Wood Heating Procurement Guidelines

Wood Heating Procurement Guidelines
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Procurement Guidelines For
Wood Biomass Heating
Sustainable Energy Ireland
Renewable Energy Information Office
Authors:
Aine Carr, SEI – REIO
Paul Kellett, SEI – REIO
Xavier Dubuisson, SEI – REIO
Buro Happold, Dublin
22 July 2005
Disclaimer
This document is provided as an information guide only. It is intended to enhance public and
professional access to information on the planning, design and installation of renewable heating
systems. While every effort is made in preparing material for publication no responsibility is
accepted by or on behalf of Sustainable Energy Ireland's Renewable Energy Information Office
(SEI REIO) for any errors, omissions or misleading statements in this document or further
documents or websites to which the document refers. SEI REIO reserves the right at any time to
revise, amend, alter or delete the information provided in this document.
While all reasonable care has been taken in the compilation and publication of this document, SEI
REIO makes no representations or warranties, whether expressed or implied, as to the accuracy or
suitability of the information or materials contained in this document.
Use of the information herein is entirely at the risk of the user. SEI REIO shall not be liable, directly
or indirectly, to the user or any other third party for any damage resulting from the use of the
information contained or implied in this document.
SEI REIO does not assume legal or other liability for any inaccuracy, mistake, mis-statement or
any other error of whatsoever nature contained herein.
SEI REIO hereby formally disclaims liability in respect of such aforesaid matters.
The information contained in this document is of a condensed and general informational nature
only and can change from time to time. It should not, by itself, be relied upon in determining legal
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where such course has been appropriate. Where any attribution has been missed or overlooked
SEIO REIO, on being informed, will correct this omission.
CONTENTS
1. Objective of these Guidelines
1
2. Scope of this Document and Assumptions
1
3. Special Considerations When Planning a Biomass Heating System
1
4. Typical Steps Towards Establishing Biomass Heating
2
5. Project Feasibility
3
5.1
5.2
5.3
Determine Energy Demands
Site Survey
Determine Fuel Source
6. Specification Guidance Notes
6.1
6.2
6.3
6.4
6.5
6.6
6.7
6.8
6.9
General
Boiler House or ‘Plug and Play’ Container
Fuel Supply
Fuel Bunker/Silo
Fuel Handling and Feeding System
Boilers
Flue System
Installation and Commissioning
Technical Support
7. Further Information about Biomass Heating Systems
APPENDICES
Appendix 1
Appendix 2
2.1
2.2
2.3
BIOHEAT Technical Guide to Wood Heating
Wood Fuels Technical Guidance Notes
Properties of Wood Fuels
Wood-fuel Specifications
European Wood Fuel Standards (CEN)
2.3.1 Specifications for wood fuels for domestic use
2.4
Fuel Quality Template for Fuel Contract
2.5
Fuel Logistics & Storage
2.5.1 Austrian Standard ONORM M7137 Wood Pellet Storage
2.5.2 Austrian Standard M7136 Wood Pellet Transport
Appendix 3 Emissions Information
3.1
Emissions for Boiler Standards EN303-5
3.2
Emissions for Heat Producing Technologies
3.3
Emissions for Electricity Producing Technologies
4
5
5
6
7
8
10
11
11
12
1
Objective of these Guidelines
These guidelines are intended to assist planners, architects, heating engineers and other
professionals to prepare Wood Biomass Heating System specifications as required when
tendering for the purchase of equipment. The guidelines detail the specific features, design
standards and components that are considered essential for achieving reliable and cost effective
performance comparable to either gas or oil fired systems.
2
Scope of this Document and Assumptions
These guidelines cover the standards and best practice specifications for fully automatic stoker
wood burning systems that utilise:
•
•
Wood pellets
Wood chips
It is beyond the scope of this document to provide a full and detailed guide on how to design
biomass heating systems nor is it intended to be used as a manual that covers the aspects of
assessing and evaluating biomass heating applications. It is therefore assumed that readers are
familiar with automatic wood heating systems, the components involved and have a basic
understanding of how they work. Where appropriate the guidelines do refer readers to reference
sources that can provide more technical support. Basic information on wood fuels and wood
heating systems is provided in the appendices.
3
Special Considerations when Planning a Biomass Heating System
Modern wood-fuelled heating systems have been developed as an alternative to either oil or gas
fired systems. In this regard they can usually be plumbed directly into existing systems. They can
be operated as independent standalone boilers, can be installed in series with other biomass or
oil/gas fired boilers, or can be installed in parallel with gas/oil boilers to operate as the lead boiler.
They are fully controllable using programmable timers and room or zone thermostats and can be
incorporated into building energy management systems. ‘Plug and Play’ factory commissioned
wood boiler units combine hot water storage, boiler system and fuel store in one portable
container and are increasingly popular.
Wood-fuel boilers do have some features and attributes that make them different from oil or gas
boilers and thes e need to be considered, as described in Table 3.
Table 1 Significant differences between biomass boilers and oil/gas boilers
Unique features of Biomass heating
Wood fuels such as wood chips are more
bulky
Refined wood fuels such as wood pellets are
significantly less bulky and can be delivered
more easily
Wood chip quality is difficult to monitor
Wood Boilers can be more bulky depending
on the wood fuel
Design considerations
Requires purpose built silos and fuel stores
or integrated plug and play unit.
Special access is required for wood chip
delivery vehicles.
Size of fuel store needs to be determined
according to usage and necessity to minimise
frequency of deliveries.
Boiler grate design needs to specified
according to typical fuel quality available
Wood chip boilers need larger boiler rooms
and may not fit into existing boiler rooms
typically used for oil or gas.
Wood pellet boilers are similar in size to oil
-1-
Wood Boilers contain more thermal mass
and take longer to establish full power.
Wood Boilers can be more expensive
Boilers operate most effectively at full power
but many are designed to operate at outputs
as low as 20% of maximum design load.
Below this level the performance deteriorates
and it can lead to higher emissions.
Multiple boiler banks: It is typical in many
industrial situations to have multiple oil or gas
boilers. This allows the boilers to be
sequenced in order to match the heat loads.
Due to the higher cost of some biomass
boilers it may be better to adopt a larger
buffer tank storage approach for wood-fuel
systems.
4
and gas boilers.
It is therefore advised that biomass boilers
are used in conjunction with a buffer tank.
The use of a buffer tank increases boiler
system efficiency.
To reduce costs do not oversize boilers
Do not oversize boilers, as this means that
they will turn themselves on/off more
frequently. It is advised to size boilers such
that they operate on a continuous basis
rather than frequent on/off phases.
In such circumstances it is often more cost
effective to install one biomass boiler to meet
all base loads and install either gas or oil as a
back up system or to meet peak loads or to
provide a larger buffer tank heat store.
Adding solar thermal panels to meet the hot
water needs during the summer can also be
an attractive cost advantage as the solar
system can use the same buffer store, saves
fuel and limits unnecessary boiler cycling.
Typical Steps Towards Establishing Biomass Heating
Oil and gas boilers have become so common that skills to plan, design and install such systems
are numerous and widespread. Whist most of the skills are also applicable to biomass heating
systems some additional skills are required - it is therefore worth considering the step by step
approach to establishing a successful biomass heating system as outlined below.
1.
2.
3.
4.
5.
6.
Pre-feasibility: to check heat demand, boiler and fuel store space and fuel delivery
vehicle access.
Feasibility study: to determine heat demand and use trends; cost effectiveness of
biomass; site and location issues likely to affect project, fuel supply and delivery
considerations; and specific user need and requirements.
Planning and system design: Boiler sizing and matching to demand; provision for back up
heating and or means to meet peak loads; coordination with building design and
regulations; making fuel supply procurement agreements.
Procurement: Boiler procurement and issuing of tenders and contracts for civil works and
plumbing.
Installation: There are very few specific installation considerations other than some woodfuelled boilers tend to be physically larger than similar rated oil and gas boilers and some
are typically installed as complete units rather than in sections. With any larger sized
units consideration must be given to ensuring that access to the boiler house is sufficient
to enable the boiler to be installed, i.e. large doorways, removable roof etc.
Commissioning: It is essential that a commissioning process is fully developed and
reported. All equipment and components installed should be checked to ensure they
perform to the client’s specification. Training of operators should be completed before the
installer hands over responsibility to the user.
Plug and play factory pre-assembled units can significantly simplify the design and installation
processes as well as shorting project implementation times.
-2-
5
Project Feasibility
Before commencing any large biomass project it is essential that a feasibility study is carried out.
Depending upon the complexity of the proposed project this may take somewhere between half a
day and several days. The findings will determine the most viable biomass option, determine the
basic project requirements, infrastructure needs (access road, new boiler house or hard stand for
plug and play unit, 3-phase electricity supply etc) and provide the basis for developing
procurement specifications.
Recommended feasibility software is freely available from the Government of Canada at
www.retscreen.net. A full feasibility study should also comprise a detailed site visit and meeting
with the owner and/or agent to cover the following issues:
5.1 Determine Energy Demands
In summary, experienced professionals can predict energy demand as follows:
• Maximum heating demand through building heat loss analysis
• Hot water demands, based on occupancy levels or measured consumption
• Annual energy consumption using kWh/m2 assumptions
• Energy demand variations and system reaction times
• System flow and return temperatures
• Details of other heating appliances used
These estimates should be informed by comparison of energy bills (if available), use of standard
rules, or detailed thermal analysis model. RETScreen passive solar heating, water heating and
biomass software tools are useful here.
5.2 Site Survey
The initial site survey should consider the following aspects:
• Access for delivery of biomass fuel
• Planning restrictions for the height of the silo and chimney
• Air quality and local wind direction
• Adaptability of the existing heating system
• Site layout and space for external boiler house and storage
• Site layout and space for plug and play unit
• Topography of the site
• Distance from users
5.3 Determine Fuel Source
Determining the fuel source requires many considerations including:
• The availability of a local secure supply in the long term
• quality control, e.g.
o fuel density
o fuel moisture content
• transport systems and ease of delivery
• fuel cost
• contractual aspects
-3-
6
Specification Guidance Notes
These notes are intended to guide the reader through the areas that need to be considered when
developing a specification for the supply and installation of an automatic wood-fuelled boiler. The
notes provide a brief description of each item that needs consideration and suggest what
information should be included in the specification. Where appropriate tick boxes have been
included to act as a checklist for the specifier and where statements are required examples have
been given. The short technical guidance document titled ‘Heating large buildings with wood
fuels’ is recommended and freely available at www.bioheat.info/handbook/index_en-ie.html.
6.1
General
It is important to have at the beginning of a specification some general background details about
the site and to set out what the supplier/installer is and is not quoting for.
Description
6.1.1 Details of building(s) to be heated
Building use, location, whether an existing heating system is in place,
current fuel used etc (no more than three sentences).
Example: The site is an office building located in …. The office
currently uses around ….kWh/litres of gas/oil per year to provide
space heating (wet central heating) and hot water.
6.1.2 Scope
Set out the sites general requirements for a wood-fuelled boiler.
Example: This specification describes the requirements for the
supply and installation of a 300kW wood-fuelled boiler for the supply
of hot water for an existing/new wet central heating system and
domestic hot water.
6.1.3 Set out what is covered by the specification:
Example: This specification covers the requirements for the supply
and installation of a fully automatic wood-fuelled boiler, fuel storage
silo, flue system and connection to the heating mains. The system
requires a minimum of attendance, typically less than … hour(s) per
day/week/month, for system checking and maintenance (including
removal of ash etc).
6.1.4 What the specification does not cover
Example: This specification does not cover the installation of the
hot water distribution system, or modifications or repairs to the
existing structure in which the boiler and ancillary components will be
installed.
6.1.5 Power supply
The majority of boilers available require a 3 –phase supply although
some smaller boilers can work on single phase. The specifier must
provide details of the electricity supply available on site.
6.1.6 Power consumption
Wood-fuel boilers consume electricity (motors, fans etc) and it may
be useful for the user to know what the peak demand for electricity
from the system will be.
Example: The power rat ing of any electrical consumers must be
specified by the supplier/installer. Where possible all electric circuits
show draw zero power in the quiescent state.
-4-
Information required for
specification
See example
See example
See example
See example
? 3-phase 400V ….. amps
? 1- phase 240V …..amps
See example
6.1.7 Water supply
The quality of the water supply on site may be an important
consideration in terms of boiler operation and water treatment.
Details of delivery pressure and chemical analysis should be
included. Chemical analysis should be available from the supply
utility, or if self supply, from the appropriate regulatory authority.
? Mains supply
? Self supply (give details)
? Provide water quality data
(pH, colour, hardness,
alkalinity etc).
6.2 Boiler House or ‘Plug and Play’ Container
The rules and regulations covering the construction and operating of a boiler house for use with a
wood-fuelled boiler will be similar to those for oil or gas boilers. However, wood-fuelled boilers do
have some requirements in addition to, or are significantly different to, the requirement for gas
and oil boilers that need special consideration.
Description
6.2.1 Boiler house and fuel bunker/silo
The boiler house must conform to local and national building
regulations. Wood-fuelled boilers can be very heavy and so the floor
of the boiler house must be capable of taking the weight. Plug and
Play units require a hard stand capable of taking their weight.
6.2.2 Ventilation
Wood-fuelled boilers require more excess air than oil or gas boilers
and so greater permanent ventilation is required. The
supplier/installer should provide details of the level of ventilation
required.
6.2.3 Access for cleaning
Due to their large size, provision must be made to ensure there is
sufficient space to clean the boiler tubes either above the boiler, in
the case of horizontal tubes, and in front of the boiler in the case of
vertical tubes. Provide boiler room dimensions and, if available, a
drawing or sketch with the specification.
6.2.4 Access for installing the boiler
Due to the large size of the boiler provision for easy access must be
made. This may include larger doorways or removable roof.
6.3
Information required for
specification
? Check that boiler house
conforms to all local and
national regulations
? Supplier/installer to provide
details of boiler (wet) weight..
? Permanent air vent of
2
……mm to be installed in
the boiler house.
? Boiler house size:
Length ……
Width …….
Height ……
? Boiler house drawing
included
? Provide access details in
the specification giving all
pertinent dimensions.
Fuel Supply
Description
6.3.1 Fuel type
There are differences between boilers designed for use with woodchips and wood-pellets. Boilers using wood-chip tend to have heavy duty fuel feed system while pellets, being free flowing, require much
lighter and cheaper feed systems. Note: most wood-chip boilers are
suitable for use with wood - pellets but pellet boilers are not suitable
for use wi th wood-chip.
6.3.2 Wood-chip fuel specification
To ensure that the boiler supplied is suitable for use with the woodchip that is available it is important to specify the fuel grade and the
% moisture content (M.C.). The M.C. should be given on either a wet
basis (wb) or dry basis (db). The grade should be specified by range
of size and the amount of dust and oversized pieces allowed or
reference made to the CEN standard:
CEN/TS 14961: Solid biofuels – fuel specification and classes
-5-
Information required for
specification
Tick one box only
? wood-chip
? wood-pellet
? wood-chip & pellet
? ..…..% MC (wb) or (db)
? Grade: …… (specifier to
state range or give reference
to the CEN standard)
6.3.3 Wood-pellet specification
There is no European wide pellet standard but a number of EU
countries have developed their own standard which specifies
diameter, density, moisture content, ash content, and allowable level
of foreign matter and contaminates (if applicable). The
supplier/manufacturer will need to know the diameter of the pellet
that is to be used and the standard that it will conform to (see
Appendix 2.3 for details of standards available).
