Direct-Fired Absorption Chillers

Direct Fired Vapor Absorption Chiller
EcoChill Nxt
Direct Fired Vapor Absorption Chiller
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C o n t e n t s
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Company Profile............................................................... 3
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Introduction....................................................................... 5
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Installations....................................................................... 9
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Certificates........................................................................ 11
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Working Principle.............................................................. 13
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Design Philosophy............................................................ 15
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Refrigeration Cycles ......................................................... 17
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Constructional Features and Mechanical Design
Considerations ............................................................... 21
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Supply List and Scope of Work ...................................... 23
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Utility Requirements ........................................................ 25
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Selection Criteria and Procedure .................................... 27
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Thermax Nomenclature and the Product Basket ........... 28
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Performance Data ........................................................... 29
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Piping and Instrumentation Diagram .............................. 30
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General Arrangement and Foundation Drawing ............ 32
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Instrumentation and Safety Features .............................. 33
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Machine Room Layout Considerations .......................... 37
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Site Unloading and Installation ....................................... 39
Company Profile
T
hermax is an engineering major providing energyenvironment solutions, systems and products in
global markets. The US $ 490 million Thermax is
featured in the Forbes List of 'Best Under a Billion'
Companies in the Asia Pacific. It offers business - to business solutions to industrial and commercial
establishments in the areas of heating, cooling, captive
power, water treatment, air pollution control, waste
management & resource recovery, and chemicals. It
supports a wide spectrum of industry in over 50 countries
in South East Asia and Japan, Africa and Middle East,
CIS countries, USA, South America and Europe.
In the energy business, Thermax executes projects in the
areas of process heat, captive power and waste heat
recovery. The company also offers a range of boilers and
thermal oil heaters, energy efficient chillers and
customized products such as waste heat and exhaust
gas boilers. Thermax's integrated expertise in energy has
helped it to offer its customers Combined Heating Power
and Cooling (CHPC) projects.
Thermax offers industry its expertise over a hundred fuels
- oil, gas and a wide variety of solid fuels including
biomass. Through diverse installations in several
countries, it has also developed reliable project
management capabilities.
EcoChill Nxt
Direct Fired Vapor Absorption Chiller
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Leveraging its leadership position in electricity saving vapour absorption technology, Thermax offers process industries
and commercial establishments like hotels, shopping malls and offices vapor absorption machines a boon in powerstarved areas. These eco-friendly, energy efficient equipments have found prestigious customers such as BBC,
Mercedes Benz, Audi, Bosch, Panasonic, and Henry Ford Museum.
In the environment area, Thermax offers waste management expertise for solid, liquid and air pollution. Thermax
provides solutions from pre-treatment to waste water treatment and chemical conditioning of water for boiler and
cooling water systems. Water recycling is a thrust area for Thermax. Hi-grade ion exchange resins from Thermax have
found niche customers in the US and Japanese markets.
Thermax has an extensive international marketing network. Headquartered in Pune (Western India), Thermax's 17
international offices are located in South East Asia, Middle East, Africa, Russia, UK and the US. Its overseas
subsidiaries - Thermax Europe Ltd (UK) and Thermax Inc (USA) play a significant role in business development.
The Thermax group's manufacturing facilities spread over 14 plants, measuring a covered area of over 700,000 sq. ft,
are ISO 9001, ISO 14001 and OHSAS 18001 accredited. Thermax manufactures to international standards like ASME,
BS, DIN, and GOST. Lloyds, Bureau Veritas, SGS, and TUV have inspected the facilities.
Thermax's business is inspired by the conviction that 'Improving your business is our business.'
Introduction
EcoChill Nxt Chillers and Heaters are available from 100 1110 USRT and can achieve chilled water temperature
down to 38OF.
The EcoChill Nxt Series product range represents a
culmination of Thermax's global expertise in energy and
environment, continuous innovation through focused
Research and Development, world-class manufacturing
capabilities, efficient and responsive service and a deep
commitment to quality and reliability. Testimony to this is
provided by over 2500 installations in the last 15 years
across 40 countries, appreciation from our customers
and several prestigious awards and honors.
Salient features of
n
R
efrigeration is a process of extracting heat from a
low temperature medium and transferring it to a
high temperature heat sink. Refrigeration
maintains the temperature of the heat source below that
of its surroundings while transferring the extracted heat to
a heat sink. This operation finds applications in many
industries ranging from process, engineering,
manufacturing, medical, dairy and confectionery, to
beverage, hospitality, education and commercial
establishments.
Absorption chillers, instead of using electricity (high
grade energy), use heat as energy source which is low
grade energy. The energy source may be gas or oil, or
hot water, or it may be waste heat as in exhaust gas from
an engine and steam. Thermax offers a wide range of
solutions for each of these sources of energy,
representing a major advance in Absorption Chilling
Technology. EcoChill Nxt Vapour Absorption Chillers
derive energy from gas (Natural gas, LPG, CNG), light oil
(HSD, naphtha, SKO) or medium oil (LDO, FO) to provide
the desired chilling-heating effect. The Direct Fired
Series flow In series flow cycle, maximum
concentration and maximum temperature do not
occur simultaneously in any generator. In other cycles,
maximum concentration and maximum temperature
occur simultaneously in the High Temperature
Generator (HTG). Corrosion rates depend on
concentration and temperature. However, when
highest concentration and temperature occur
simultaneously, corrosion potential increases
exponentially. The table below gives approximate
values of concentration and temperature in High
Temperature Generator (HTG) and Low Temperature
Generator (LTG) for various cycles.
Cycle
Series flow
High Temperature
Generator
Low Temperature
Generator
Concentration Temperature
(%)
(0F)
Concentration Temperature
(%)
(0F)
61
< 320
64
<212
Para flow
64 or more
> 320
61- 62
< 212
Reverse flow
64 or more
>320
61- 62
< 212
Thus, due to series flow cycle, the corrosion rate is the
least in Thermax chillers.
n
Concentration display and measurement:
Concentration in absorption chiller is analogous to
current in electric motor. Motor meets higher load by
drawing more current. Similarly, absorption chiller
meets higher load by attaining higher concentration.
However, when motor draws current more than it's
rated limits, it may burn. Similarly, in an absorption
chiller, if concentration increases beyond rated value,
the chiller crystallizes. Hence, continuously knowing
EcoChill Nxt
Direct Fired Vapor Absorption Chiller
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the Lithium Bromide concentration is as important as
knowing the current drawn by motor. Thermax has
developed and offers a unique technology to
determine the concentration, which is
continuously displayed on the PLC.
n
n
Crystallization protection: Due to the unique
feature of determining concentration and knowing
temperature of Lithium Bromide coming out from Low
Temperature Heat Exchanger (LTHE), an intelligent
PLC constantly monitors the distance from
crystallization line. If this distance is reduced below
18 0F, the PLC proactively takes suitable measures to
restore it to 18 0F. In other chillers, crystallization
prevention measures are taken after inception of
crystallization. However, due to advanced technology
and intelligent panel, Thermax chillers take suitable
measures before Lithium Bromide approaches
crystallization.
