems for all energy sources and applications Switzerland 332/333 Futureproof heating technology for all requirements Energy consumption worldwide has doubled since 1970 and will triple by 2030. The result: The fossil fuels, oil and gas, are dwindling, energy prices are on the rise and excessive CO2 emissions continue to affect our environment. Energy efficiency is a must if we want our future to be secure. In these projects, Viessmann again and again faces up to the most varied challenges to supply efficient heating technology by offering innovative solutions – in historical listed buildings as well as in modern industrial complexes or in the large-scale residential and industrial arena. In almost every industrial nation, supplying heat to residential and commercial buildings accounts for the largest share of energy consumption – consequently it also offers the greatest savings potential. Advanced efficient heating systems from Viessmann are in use around the world, not only in many private households, but also in numerous major international projects, where they make a sizeable contribution to the efficient use of energy resources. City of Tomorrow, Malmö, Sweden The company 334/335 Viessmann – climate of innovation The Viessmann brand promise concisely expresses all that we hope to achieve. It is our key brand message and, together with our brand label, is an identifying feature throughout the world. "Climate of innovation" is a promise on three levels: It is a commitment to a culture of innovation. It is a promise of high product utilisation and, at the same time, an obligation to protect the environment. Comprehensive range of products and services for all fuel types Viessmann is one of the leading international manufacturers of heating systems and, with its comprehensive range of products and services, offers individual solutions in the shape of efficient systems for all applications and types of fuel. As an environmental pioneer, the company has been supplying particularly efficient and clean heating systems. Acting in a sustainable manner For Viessmann, to take responsibility, means a commitment to act in a sustainable way. This means bringing ecology, economy and social responsibility into harmony with each other, ensuring that current needs are satisﬁed without limiting the basis for life for the generations to come. Efficiency Plus With the sustainability project "Efficiency Plus" Viessmann shows at its Allendorf site, that the political goals set for 2020 with regard to climate and energy can already be achieved today with commercially available technology. This project demonstrates: Environmental protection Efficiency with resources Securing manufacturing sites for the future Viessmann won the German Sustainability Award 2009 for its commitment to climate protection and efficient use of resources. As a result, fossil fuels have been cut by 40 percent and CO2 emissions reduced by a third. For the particularly efficient utilisation of energy through the innovative heat recovery centre at the company's main site in Allendorf/ Eder, Viessmann was rewarded with the Energy Efficiency Award 2010. Viessmann Werke GmbH & Co. KG Company details Established in: 1917 Employees: 9000 Group turnover: €1.7 billion Export share: 50 percent 1 6 factories in Germany, France, Canada, Poland, Hungary, Austria, Switzerland and China Sales organisation in 37 countries 120 sales offices worldwide 3 service providers Performance spectrum Condensing technology for oil and gas Solar thermal systems Heat pumps Wood combustion systems CHP modules Biogas plants Services Imprint Technical Guide for steam boilers Publisher Viessmann Werke, Allendorf (Eder) Author Gerd Sattler Tilman Schibel Editing & Design agentur mp2 GmbH, Melsungen Overall production Grafisches Centrum Cuno, Calbe (Saale) © 2011 Viessmann Werke Sources Unless otherwise specified, all graphics and photographs are from Viessmann. p 12 p 13 p 14 p 16 p 18 p 54 Stiftung Deutsches Technikmuseum, Photo: Tilman Schibel BLS-Energieplan Berlin Silvia Schibel Tilman Schibel Co. Fissler Peter Kuhlmann 336/337 G.1 Appendix [A 1] G.1 Appendix [A 1] G.1 Appendix [A 1] G.1 Appendix [A 1] 5470 700 GB 03/2011 Copyright Viessmann. Duplication and alternative use only with prior written consent. Subject to technical modiﬁcations.
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