? …..mm diameter
Boiler should be suitable for
use with wood-pellets
conforming with …/ (state
standard and provide details
in the specification)
Relevant standards
CEN standard -TS 14961: Solid biofuels – fuel specification and classes. See Appendix 2.3
6.4
Fuel Bunker/Silo
Description
6.4.1 Wood-chip
There is no EU wide standard for a wood-chip bunker/silo.
6.4.2 Wood-pellet storage
There is no EU wide standard for wood-pellet storage. However,
Austrian standard Önorm M7137 (Pellet storage at the customers
premises) defines quality crieteria for wood pellet storage rooms and
bunkers. It is recommended that Önorm M7137 is refer red to when
specifying the bunker/silo and associated delivery equipment (These
standards are included in Appendix 2.5).
6.4.3 Bunker/silo size
The size of the bunker/silo depends on many factors including fuel
demand, frequency of deliveries, fuel type (chips or pellets), space
available, vehicle access etc.
While there are no fixed rules on sizing the bunker/silo it is
recommend that for most sites it should be large enough to provide
at least two weeks supply of fuel (to minimise fuel deliveries).
Information required for
specification
? Supplier/installer to provide
specification for bunker/silo
? Supplier/installer to specify
OR
? Specify that bunker/silo
must conform to Önorm
M7137 and provide summary
? Provide site plan showing
location of boiler house, fuel
store and access roads.
? Indicate delivery frequency
required (i.e. 2 weeks, 1
month etc)
Relevant standards:
Önorm M7137 – Presslinge aus naturbelassenem Holz-Holzpellets, Anforderungen an die
Pelletslagerung bein Verbraucher (Compressed wood in natural state - woodpellets Requirements for storage of pellets at customers premises). See Appendix 2.5.2
Önorm M7136 – Presslinge aus naturbelassenem Holz-Holzpellets, Qualitatssicherung in der
Transport and lagerlogistik (i.e. woodpellet transport and logistics). See Appendix 2.5.1.
-6-
6.5
Fuel Handling and Feeding System
Description
6.5.1 Fuel feed mechanism – Wood Chips
Fuel is fed from the bunker/silo to the boiler via an auger. There are
two basic configurations; the single feed auger or the double feed
auger. The single feed auger tends to be used on smaller systems
using two -stage burn-back protection. Double feed auger systems
are used where a drop-cell and rotary valve is specified with one
auger transporting fuel from the bunker/silo to the top of the drop cell
and the other transporting fuel from the bottom of the drop cell to the
grate.
6.5.2 Fuel feed mechanism – Wood Pellets
Fuel is fed from the bunker/silo to the boiler via an auger or
pneumatic feed system. There are two basic auger configurations as
described above for wood chips. A pneumatic suction system is only
suitable for pellets and the distance between the store and boiler
room can be up to 15 meters.
6.5.3 Fuel silo agitator (wood-chip only)
Wood-chip is not a free flowing material and bridging is a common
occurrence in bunkers and silos. To prevent this, simple agitators are
fitted into the bunker or silo to help keep the chips moving. There are
four basic types: rotating spring/articulated arms capable of
sweeping a floor area of up to 7m x 7m; conical augers; walking
floors for very large bunkers or silos; and portable fuel stores for the
hook bin systems.
6.5.4 Changes in direction
Due to limited space or access issues it may be necessary for the
feed augers to change direction. The number of changes should be
minimised, as each auger will require a drive motor and each change
of direction some kind of coupling. The supplier/installer should be
asked to design the feed system.
-7-
Information required for
specification
? Supplier/installer to specify
the feed system included.
? Single feed auger
? Double feed auger
? Supplier/installer to specify
the feed system included.
? Auger feed
? Pneumatic feed
Tick one box only
?
?
?
?
Spring/articulated arm
Conical auger
Walking floors
Supplier/installer to specify
? Provide a floor plan
showing the relative position
of the fuel store and boiler
house. Request
supplier/installer to specify.
6.6
Boilers
There are many different makes of automatic wood-fuel boiler available, produced to different
standards and with different levels of equipment, some of which manufacturers offer as standard
and others as options. The aim of this section is ensure that a boiler is fully specified with all the
equipment needed to suit a particular situation.
Description
6.6.1 Boiler output
The boiler output required should be given in kW. This information
should be evaluated as part of a site assessment.
6.6.2 CE marked
CE marking is a declaration by the manufacturer that the product
meets all the appropriate provisions of the relevant legislation
implementing certain European Directives. The directives covering
automatic wood -fuelled boilers include:
• The Low Voltage Directive – 73/23/EEC
• The Machinery Directive - 98/37/EC
A full list of Directives where the CE mark is applicable is published in
the ‘Blue Guide’ (Guide to the Implementation of Directives Based on
the New Approach and Global Approach) which is available for
download from the Commission’s website:
http://europa.eu.int/comm/enterprise/newapproach/legislation/gui
de/legislation.htm
6.6.3 Grate system
There are three basic grate systems readily available: the plane grate
(includes underfed grate, side feed grate and burner heads) suitable
for use with low moisture fuels (> 35%), the stepped grate and the
moving grate (which includes the moving step grate) both of which
can be used with wetter fuels (up to 45% MC). Stepped and moving
grate boilers tend to be more expensive than those using a plane
grate (see section 3 for details).
Information required for
specification
? …….kW
? The boiler must be CE
marked.
Tick one box only
? Grate system must be
capable for use with a
feedstock moisture content of
….% (wb) or (db)
? Supplier/installer to provide
details of grate system
6.6.4 Boiler efficiency
Wood-fuel boiler efficiencies are typically between 80 and 90%. The
manufacturer should have efficiency independently verified in
accordance with EN303-5 or another recognised national standard.
It may be useful to consult the following Austrian Laboratory to check
boiler manufacturer test to the Austrian boiler standard
http://www.blt.bmlf.gv.at/menu/index_e.htm
? Request independent
verification of efficiency to a
recognised standard such as
EN303-5.
? EN303-5 Class 3 boilers are
the most efficient defined under
the EU Standard
6.6.5 Turndown
Most wood-fuel boilers can turn down to between 20 and 30% of the
maximum design load. The specifier should give the range of outputs
over which the boiler is likely to operate (i.e. summer and winter
loads) and request details of whether the boiler can operate over this
range and the effect on boiler performance of operating below
maximum design load for long periods.
? Provide details of range of
outputs
? Request manufacturers
information on effects of
operating below maximum
design load and maximum
turndown
-8-
6.6.6 Burn-back protection
Burn -back protection is an essential requirement to minimise the
potential for the fuel to burn back along the fuel -feed system and into
the fuel store. All manufacturers fit some form of burn-back protection
devices either a two stage or a three stage. A three stage system
comprising of a drop -cell fitted with rotary valve (or other device such
as an airtight shutter), a water dousing system and a flame detection
or thermal cut -out device is the safest system and is essential for
boilers located in or adjacent to occupied buildings. A more basic twostage protection comprising of water dousing system and a sealed
airtight fuel store may be acceptable for boilers located in boiler house
set some distance from occupied building where regular attendance of
the boiler is available.
?
Three stage burn-back
protection must include a drop
cell with rotary valve and water
dousing system. Request
information on third stage
device fitted.
6.6.7 Force draught (FD) fans
Natural draught alone is not sufficient to obtain good combustion
conditions and all modern automatic wood-fuel boilers are fitted with
FD fans as standard. The more basic models use a single fan that
provides both primary and secondary air. The number of FD fans
fitted is a function of the design, controllability, grate system used, and
combustion efficiency of the boiler and does not therefore have to be
specified. However, electrical requirements fans should be provided.
? Request details of electrical
consumption of fans and power
supply required (i.e single
phase or, 3-phase, voltage and
amperage etc).
6.6.8 Flue gas induced draught (ID) fans
As a general rule ID fans are usually required on boilers over 100kW
but may be required on smaller units. As a rule of thumb all boilers
below 100kW with a stack height of less than 8m should be fitted with
a flue gas ID fan.
6.6.9 De-ashing
Automatic de-ashing reduces the amount of manual intervention
required and helps to maintain high levels of efficiency and is
essential for a situation where regular attendance is not available.
Most, but not all, manufacturers offer automatic de-ashing and some
fit it as standard. Therefore the specification will need to state whether
it is required or not.
6.6.1 Tick one box only
? Flue gas ID fan required.
? Provide information on height
of proposed flue.
6.6.10 Boiler emissions
For boilers up to 300kW, boiler emissions should conform to EN303-5
1999. For boilers >300kW local regulations may apply and therefore
consultation with the Local Authority is required and these emissions
levels agreed.
Boilers up to 300kW must meet
the requirements of Euro Norm
EN 303-5 1999.
Supplier/manufacturer to
provide copy of independently
verified test results and
certificate to Class 3 efficiency.
For boilers above 300kW
Emissions must conform to the
following (list LA requirements).
The supplier to provide a copy
of independently verified test
results and certificate.
See Appendix 3.1 for details of EN 303-5 emission limits
EN303-5 Class 3 boilers are the most efficient defined under the EU
Standard
? Two stage burn-back
protection including waterdousing system. Request
information on second stage
protection provided.
Automatic de-ashing required
for:
? Grate
? Heat exchanger tubes
Relevant standards:
EN 303-5:1999. Heating boilers with forced draught burners. Heating boilers for solid fuels, hand
and automatically fired, nominal heat output of up to 300 kW. Terminology, requirements, testing
and marking. Available from NSAI www.standards.ie
-9-
TH 42075. The Low Voltage Directive. A guide to CE marking (Low Voltage Directive 72/23/EEC)
TH 42073. CE Marking for Machinery. A guide to the European Directive (Machinery Directive
98/37/EC)
6.7
Flue System
Description
6.7.1 Independent flue
The flue should be twin walled insulated stainless steel. The inner
should be grade 316 and the outer 306 or better. Insulation can be
either mineral wool or loose fill. The flue should be certified as
suitable for use with wood-fuels. The boiler manufacturer/supplier will
have to provide details of flue diameter.
6.7.2 Existing or new masonry chimney
If an existing, or a new, masonry chimney is to be used it may have
to be lined and backfilled with insulation. It is also important to make
sure that the cross section and the height of the chimney is sufficient
for use with the boiler to be installed. Building regulations will need to
be consulted and the boiler supplier will need to provide details of
flue cross section and height required.
For boilers up to 45kW refer to:
Building Regulations 1997: Technical Guidance Document J – Heat
producing appliances.
For boilers over 45kW refer directly to the local planning authority.
6.7.3 Access for cleaning and dust removal
With wood chip the flue will require cleaning up to twice a year. With
wood pellets the flue will require cleaning up to once a year.
Example: Access for cleaning the flue by sweeping and removal of
the deposits is required. Manufacturer/supplier to provide details of
cleaning method recommended and access.
6.7.4 Flue pipes and transition pieces.
All transition pieces and flue pipes for connecting the boiler to the
flue should be made from stainless steel grade 316 or better and be
certified suitable for use with wood-fuels. The flue pipes should be
insulated.
6.7.5 Draught stabiliser
For boilers without ID fans it may be necessary to fit a draft stabiliser
especially if a tall flue is required. Supplier/installer to specify.
Information required for
specification
? Stainless steel twined wallinsulated flue. Inner flue SS
grade 316 and outer 304 or
better. Must be certified by
the manufacturer as suitable
for use with wood-fuels.
? Existing masonry chimney
to be used
? New masonry chimney to
be used
? Diameter of flue to
suppliers specification.
Provide details of chimney
dimension (cross-section)
and requirements of local
regulations concerning lining
and insulation.
As per example
As per description
? Request supplier/installer
to specify
Relevant standards:
Building Regulations 1997. Technical Guidance Document J – Heat Producing Appliances,
Department of the Environment, Heritages and Local Government, Ireland.
BS 4543-2:1990. Factory-made insulated chimneys. Specification for chimneys with stainless
steel flue linings for use with solid fuel fixed appliances.
BS 6461-1:1984. Installation of chimneys and flues for domestic appliances burning solid fuel
(including wood and peat). Code of practice for masonry chimneys and flue pipes
EN 1443:2003. Chimneys. General requirements
EN 1457:1999. Chimneys. Clay/ceramic flue liners. Requirements and test methods
- 10 -
6.8
Installation and Commissioning
The installation and commissioning of the boiler and ancillary equipment is primarily a
responsibility of the supplier/installer. However, for the purposes of planning and co-ordinating the
installation the specifier will need information from the supplier/installer.
Description
6.8.1 Location of boiler
Provide details of the location of the boiler house, fuel store
6.8.2 Installation schedule
The supplier/installer is to provide details of the lead-time for the
supply of all material and equipment to site.
6.8.3 Boiler installation
The supplier/installer is to provide a method statement for the
installation of the boiler and all ancillary equipment (such as agitator,
flue etc.) and is required to complete the installation in accordance
with the quotation. The supplier/installer should also provide details
of any services (electricity, water, IT etc) or personnel required to be
supplied by the client during the installation period.
6.8.4 Commissioning
Supplier/installer to provide a commissioning protocol and copies of
hand over documentation. The supplier/installer should also provide
details of any services (electricity, water, IT etc) or personnel
required to be supplied by the client during the commissioning
period.
6.9
Information required for
specifica tion
? Include site plan
As per description
As per description
? Supplier/installer to provide
copies of commissioning
protocol
Technical Support
Description
6.9.1 Operator training
It is normal for operator training to be conducted on site during or at
the end of the commissioning phase. Unless the end user is already
familiar with the operation and maintenance of wood-fuel boilers
training should be included in the specification.
6.9.2 Remote Monitoring
Remote monitoring can be very useful in ensuring the optimum
performance of the biomass heating system as well as quickly
alerting the servicing staff of maintenance or repair needs. The
manufacturer normally carries out the remote monitoring under a
service agreement. The system owner or operator can also have
internet access to see real time and historic performance data.
6.9.3 Operating manuals
The supplier/installer should supply at least two copies of all
manuals, one of which should always be available in the boiler
house.
- 11 -
Information required for
specification
? Supplier/installer to provide
operator training.
? Telephone/Data line
connection (give details)
? Request supplier/installer
to specify
? Supplier/installer to provide
two copies of all manuals
required to ensure the safe
and reliable operation of the
boiler and ancillary
equipment.
7
Further Information About Biomass Heating Systems
Relevant organisation web sites:
RETScreen
AEBIOM (Euroepan Biomass Association)
Bioheat.
British Biogen.
Irish Bioenergy Association.
Pellet Fuel Institute.
Pellet Information Centre
SEI REIO
http://www.retscreen.net/
http://www.ecop.ucl.ac.be/aebiom
http://www.bioheat.info/
http://www.britishbiogen.co.uk/
http://www.irbea.org/
http://www.pelletheat.org/
http://www.pelletcentre.info/
http://www.sei.ie/reio.htm
Publications:
British Biogen et al (1998), Wood fuel from forestry and arboriculture good practice guidelines.,
British Biogen, 1998.
Dulas (2001), Woodfuel Heat and Power Solutions, Dulas 2001, CD ROM
Salvolainen, V & Berggren, H (2000). Wood fuels basic information pack, Gunmerus Kirjapaino
Oy, Sweden 2000.