Low Cooling Water Supply Temperature
without crystallization: Due to sophisticated
crystallization protection, Thermax absorption chillers
can work at rated capacity even with cooling water
supply temperature of 50 0F while most of the other
manufacturers require cooling water supply
temperature of 68 0F or above.
n
Multi-fuel capability: The generator design is
such that the chiller can handle gaseous fuels as well
as liquid fuels.
n
In the Direct-fired chiller, furnace is welded to the
chiller frame. When the chiller is started and reaches
its capacity, the furnace metal temperature increases.
Such increase in temperature is likely to cause
expansion in the furnace length. Since structural
members restrict the furnace, compressional stresses
are developed in the furnace body and in the
members supporting the furnace. For lower models,
furnace length is small. Therefore, forces restricting
expansion are small and hence stresses are low so
that they can be easily borne by steel. However, for
higher models (frame size 60 and above), even
though stresses developed in the furnace body are
less than the ultimate tensile stress, over a period of
time, parts can buckle under fatigue. To increase
reliability and to ensure longer life, furnace of all
models with frame size 60 and above, is corrugated
type. Corrugated furnace acts like a bellow that neither
generates nor passes on the stresses to other
Corrugated furnace
structural members.
n
Long Life: For a capital equipment like Absorption
Chiller, life expectancy is 20 years. Thermax
Absorption Chillers are carefully designed for long
life. For example, for maintaining the required
pump NPSH, height of the chiller is never
compromised. If NPSH is not maintained, life of the
pump will be reduced. After many years of service,
some parts like heat exchangers, pumps may require
repair/replacement. During the repair/replacement,
minimum cutting should be required so that exposure
of the chiller internals to air will be limited thereby
arresting corrosion. Hence, all parts are deliberately
kept accessible for increased life of the chiller. If
chiller is made over compact, initially some space
advantage can be derived but such advantage will be
lost to life reduction later.
>0.5m
>0.5m
NPSH (R) maintained
n
Thermally efficient cycle: Efficient heat
utilization within the system reduces energy
consumption and improves overall system efficiency.
n
Gravity feed system: Gravity feed of refrigerant
and absorbent enhances heat transfer efficiency and
overcomes the problems of wear and tear and
clogging of nozzles, which use pressurized spraying
techniques.
n
and data-logging system ensure easy and smooth
operations. Branded PLC enhances reliability of the
chiller.
DHE
Easy access to all parts of the chiller
Adjoining pictures (front and rear side of chiller) show
n
easy access to Low Temperature Heat Exchanger
Temperature Heat Exchanger (HTHE).
n
HTHE
Isolation valves are provided on the pumps,
n
Factory mounted on-line purging system maintains
low vacuum in the shell and ensures consistent
performance. Any non-condensable gas, generated
inside the chiller during operation, is purged
continuously into the storage tank, thus eliminating the
need for a replaceable palladium cell. Moreover, as
peak concentration and temperature do not occur
simultaneously, corrosion rates are low, thereby
enabling a small purge tank.
n
Rupture disc is provided for protection against
generation of high pressure inside the chiller.
n
facilitating on-line pump maintenance without any loss
of vacuum in the system due to the exposure to air.
n
Double protection, in terms of differential
Choices for part load operation: User can
select a chiller with modulating type burner or staged
burner.
Constructional features, such as side exit
nozzles, provide ease of maintenance and ensure
lower downtime. Hinged absorber and condenser
headers provide easy access to the tube bundle,
eliminating the need for heavy lifting arrangements.
Crossover piping is factory installed, to avoid work at
site.
pressure switch and flow switch, is provided for freeze
protection.
n
Effective corrosion inhibitors: The corrosion
inhibitor minimizes the rate of copper and ferrous
metal corrosion on the solution side of the unit. The
corrosion inhibitor used - Lithium Molybdate - is nontoxic and does not generate ammonia, thus
protecting the copper tubes in the chiller. Use of
Lithium Molybdate is more effective than
conventionally used corrosion inhibitors.
(LTHE), Drain Heat Exchanger (DHE), and High
LTHE
PLC based control panel, user-friendly interface
n
Optional features include VFD control for part
load conditions, standby canned motor pumps,
flameproof construction, high pressure headers,
EcoChill Nxt
Direct Fired Vapor Absorption Chiller
online bearing monitoring, special tube material for
Evaporator, Absorber and Condenser, depending on
the available water quality, multi-sectional shipment
and ‘Factory Performance Test’.
n
Service: A global network, powered by over 100
highly trained service personnel, ensures quick
response and delivers the right solution to customers.
Also on offer are value-added services such as 'ereach' - remote access for chillers, preventive
maintenance contracts, operations and manning and
localized customer training programs.
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Certificates
EcoChill Nxt
Direct Fired Vapor Absorption Chiller
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Working Principle
T
he boiling point of water is directly proportional to
pressure. At atmospheric pressure, water boils at
212°F. At a lower pressure, it boils at a lower
temperature. At 0.24 inch Hg absolute pressure, the
boiling point of water is 39°F.
To change water from liquid to vapor it has to be heated.
The water absorbs the applied heat and its temperature
starts rising, until it reaches the boiling point. At boiling
point, the temperature remains constant but liquid water
vaporizes. The heat required to change the phase of a
liquid to vapor is called the ‘Latent heat of Vaporization’.
Similarly the heat rejected by the vapors during
condensation is called the ‘Latent Heat of Condensation’.
For the LiBr - water system, the absorption varies directly
in proportion with the solution concentration and inversely
with the solution temperature. Lithium Bromide (LiBr) is a
water soluble chemical, and LiBr - water solution (used
as refrigerant) has an inherent property to absorb water
due to its chemical affinity.
Also, there is a large difference between vapor pressure
of LiBr and water. This means that when the LiBr water
solution is heated, the water will vaporize but the LiBr will
stay in the solution and become more concentrated.
Absorption Cycle Overview:
1
Water (refrigerant)
Closed vessel
Water circulating in the
Heat Exchanger tubes
Chilled water
Vacuum
Absorption systems use heat energy to
produce a refrigerating effect. In these
systems the refrigerant, i.e. water, absorbs
heat at a low temperature and low pressure
during evaporation and releases heat at a
high temperature and high pressure during
condensation.