SWS Group (2004). Heating Large Buildings with Wood Fuels – Basic Information for Project
Planners, SWS Group, Bandon, Ireland. Download from www.bioheat.info or see Appendix 1.
References:
EN 303-5:1999. Heating boilers. Heating boilers with forced draught burners. Heating boilers for
solid fuels, hand and automatically fired, nominal heat output of up to 300 kW. Terminology,
requirements, testing and marking. Available from NSAI www.standards.ie, see Appendix 3 for
further details.
Hahn, Dr Brigitte (Undated): Quality Standards for Logistics – Distribution and Storage of
Pellets for Residential Consumers, UMBERA GmbH, Austria.
Further Resources from SEI REIO
Bioenergy DVD/CD
A comprehensive and up-to-date Bioenergy DVD (available as 3 CD set also) containing over 5
years of collated information is available to order directly from us for a nominal
charge of €5 (including post & packing). Online credit card ordering can be
found at our bookstore http://www.sei.ie/reio/reiobookshop.html or you can post us a cheque
or postal order. Provides comprehensive information on wood energy, and a compilation of
presentations from Wood Energy conferences (2002-2005) as well as SEI REIO facilitated Study
Tours to Finland and Sweden. The DVD also contains an introduction to wood heating technology
for the built environment.
Publications
Wood Energy Publications available from the SEI REIO bookstore
http://www.sei.ie/reio/reiobookshop.html
SEI REIO publish 4 Newsletters annually-Energy Update and Bioenergy News with extensive
coverage of wood energy development in Ireland. Contact [email protected] to subscribe
SEI REIO publish a monthly email newsletters with information on the latest developments in
renewable energy. Email [email protected] to subscribe
- 12 -
Contents
Preface
2
Contents
3
Why heat with wood?
(1) Political support
(2) Uncertainty regarding future energy supply
(3) The availability of advanced technology
(4) Ability to compete
(5) Benefits for the environment
(6) Growing market
4
4
4
4
5
5
6
Building a wood-fired heating system
(1) Basic considerations
(2) Estimating the right boiler size and fuel requirements
(3) Estimating the feasibility
7
7
7
8
Selecting the fuel
(1) Properties of pellets and chips
(2) Pellets or chips / pellets and chips
10
10
10
Storing the fuel
(1) Store size
(2) Specifications for store and boiler room
(3) Safety features for a pellet store
(4) Fuel supply
11
11
12
12
12
Automatic wood-fired boiler
(1) Selecting the boiler
(2) Strategies for compensating for
fluctuations and ensuring reliable supply
(3) Safety features
13
13
14
15
Noise
16
Hot water supply and the integration of solar energy
System 1: Two-conductor system with local
hot water storage
System 2: Two-conductor system with hot water supply
based on direct heat exchangers
16
17
17
Key points when planning a solar heating system
combined with biomass
18
System care and maintenance
19
Disposing of the ash
19
3
Why heat with wood?
There are many reasons in favour of heating large buildings with wood. Apart from
the fact that such systems are eco-friendly and have proven themselves in technical
terms, they constitute an economically viable solution. Wood fuels are domestic raw
materials in reliable supply and at stable prices.
(1) Political support
(2) Uncertainty regarding future energy
supply
The Kyoto Protocol demands a substantial reduction
in greenhouse gas emissions. Using wood fuel for
heating is one of the most cost-effective ways of
achieving this objective.
Indeed, the European Commission expressly supports
the increased use of wood fuel for heating purposes.
A growing number of European countries promote
the use of wood fuel in national programmes.
The Irish market is at the very early stage of
development. However, support is provided under
The Renewable Energy (RE) Research Development &
Demonstration
(RD&D) Programme which is
administered by Sustainable Energy Ireland.
The programme which comes under the Economic &
Social Infrastructure Operational Programme of the
National Development plan offers grant support for
Renewable Energy Projects and so will help to develop
wood heat projects.
For further information contact the Renewable Energy
Information Office at www.sei.ie/reio.htm
It is not only ecological reasons that are behind the
political support for renewable energy. In the green
paper “Towards a European strategy for the security
of energy supply” COM 769 (2000) the European
Union expressed major concerns regarding the
security of future supplies of fossil fuels. The European
Commission expects a drastic increase in Europe’s
dependence on energy imports.
According to studies by the International Energy
Agency, there will be a sharp rise in dependence on
supplies in the Middle East over the next few years
due to declining oil production in the North Sea and
most other production areas in non-OPEC countries
(caused by the successive depletion of reserves). From
2015 world production of oil could begin to fall.
Ireland has the highest import dependence of all
OECD countries importing about 90% of all fuels.
(3) The availability of advanced technology
Over the past 20 years tremendous progress has been made in wood boilers.
Emissions of state of the art boilers have been reduced to a hundredth of the original
figures and efficiency is now in the same range as for oil or gas boilers. Technical
progress has also led to high reliability in automatic boiler operation.
Efficiency factor of a wood-fired boiler
100
90
Efficiency %
80
70
60
50
40
Year 80
82
84
86
88
90
92
94
Figure 2: Each point is a new type of boiler which was tested.
Source: Bundesanstalt für Landtechnik Wieselburg
4
H E AT I N G
W I T H
W O O D
96
98
EURO / kW
Investment costs for biomass heating systems
1400
Family
homes
Local district heating systems
1200
1000
800
600
400
Heating systems
for large buildings
200
0
10
100
Figure 2
1000
10.000 kW
Source Styrian Chamber of Agriculture 1998, E.V.A.1999
(4) Ability to compete
Investment costs for installing a wood heating system
are slightly higher compared to oil and gas systems.
However, fuel costs are lower and stable.
This will quickly compensate for the initial high
investment cost in the long term.
(5) Benefits for the environment
When comparing the environmental impact, not
only should boiler emissions be examined. Emissions
are also caused during manufacture, the transport of
the fuel and other processes (e.g. manufacture and
disposal of the boiler). To calculate the total
emissions over the entire life cycle, the GEMIS
database was used. The results are based on the
emission figures for state-of-the-art boilers. To
calculate the emissions from pellet transport, 300 km
transport by truck was assumed.
Comparison of the eco-balances in Fig.3 shows that
pellets rate best in terms of CO2 and CO emissions.
Regarding SO2 emissions, pellets are much better
than oil, but somewhat less favourable than natural
gas.
Total dust emissions are higher than for oil or gas,
however still very low in absolute terms: the
assumed 400 kW system gives rise to some 30 kg of
dust emissions annually.
The whole study can be downloaded from
http://www.eva.ac.at/projekte/oekobilanz.htm.
5
Annual emissions taking the entire life cycle
into consideration
250
Annual Emmissions in kg (CO2 in tonnes)
SO2
Dust
200
CO
CO2
150
100
50
0
Heating oil
Natural gas
Pellets
Figure 3
Source: E.V.A.
(6) Growing market
The heating market is a very large energy market. In
many countries, such as Austria, Denmark, France,
Germany and Sweden, there has been rapid growth
in the use of wood fuels over the past few years.
This opens up attractive economic perspectives for
all the sectors involved. Innovative companies that
become established right from the outset as
competent partners for installing wood heating can
expect substantial growth.
Wood Heated large Buildings in Austria
80
Amount of Projects
70
60
50
40
30
20
10
0
1992
Figure 4
1993
1994
1995
1996
1997
1998
1999
2000
Figure : E.V .A.
Fig.5 shows the growth in the number of apartment blocks heated by biomass in
Austria. (source: http://www.eva.ac.at/projekte/holzwaerme.htm). Most of these
projects are to be found in the Province of Salzburg where 47% of all the newly built
subsidised floor space was heated with wood by 2001.
6
Building a wood-fired
heating system
market. Galtee Fuels also hope to begin building a
wood pellet production plant in the very near future.
Automatic wood boilers require slightly more
maintenance than oil or gas ones. The question of
periodic cleaning of the boiler, disposing of the ash
and supplying the fuel therefore has to be addressed
in advance.
(1) Basic considerations
Nowadays, modern wood heating systems operate
just as well as conventional oil or gas systems; they
are just much less common. Consequently, much
more communication is required when carrying out
a wood-heated project. All the relevant people, i.e.
the building contractor, potential users of the
building, neighbours and the applicable local
authorities, have to receive detailed information on
the project in good time.
A wood heating system requires a little more room
for the boiler and the fuel storage. Access for fuel
delivery vehicles must be easy. It is a great
advantage if a new building is being erected, as
these requirements can be taken into consideration
during the planning stage. Good communication
between the architect and designers plays a vital role
here.
In Ireland up until recently, securing a reliable source
of wood fuel involved quite some organisation.
Fortunately, there have been considerable
improvements in this area. For example, both
Galtee Fuels in Limerick and Celtic Flame in Dublin
import and distribute wood pellets. Balcas in
Enniskillen have plans to open Ireland’s first pellet
production plant in 2004. Feasibility studies for four
other wood pellet plants are at an advanced stage
and should herald the opening of Ireland’s wood fuel
(2) Estimating the right boiler size and fuel
requirements
Selecting the right capacity for the boiler is very
important if it’s operation is to be economical and
trouble-free. In well-insulated, modern buildings in
particular, the heating systems are frequently far too
big, as a current E.V.A. study has shown (Fig.5). lt
classifies heating systems as extremely
overdimensioned if the boiler capacity is over twice
as high as the building’s heating load.
Dimensioning of heating systems in low energy buildings
35
No. of Projects
30
25
Extremely
overdimensioned
20
22
Overdimensioned
15
Correctly
dimensioned
10
14
8
5
0
‹ 51
51 - 100
› 100
Installed heat load (W/m2 useful floor space)
Source : E.V .A.
Figure 5
7
P R E - R E Q U I S I T E S
F O R
W O O D - F I R E D
H E AT I N G
S Y S T E M S
If wood heating is to replace a system in an existing
building, the previous fuel consumption is the best
basis for calculating the future requirements and the
heat load (which does not correspond to the existing
boiler rating in many cases). The correct heating
load can be calculated from the net energy
requirement (fuel consumption multiplied by
estimated boiler efficiency) by dividing it by the
number of full load hours, which depends on the
local climate and building use.
For example, as a rule of thumb, the heating load
for a typical office block in Ireland may be calculated
as follows:
Assumptions:
Floor Area = 2000 m2
Oil Consumption = 25,000 litres/year (for heating
purposes)
Energy Content of Oil = 10.56 kWh/litre
Boiler Efficiency = 80%
2,500 hours per year full load
Step 1
Convert the annual oil consumption from litres to
kWh
Oil Consumption = 25,000 litres/year * 10.55
kWh/litre = 263,750 kWh/year
full load
Heating requirement = 211,000 Wh/year / 2,500
h/year = 84.4 kW
To calculate the heating requirement for an
alternative building, use the three steps outlined
above using appropriate values.
When replacing an existing heating system, it is
strongly advisable to consider improving the
building’s insulation as the new system could then
be adapted to the lower requirements following
renovation.
If a system is installed in a new building, an accurate
calculation of the heat load is vital. In the case of
well-insulated buildings the hot water requirements
play a more important role in the heat rating
calculations than in conventional buildings and have
to be taken into consideration accordingly.
(3) Estimating the Feasibility
The simplest way to compare the feasibility of
various heating systems is the standard calculation
method VDI 2067. Using a calculation model
developed by E.V.A. on the basis of this standard,
which can be downloaded from www.bioheat.info, it
is possible to calculate the total costs for the system
and to compare various alternatives.
Step 2
Calculate the useful heating delivered
Oil delivered as useful heating = 263,750kWh/year
*0.8 = 211,000 kWh/year
Step 3
Calculate the heating requirement and divide the
useful heating by the number of hours per year at
The Austrian consultant “Regionalenergie Steiermark” (www.regionalenergie.at)
which has already promoted and provided advice for over 70 wood heating projects,
examined 26 completed projects in autumn 2002. This study showed the following
average distribution of the investment costs for heating buildings with biomass:
Breakdown of Investment Costs
Own Work 9%
Boiler with
Automatic Feeder
52%
Planning 1%
Chimney 3%
Construction 23%
Electrical
Installation 3%
Water
Installation 9%
Figure 6
8
S T E P S
T O
A
S U C C E S S F U L
Source: Regionalenergie Steiermark
P R O J E C T
Fig. 7 shows a wide range of the costs, a sign that
the market is still young. It is noteworthy that the
specific costs in the investigated power range are at
a minimum at 100kw.
This is due to the availability of compact boilers for
this size
€/kW Investment costs per kW boiler capacity according to size
500
450
400
350
300
250
200
150
100
50
0
0
Figure 7
50
100
150
200
250
Installed boiler load in kW
300
350
400
Source: Regionalenergie Steiermark
9
Selecting the fuel
(1) Properties of pellets and chips
Wood pellets and chips are the two most suitable
fuels for automatically fired heating systems in large
buildings. Pellets are a standardised fuel that are
made by pressing dry shavings or saw dust. The
production process does not use chemical additives
– only high pressure and steam. To improve the
mechanical stability of pellets often 1-3% of organic
additives, such as potato starch, corn flour or waste
liquor from the paper and pulp industry are added.
Depending on the moisture, the energy content of
pellets lies between 4.7-4.9 kWh/kg – 2 kilos of
pellets therefore have a slightly lower calorific value
than a litre of extra light fuel oil (10 kWh).
Chips are small pieces of wood that are 5-50 mm
long (measured in the direction of the fibre). There
may also be some longer twigs and finer material
among them. The quality of the chips depends on
the raw material and the chipping process (sharp
chipper blades).
Two sources for chips are available:
1. Chips from the sawmill industry: should have a
maximum water content of 30% and be of uniform
quality and size. They are suitable for boilers in large
buildings.
2. Forest chips: Given their water content of
between 40% to 60%, they can only be used in
large boilers. Large pieces of wood or high humidity
can cause problems with boiler operation. For this
reason ensuring the quality of woodchips is an
essential precondition for their successful use as fuel.
The following table provides an overview of the key
data on pellets and dry chips. The figures for density
refer to loose material.
Wood Pellets
Chips
Calorific Value
17,0 GJ/t
13,4 GJ/t
- per kg
4,7 kWh/kg
3,7 kWh/kg
- per m
ca. 3077 kWh/m
3
Water content
Density
3
ca. 750 kWh/m3
8%
25 %
3
200 kg/m3
0.5 %
1%
650 kg/m
Ash content (% of mass)
(2) Pellets or chips/ pellets and chips
Pellets and chips have various advantages and disadvantages that have to be weighed up. Which fuel is used will
depend very much on local conditions. Preferably systems should be installed, that can use both fuels and can
therefore respond flexibly to the future market situation.
Chips
Pellets
+ Local availability
+ Favourable effect of production on the local job market
+ Cheaper than pellets
- Large storage space required
- High, uniform fuel quality is important, but possibly
difficult to obtain
- More work required for system maintenance
+ Standardised fuel – greater reliability
+ Smaller fuel store
+ Less work for service and maintenance
- Higher fuel costs
- Less favourable for the local economy
To allow fuel flexibility boilers should be selected, that can be operated both with dry
chips and pellets. Such boilers have an electronic control system that adjusts the
combustion parameters to the selected fuel. It is important that the feed system is
suitable for handling both fuels. As chips (unlike pellets) are not generally blown in,
the store should be designed to enable the fuel to be delivered by tipper truck if
chips are expected to be used. The advantage of above ground silos for Pellets is
their lower cost.
10
F U E L
S E L E C T I O N
A N D
S T O R A G E
Storing the fuel
Wood fuels can either be stored in the existing
building in a room near the boiler or in a
separate store outside the building. The latter could
be an underground store or overground
silo from where the fuel is fed to the boiler by
conveyor. Another option is a container with
loading ramp located at the side of the building,
which can be replaced by truck. The illustrations
below show two common examples for the location
of the fuel store. If it is not possible to locate the
filling opening in the middle of the store, screw
conveyors can be used to distribute the fuel evenly
as shown in the first picture. In underground stores
for pellets, it is important to ensure that no moisture
can get in. Stores for chips should be well ventilated
to let the wood dry and prevent mould.
Figure 8
The fuel can be transported from the store to the
boiler in various ways:
• Flat floor with horizontal hydraulic feed bar –
expensive, but the best possible use of the space,
can handle any fuel.
• Rotating spring feed is cheaper and can be used
for both pellets and chips.
• Inclined floor with a screw conveyor (only
suitable for pellets) – as the gradient has to be at
least 35°, the store should be long and narrow to
keep the unused volume down to a minimum.
• Inclined floor with a suction pipe – only suitable
for pellets. The distance between the store and
boiler room may be up to 15 metres with a
pneumatic feed system.
The selection of the storage system has implications
for the transport and delivery systems, which must
be considered. Above ground silos need delivery
vehicles that can blow in the fuel. Subsurface silos
can be filled by all vehicles with tip loading. This is
the most common solution in Austria.
(1) Store size
The size of the fuel store depends on many factors: anticipated fuel requirements,
fuel type, reliability of deliveries, space available, delivery vehicle capacity etc. In
existing buildings adjusting the fuel delivery intervals to the available storage space is
cheaper in most cases than putting in a new store outside the building.
If you need to build a new store, you should ensure that the storage space is larger
then the actual truck load to ensure cost-effective fuel delivery. Underground pellet
tanks have recently come on to the market. An Austrian company, ‘Geoplast’ produce
the ‘Geotank’. Leitl, another Austrian company also supply ‘Earthtanks’. For further
information log onto www.eurotank.at/leitl.htm.
Software for calculating fuel demand and feasibility can be downloaded from
www.bioheat.info.
11
S T O R I N G
T H E
F U E L
(2) Specifications for store and boiler room
(3) Safety features for a pellet store
The boiler room has to be separate from the store
for reasons of fire safety. When planning the boiler
room, sufficient space should be allowed for daily
operation, maintenance and repair work. Experience
has shown that replacing the screw conveyor for fuel
feeding requires most space. Also ensure that there
is enough room for cleaning the surface of the heat
exchanger (except if there is an automatic system).
The average space required for a boiler in the
relevant power range should be between 20 -30sqm.
Pellet stores have to meet special safety
requirements to prevent problems such as damage
to the store, dust explosions or moisture absorption
from occurring.
The ideal pellet store would therefore display the
following features:
• Solid walls that can withstand the pressure of the
pellets and are fire resistant for 90 minutes
• Completely dry
• A protective rubber mat covering the wall that
the pellets hit when being pumped in
• Fireproof, properly sealing door to the store with
wooden boards protecting it against the
pressure of the pellets
• No electrical installations
• Earthed pump pipes that prevent electrostatic
sparks from occurring during loading
Once a year the dust that has collected should be
removed and the screw conveyor bearings
lubricated.
(4) Fuel supply
Wood fuels are generally delivered by truck or tractor trailer that tips the fuel into the
opening in the store. Pellets are usually delivered in tankers.
Figure 9: Example of a store location in a
smaller building with pellet delivery by
tanker that pumps them into the store
Delivery points
PELLETS
max. 30m
PELLETSTruck
Boiler
Room
As 1 cubic metre of pellets has four times the calorific value of 1 cubic metre of dry chips, the
frequency of deliveries is much lower than for chips. As a result, pellet heating systems may be a
better solution in urban areas where the traffic plays an important role.
There should be enough room for the delivery vehicle to turn.
If pellets are pumped into the store, the following safety precautions should be taken:
• The driver must check before unloading that the store meets the safety standards
• He has to ensure that the boiler is not in operation (lower pressure in the store
could cause backburning)
• The load pressure should be limited to avoid damage to the store and prevent
the pellets from crumbling.
If wood fuels are tipped into the store, the following points should be observed:
• Deliveries should be made at times when they cause least disturbance to
residents (e.g. late morning)
• Safety precautions should be taken to ensure that nobody could fall into the
store. A steel grid is the best guard. However, the mesh has to be wide enough
to prevent it from becoming choked during unloading (at least 20x20 cm)
• When deciding the location of the openings in the store, the fact that dust
emissions occur during unloading should be taken into consideration
• Any fuel left lying after unloading should be removed to prevent problems with
the neighbours
12
S T O R I N G
T H E
F U E L
Automatic wood-fired boilers
(1) Selecting the boiler
Automatic boiler models are available in various capacities from 50 to 500 kW. The most common include:
• Compact units: these are larger versions of household pellet boilers – they are comparatively cheap and very
suitable because they are designed as household boilers and not for use in the wood industry. This means that
they have such comfort features as automatic cleaning, electric ignition and high reliability.
1
9
8
6
7
Compact unit
Key
1 Insulation
2 Burner head
3 Ash pan
4 Sensor
5 Ring for secondary air intake
6 Heat exchanger
7 Automatic heat exchanger cleaner
8 Flue connection
9 Lambda sensor
10 Primary air intake
5
4
2
10
3
Figure 10
13
A U T O M AT I C
W O O D - F I R E D
B O I L E R S
• Underfeed burner: these boilers are suitable for dry fuels with a low ash content,
such as chips or pellets and were designed for use in the wood industry.
Check if reliability and operational comfort are confirmed by the experiences of
other users in building applications.
Underfeed burner
6
7
8
5
4
Key
1 Auger feed
2 Burning wood
3 Primary air intake
4 Secondary air intake
5 Combustion chamber
6 Heat exchanger
7 Flue gas dedusting
8 Ash discharge
3
2
1
8
Figure 11
• Boilers with grate feed: these are more expensive, but are also suitable for wood
fuels with a high moisture and ash content
6
5
7
8
4
1
Key
1 Auger feed
2 Moving grate
3 Primary air intake
4 Secondary air intake
5 Combustion chamber
6 Heat exchanger
7 Flue gas dedusting
8 Ash discharge
2
3
8
Figure 12
• Converted oil boilers with a pellet burner: a common solution in Scandinavia. It
involves fitting a pellet burner to an existing oil boiler. A very cheap alternative, it
does however have certain disadvantages: the boiler output sinks by about 30%,
and ash removal and boiler cleaning can involve considerably more work.
14
A U T O M AT I C
W O O D - F I R E D
B O I L E R S
Sochinsky's Annual Load Duration Curve
Heat Output P (T) in %
100
90
80
70
60
50
40
30
20
10
0
0
2.000
Figure 13
4.000
6.000
8.000
10.000
Operation Hours (h)
)
(2) Strategies for compensating for load variations
In winter every heating system is subject to great load fluctuations that depend on the weather, users’ habits
etc. The maximum output is only utilised very briefly during periods of very cold weather. In contrast, the boiler
is operated for long intervals at low load. It is therefore important for the boiler to be operated efficiently in offpeak periods. This can be achieved in one of the following ways:
• 1) A conventional (oil or gas) boiler supplements
the wood one to cover the peaks and act as a
back-up system. The wood boiler’s capacity is
reduced to around 60-70% of the maximum
output. It can thus provide 90-95% of the power
required for heating, as the demand peaks are only
of short duration. To guarantee 100% supply
security, the capacity of the oil boiler should be
able to cover the maximum output. This solution is
particularly good if an existing oil or gas heating
system can be used.
3) Combination of two wood boilers. The second
boiler increases the reliability of supply (for this
reason it should have a separate fuel supply
system) and ensures that the heating operates
efficiently, even in off-peak periods. The best of
the three alternatives has to be worked out in each
individual case. What is important is that the heat
load calculations are correct.
2) The wood boiler can provide the maximum
capacity, while a buffer (a hot water tank) covers
short-term load fluctuations and ensures that the
boiler can be operated efficiently during off-peak
periods. In summer the buffer can be used for
storing solar energy. This solution has the
advantage that only one flue is required.
(3) Safety features
A biomass boiler has a somewhat slower response
time than an oil or gas-fired one. If there is a power
failure, the fuel in the boiler carries on burning thus
generating additional heat that has to be dissipated.
One option is an open expansion tank to enable the
steam to escape as soon as the water temperature
reaches 100°C. An alternative is a safety heat
exchanger that is cooled with running water if the
boiler temperature gets too high. A buffer with
natural circulation by convection is another solution.
As a power failure can disrupt the electronic boiler
control system, the pumps responsible for circulating
the hot water in the home should not be controlled
by the boiler electronics.
To prevent backburning in the fuel store from the
boiler, additional safety features are required. They
usually consist of an interruption to the fuel
transport system (e.g. a star feeder or chute for the
fuel to fall into the boiler) and a sprinkler system,
which floods the fuel transport line in the event of
backburning.
Another important feature is a device that mixes the
cool return flow to the boiler with the hot outflow
before it enters the boiler to prevent condensation of
the flue gas in the boiler which can cause corrosion.
All the relevant safety standards are described in EN
303-5.
15
Noise
1. Adjust the architecture. Bedrooms should not be
located directly above the boiler room. Where
possible, the chimney should also not run past the
bedrooms.
5. Visit reference systems to listen to and compare
the noise emissions during boiler operation. No
standardised noise level has been determined to
date, as the noise emissions depend very much on
local conditions. There can be considerable
differences in boiler quality in terms of noise.
Delivering and unloading the fuel can also cause
noise. Problems can be avoided by selecting a
suitable fuel store location and having fuel delivered
at times when only a few neighbours are at home.
2. If it is a new building, elastic filler should be
inserted between the concrete floor and the walls in
the boiler room and the store.
Emission Limits
Biomass boilers that are not installed properly may
cause noise pollution. Sources of noise are primarily
the air and flue gas fans and the fuel feed system. To
prevent noise problems, the following points should
be taken into consideration:
3. All the contact points between mechanical parts
and walls or floor should be sound proofed (e.g.
where the screw conveyor from the store goes
through the wall into the boiler room, the boiler
base etc.)
4. Ask the boiler manufacturer what steps have been
taken to keep noise emissions down to a minimum
(e.g. careful selection of the motor, R&D projects to
reduce noise etc.). Sound proofing material such as
rubber mats etc. should be supplied with the boiler.
Currently, a testing standard or emission limit does
not exist for small wood fired boilers in Ireland.
However wood fired boilers from Austria are tested
according to the European Standard EN 3035(Heating boilers for solid fuels, hand and
automatically stoked, nominal heat output of up to
300kW). For information on emission limits log onto:
www.blt.bmlf.gv.at Commercial sector (Austria BGBl
331.Verordnung: – FAV, 1997)
This standard is valid for medium scale wood fired
boilers with automatically fed systems, which are
used for space heating and/or water heating.
Heat losses through exhaust gas should be below 19%. Emission limits for Commercial boilers (100-350kW)
Boiler Capacity
Emission limits [mg/m3]
50 kW ≤ 100 kW
Dust
150
CO
800*
NOx1
250-500
HC
50
>100 kW ≤350 kW
150
800
250-500
50
Hot water supply and the
integration of solar energy
The combination of a biomass boiler and a solar hot
water system can be a particularly attractive
alternative. In the summer months the biomass
boiler can be switched off as the solar system can
supply hot water demand. This not only reduces the
maintenance work, but also emissions and energy
loss caused by operation at low heat loads. The
buffer required for the solar system can be used in
winter for compensating for load fluctuations, which
is a considerable advantage both at peak and low
loads. If a low-temperature heating system is
installed, solar energy can also be used for heating
the space in addition to the water – especially in
between seasons. Another advantage is that a solar
system is clearly visible thus enhancing the image of
the project.
16
N O I S E
In Austria where the most combined systems for
solar energy and biomass have been installed in
Europe, two concepts have become established that
offer considerable advantages in terms of simplicity,
costs and energy efficiency. Both involve providing
hot water and heating with a two-conductor system.
A two-conductor network reduces heat loss,
installation is less work, it can be easily extended
and enables low return flow temperatures – a basic
condition for efficient operation of the solar
collectors.
System 1: Two-conductor system with local hot water storage
with relatively long pipes. In summer circulation loss
can be reduced with this system, as the water only
circulates periodically (e.g. twice a day) to fill the
local hot water tank.
Heat is generated by the solar collectors or the
boiler. It is distributed throughout the house and
circulated through the radiators if required. To
provide hot water there is a heat exchanger that
supplies the local hot water tank. This system is an
attractive solution for example for terraced houses
Radiator
Boiler
Co
llec
tor
Heat
Storage
Tank
Flat plate heat
exchanger
Radiator
Flat plate
heat
exchanger
Boiler
Biomass
Boiler
Fig. 14: Two-conductor system with
local hot water storage
Flat plate heat exchanger
System 2: Two-conductor system with hot water supply based on direct heat exchangers
A two-conductor system with direct hot water supply
using a plate heat exchanger is particularly costeffective. The heat exchanger is integrated in a heat
transfer station also containing a heat meter, cold
water meter, differential pressure control for the
radiator circuit, etc. Suitable products supplied by
the following manufacturers are used in Austria:
Radiator
Suitable products supplied by
the following manufacturers are
used in Austria:
Gemina Thermix A/S: C3-009
Navervej 15-17, 7451 Sunds,
Denmark, Tel +45 (0)97 141444,
Fax: +45 (0)97
141159, E-mail: [email protected]
Redan: Sindalsvej 33-35m
8240 Risskov, Dänemark
Tel +45 (0)8621 2211
Fax +45 (0)8621 4212
E-mail: [email protected]
www.redan.dk
Logotherm Haustechnik
GmbH:
Ringstraße 18
04827 Gerichshain
Deutschland
Tel +49 (0)34292 7130
Fax +49 (0)34292 71347
E-mail: [email protected]
www.logotherm.de
ll
Co
ect
or
Heat
Storage
Tank
Continuous-flow
waterheater (flat
plate exchanger)
Radiator
Flat plate
heat
exchanger
Biomass
Boiler
Fig. 15: Two-conductor system with direct
hot water supply from a heat
exchanger
Continuous-flow
waterheater (flat
plate exchanger)
17
HOT
WATER
SUPPLY
AND
THE
INTEGRATION
OF
SOLAR
ENERGY
Key points when planning a solar heating system combined with biomass
• Architecture: the integration of a solar system
should be taken into consideration at the early
stages of planning – to ensure considerable savings
in costs. Solar collectors that are a substitute for
the roof are both more cost-effective and more
aesthetic compared to collectors mounted on the
roof. The collector elements should form a closed
surface that is not interrupted by chimneys etc.
• Return flow temperature: the cooler the water
when entering the solar collectors, the higher the
energy absorption. It is very important to adjust
the heat use in the house to this requirement, e.g.
by using the hydraulic concepts described above
and installing low temperature heating systems
(e.g. underfloor heating).