When maintained at high vacuum, water will boil and flash cool itself.
2
Refrigerant
Concentrated LiBr solution
Cooling water
Chilled water
Vaporized refrigerant
Absorption process
Concentrated Lthium Bromide solution has affinity towards water.
The solutionAbsorbs vaporized refrigerant water.
LiBr solution, which acts as the absorbent, is
used to absorb the vaporized refrigerant. The
evaporation of the refrigerant takes place at
a low pressure.
EcoChill Nxt
Direct Fired Vapor Absorption Chiller
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The dilute solution, which contains the
absorbed refrigerant vapor, is heated at a
higher pressure.
Refrigerant vapor
Concentrated LiBr solution
Water (refrigerant)
Driving heat source
Chilled water
Cooling water
Diluted solution
Absorption pump
As Lithium Bromide becomes dilute it loses its capacity to absorb water
vapor. It thus needs to be reconcentrated using a heat source.
4
Refrigerant Vapor
Cooling water
Condenser
Generator
Concentrated
Liquid
solution
refrigerant
Driving
heat
source
Absorber
Chilled water
Cooling water
This leads to the vaporization of the
refrigerant and thus the solution is restored
to its original concentration. The cycle keeps
repeating itself to give the desired chilling
effect. In a double effect absorption chiller,
the latent heat of condensation, contained in
the vaporized refrigerant, is used in a
second stage generator to enhance the
efficiency of the cycle.
Evaporator
Absorbent pump
This heat causes the solution to release the absorbed refrigerant in
vapor form. This vapor is cooled in a separate chamber to become
liquid refrigerant.
5
Refrigerant vapor
Condenser
Generator
Cooling
water
Chilled water
Driving
heat
Cooling water source
Absorbent pump
Evaporator
Absorber
The basic operation cycle of the single effect vapor absorption chiller.
The refrigerant goes through a series of
processes to complete the refrigerating
cycle. These are namely evaporation,
absorption, pressurization, vaporization,
condensation, throttling and expansion.
During this cycle, the refrigerant absorbs
heat from a low temperature heat source
and releases it to a high temperature sink.
Design Philosophy
he design philosophy of Thermax Absorption
Chillers is based on three important factors viz.
reliability, energy consumption and ease of
maintenance.
T
Thermax chillers offer one of the best COPs.
Reliability: While designing absorption chillers, two
Ease of maintenance: This is an important aspect
major problems have to be considered viz. corrosion and
crystallization. Since corrosion is caused by temperature,
concentration and leakages of Lithium Bromide, Thermax
has carefully selected Series Flow Cycle (after
manufacturing Series Flow, Parallel Flow and Reverse
Flow Chillers) so that the highest temperature of Lithium
Bromide is limited to less than 320oF and maximum
concentration is limited to 64 %. A detailed comparison
as tabulated on page 5 coupled with the features like
Crystallization Protection and Concentration
measurement and display, clearly shows that Thermax
Chillers are reliable compared to the other Chillers.
of our design philosophy. Even after 5 years of use,
absorption chillers require some small maintenance. So,
if ease of maintenance is ignored in the design
philosophy, this small maintenance can turn into big
maintenance. In addition to the design features listed on
pages 5 and 6, illustrated below are some more design
features in Thermax chillers that play a role in making
maintenance easy
The normal method of sensing the high concentration
from generator temperature has a flaw - it fails to work
when it is most required. It is a well-known fact that the
possibility of crystallization is more when the cooling
water temperatures are low. At low cooling water
temperatures, the generator pressure lowers and the
boiling point curve shifts down. Thus, when the cooling
water temperatures are low, the boiling temperature of
Lithium Bromide does not reach the high temperature set
point and becomes ineffective protection, even if high
concentration is reached. When cooling water
temperatures are normal, it works well but the possibility
of crystallization is far less. Monitoring the distance from
the crystallization line eliminates such flaws, enabling
Thermax to design chillers which can even work at 50oF
Coefficient of Performance (COP): Today,
n Double sealed valves: All isolating valves and
service valves have a double seal. More importantly,
the outer seal has no moving parts.
n Use of branded components: The Thermax
philosophy makes it mandatory to use branded
components. Some examples are PLC and Low
Temperature Heat Exchangers. This is because while
Thermax conducts exhaustive reliability tests on self
made components, it still cannot match the years of
research and experience put in by internationally
reputed PLC or Plate Heat Exchanger
manufacturers.
O-RING FOR
MAIN SPINDLE
EXTERNAL
CAP
INLET
MAIN
SPINDLE
GASKET FOR
EXTERNAL CAP
SEAT
SEALING
OUTLET
In the series flow cycle, crystallization can occur only in
the Low Temperature Heat Exchanger, whereas in other
cycles it can happen in both, the High Temperature Heat
Exchangers and Low Temperature Heat Exchangers. It
was discovered during the research, that the time taken
to de-crystallize High Temperature Heat Exchanger was
10 times more than that taken to de-crystallize the Low
Temperature Heat Exchanger. To eliminate the possibility
of crystallization in the Low Temperature Heat Exchanger,
the distance of state point from crystallization curve
is continuously monitored, and if the distance is less
than the prescribed value, crystallization control takes
over and performs suitable actions to prevent
crystallization.
cooling water temperature.
A Double Sealed Valve
n Canned Motor Pump : In Thermax Absorption
Chillers, these pumps are in bolted construction
(except for 20 frame, small chillers) so that if required,
bearing and filters can be cleaned after few years of
operation. In case of welded pumps, replacement of
the entire pump is the only solution.
EcoChill Nxt
Direct Fired Vapor Absorption Chiller
Bolted CANNED Motor Pump
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Welded CANNED Motor Pump
What is a Canned Motor Pump?
CANNED motor pump is some times misinterpreted as a pump similar to hermetically sealed compressor of
a window air-conditioner.
CANNED motor pump is a single unit of a pump and a motor, and has no shaft seal. Shaft seal is a moving
joint and cannot pass through stringent helium leak test.
In the CANNED motor pump, the pumped liquid is used for cooling motor as well as lubrication of bearings.
Hence, the pumped liquid enters the motor section, and in order to keep the liquid away from the motor coil
and the rotor, the motor coil and the rotor are sealed with CANS, which are thin metal cylinders.
Bolted canned motor pump, bit costly though, offer advantage like replacement of parts, which may be
needed after many years of service. Only non-moving parts are bolted and hence they offer excellent leak
proof properties while offering maintainability simultaneously.
Refrigeration Cycle
T
he Direct Fired Vapor Absorption chiller functions in
one of the following modes: Cooling mode,
Heating mode or in both modes simultaneously.
Cooling Mode
Evaporator
The Evaporator consists of a tube bundle, an outer shell,
distribution trays and a refrigerant pan.