• Hydraulic solar collector connection: the collectors
should be connected according to the low-flow
principle (10-18 kg/m2 specific mass flow). As a
result, there are greater differences in temperature
in the collectors, lower heat loss, lower pump
energy consumption, better layering in the buffer
and lower pipe diameter. The collectors should be
connected in series and not in parallel. No
Tichelmann connection! Hydraulic compensation
should be achieved with the right dimensioning
and not with fittings where possible.
• Heat storage management: the heat should only
be stored in one buffer where possible (more costeffective and less loss). The buffer should be well
insulated and not very far away from the
collectors. If the solar energy is to be used
efficiently, it is very important for the buffer to
display good temperature layering and the hot and
cold water not to be mixed. Self-regulating layer
chargers should be preferred. The biomass boiler
intake should be connected to the middle or upper
area of the tank to enable part of the buffer to
be used for compensating for load fluctuations.
• Orientation of the solar collectors: the collectors
should be oriented to face south. Deviation of 30
degrees to the west or east only leads to slight
reductions in energy absorption. To use the sun’s
energy to the full in summer, the angle of the
collectors should be 30-45 degrees. If solar heating
plays an important role during the colder months,
the collectors should be tilted more.
• Dimensioning of the solar system: the collectors
should be designed to cover 90% of the hot water
demand in summer (or slightly less) for financial
reasons. Simulation calculations should be carried
out to determine the right size for the collector
area and the buffer. Fig.16 shows the result of
such simulation calculations for a building with a
rating of 100 kW that was carried out by the
Institute of Heat Engineering at Graz University of
Technology.
RETScreen provides software for renewable energy
project analysis, including wind.
The software can be downloaded free of charge
from this Canadian Government
Natural Resources website.
http://www.retscreen.net/
In addition there is a software programme
available here in Ireland; known as T-sol it is
available through the REIO Bookstore on
www.sei.ie/reio.htm T-sol will help in the
professional design for a solar thermal system for
both solar water and space heating.
REIO Solar CD
This resource contains a “best of” selection of
presentations, papers and brochures from SEI
REIO’s solar energy events over the past three
years. The CD is an invaluable source of
information for professionals and decision makers
on:
-solar technologies and their use in Ireland
-policies and regulations supporting the
development of solar energy
-tools for implementing solar energy in buildings
To order your free copy, email [email protected]
Degree of summer cover for a solar system
combined with a 100 kW biomass boiler
Summer cover degree %
120
100
80
60
40
40 m2 collector area
70 m2 collector area
100 m2 collector area
200 m2 collector area
20
0
0
1
2
3
4
5
Buffer Volume (m3)
6
7
3
)
8
9
OF
SOLAR
10
Fig. 16
18
HOT
WATER
SUPPLY
AND
THE
INTEGRATION
ENERGY
System care and
maintenance
It is very important to agree on a maintenance
contract with the boiler manufacturer. Carrying out
an annual service is vital for long-term trouble-free
operation.
Furthermore, a maintenance contract frequently
includes an extension to the warranty period and
guarantees that any faults will be rectified at short
notice.
The amount of work involved in maintaining an
automatic wood-fuelled heating system depends on
various factors, such as whether the boiler has an
automatic cleaner for the heat exchanger and
automatic ash discharge, whether remote
monitoring of the system is possible, whether chips
or pellets are used etc.
Typical activities to be carried out include:
• Visual inspection of the boiler
• Rectifying minor problems
• Purchasing the fuel
• Removing the ash
Disposing of the ash
Wood ash is not dangerous and is frequently used as
a fertiliser. In urban areas it can usually be disposed
of with domestic waste.
Local regulations should be observed.
The time required naturally depends on the size of
the system and fuel consumption – i.e. fewer hours
for smaller systems. According to the boiler
manufacturers supplying compact, fully automatic
boilers for large buildings, the maintenance work for
state-of-the-art boilers using pellets or high quality
chips does not exceed 30 minutes a week.
The table below shows the main constituents of
wood chip ash (Obernberger 1997)
If the following steps are taken, the work involved
can be reduced:
• Operation and maintenance of the system
contracted out to a facilities management company
• Automatic ash discharge
• Automatic heat exchanger cleaning
• Fuel delivery organised by the pellet suppliers
In Austria most problems have occurred to date
because the operator did not receive
adequate training on how to run the boiler.
Training should cover at least the following points.
• Start up
• Routine operation
• Typical faults
• Rectifying the faults
• Controlling combustion
Ash constituents
(% of weight)
SiO2
24.6
CaO
46.6
MgO
4.8
K 2O
6.9
Na2O
0.5
P 2O
3.8
The zinc content may be between 260-500 mg/kg, while cadmium can
account for 3.0-6.6 mg/kg.
19
S Y S T E M
C A R E
A N D
M A I N T E N A N C E
i
Further Information:
www.bioheat.info
Bioheat Hotline:
023 29171
Impressum • Eigentümer, Herausgeber & Verleger:
Energieverwertungsagentur –
the Austrian Energy Agency (E.V.A.)
A-1060 Wien; Otto-Bauer-Gasse 6, Tel +43-1-5861524;
Fax +43-1-5861524 40; E-mail: [email protected] •
www.eva.ac.at •
• Ann McCarthy - Bioheat 11 Project Partner Ireland•
Hotline number: +353 23 29171 •
• www.bioheat.info •
Für den Inhalt verantwortlich:
Dr. Fritz Unterpertinger •
Redaktion: Dr. Christian Rakos • Grafikdesign &
Produktion: Enöckl Visuelle Kommunikation •
Verlags- und Herstellungsort: Wien, 2003 •
Die Herstellung dieser Broschüre wurde gefördert
aus Mitteln des ALTENER Programms (Projekt
BIOHEAT, 4.1030/C/00-163/2000) sowie aus Mitteln
des Bundesministeriums für Wirtschaft und Arbeit, des
Bundesministeriums für Land- und Forstwirtschaft,
Umwelt und Wasserwirtschaft und der Niederösterreichischen Landesregierung (Wohnbauforschung).
ISBN 3-902136-08-1
20
Appendix 2
2.1 Properties of Wood Fuels
2.2 Wood Fuel Specifications
2.3 CEN Standards for Wood Fuels
2.3.1 Specifications for wood fuels for domestic use
2.4 Fuel Quality Template for Fuel Contract
2.5 Fuel Logistics and Storage Standards (Austria)
-SEI REIO-Procurement Guidelines for Wood Biomass Heating-1
Appendix 2.1 Properties of Wood Fuels
Modern automatic wood-fuel boilers are designed for
use with either wood-chips or wood-pellets (see Figure
1). Wood -chips are small pieces of wood ranging in
size from around 5 to 50mm (measured in the
direction of the fibre). There may also be some longer
twigs and finer material among them. Very fine dusty
material can upset combustion in a boiler, and large
chunks and long stringy material can block feed
systems, so any grading system must put limits on
these constituents. The quality of the chips depends
on the raw material, chipper type (drum, disc or
screw), and the chipping process (sharp
blades etc).
Typical 6 mm pellets
Typical wood-chip
Figure 1 Wood-fuels
Wood-pellets are usually made from shavings and fines which have been compressed under high
pressure to form a cylindrical shape usually between 6 and 10mm in diameter and 10 and 30mm long.
The production process does not use chemical additives although organic additives such as potato starch
and corn flour can be added to improve mechanical stability. As a result of the production process pellets
are highly standardised with low moisture content and a high density enabling them to be transported
more cost-effectively and require less storage space compared to wood-chips. Typical properties are
given in Table 1.
Table 1 Typical properties of wood-chip and pellet
Wood pellets
Calorific Value
17.0 GJ/t
- per kg
4.7 kWh/kg
3
3
- per m
Ca. 3077 kWh/m
Moisture content
8%
3
Density
650 kg/m
Ash content (% mass)
0.5%
Source: Heating Large Buildings with Wood Fuels – Basic
Planners, SWS Group, Ireland (undated)
Wood-chip
13.4 GJ/t
3.7 kWh/kg
3
Ca. 750 kWh/m
25%
3
200 kg/ m
1%
Information for Project
There are relative advantages and disadvantages between wood-chip and pellets (see Table 2) which
need to be considered when deciding which fuel to adopt. It is worth considering installing boilers that can
use both fuels and therefore allowing the end user to respond to future market conditions.
Note: Most wood-chip boilers are suitable for use with wood- pellets but pellet boilers are not suitable for
use with wood-chip.
-SEI REIO-Procurement Guidelines for Wood Biomass Heating-2
Table 2 Relative advantages and disadvantages of wood-chip and pellets
Advantages
Disadvantages
Wood-chip
Locally available product
Cheaper than pellets
Production of chips can have a
positive effect on local employment
and economy
Larger storage space required
High, uniform fuel quality is
important but may be difficult to
achieve
More maintenance and servicing
Pellets
Standardised fuel
Smaller storage space required
Less maintenance and service
Cheaper boilers
More expensive than chips
Less favourable to the local
economy
-SEI REIO-Procurement Guidelines for Wood Biomass Heating-3
Appendix 2.2 Wood-fuel specifications
The specification of wood-fuel is a very important consideration as the grade and moisture content can
affect operational performance of wood-fuel boilers. A European -wide standard (CEN) has now been
developed for the specification of wood fuels (See Appendix 2.3)
A2.1
Moisture content
Moisture contributes nothing to the available energy of a fuel and will reduce its useful energy. Also the
moisture content of a fuel will affect the amount of fuel required for a given output and the performance of
the boiler. Figure A1 shows the effect of moisture on calorific value
Calorific value (kWh/kg)
6.00
5.00
4.00
3.00
2.00
1.00
0.00
0.00 0.05 0.10 0.15 0.20 0.25 0.30 0.35 0.40 0.45 0.50 0.55 0.60 0.65 0.70
Moisture content (kg water/kg dry matter)
Figure A1 Effects of moisture on calorific value
When specifying wood-fuel the moisture content should be stated as a percentage either on a wet basis
(wb) or dry basis (db) for example 30%(wb). Generally speaking the wet basis is used as the norm but it
is important to be clear which method is being used as they are calculated differently and are not directly
comparable for a given sample (see Box A1).
-SEI REIO-Procurement Guidelines for Wood Biomass Heating-4
Box A1 Determination of moisture content on wet and dry basis
To determine the moisture content a sample, or number of samples, of the biomass is weighed wet then
oven dried to expel all the moisture. The oven-dried weight is subtracted from the wet wood weight to
determine the amount (mass) of water that was present.
In the wet basis, the mass of the water is divided by the mass of wet biomass. In the dry basis the moisture
content is then calculated by dividing the mass of the water by the mass of the oven dried biomass. The
following example demonstrates the difference between the two methods
Example: A quantity of wood has a mass of 10kg. After drying in an oven it has a mass of 8kg. What is
its moisture content on a) a wet basis and b) a dry basis?
WET BASIS
Mass of wet wood (10kg) – mass of oven dried wood (8kg) = mass of water (2kg)
Mass of Water ( 2k g)
Mass of Wet Wood (10 k g)
DRY BASIS
A2.2
Mass of Water (2kg)
Mass of Dry Wood (8kg)
= 0.20 M .C . ( wet basis) i.e. 20%
= 0 .25 M .C. (dry basis) i.e. 25%
Wood-chip grade
Wood-chip boilers will generally operate best on material between 2 and 30 mm thick although
some manufacturers now produce boilers that can be adapted for use with larger material.
However, it is accepted that the fuel production methods produce a wider range of particle sizes
than this. Very fine dusty material can upset combustion in a boiler, and large chunks and long
stringy material can block feed systems, so any grading system must put limits on these
constituents.
A CEN standard, TS 14961: Solid biofuels – fuel specification and classes, was published in
2005 which outlines the specifications for wood chips and wood pellets. See Appendix 2.3
-SEI REIO-Procurement Guidelines for Wood Biomass Heating-5
Appendix 2.3 European Wood Fuel Standards
CEN/TS 14961:2005
Table A Specification of properties for pellets
Master table
Origin:
According to 6.1 and Table 1
Woody biomass (1),
Herbaceous biomass (2),
Fruit biomass (3),
Blends and mixtures (4)
Pellets
Traded Form (see Table 2)
Dimensions (mm)
Normative
D
L
a
Diameter (D) and Length (L)
D06
≤ 6 mm ± 0,5 mm and L ≤ 5 x Diameter
D08
≤ 8 mm ± 0,5 mm, and L ≤ 4 x Diameter
D10
≤ 10 mm ± 0,5 mm, and L ≤ 4 x Diameter
D12
≤ 12 mm ± 1,0 mm, and L ≤ 4 x Diameter
D25
≤ 25 mm ± 1,0 mm, and L ≤ 4 x Diameter
Moisture (w-% as received)
M10
≤ 10 %
M15
≤ 15 %
M20
≤ 20 %
Ash (w-% of dry basis)
A0.7
≤ 0,7%
A1.5
≤ 1,5 %
A3.0
≤ 3,0 %
A6.0
≤ 6,0 %
A6.0+
> 6,0 % (actual value to be stated)
Sulphur (w-% of dry basis)
S0.05
Sulphur is normative only for chemically treated
≤ 0,05 %
biomass and if sulphur containing additives have
S0.08
≤ 0,08 %
been used
S0.10
≤ 0,10 %
> 0,20 % (actual value to be
stated)
a
Mechanical durability (w-% of pellets after testing )
DU97.5
≥ 97,5 %
DU95.0
≥ 95,0 %
DU90.0
≥ 90,0 %
Amount of fines (w-%, < 3,15 mm) after production at factory gate
a
F1.0
≤ 1,0 %
At the last possible place in the production site
F2.0
≤ 2,0 %
F2.0+
> 2,0 % (actual value to be stated)
Additives (w-% of pressing mass)
Type and content of pressing aids, slagging inhibitors or any other additives have to be stated
Nitrogen, N (w-% of dry basis)
N0.3
Nitrogen is normative only for chemically treated
≤ 0,3 %
biomass
N0.5
≤ 0,5 %
N1.0
≤ 1,0 %
N3.0
≤ 3,0 %
N3.0+
> 3,0 % (actual value to be stated)
Net calorific value, qp,net,ar (MJ/kg as received) Recommended to be informed by retailer.
3
or energy density, E ar (kWh/ m loose)
Informative
S0.20+
a
3
Bulk density as received (kg/m loose)
Chlorine, Cl (weight of dry basis, w-%)
Recommended to be stated if traded by volume
basis
-SEI REIO-Procurement
for Wood
Biomass Heating-6
RecommendedGuidelines
to be stated
as a category
Cl 0.03, Cl 0.07, Cl 0.10 and Cl 0.10+ (if Cl > 0,10
% the actual value to be stated)
Maximum 20 w-% of the pellets may have a length of 7,5 x Diameter.
Table B Specification of properties for wood chips
Normative
Master table
Origin:
According to 6.1 and Table 1.
Traded Form
Dimensions (mm) a
Main fraction
> 80 % of weight
P16
3,15 mm ≤ P ≤ 16 mm
Woody biomass (1)
Wood chips
Fine fraction < 5 %
< 1 mm
P45
3,15 mm ≤ P ≤ 45 mm
P63
3,15 mm ≤ P ≤ 63 mm
P100
3,15 mm ≤ P ≤ 100 mm
Moisture (w-% as received)
M20
≤ 20 %
M30
≤ 30 %
M40
≤ 40 %
M55
≤ 55 %
M65
≤ 65 %
Ash (w-% of dry basis)
A0.7
≤ 0,7 %
A1.5
≤ 1,5 %
A3.0
≤ 3,0 %
A6.0
≤ 6,0 %
A10.0
≤ 10,0 %
< 1 mm
< 1 mm
< 1 mm
Coarse fraction
max. length of particle,
a
max 1 % > 45 mm, all < 85
mm
a
max 1 % > 63 mm
max 1 % a > 100 mm
a
max 1 % > 200 mm
Dried
Suitable for storage
Limited for storage
Nitrogen, N (w-% of dry basis)
N0.5
≤ 0,5 %
N1.0
≤ 1,0 %
N3.0
≤ 3,0 %
N3.0+
> 3,0 % (actual value to be stated)
Nitrogen is normative only for chemically treated biomass
Net calorific value qp,net,ar (MJ/kg as received) Recommended to be specified when retailed.
3
or energy density, Ear (kWh/m loose)
Informative
3
Bulk density as received (kg/m loose)
Recommended to be stated if traded by volume basis in
categories (BD200, BD300, BD450)
Chlorine, Cl (weight of dry basis, w-%)
Recommended to be stated as a category
Cl 0.03, Cl 0.07, Cl 0.10 and Cl 0.10+ (if Cl > 0,1 % the
actual value to be stated)
a
The numerical values for dimension refer to the particle sizes passing through the mentioned round hole
sieve size (3,15 mm, 16 mm, 45 mm, 63 mm and 100 mm). Dimensions of actual particles may differ from
those values especially the length of the particle.
-SEI REIO-Procurement Guidelines for Wood Biomass Heating-7
The above standards are available to purchase from the National Standards Authority of Ireland
(NSAI)
NSAI Standards Sales Office
Glasnevin
Dublin 9
Phone: (01) 8073868
Email: [email protected]
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Appendix 2.3.1 Specifications for wood fuels for domestic use
The following examples are specifications for high quality classes of solid biofuels recommended for
household usage. Household usage needs special considerations for the following reasons:
— Small-scale equipment does not usually have advanced control and gas cleaning
— Unprofessional management
— Often located in living and populated districts
A.2
Wood pellets (selected from Table A)
Origin:
1.2.1.1 Chemically untreated wood without bark
Moisture content:
Mechanical durability:
Amount of fines:
M10
DU97.5
F1.0 or F 2.0
Dimensions:
Ash content:
D06 or D08
A0.7
Sulphur content:
S0.05
Additives:
Energy density:
A.3
< 2 w-% of dry basis. Only products from the primarily agricultural and forest
biomass that are not chemically modified are approved to be added as a pressing
aids. Type and amount of additive has to be stated.
E4.7 [kWh/kg] (q
p,net,ar
≥ 4,7 kWh/kg = 16,9 MJ/kg)
Wood chips (selected from Table B)
Origin:
Moisture content:
Dimensions:
Energy density:
1.1.2 Stem wood
M20 or M30
P16, P45 or P63
3
3
E0.9 [kWh/loose m ] (E ar ≥ 900 kWh/loose m )
-SEI REIO-Procurement Guidelines for Wood Biomass Heating-8
Appendix 2.4 Fuel Quality Template for Fuel Contract
Example of 20 kg pellet bag.
The following template could be adapted for bulk deliveries and used for fuel contract specifications.
-SEI REIO-Procurement Guidelines for Wood Biomass Heating-9
Appendix 2.5 Austrian standards for Fuel Logistics and Storage
The Onorm M7137 standard relates to pellet storage at the customers premises.
It defines quality criteria for pellet storage rooms and bunkers (underfloor and above) at the
customers premises to ensure storage conditions do not affect pellet quality. The main criteria for
the standard are:
•
•
•
•
•
•
•
•
•
The storage room or bunker has to be watertight to prevent the penetration of moisture
into the pellets.
The storage room or bunker must be made tight against dust.
The filling inlet couplings must be situated such that a standard filling pipe from a tanker
blower can reach them using a 30m (maximum) long filling pipe.
Electricity, water or wastewater installations should not be located within the storage
room or bunker.
For storage tanks without suction connectors, a vent of least 0.5m2 (Ø400mm or 750 x
750mm) is required in the storeroom or bunker to enable air to escape while filling.
All local and national fire protection regulations must be fulfilled.
Filling couplings must be made of metal and should be earthed.
Except during filling couplings should be closed with a special screw top.
Filling tubes should be as short as possible with changes in direction of not more than
45o and radii of not more than 500mm.
Appendix 2.5.1 Austrian standards for Fuel Logistics and Storage
Önorm M7137 Standard is reproduced in its entirety as follows:
Önorm M7137 –Compressed wood in natural state - woodpellets - Requirements for
storage of pellets at customers premises
(Not authorized translation of the Austrian Standard provided by ofi Austrian research
Institute for Chemistry and Technology)
To assure the quality of pellets according to ÖNORM M 7135 from the producer to firing, this
ÖNORM specifies relevant requirements for the storage of pellets by consumers.
ÖNORM M 7135 lays down requirements and test procedures for pellets. The requirements and
test procedures for automatically stoked furnaces are laid down in ÖNORM EN 303-5.
Requirements for transport and storage are specified in ÖNORM M 7136.
Storage rooms of consumers built according to this ÖNORM shall assure operating safety, fire
protection, compliance with static requirements and the preservation of pellet quality.
1 Scope of application
This ÖNORM shall apply to HP1 pellets according to ÖNORM M 7135 and specifies requirements
for the construction and equipment of pellet storage rooms of consumers. It addresses all
persons that want to build or equip such storage rooms.
2 Normative references
The following documents specifying standards contain regulations that, by reference in this text,
shall be part of this ÖNORM Standard. Dated references do not include subsequent modifications
or revisions of these publications. How-ever, it is recommended to contract parties that apply this
ÖNORM Standard to check whether it would be possible to use the latest issues of the
documents specifying standards as listed below. In the case of undated references, the latest
issue of the relevant document specifying standards shall be used. Any legal provisions shall be
applied as amended.
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ÖNORM M 7135 Compressed wood and compressed bark in natural state – Pellets and
briquettes – Re-quirements and test specifications
ÖNORM M 7500 (all parts) Heat loads of buildings
DIN 14309 Aluminium alloy solid coupling type A, with sealing ring for pressure and suction
purposes; nominal pressure 16
DIN 14323 Aluminium alloy delivery and suction coupling type A; nominal pressure 16
TRVB H 118 Automated wood firing systems
3 Definitions
For the use of this ÖNORM, the following definition apply:
Storage tank
A tank that is covered on all sides and set up independent of other building structures.
This includes, for instance, tanks made of metal, plastics, wood or textile fabrics.
4 Requirements
4.1 General requirements
4.1.1 Location of the storage room
The transport vehicle shall be able to go sufficiently close to the injection connectors that that the
quality of the pellets is not affected significantly by the mechanical stress during the filling
process.
If the storage room is filled by a lorry with a bin container, the hose length shall not exceed 30 m.
The relevant access routes shall be adequate for the transport vehicles used. In the case of
heavy lorries, a minimum road width of 3 metres and a minimum headroom of 4 metres are
required.
4.1.2 Building requirements
Any walls and supporting parts shall be constructed in such a way that they will bear the
corresponding static loads.
4.1.3 Fuel demand
The storage room shall be large enough to hold the fuel needed for one heating period. The fuel
3
3
needed for one heating period is assumed to be between 0.6 m and 0.7 m pellets per kW heat
load. The heat load may be calculated according to ÖNORM M 7500.
3
NOTE: 1 m of pellets corresponds to a mass of approximately 650 kg.
4.1.4 Protection against moisture and wetness
The storage rooms shall safely be protected against the penetration of moisture both during
storage and upon filling. In addition, any condensation of water (e.g. on exposed water pipes)
must be prevented.
As pellets may absorb air humidity, the storage room should not be ventilated.
4.1.5 Dust protection
The storage room shall be dustproof on all sides.
4.1.6 Installations, wirings and fittings
-SEI REIO-Procurement Guidelines for Wood Biomass Heating-11
Any electrical installations, water and waste water fittings as well as any other installations,
wirings and fittings shall be concealed or adequately insulated and protected against mechanical
stress. In addition, the requirements of TRVB H 118 shall be met.
For reasons of safety, any storage room according to Section 4.2 shall not be equipped with any
exposed electrical instal-lations (lamps, wirings, distributing boxes, wall outlets, light switches,
etc.).
4.1.7 Access to the storage room
Access to the storage room shall be ensured in such a way that any necessary maintenance and
cleaning may be carried out.
4.1.8 Fire protection
The basic fire protection requirements for pellet storage rooms according to TRVB H 118 shall be
met.
NOTE: In addition any applicable legal provisions shall be observed.
4.1.9 Injection connectors and injection pipes
When the storage room is filled from a lorry with a bin container, the following requirements shall
be met:
– The injection and suction connectors shall preferably lead to outdoor areas. In any case,
sufficient space for turn-ing the vehicles to connect the injection hoses shall be provided.
– Injection pipes shall be as short as possible (maximum length: 10 m) and changes of
direction shall be kept to a minimum. In the cas e of changes of direction, only curves shall
be used.
– If the injection connectors are not located outdoors and the injection pipes pass other rooms,
these rooms shall meet the requirements of TRVB H 118.
– The injection and suction connectors shall be made of metallic materials and the shall be
installed in a way that prevents torsion. They shall be earthed.
– The coupling of the injection connector shall either be a type A delivery and suction coupling
according to DIN 14323, but for hoses with inside diameters of d = 100 mm, or it shall be a
type A solid coupling according to DIN 14309, but with a G 4 thread (corresponding to
A/110).
– The coupling of the suction connector shall either be the same as the one for the injection
connector or a coupling for hoses with inside diameters of 150 mm (F/150).
– After filling, the connectors shall be tightly closed by corresponding cap couplings.
4.1.10 Sound insulation
Any bearings and fixings as well as wall bushings for feed systems shall be built in such a way
that the transmission of structure-borne sound to the building is prevented.
4.1.11 Measures against accumulation of fines
The manufacturers of the boiler and feed systems shall provide information on the intervals at
which the storage room shall be emptied completely and in which way any accumulations of fines
shall
be
treated.
4.2 Storage rooms
Ideally, the storage room should have a rectangular ground plan. The injection and suction
connectors should be located at one of the narrow sides. If possible, the storage room should
have one external wall, which also holds the connectors.
2
NOTE: On grounds of technical equipment, as a rule only approximately
/ of the storage room
3
volume is actually available as a filling volume for pellets.
-SEI REIO-Procurement Guidelines for Wood Biomass Heating-12
4.2.1 Protection against moisture and wetness
Protection against rising moisture in the walls shall be ensured.
4.2.2 Dust protection
-SEI REIO-Procurement Guidelines for Wood Biomass Heating-2005-13
Special care should be taken to ensure a dust-proof door or access hatch (see Figure 3).
In order to prevent dust from being carried to other rooms, any existing installations, wirings and
fittings (e.g. wall outlets, light switches, distributing boxes, etc.) shall be removed, and any
corresponding openings shall be closed and plastered.
4.2.3 Building requirements
4.2. 3.1 Walls and ceilings
The walls of the storage room as well as their connections with to the surrounding building
structures shall appropriately be constructed according to the relevant technical rules.
Any ceilings and walls shall be constructed in such a way that the fuel is not contaminated due to
abrasion or separation of particles.
With regard to fire resistance classes, the requirements of TRVB H 118 shall be met.
4.2.3.2 Access to the storage room
The door or access hatch shall at least correspond to fire resistance class T30 and shall open
out. At the interior side, a pressure relieve against the stored pellets is required so that the room
may be entered at any time.
NOTE: If possible, the door should be near the injection connector. In this way, the storage room
will remain accessible for the longest possible time, because during the filling process the pellets
will accumulate at the wall opposite the injec-tion connector.
The pressure relief device for the door may consist of large wooden boards or groove-and-tongue
boards that are laterally fitted into corresponding profiles.
It is recommended to consider an optical filling check device (e.g., a window).
4.2.4 Equipment
4.2.4.1 Injection and suction connectors
The injection and suction connectors shall be labelled permanently and unambiguously. The
length of the storage room, measured towards the injection connector, shall be given on a plate
near the couplings.
The connectors shall be mounted to the same wall, at a minimum distance of 20 cm (measured
between ceiling and up-per pipe edge) to the ceiling.
The suction pipe shall be flush with the wall at the interior side of the room and should be located
near the door.
The injection pipe should be installed centrally in the wall and at least 30 cm of the pipe should
extend into the room.
Connectors mounted in subterranean cellar windows (light wells) shall be led upwards in a curve
(see Figure 4) so that the couplings are freely accessible. 90° curves shall be avoided.
-SEI REIO-Procurement Guidelines for Wood Biomass Heating-2005-14
If, due to the specific situation of the room, a standard configuration is not possible, special
solutions may be adopted after consulting with experts of a corresponding enterprise (e.g.,
storage rooms that have to be fed from the longer side – 2 filling connectors or diagonal filling;
see Figures 5 and 6).
-SEI REIO-Procurement Guidelines for Wood Biomass Heating-2005-15
-SEI REIO-Procurement Guidelines for Wood Biomass Heating-2005-16
4.2.4.2 Deflector plate
It is necessary to mount a deflector plate that is resistant to abrasion and tearing. It shall be
situated at a right angle to the injecting direction at or in front of the wall opposite the injection
connector.
NOTE: HDPE sheets of a thickness of 1 mm or more, sized 1.5 m x 1.5 m, have proved to be a
reliable deflector plate.
4.2.4.3 Wall outlet for suction fan
A wall outlet with a voltage of 230 V and 16 A fuse protection has to be accessible outside the
storage room.
4.2.4.4 Angled floor
The angled floor (see Figure 2) shall be mounted at an angle of 40°. Deviations of ±5° are
permissible. The angled floor shall not deform under static load and shall have a smooth, nonabrasive surface (e.g., floor with melamine resin coating or hard-board with the smooth side
facing upwards).
NOTE: In order to ensure an unobstructed transport of the pellets to the feeding system, edges or
ridges shall be avoided.
4.3 Buried tanks
4.3. 1 Protection against moisture and wetness
Buried tanks shall be produced free of joints. Both the tank and the tank cover shall be made of
non-corrosive materials that are resistant to weathering. The corresponding materials shall be
chosen in such a way that entry of moisture to the fuel is sustainably prevented.
The tank cover shall close the tank in a water-tight way, the fittings of the tank cover shall permit
water-tight closing, or other equivalent measures shall be taken to ensure that no water may
permeate into the tank.
Any uncontrolled air exchange between the tank and the outdoor environment is inadmissible.
The tank shall be equipped with a dome shaft with a walk-on or drive-on cover that prevents rain
water from entering the dome shaft.
The connection between the tank and the dome shaft shall be water-tight.
-SEI REIO-Procurement Guidelines for Wood Biomass Heating-2005-17
The connections between the protection pipe and the pipes to the dome shaft as well as the
connection between the protection pipe and the cellar shall be water-tight (see Figure 9).
4.3.2 Protection against electrostatic charge
Any conductive parts of the tank, the tank cover as well as any connecting fittings and the
removal system shall be earthed. As electrostatic charging is possible, the storage tank shall be
constructed in such a way that ignition by sparking is prevented. The manufacturer of the tank
shall submit the corresponding proof.