A refrigerant pump is used to circulate the refrigerant
from the refrigerant pan to the distribution trays. From
these trays, the refrigerant falls on to the evaporator
tubes.
The evaporator shell pressure is maintained at ~ 0.24
inch Hg (a). At this low pressure, the refrigerant
evaporates at a low temperature of ~39°F (for its
evaporation, the refrigerant extracts the required heat
from the water which is circulated through the evaporator
tubes). As a result, the water in the tubes becomes
chilled.
Absorber
Low Temperature Heat Exchangers
The Absorber consists of a tube bundle, an outer shell
(common with the Evaporator) and distribution trays.
where it absorbs heat from the condensed refrigerant in
the Low Temperature Generator.
The Low Temperature Generator is housed in the upper
shell, just above the Absorber. From the Low Temperature
Generator, a concentrated absorbent solution is fed into
the distribution trays, which fall on to the absorber tubes.
The remaining absorbent passes through the Low
Temperature Heat Exchanger, where it absorbs heat from
the concentrated absorbent.
On the other hand, the vaporized refrigerant from the
Evaporator is absorbed by the concentrated absorbent,
leading to its dilution. Due to this absorption, the vacuum
in the shell is maintained at a low pressure, leading to the
desired chilled water temperature. During this process
'Heat of Dilution' is generated. This heat is removed by
the cooling water circulating through the absorber tubes.
As the absorbent solution loses its heat to the cooling
water, it is able to absorb more refrigerant vapor, and
gets further diluted. This diluted absorbent gets collected
at the bottom of the shell.
Heat Exchangers
The dilute absorbent is pumped into the High
Temperature Generator by the absorbent pump.
A part of it first passes through the Drain Heat Exchanger,
Both these dilute solutions mix at the inlet of the High
Temperature Heat Exchanger. During its flow through the
High Temperature Heat Exchanger, this dilute solution
absorbs heat from the intermediate absorbent solution.
The solution then enters the High Temperature Generator.
The Heat Exchangers heat the cool absorbent solution
before its entry into the High Temperature Generator for
regeneration. This reduces the heat input required in the
High Temperature Generator, thereby increasing the
efficiency of the cycle.
High Temperature Generator (HTG)
The High Temperature Generator consists of a furnace,
with a shell and tube arrangement on top.
Heat is supplied to the HTG by fuel combustion. As a
result, hot flue gases pass through the HTG tubes and
EcoChill Nxt
Direct Fired Vapor Absorption Chiller
15 / 16
the dilute absorbent surrounding these tubes gets
heated. The temperature of the solution keeps on
increasing till it reaches its boiling point and the
absorbed refrigerant boils out of the solution. The
solution concentration increases and it (the increased
concentration) is referred to as the intermediate
concentration. The vaporized refrigerant generated
passes through the Eliminators and goes to the tube side
of the Low Temperature Generator.
Low Temperature Generator (LTG) and
Condenser
The Low Temperature Generator and condenser tube
bundle are enclosed in the upper shell with an insulation
plate separating the two. The vaporized refrigerant flows
into the LTG tubes. It heats the intermediate absorbent
outside and in the process gets condensed. This
condensed refrigerant flows to the Condenser through
the Drain Heat Exchanger.
On the other hand, the refrigerant, vaporized in the Low
Temperature Generator, passes through the Eliminators
to the Condenser. Cooling water circulates inside the
condenser tubes. The refrigerant vapor condenses on the
outside of the condenser tubes and collects at the
bottom of the Condenser.
Finally, the condensed refrigerant from the LTG and the
condenser mix, and flow into the Evaporator. The
absorbent, now concentrated in the LTG, flows to the
Absorber to begin a new absorbent cycle.
Side-by-side Evaporator and Absorber
High Temperature Generator pass directly to the
Evaporator through the changeover valve and condense
on the outside of the evaporator tubes. In turn, the water
flowing inside the evaporator tubes gets heated. The
condensed refrigerant gets collected at the Evaporator
bottom and eventually overflows into the Absorber. To
enable overflowing, the refrigerant pump is kept switched
off.
Absorber
Concentrated absorbent solution, from the High
Temperature Generator flows into the Absorber through
another changeover valve, kept open in the heating
mode. This concentrated absorbent mixes with the
overflowing refrigerant from the Evaporator and gets
diluted.
High Temperature Generator (HTG)
The High Temperature Generator consists of a furnace,
with a shell & tube arrangement on the top of it.
The LTG and the Condenser
Heating Mode
Evaporator
In heating mode, the hot water flows inside the
evaporator tubes. Also, the refrigerant vapors from the
Heat is supplied to the HTG by combustion of fuel. The
hot flue gases pass through the HTG tubes. The dilute
absorbent surrounding these tubes gets heated. The
temperature of the solution increases until it reaches its
boiling point. The absorbed refrigerant boils out of the
solution. The solution concentration increases. This
concentrated absorbent flows into the Absorber. The
vaporized refrigerant passes through the Eliminators and
goes to the Evaporator.
In heating mode, the refrigerant vapors from the High
Temperature Generator flow directly to the Evaporator
through the changeover valve.
Cooling water does not flow through the Absorber and
the Condenser, during this mode.
S
EVAP
LTG
EVAP
REFRIGERANT
COOLING
WATER INLET
ABSORBER
CONCENTRATED ABSORBENT
ABSORBENT PUMP
REFRIGERANT PUMP
SOLENOID VALVE
REF BLOWDOWN
VALVE
HOT WATER
INLET
HOT WATER
OUTLET
COOLING
WATER INLET
CONDENSER
PURGE DEVICE
PURGE
PUMP
DILUTED ABSORBENT
OVER FLOW PIPE
HIGH TEMPERATURE
HEAT EXCHANGER
VAPORIZED REFRIGERANT
LOW TEMP HEAT EXCHANGER
DRAIN HEAT
EXCHANGER
INTERMEDIATE ABSORBENT
BURNER
HIGH TEMPERATURE
GENERATOR
EXHAUST GAS
Cooling Cycle
S
EVAP
ABSORBER
CONCENTRATED ABSORBENT
ABSORBENT PUMP
REFRIGERANT PUMP
SOLENOID VALVE
REF BLOWDOWN
VALVE
HOT WATER
INLET
HOT WATER
OUTLET
CONDENSER
LTG
REFRIGERANT
EVAP
PURGE DEVICE
PURGE
PUMP
DILUTED ABSORBENT
OVER FLOW PIPE
HIGH TEMPERATURE
HEAT EXCHANGER
VAPORIZED REFRIGERANT
LOW TEMP HEAT EXCHANGER
DRAIN HEAT
EXCHANGER
INTERMEDIATE ABSORBENT
BURNER
HIGH TEMPERATURE
GENERATOR
EXHAUST GAS
EcoChill Nxt
Direct Fired Vapor Absorption Chiller
Heating Cycle
17 / 18
Constructional Features And
Mechanical Design Considerations
E
coChill Nxt chiller can be designed to conform to
the codes and standards given below. Whenever
no specific standard is applicable, the design is
according to good and proven engineering standards.