4.3.3 Building requirements
The walls of the tank shall be constructed in such a way that they will bear the static loads
occurring during and after the installation of the tank.
The tank and the heating cellar shall be connected by means of a protection pipe that runs
underground at a minimum depth of 300 mm and through which the earthed pipes of the removal
system and other piping shall be led.
4.3.4 Equipment
The tank shall be equipped with a conveying system suitable for the discharge of pellets when the
tank cover and the fittings are closed.
Residual quantities in the tank that cannot be removed shall not exceed 5% of the nominal
volume of the tank.
The couplings (for specifications see Section 4.1.9) shall be freely accessible in the dome shaft of
the tank; they shall be arranged in a way that permits unproblematic filling and emptying of the
tank.
After filling, the connectors shall be tightly closed by means of corresponding cap couplings.
4.3.5 Fire protection
The basic fire protection requirements according to TRVB H 118 shall be met.
4.4 Storage tanks
4.4.1 Building requirements
Metal tanks shall be earthed and protected against corrosion.
-SEI REIO-Procurement Guidelines for Wood Biomass Heating-2005-18
In the case of tanks made of non-conductive materials, any conductive parts as well as any
connecting fittings and the removal system shall be earthed. As electrostatic charging may occur,
the tank shall be constructed in such a way that ignition by sparking is prevented. The
manufacturer of the tank shall submit the corresponding proof.
Flexible storage tanks shall be placed at a sufficient distance to walls and ceilings to ensure
access by installation staff and to prevent damage to the fabric caused by rubbing along walls.
In the case of flexible storage tanks, antistatic materials shall be used.
4.4.2 Injection and suction connectors
The injection and suction connectors may be led outside through the exterior wall of the room
where the tank is placed, or, if a direct opening to the outside, like a window, door or cellar well
exists, they may be attached directly to the storage tank.
In the case of tanks without suction connectors (e.g., flexible storage tanks), it must be possible
to lead the air removed from the tank out of the room (e.g., through an open door or window
during filling).
If the suction fan is to be placed outdoors, a distance of approx. 2.5 m between the suction
connector of the tank and an opening to the outside (e.g., a window) shall not be exceeded (see
Figures 10 and 11).
-SEI REIO-Procurement Guidelines for Wood Biomass Heating-2005-19
4.4.3 Fire protection
The basic fire protection requirements according to TRVB H 118 shall be met.
Figure 12 – Example of a flexible storage tank made of textile fabric
-SEI REIO-Procurement Guidelines for Wood Biomass Heating-2005-20
4.5 Storag e room for small quantities
For small quantities, either in bulk or packaged, the requirements given in Section 4.1 shall apply
mutatis mutandis. Easing of the relevant fire protection regulations may be granted in accordance
with the applicable local legislation.
-SEI REIO-Procurement Guidelines for Wood Biomass Heating-2005-21
Appendix 2.5.2 Austrian standards for Wood Pellet Logistics
The following standard is reproduced in its entirety to assist specifiers of wood heating
systems in the requirements of fuel storage and delivery.
ÖNORM M 7136 Wood pellets - Quality assurance in the field of logistics of transport and
storage
(Not authorized translation of the Austrian Standard provided by ofi Austrian research Institute for
Chemistry and Technology)
This ÖNORM specifies requirements for transport and intermediate storage of pellets to maintain
the quality according to ÖNORM M 7135(pellet manufacture standard) between the producer and
the combustion.
Applying this ÖNORM intends to assist pellet manufacturers, hauliers and traders to avoid
mistakes and ensure customer satisfaction.
ÖNORM M 7135 lays down requirements and test procedures for pellets. Requirements and test
procedures for automatically charged furnaces are specified in ÖNORM EN 303-5.
ÖNORM M 7137 specifies the standards for the storage of pellets.
Scope
This ÖNORM applies for wood pellets HP1 „ÖNORM M 7135 tested“ („ÖNORM M 7135 geprüft“)
only and specifies the quality assurance for transport and (intermediate) storage. It is intended for
manufacturers, traders, operators of store-houses and all other persons involved in pellet
transport.
Definitions
For the use of this ÖNORM, the following definition apply:
Intermediate storage -any storage facilities between production and storage at the consumer
Documentation
In all delivery documents including delivery note and invoice, the labelling of the fuel according to
ÖNORM M 7135 must be stated. The dealer / haulage company has to furnish proof that only
wood pellets HP1 „ÖNORM M 7135 tested“ have been delivered.
Purity
Wood pellets HP1 „ÖNORM M 7135 tested“ have to be stored and transported separately from
pellets not complying with the standard and from other goods. Blending of pellets with different
diameters is not permitted.
Transport vehicles must be thoroughly cleared from previously transported goods. Ancillary
equipment (e. g. awnings) must be clean.
Protection against moisture and wetness
Woodpellets must be kept dry during storage and transport.
Requirements for intermediate storage
Delivery
Working surfaces (e. g. gutters in silos) were wood pellets are handled must be covered.
Storage
Wood pellets must be stored in storehouses that are covered on all sides. The ground must be
equipped with a sub-base (e. g. concrete, asphalt). They can also be stored dry in closed silos.
-SEI REIO-Procurement Guidelines for Wood Biomass Heating-2005-22
At all times wood pellets have to be kept dry, they have to be especially protected against direct
rain, snow and wet walls or condensation. The requirements regarding water content, abrasion
and raw density according to ÖNORM M 7135 have to be adhered to.
Handling areas and storage surfaces must be free from contaminations (e.g. grit, soil, sand).
Silos and conveyors have to be discharged and must be cleaned completely if other goods were
conveyed or stored before.
Loading of transport vehicles
Before transport vehicles are loaded for delivery to consumers, the fine fraction shall be
separated. After separation, the content of fine fraction shall not exceed 1% (w/w).
The separation of the fine fraction may be omitted when pellets are reloaded from e. g. Big Bags
or form a silo-trailer if the separation was performed accordingly before loading.
Requirements for transport vehicles for the delivery to end consumers
Protection from wetness
The wood pellets must be delivered in transport vehicles that ensure protection against wetness
throughout the transport as well as during loading and unloading.
Mechanical stress on pellets due to conveying systems of the lorry
The fine fraction may increase by maximum 1 % due to mechanical stress on pellets.
On-board weighing systems
For payloads of more than 8 000 kg transport lorries have to be equipped with a calibrated onboard weighing system.
Lorry with bin container Suction filtration
An equipment for suction of the blast in air from the storage room must be in place. The
discharge capacity of the suction system must exceed the capacity of the lorry compressor. Any
overpressure in the storage room must be avoided.
Minimum length of hose
The standard equipment of the silo lorry shall consist of a hose with a minimum length of 30 m.
Suitable adaptors and connections are also part of the standard equipment.
Other vehicles
Equivalent transport vehicles are permitted.
Requirements for the qualification of the delivery staff
Job instructions (4.4.1)
The dealer/ hauling contractor delivering wood pellets in accordance with this ÖNORM, has to
draw up job instructions for the training of the delivery staff.
These job instructions must include at least the following points:
– transport form one intermediate storage to another intermediate storage
– customer relations (notification of date including the remark that the heating has to be turned
off in time etc.)
– filling in of the checklist as below
– preparation for filling the fuel storage room
– advices for careful unloading of the pellets
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– technical procedure of unloading
– correct application of the suction filtration ( switching on of suction filtration before
unloading, using dry and clean exhaust filters only)
-SEI REIO-Procurement Guidelines for Wood Biomass Heating-2005-24
– avoiding excess pressure in the storage room
– closing of inject and exhaust nozzle after use
Checklist
The check list has to be filled in for every delivery to a customer by the delivery staff and has
to contain at least the follow-ing information:
– heating switched off YES/NO
– storage room closed YES/NO
– nature and estimated amount of remaining fuel stock in the storage room
– length of hose used in m
– other remarks (e.g. deflector plate missing, accumulation of a fine fraction).
The checklist must be included in the delivery documents and may be included in the delivery
note.
Test procedures
General - Documentation
It has to be checked by random sampling if the note „ÖNORM M 7135 tested“ is printed on all
documents.
Verification of the sale of HP1 “ÖNORM M 7135 tested” wood pellets is established through
checking of incoming goods, outgoing goods and inventory. The company must be in a
position to produce incoming goods, outgoing goods and inventory in an edited and clear
presentation that is available at any time. The person carrying out the checks has the right to
inspect all delivery documents. He is authorized to examine the supplier’s and the customer’s
data at a random basis.
Purity of the product (product conformity)
Visual controls on the premises.
Protection against moisture and wetness
Visual controls on the premises..
Storage
Visual controls on the premises. From the stock, samples have to be taken in accordance
with ÖNORM M 7135 and have to be tested for abrasion, water content and raw density.
Loading of transport vehicles
At the exit of the filling hose at least three samples with a mass of at least 5 kg must be taken
out of the flow of pellets. The individual samples must be taken staggered that a multifold
amount of pellets passes the point of sampling between the withdrawal of samples (at least
10 times as much).
The individual samples are then combined to a mixed sample. The determination of the fine
fraction of the mixed sample is done by manual sieving applying a 3.15 mm sieve according
to DIN ISO 3310-1.
Transport vehicles for delivery to the end consumer
There must be visual checks to establish that the technical equipment is in working order.
Protection against wetness
Visual controls shall be carried out on the premises.
Mechanical stress of pellets caused by conveying systems of the transport vehicle
-SEI REIO-Procurement Guidelines for Wood Biomass Heating-2005-25
The inspection shall be carried out during standard operating conditions. At the end of the
unloading system of the trans-port vehicle (for lorries with bin containers a hose length of at
least 10 m required) at least 3 individual samples of at least 5 kg must be taken from the flow
of pellets. The individual samples must be taken staggered that a multifold amount of pellets
passes the point of sampling between the withdrawal of samples (at least 10 times as much).
The individual samples are then combined to a mixed sample. The determination of the fine
fraction of the mixed sample is done by manual sieving applying a 3.15 mm sieve according
to DIN ISO 3310-1.
On-board-weighing systems 4.3.1.3
Visual controls shall be carried out on the premises. The calibration must be checked.
Lorry with bin container
Suction filtration
The capacity of the exhaust fan and of the vehicle compressor at rated speed as per
specification must be stated in the test report.
Minimum length of hose
Visual controls shall be carried out on the premises
Other vehicles
The equivalence of other vehicles has to be proved
Qualification of delivery staff
The job instructions as per 4.4.1 must be presented and their completeness must be checked.
Proof of internal training courses as under these job instructions must be presented. Random
checks are carried out on the checklists as under 4.4.2.
Interim arrangement
The on-board weighing system according to 4.3.1.3 shall be in place at least 3 years after
publication of this ÖNORM.
http://www.on-norm.at
-SEI REIO-Procurement Guidelines for Wood Biomass Heating-2005-26
Appendix 3
3.1 Summary of emissions limits from
Boiler Standard EN303-5
3.2 CO 2 emissions for heat producing technologies
3.3 CO 2 emissions for heat producing technologies
SEI REIO-Procurement Guidelines for Biomass Wood Heating-2005-1
Appendix 3.1 Summary of emissions limits from EN303-5
CEN, the European Committee for Standardization, approved the standard EN 303-5
(Heating boilers for solid fuels, hand and automatically stoked, nominal heat output of up to
300 kW) in November 1998. Standard EN 303-5 also covers other solid fuels in addition to
wood.
The flue gas emissions and efficiency are determined at nominal output and minimum output.
At least a 50 % minimum output shall be achieved for manually fed boilers, and at least a
30 % output for automatically fed boilers. If a manually fed boiler is not able to achieve the
50% part output it shall be equipped with a heat accumulator and the manufacturer shall give
information about it.
The combustion cycle of manually fed boilers with one fill shall be at least two hours when
burning biomass and at least four hours when burning fossil fuels. The operation time of
automatically fed boilers shall be at least six hours.
The output of the boiler is measured on the basis of water flow and temperature difference.
The fuel consumed during the test is weighed. The total efficiency of the system is calculated
on the basis of these with a so-called direct method when the energy fed into the system and
that obtained for cooling are known.
The EN 303-5 standard classifies the boilers into three classes on the basis of capacity. CO
content, content or organically bound carbon (OGC) and particle content in flue gas emissions
are measured. Emission limits for various boiler classes are presented in the table below.
An analyser based on flame ionisation detector (FID) is used for measuring organically bound
carbon. This device hence measures all carbon that exists in organic form in flue gases. The
FID analyser is a commercially available continuously operating device, which measures the
content in undried flue gas. Prior to leading the gas into the analyser particles are filtered from
the gas.
The requirements of efficiency for the boiler classes are as follows:
class 1 η = 47 + 6 log Qn
class 2 η = 57 + 6 log Qn
class 3 η = 67 + 6 log Qn
where Qn is the nominal output of the boiler (kW).
For example, if the nominal output of the boiler is 20 kW the requirements of
minimum efficiency in the boiler classes are as follows:
class 1 54.8 %
class 2 64.8 %
class 3 74.8 %
Heating boilers for solid biofuels, automatically fired, nominal heat output up to 300kW.
Nominal heat
Emission limits
output kW
CO
OGC
Dust
3
Mg/m at 10% O2
Class Class Class Class Class Class Class Class Class
1
2
3
1
2
3
1
2
3
<50
15000 5000
3000 1750
200
100
200
180
150
50 to 150
12500 4500
2500 1250
150
80
200
180
150
150 to 300
12500 2000
1200 1250
150
80
200
180
150
Note: OGC=Organically Bound Carbon
SEI REIO-Procurement Guidelines for Biomass Wood Heating-2005-2
Appendix 3.2 CO2 emissions for heat producing technologies
Technology
Particulates
Operational Emissions
CO 2
SO 2
(kg/TJ)
NOx
Renewable energy sources
Solar thermal heat
Biomass heat
Geothermal heat
Biodiesel fuels
Bioethanol fuels
1
Fossil fuels
0
5 –8
0
140
148
0
38 – 166
0
150
170
0
3 – 79
0
21
16
0
2000
2000
0
0
Industrial coal boiler
Industrial gas boiler
Diesel
1396
0
107
236
126
1167
208
0
11
110000
65000
68000
(For ‘biomass’ technologies, CO2 emissions are for fossil fuel components since biomass is taken to be CO2
neutral.)
Source: EU Thermie Atlas Project Report, 1997
Appendix 3.3 CO2 emissions for electricity generating technologies
Technology
Operational Emissions
CO2
SO2
NOx
Particulates
(g/MWh)
2
Fossil Fuels
Coal fired electricity generation
Oil plant
Diesel
Gas – CCGT
(with FDG & low NOx burners)
Renewable energy
sources
Waste combustion
Biomass: gasification
Biogas: anaerobic digestion
Tidal
Biomass: steam cycle
Biogas: landfill
Biomass: co – firing
Wind
Small hydro
Photovoltaic
Wave
125
13,463
11
0
2,828
3,601
11,772
11
162
421
108
0
886,730
732,360
685,690
488,240
2,502
47
359
68
84
298
na
0
0
0
0
3,026
0
768
18
1,784
2,082
Na
0
0
0
0
262
36
29
0
854
101
na
0
0
0
0
359,000
14,360
10,770
7,180
0
0
na
0
0
0
0
3
na – Not Available
For ‘biomass’ technologies, CO2 emissions are for ‘non – biomass’ sources, since biomass is taken to be
CO2 neutral.