n
n
ISO 9001:2000 n ISO 14001 n ETL n CE
TUV n DNV n ASME n OHSAS 18001
n
PED
114 psi (g). Gravity feed spraying technology is applied
to spray the solution in the Absorber and Evaporator. The
solution in the spraying tubes sprays downward to
ensure good film thickness and better heat transfer. The
Absorber and Evaporator are separated by an Eliminator
that prevents the carryover of LiBr from Absorber to
Evaporator, while allowing the water vapor from
Evaporator to cross over to the Absorber. The lower shell
is mounted on the base frame.
The upper shell houses a Low Temperature Generator
and a Condenser. This shell is also fabricated from
carbon steel plates. Smooth copper tubes are used in the
Condenser and finned carbon steel tubes in the Low
Temperature Generator. An Eliminator separates the Low
Temperature Generator and Condenser. This Eliminator
prevents the carryover of LiBr from the Low Temperature
Generator to the Condenser. The upper shell rests on the
lower shell. A rupture disk is provided for protection
against high pressure.
The High Temperature Generator is a shell and Tube Heat
Exchanger with carbon steel tubes located on top of a
furnace. The shell is fabricated from carbon steel. Hot
gases, generated through oil/ gas combustion, provide
heat to the absorbent and are vented through the
exhaust gas duct.
The lower shell with a sight glass
The lower shell houses two shell and tube heat
exchangers: the Absorber and Evaporator. This shell is
fabricated from formed carbon steel plates with fusion
welded seams. Carbon steel tube sheets are drilled and
reamed to accommodate absorber and evaporator
tubes, and the tube ends are expanded to ensure no
leakages between the shell and tube side. The support
plates inside the shell are also fabricated from carbon
steel plates. Enhanced copper tubes are used in the
Absorber and Evaporator. Maximum working pressure is
The Burner is of forced draft type with cast aluminum
housing. If required, it is capable of operating on both
liquid and gaseous fuels. For ease of service, the burner
swings open laterally. In addition, a removable cover
allows access to the serviceable components. It
incorporates a self-regulating differential combustion air
pressure switch and a burner flange safety interlock
switch. A sight glass is provided to enable flame viewing.
The combustion air fan is statically and dynamically
balanced. Air intake consists of multiple aluminum vanes
on the suction side for combustion air regulation. This
combustion air can also be adjusted to suit the firing rate.
The combustion head consists of stainless steel alloy
flame tubes and a stainless steel alloy diffuser assembly.
Whenever required, the fuel changeover is simple and
does not re-adjustments. The 3-phase TEFC blower
EcoChill Nxt
Direct Fired Vapor Absorption Chiller
19 / 20
Marine type headers
motor is fully compatible for use with a variable frequency
drive.
By utilizing the heat within the system, the Regenerative
Heat Exchangers increase the efficiency of the cycle.
Marine type water boxes are provided with the Absorber
and Condenser. These boxes enable easy tube cleaning
and replacement. The drain and vent connections
attached to these boxes are of great help while removing
the cooling water hold-up when the chiller has not been
in use for a long time.
The absorbent and refrigerant pumps are canned motor
type and are factory mounted. The motor is directly
coupled with the pump. Isolation valves are welded at the
inlet and outlet, enabling easy maintenance of pumps
without loss of vacuum. All valves, for adjusting solution,
are fully welded to prevent leakage of air into the unit.
Non-condensable gases are removed from the chiller
chiller by operating the vacuum pump and by opening
the manual purge valves. Service valves are provided for
N2 charging, for sampling, and for connecting the
Manometer.
Purge System
Supply List And Scope Of Work
Sr. No.
Description
Remarks
A
Lower Shell
1.
Evaporator
Common Shell and Tube sheets,
2.
Absorber
separate water boxes
3.
Base Frame
B
Upper Shell
4.
Low Temperature Generator
Common Shell and Tube sheets,
5.
Condenser
separate water boxes
C
High Temperature Generator
High Temperature Generator with
with Burner Assembly
combustion chamber and burner
assembly.
D
Heat Exchangers
6.
Low Temperature Heat Exchanger
Plate Heat Exchanger
7.
High Temperature Heat Exchanger
Plate Heat Exchanger
8.
Drain Heat Exchanger
Plate Heat Exchanger
E
Pumps and Motors
9.
Absorbent Pump and Motor
Canned Motor Pump Set
10.
Refrigerant Pump and Motor
Canned Motor Pump Set
11.
Purge Pump and Motor
Vacuum Pump
F
Purge System
For Separation of Non-condensable
gases from absorbent and its storage.
G
Piping
Inter-connecting Piping
H
Instrumentation
Control Panel, Field Instruments, Cabling.
I
Electricals
Starters, Circuit breakers, Wiring within
battery limits.
J
Documents
Operation and Maintenance Manual,
Packing List.
EcoChill Nxt
Direct Fired Vapor Absorption Chiller
21 / 22
Distribution of Scope of Work Manufacturing, Transportation and Installation
Item/ Activity
Thermax
Customer
Remarks
Chiller
Chiller Manufacture with accessories
Burner
P
P
Refer to Supply List.
P
Thermax Optional Feature.
Supplied by Thermax specified
vendor.
Testing
Factory Testing
On-site Erection
P
Supervision of Commissioning
P
P
Customer to assist, Thermax
Representative will supervise
the commissioning.
Transportation
Loading at Thermax Factory
Factory to Port
P
P
Port in India to port of destination*
Port to Job-site
Unloading at Job-site
Storage at Job-site
P
P
P
P
If required.
Construction and Installation
Handling at Job-site
P
Civil foundation
P
P
Piping outside battery limits
Butterfly valve in the cooling water line
P
P
P
P
Chiller insulation*
Piping insulation outside battery limits
Electrical connections outside
Battery limits
Assembly and on-site connections
P
Rigging, Shifting to actual
location.
Refer to Supply List.
If required. (Refer to Safety
Functions under Instrumentation
and Safety Features.)
Refer to Supply List.
Refer to Supply List.
For (a) Burner and (b) MultiSectional Shipment (Optional).
Operation and Maintenance
Training of Customers’ Operators
during commissioning (maximum
period of 7 days)
Operation
P
P
NOTE: * indicates that the scope of supply can also be included by Thermax, as an option.
Utility Requirements
Chilled/ Hot Water: The chiller's design ensures in
delivering the desired cooling capacity. The chilled water
flow rate to the chiller is kept constant. Hence its capacity
is proportional to the difference in the temperatures of the
inlet and the outlet chilled water.
Cooling Water: Cooling water is used to remove
heat of absorption and condensation. The chiller can be
designed to suit the rated cooling water temperature of
75 - 97oF.
Energy Source: The chiller is designed for fuel
flexibility. The liquid and gaseous fuels that can be used
are Light Oil, SKO (Superior Kerosene Oil), Natural Gas,
CNG and other gaseous fuels.
Air: Compressed air is required for the pneumatic
operation of the control valve. The supplied air should be
moisture free and the required pressure is 100 psi(g).
Electricity: The power supply to the chiller shall be
strictly as per the voltage and frequency rating given on
chiller nameplate.
To avoid scaling and corrosion, we recommend
maintaining water quality as given in the instructions. If
the water quality at the installation site is different, the
chiller can be designed to adjust to it.
Chilled Water and Cooling Water
Treatment
Water treatment of the chilled and cooling water is
important to get desired chiller performance and for its
long life.
If the water quality is bad, it shows scaling and/or
corrosion tendency. As a result, sludge and scale can
adhere to the inside of the tubes. This impedes heat
transfer between the chilled water and refrigerant and
between the cooling water and LiBr solution.
Consequently, there can be an increase in the respective
temperatures of the LiBr solution and the condensed
refrigerant, leading to an increase in the fuel consumption
and thus hampering the capacity and efficiency of the
chiller. In cases of prolonged corrosion, the tubes will
require maintenance or, in some cases, they may even
have to be replaced.
As the cooling water circuit is open, the salts get
concentrated due to evaporation taking place in the
cooling tower. This can be adjusted by controlling cooling
water blow-down and make-up. Moreover, exposure to
sunlight favors biological growth. Slime is more
detrimental to heat transfer than scale. Dosing biocides
during cooling water treatment can minimize these
adverse effects.
Unlike the cooling water circuit, which is always open, the
chilled water circuit may be open or closed. Due to the
lower temperature, chilled water circulating in an open
circuit does not have severe consequences. Soft water is
recommended for use in this circuit.
EcoChill Nxt
Direct Fired Vapor Absorption Chiller
23 / 24
JIS recommends the following water quality for copper tubes:
Description
Sr. No.
Specifications
Unit
Chilled Water
1
pH at 77oF
2
Electrical Conductivity (max.)
3
M Alkalinity (max.)
4
Total hardness (max.)
5
Make-up Water
6.5 - 8.5
6.5 - 8.5
Fs/cm
500
200
ppm
100
50
mg CaCO3/lit
100
50
Chloride ion (max.)
mg Cl/lit
100
50
6
Sulphate ion (max.)
mg SO4/lit
100
50
7
Total Iron (max.)
mg Fe/lit
1
0.3
8
Sulphide ion
mg S/lit
9
Ammonium ion (max.)
mg NH4/lit
0.5
0.2
10
Silica ion (max.)
mg SiO2/lit
50
30
11
Free carbonic acid (max.)
mg CaCO3/lit
10
-
12
Turbidity
NTU
10
5
13
BOD/ COD (max.)
mg/lit
160
160
Description
Sr. No.
Not detected
Specifications
Unit
Cooling Water
1
pH at 77oF
2
Electrical Conductivity (max.)
3
M Alkalinity (max.)
4
Total hardness (max.)
5
Make-up Water
6.5 - 8.5
6.5 - 8.0
Fs/cm
800
200
ppm
100
50
mg CaCO3/lit
200
50
Chloride ion (max.)
mg Cl/lit
200
50
6
Sulphate ion (max.)
mg SO4/lit
200
50
7
Total Iron (max.)
mg Fe/lit
1
0.3
8
Sulphide ion
mg S/lit
9
Ammonium ion (max.)
mg NH4/lit
1
0.2
10
Silica ion (max.)
mg SiO2/lit
50
30
11
Suspended solids (max.)
mg/lit
20
5
12
Turbidity
NTU
20
5
13
BOD / COD (max.)
mg/lit
160
160
Not detected
Selection Criteria And Procedure
Selection Criteria
Selection Procedure
The following factors govern model selection:
Absorption is a complex phenomenon involving heat and
mass transfer. The chiller consists of multiple interlinked
heat exchangers. In such a complex mechanism,
deration factors and two-dimensional graphs can lead
only to approximation. At Thermax, every selection is
done with the help of a computer program that does
detailed heat and mass transfer calculations for each
heat exchanger and accurately determines performance
of the chiller. When using media other than water or for
non-standard fouling factors, the selection considers
appropriate properties to evaluate overall heat transfer
coefficient. The program facilitates optimization of the
energy / fuel consumption, the chilled and the cooling
water flow rates and the pressure drops.
Energy Source Parameters: Energy source can
be either natural gas or light oil (containing less than 1%
sulfur). Required gas pressure is 65 mbar. Both
modulating and Hi-Low burners are available for the
machines; 3-stage burners can also be offered as an
option. Fuel consumption given is based on standard
natural gas and oil HHV. However, for different gas / oil,
fuel consumption will be proportional to the ratio of LHV.
Chilled and cooling water temperature:
Capacity of the chiller varies based on chilled water outlet
temperature and cooling water inlet temperature. The
chiller is capable of delivering higher than its rated
capacity if chilled water temperature is higher than the
rated temperature or cooling water temperature is lower
than the rated temperature. Conversely, the chiller
capacity is likely to be reduced if chilled water
temperature is lower and cooling water temperature is
higher than their respective rated temperatures. Thermax
has designed and installed chillers for chilled water
temperatures ranging from 38oF to 70oF and cooling
water temperatures varying from 50oF to 97oF.
Chilled and cooling water circuit pressure:
Thermax's standard product range is designed for a
maximum pressure of 114 psi (g) in the chilled and
cooling water circuits. Thermax also offers special design
for higher pressures.
Size: If there are constraints relating to the
transportation of the chiller or machine room access,
Thermax offers the option of multi-sectional shipment.
Typically, this can be in three sections viz. lower shell,
upper shell and High Temperature Generator. These
sections can be assembled at the installation site by just
welding a few connections.
Optional features: These include tube material of
construction, frequency drive for double effect absorbent
pumps, flame proof construction, claded tube sheets and
special electronics and instrumentation.
The following document provides performance data and
the dimensional data for all the standard models.