Source: EU Thermie Atlas Project Report, 1997
Further Emissions and Unit Converter Calculators are available online in the Reference Centre at
www.sei.ie/reio.htm
SEI REIO-Procurement Guidelines for Biomass Wood Heating-2005-3
1
General Description and Scope Work.................................................................2
1.1
Details of building(s) to be heated........................................................................................... 2
1.2
Scope.......................................................................................................................................................... 2
1.3
This specification covers ................................................................................................................. 2
1.4
This specification does not cover............................................................................................... 2
1.5
Power supply.......................................................................................................................................... 2
1.6
Power consumption............................................................................................................................ 3
1.7
Water supply .......................................................................................................................................... 3
2
Boiler House or ‘Plug and Play’ Container......................................................... 3
2.1
Boiler House or Plug and Play Container .............................................................................. 3
2.2
Boiler house and fuel bunker/silo .............................................................................................. 3
2.3
Access for cleaning ............................................................................................................................. 3
2.4
Access for installing the boiler .................................................................................................... 3
3
Fuel.............................................................................................................................. 3
3.1
Fuel type................................................................................................................................................... 3
3.2
Wood- fuel specification ................................................................................................................... 3
3.3
Fuel Supply ............................................................................................................................................. 3
4
Fuel Bunker/Silo ......................................................................................................4
4.1
Storage System.................................................................................................................................... 4
4.2
Wood- pellet storage .......................................................................................................................... 4
4.3
Bunker/silo size .................................................................................................................................... 4
5
Fuel Handling and Feeding System .....................................................................4
5.1
Fuel feed mechanism........................................................................................................................ 4
6
Boilers......................................................................................................................... 4
6.1
Boiler output .......................................................................................................................................... 4
6.2
CE marked ............................................................................................................................................... 4
6.3
Grate system......................................................................................................................................... 4
6.4
Boiler efficiency.................................................................................................................................... 5
6.5
Turndown ................................................................................................................................................. 5
6.6
Burn- back protection ........................................................................................................................ 5
6.7
Force draught (FD) fans .................................................................................................................. 5
6.8
Flue gas induced draught (ID) fans ......................................................................................... 5
6.9
De-ashing................................................................................................................................................. 5
6.10 Boiler emissions ................................................................................................................................... 5
7
Flue System............................................................................................................... 5
7.1
Independent flue................................................................................................................................. 5
7.2
Cleaning and dust removal........................................................................................................... 5
7.3
Flue pipes and transition pieces................................................................................................. 5
8
Installation and Commissioning ..........................................................................6
8.1
Location of boiler................................................................................................................................. 6
8.2
Installation schedule ......................................................................................................................... 6
8.3
Boiler / system installation............................................................................................................ 6
8.4
Commissioning ..................................................................................................................................... 6
9
Technical Support ....................................................................................................6
9.1
Operator training................................................................................................................................. 6
9.2
Remote Monitoring ............................................................................................................................. 6
9.3
Operating manuals ............................................................................................................................. 6
9.4
Service Agreement / Warranties ............................................................................................... 6
10 Solar Water Heating System................................................................................. 7
10.1 General...................................................................................................................................................... 7
10.2 Buffer Tank ............................................................................................................................................. 7
10.3 Procurement........................................................................................................................................... 7
-1-
Example Biomass Heating Specification
1
General Description and Scope Work
Description
1.1 Details of building(s) to be heated
The site is the Inchydoney Lodge & Spa Hotel located near Clonakilty, Co. Cork, Ireland. This site is
a 67-bedroom hotel and Spa with a Leisure Centre & Treatment Rooms. The hotel uses around
2,250,000 kWh of fuel per year to provide both space heating and hot water provided by about
2
315,000 litres of LPG. The floor area to be heated is 5,500 m . The existing LPG boilers had a
capacity of 2400 kW, a seasonal efficiency of 60% and a maximum efficiency of 70%.
1.2 Scope
This specification describes the requirements for the supply and installation of a wood-fuelled boiler
system for the supply of hot water for an existing wet central heating system and service hot water
system that should meet the calculated peak heat load of 400 kW.
1.3 This specification covers
This specification covers the requirements for the supply, installation and commissioning of a fully
automatic wood -fuelled boiler, fuel storage silo, flue system, connection to the exisitng heating mains,
online control and maintenance system, hot water tanks, hot water buffer tanks and associated
ancillary equipment. The equipment specified is intended to meet the highest level of independently
certified quality, as well as being straightforward and fast to install.
This specification also covers the ongoing service and maintence of the wood heating system, which
is to require a minimum of service attendance, maintenance and repair over its entire lifetime.
2
The site is also to be supplied with a solar water heating system, consisting of 160 m of solar panels
and an air heat recovery system from communal areas using heat pumps. Whilst a seperate
specification is provided for the solar and heat pump systems, the biomass system, including controls
must be demonstrationably compatible with both.
A povisional cost sum of 10% of the total installed cost price (based on this specification) must also
be included in the suppliers offer for the purpose of general system efficiency improvements to be
impemented, as determined by the customer in writing, by agreement with the supplier, under
recognised standard contracting terms and conditions following contract placement.
The implementation and commissioning works required under this specification are to be carried out
and completed within 15 calender weeks following legally agreed placem ent of contract with the
selected supplier. These works are to be conducted so as to cause a minimum of distruption to the
normal operation of the hotel, including the provision and availability of service and space heating.
The supplier should note that this may entail some work outside of normal working hours.
1.4 This specification does not cover
This specification does not cover modification or repair works to the existing hot water distribution
system outside of the main heating and electrical plant or service rooms. Nor does the specification
cover modifications or repairs to the existing building fabric or structure in which the boiler and
ancillary components are to be installed. Costs for any such proposed modifications or repairs, as
deemed necessary by the supplier for the fulfilment of the specification or full contract execution,
must be clearly detailed and costed separately using recognised standard contract terms.
1.5 Power supply
The installed boiler requires a
3-phase 400V
1-phase 240V
electricity supply on site.
The customer will be responsible for providing this power supply at the plant room distribution panel.
-2-
1.6 Power consumption
The peak demand for parasitic electricity from the Wood Heating system is not to exceed 5 kW per
boiler.
1.7 Water supply
The water supply is:
Mains supply
Water testing costs to be bourn by supplier if
Self supply (give details)
required.
2
Boiler House or ‘Plug and Play’ Container
Description
2.1 Boiler House or Plug and Play Container
There are two existing boiler plant rooms used for the hot water tanks, hot water buffer tanks, heat
exchangers, the heat pump and the control and maintenance system. The wood-fuelled boilers are
To be located in a:
Boiler House
Plug and Play Container(s)
The dimensions of the container(s) are: Length: 12.19 m
Not to exceed standard shipping
Width:
2.44 m
container dimensions – can be stacked Height:
2.89 m
2.2 Boiler house and fuel bunker/silo
There are no local and national building regulations since the container is a movable unit. However
for fire purposes the container should be designed and located so as to avoid the spread of flame
through any of the building openings such as windows or doors located above or adjacent to the
unit’s access doors or chimney for example.
2.3 Access for cleaning
The boiler tubes should have an automatic self-cleaning mechanism. The ash should be
automatically deposited and collected in ash boxes that can be easily emptied when required. The
access for cleaning and emptying these boxes should be through easily accessible doors at the front
of the Boiler(s).
2.4 Access for installing the boiler
The Plug and Play Container boilers should be factory preinstalled and pre commissioned so as to
avoid unnecessary site works as far as possible. The system should require a minimum of installation
time and cause a minimum of disturbance to the running of the Hotel business.
3
Fuel
Description
3.1 Fuel type
The boiler used is suitable for
3.2
Wood-fuel specification
Moisture Content
Particle size distribution
Wood-chip
Wood-pellet
Wood-chip & pellet
Wood Pellets
(CEN TS 14961)
M10: = 10 %
D06: D =6mm ± 0,5mm, L=5x D
D08: D =8mm ± 0,5mm, L =4xD
D10: D =10mm ± 0,5mm, L =4xD
A0.7: = 0.7%
Wood Chips
(CEN TS 14961)
M40: = 40%
P45: 3,15mm = P = 45mm
P63: 3,15mm = P = 63mm
Ash content
A3.0: = 3.0%
3.3 Fuel Supply
The installer is responsible for the delivery of any fuel for commissioning. The supplier is only
responsible for the on time fuel delivery for normal operation under an agreed fuel supply agreement
with the customer, which is subject to contract.
Relevant standards:
CEN standard – TS 14961: Solid biofuels – fuel specification and classes
-3-
4
Fuel Bunker/Silo
Description
4.1 Storage System
The Wood Pellets are stored in a:
Storage room
Underground storage
Storage silo
Storage container
Not to exceed standard shipping
container dimensions – can be stacked
4.2 Wood-pellet storage
The storage container is to be located on top of the boiler container. The container has to be water
tight and should conform to the Austrian OeNorm 7137 Standard “Requirements for storage of pellets
at the ultimate consumer”
4.3 Bunker/silo size
The size of the storage container is not to exceed Length: 12.19 m
Width: 2.44 m
Height: 2.89 m
Or equivalent store that is large enough to store 25 tonnes of wood pellets and has easy access for
simple refueling by a standard blown pellet delivery truck.
Relevant standards:
Önorm M7137 – Presslinge aus naturbelassenem Holz-Holzpellets, Anforderungen an die
Pelletslagerung bein Verbraucher (Compressed wood in natural state - woodpellets Requirements for storage of pellets at customers premises).
Önorm M7136 – Presslinge aus naturbelassenem Holz-Holzpellets, Qualitatssicherung in der
Transport and lagerlogistik (i.e. woodpellet transport and logistics)..
5
Fuel Handling and Feeding System
Description
5.1 Fuel feed mechanism
The wood-fuelled boiler is to be
automatically
Underfed
Horizontally fed
Overfed.
Using a double feed auger system. Supplier to detail the configuration of the feeding mechanism –
including the feeding option(s) which make the wood heating system suitable for wood pellets only.
6
Boilers
Description
6.1 Boiler output
The nominal boiler output at the site is to be capable of meeting a peak load of 400kW.
6.2 CE marked
Each boiler must be CE certified (proof of certification to accompany supplier offer).
6.3 Grate system
The grate system is a
plane grate
stepped grate
moving grate
To ensure that the system can be used with wetter fuels (up to 40% MC).
-4-
6.4 Boiler efficiency
Boiler efficiency at rated power is to be a minimum of 90%.
The boiler efficiency is to be independently verified by a certified EU Laboratory in accordance with
EN303-5 class 3 or better.
6.5 Turndown
Each installed boiler must be capable of operation at as low as one third of rated power whilst keeping
the efficiency above 90%.
6.6 Burn-back protection
The installed system must provide a three stage burn-back protection system, including an airtight
shutter, a thermal and electronic cutout device and an independent water dousing system. The function
of the back burn system should be warranteed in case of a power cut.
6.7 Force draught (FD) fans
The peak parasitic electricity demand of each boiler is 5 kW. Included in this is the demand of the force
draught fans.
6.8 Flue gas induced draught (ID) fans
A flue gas ID fan is required.
6.9 De-ashing
The system must provide an automatic de-ashing system for the grate and the heat exchanger tubes
6.10 Boiler emissions
The boiler emissions must not exceed the following limits:
Dust
60 mg/MJ
Dust partial load
60 mg/MJ
CO
500 mg/MJ
NOx
150 mg/MJ
Volatile organic substances (Corg)
80 mg/MJ
The supplier/manufacturer has to provide a copy of independently verified test results.
Relevant standards:
EN 303-5:1999. Heating boilers with forced draught burners. Heating boilers for solid fuels, hand
and automatically fired, nominal heat output of up to 300 kW. Terminology, requirements, testing
and marking. Available from NSAI www.standards.ie
TH 42075. The Low Voltage Directive. A guide to CE marking (Low Voltage Directive 72/23/EEC)
TH 42073. CE Marking for Machinery. A guide to the European Directive (Machinery Directive
98/37/EC)
7
Flue System
Description
7.1 Independent flue
The flue is to be twin walled marine grade stainless steel insulated with rock wool and certified
suitable for use with wood-fuels. The height of the flue depends on the location and height of the
neighbouring buildings. A single flue with a height of some 5 m is expected to be sufficient.
7.2 Cleaning and dust removal
The flue design is to provide for straightforward cleaning and inspection access, which is to be once
a year.
7.3 Flue pipes and transition pieces
All transition pieces, connections and flue pipes for connecting the boiler to the flue are made from
marine grade stainless steel and are to be certified suitable for use with wood-fuels. The flue pipes
are insulated with rock wool.
-5-
8
Installation and Commissioning
Description
8.1 Location of boiler
The Location of the boiler and the fuel store(s) can be seen on the attached drawing (No. 1).
8.2 Installation schedule
The supplier/installer is to provide details of the lead-tim e for the supply of all material and equipment
to site. The implementation and commissioning works required under this specification are to be
carried out and completed within 15 calendar weeks following legally agreed placement of contract
with the selected supplier.
8.3 Boiler / system installation
The boiler / system components should be pre-installed in the container(s) in so far a practicable so
as to minimise the work required on site.
8.4 Commissioning
The supplier/installer is to provide a commissioning protocol for agreement with the customer and
two copies of the hand over documentation are to be made available by the supplier.
9
Technical Support
Description
9.1 Operator training
The supplier / installer is to provide certified minimum operator training for the Hotel plant
maintenance staff.
9.2 Remote Monitoring
The customer will provide and maintain a standard telephone and a CAD5 data line connection at the
existing plant room to allow the supplier/manufacturer to carry out remote monitoring under a service
agreement. The biomass plant control system must also the customer or operator to have internet
access to see real time and historic performance data. The remote monitoring system must also
include a GSM-Modem to send alarm messages to maintenance personal using short message
services. The biomass remote monitoring system should be compatible with the solar and heat pump
data systems.
9.3 Operating manuals
The Supplier/installer will provide two copies of all manuals required to ensure the safe and reliable
operation of the boiler and ancillary equipment.
9.4 Service Agreement / Warranties
The customer invites a service agreement proposal from the supplier / installer under which the
supplier / installer handles all services and problems with the system and supplies the fuel for a pre
defined number of years.
If the customer choses not to enter into a service agreement due to reasons of economy or
otherwise, each part of the system has different warranty times and every problem will be handled
with the appropriate manufacturer by the customer himself.
Proposals to supply the biomass heat as a Contract Energy Management (CEM) project will be
considered by the customer. This means that the supplier / installer will be contracted to own,
operate the equipment and supply the heat for a pre defined number of years. During the contract
time the installer handles all services, fuel and problems with the system under the CEM agreement.
-6-
10 Solar Water Heating System
Description
10.1 General
2
There are 160 m solar panels installed on an extension of the hotel. Calculations with the Retscreen
model (www.retscreen.net) show that this could make up to 30% of the service hot water and
swimming pool hot water demand for the hotel.
10.2 Buf fer Tank
There is one low temperature hot water tank to be installed to maximise the use of the solar water
heating system. This tank is to be installed in the pool area boiler house together with a hot water
tank that is fed with hot water from the biomass boiler(s) and if the water from the solar system is hot
enough also from the solar panels.
10.3 Procurement
The specifications for the solar and heat pump systems are contained in a separate document.
-7-
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