EcoChill Nxt
Direct Fired Vapor Absorption Chiller
Thermax Nomenclature And
The EcoChill Nxt Product Basket
GD80CCX
G
80
D
C
C X
Efficiency: Extra Efficient
Machine type: Chiller
Machine size within the Frame
Frame Size
Cycle: Double Effect
Primary heat Source: Gas
OD20ACX
O
D
20
A
C
X
Efficiency: Extra Efficient
Machine type: Chiller
Machine size within the Frame
Frame Size
Cycle: Double effect
Primary heat Source: Oil
25 / 26
3
13.1
GPM
#
ftWC
Heating Capacity
GD 20B CX
OD 20B CX
130
GD 20C CX
OD 20C CX
162
GD 20D CX
OD 20D CX
192
GD 30A CX
OD 30A CX
241
GD 30B CX
OD 30B CX
272
GD 30C CX
OD 30C CX
321
GD 40A CX
OD 40A CX
360
GD 40B CX
OD 40B CX
408
GD 40C CX
OD 40C CX
452
GD 50A CX
OD 50A CX
505
GD 50B CX
OD 50B CX
560
GD 60A CX
0D 60A CX
636
GD 60B CX
OD 60B CX
709
GD 60C CX
OD 60C CX
802
890
GD 60D CX
OD 60D CX
6
4
14.8
1
2
94.28
713.3
15.7
2
392.2
15.1
1
2
94.28
845.4
19.4
2
464.8
6
16.7
2
658.5
25.6
2
777.1
21.3
2
871.5
6
22.3
2
987.7
24.0
2
21.7
2
8
22.0
2
22.0
3
22.6
3
10
14.4
2
15.4
2
1094.2 1222.5 1355.6 1539.6 1716.3 1941.5 2154.5
14.8
1
2
94.28
8
15.1
1
2
94.28
22.3
1
2
94.46
21.0
1
2
94.46
10
21.3
1
2
94.46
22.6
1
2
94.28
22.6
1
2
94.46
10
24.0
1
2
94.46
25.3
1
2
94.28
25.9
1
2
94.28
12
17.7
1
1
94.28
18.7
1
1
94.28
1061.1 1197.6 1391.3 1563.0 1774.4 1990.1 2183.8 2426.0 2800.2 3121.6 3531.1 3918.6
15.1
2
583.4
1107
10
2
16.1
36.7
1
2
95.18
14
19.7
1
1
94.28
3975.8 4887.2
14.8
2
2403.8 2679.8
8628.5 9616.5
993
GD 70A CX
OD 70A CX
17.72
19.94
23.54
26.58
29.91
33.23
37.10
41.26
46.52
51.78
58.98
65.35
72.55
80.86
13.7
17.0
18.5
162.6
22.0
22.5
24.9
25.1
30.4
34.0
kVA
6.6
6
7.0
8
9.6
8
10.6
10
32.6
36.6
5.5(9.1)
3(8)
161.4
35.1
31.3
118.9
39.0
43.4
5.5(9.1)
3.7(11)
161.4
42.3
38.1
131.9
134.3
198.8
59.1
15.6
17.7
12
25.9
67.9
12
9(17.5)
28.5
258.3
82.2
16
36.8
14(26)
6.6(17)
258.3
96.6
85.1
155.5
93.0
1.5(5)
80.0
71.7
137.0
305.9
160.2
- Control panel Electric Input = 1kVA
- Maximum Allowable pressure in chilled / cooling water system
=113.78 psi(g)
- Ambient condition shall be between 41 to 113°F
- All Water Nozzle connections to suit ASME B16.5 Class 150
- Technical specification is based on ARI 560 : 2000
10
460 V( ±10%), 60 Hz (±5%), 3 Phase+N
12.7
310.2
152.0
75.8
5.5(14)
66.6
209.4
63.5
56.7
135.0
145.3
261.4
HI / LOW (MODULATING BURNER AVAILABLE ON REQUEST)
2.6(5.1)
0.3(1.4)
161.4
27.8
191.3
124.8
kW (A)
2.1(4.2)
187.4
113.4
0.75(1.8)
2.2(6)
150.2
24.5
111.4
110.6
kW (A)
1.4(2.8)
147.8
17.9
16.3
105.9
99.2
155.9
NOTE:
- Chilled water inlet / outlet temperature = 54 / 44 °F
- Cooling water inlet temperature = 85°F
- In Heating mode, Hot water inlet / outlet temperature = 132.8 / 140 °F
- Minimum Cooling water inlet temperature is 50°F
- G.C.V. for Oil = 138296 BTU/gal
Exhaust Gas Duct Size
Power Supply
Total Electric Input
Burner Type
Electric Purge Pump Motor Rating
Supply Burner
0.6(1.2) 0.8(1.7)
1.1(3.4)
kW (A)
kW (A)
Absorbent Pump Motor Rating
Refrigerant Pump Motor Rating
Clearance for Tube Removal
94.5
15.0
inch
13.2
14.3
x 1000 lb
x 1000 lb
Max. Shipping Weight
106.3
inch
Operating Weight
116.1
101.2
inch
inch
Fuel Consumption (Heating)
14.14
Length
12.08
8.23
1137.9 1315.7 1671.3 1955.7 2450.8 2757.2 3255.0 3676.3 4135.8 4595.3 5131.4 5705.8 6433.4 7161.0 8156.7 9037.5 10033.1 11181.9
GPH
MBH
9.51
1137.9 1315.7 1671.3 1955.7 2450.8 2757.2 3255.0 3676.3 4135.8 4595.3 5131.4 5705.8 6433.4 7161.0 8156.7 9037.5 10033.1 11181.9
12.5
1
3
94.28
572.4
15.4
3
314.7
1131.5 1437.3 1681.9 2107.7 2371.2 2799.3 3161.6 3556.8 3952.0 4413.0 4907.0 5532.8 6158.5 7014.7 7772.2
GD 70B CX
GD 70B CX
Oil Consumption (Cooling)
MBH
Overall
Dimen- Width
sions Height
Fuel
Circuit
inchNB
12.8
ftWC
Connection Diameter
3
1
#
94.28
°F
#
488.7
GPM
Fuel Consumption (Cooling)
Cooling No. of passes (absorber)
Water
No. of passes (condensor)
Circuit
Friction loss
Outlet Temp
Flow rate
Chilled No. of passes (Evaporator)
Water Friction loss
Circuit
Connection Diameter
inchNB
268.7
TR
MBH
Cooling Capacity
Flow rate
111
978.6
UNITS
GD 20A CX
OD 20A CX
Model Number
Performance Data
EcoChill Nxt
Direct Fired Vapor Absorption Chiller
Typical P & I Diagrams
MAKE UP
WATER
BLOW
DOWN
PI
TO CHIMNEY
COOLING TOWER
COOLING WATER OUTLET
Light Oil Fired
TI
OIL FROM STORAGE TANK
PI
TI
CHILLED/ HEATING WATER OUTLET
FM
LSH
I
SERVICE
TANK
PI TI
LSL
CHILLED/ HEATING WATER INLET
TI
PI
VAPOR ABSORPTION CHILLER HEATER
OIL FIRED
PI
M
M
PI
PI
FM
COOLING WATER INLET
PI
AIR SUPPLY FOR
COMMON HEATER
S
TI
STORAGE
TANK
PI
M
PI
OIL PUMP
COOLING WATER PUMPS
(1 WORKING + 1 STD BY)
FILTER 40 MESH
LEGEND
GATE VALVE (OPEN)
SOLENOLD VALVE
GATE VALVE (CLOSE)
FAST ACTING VALVE
GLOBE VALVE (OPEN)
GLOBE VALVE (CLOSE)
MONO BLOCK BURNER
NON RETURN VALVE
FILTER 40 MESH
COCK
ELECTRIC HEATER
GAS REGULATOR
THERMOSTAT
THREE WAY CONTROL VALVE
AIR FILTER REGULATOR
BUTTERFLY VALVE (OPEN)
BUTTERFLY VALVE (CLOSE)
CENTRIFUGAL PUMP
"Y" STRAINER
M
MANUAL OIL VALVE
PNEUMATIC LINE
GOVERNOR
CLIENT
SCOPE
FOR REFERENCE ONLY
THERMAX
SCOPE
MOTOR
P - PRESSURE
T - TEMPERATURE
F - FLOW
I - INDICATOR
R - RECORDER
M - HIGH
C - CONTROLLER L - LOW
S - SWITCH
A - ALARM
L - LEVEL
27 / 28
MAKE UP
WATER
BLOW
DOWN
TO CHIMNEY
COOLING TOWER
COOLING WATER OUTLET
Gas Fired
PI
TI
PI TI
CHILLED/ HEATING WATER OUTLET
FM
PI TI
CHILLED/ HEATING WATER INLET
PI
NATURAL GAS
PI
PI
M
PI
PI
COOLING WATER INLET
PI
VAPOR ABSORPTION CHILLER HEATER
GAS FIRED
FM
AIR SUPPLY FOR
COMMON HEATER
S
TI
M
COOLING WATER PUMPS
(1 WORKING + 1 STD BY)
LEGEND
GATE VALVE (OPEN)
SOLENOID VALVE
GATE VALVE (CLOSE)
FAST ACTING VALVE
GLOBE VALVE (OPEN)
GLOBE VALVE (CLOSE)
MONO BLOCK BURNER
NON RETURN VALVE
COCK
FILTER 40 MESH
GAS REGULATOR
ELECTRIC HEATER
THERMOSTAT
THREE WAY CONTROL VALVE
BUTTERFLY VALVE (OPEN)
AIR FILTER REGULATOR
BUTTERFLY VALVE (CLOSE)
CENTRIFUGAL PUMP
"Y" STRAINER
MANUAL OIL VALVE
FOR REFERENCE ONLY
THERMAX
SCOPE
MOTOR
PNEUMATIC LINE
GOVERNOR
CLIENT
SCOPE
M
P - PRESSURE
T - TEMPERATURE
F - FLOW
I - INDICATOR
R - RECORDER
M - HIGH
C - CONTROLLER L - LOW
A - ALARM
S - SWITCH
L - LEVEL
PI
EcoChill Nxt
29 / 30
Direct Fired Vapor Absorption Chiller
General Arrangement Drawing
Typical General Arrangement Drawing
NOZZLE
SIZE
N7
N4
N5
NOZZLE
FL. RATING
DESCRIPTION
QTY.
NOTES
1) INDICATES THE POSITION OF ANCHOR BOLTS
2) INDICATES THE POSITION OF THE POWER
SUPPLY CONNECTION ON THE CONTROL PANEL
3) MINE INSTALLATION CLEARANCE (Min-inches)
4) CONTROL PANEL SIDE : 47.5"
5) TOP: 8"
6) OTHERS: 20"
N1 N2
L
W
N5
N2
N8
H
N1
N6
N3
For reference only
Foundation Drawing
8”
Typical Foundation Drawing
WASHER
NUT
MACHINE BASE
B
WELD
8”
ARRANGEMENT AT ANCHOR
A
8”
10”
6”
8”
SECTION “P - P”
Notes
1. There should be a drain ditch around the foundation.
2. The floor surface should be made as water proof for ease of maintenance work.
3. Finish the foundation work horizontally flat & smooth at the horizontal grade of about 1/1000.
4. The foundation shall be designed to suit the soil conditions & other design considerations at site.
MODEL NO.
A
Inches
B
Inches
Wt
W
Inches 1000xIbs
Instrumentation And Safety Features
Control Logic
The control panel includes the following
components:
! Programmable Logic Controller (PLC)
! Panel view operator interface
! Power circuit for pumps
! Panel mounted instruments
The total heat extracted from the chilled water defines the
cooling capacity of a chiller. The chilled water inlet flowrate is kept constant. Hence the cooling capacity is
proportional to the difference in the temperatures of the
chilled water at inlet and outlet.
Load changes are reflected in the rise or fall of the
temperature of the inlet chilled water. The outlet chilled
water temperature varies with the inlet chilled water
temperature. An RTD sensor notes this change in
temperature. This temperature signal is fed to the PLC.
An inbuilt software PID control loop processes this signal
with respect to the chilled water set point. A control
output signal of 4 to 20 mA is sent to the burner for
modulation.
The burner controller converts the 4 to 20 mA electrical
signal into a firing control signal, which controls the
position of the burner modulation. As the load increases,
the burner firing also increases, and vice-versa, thus
regulates the quantity of fuel entering the burner.
In High - Low type of burner, an RTD sensor in the chilled
water outlet notes the change in temperature. This signal
is fed to the PLC which then sends it to
the burner control panel as Control
output (Digital Signal, Potential free) in
terms of either HI or LOW. This signal
controls the output of the burner. As
the temperature of the chilled water
outlet drops below the set point value,
the burner is fired in Low flame and if it
continues to drop and reaches set
point minus preset value, the Burner is
switched OFF. Depending on the load
conditions, the chilled water
temperature at the outlet starts rising,
and as it crosses the control range,
(set value in the PLC), the burner is
switched ON, to control the
temperature.
EcoChill Nxt
Direct Fired Vapor Absorption Chiller
Safeties
Safety devices are provided to protect the chiller from
reaching abnormal conditions, to safeguard it from
damage, and to ensure continued availability.
stop the chiller like:
l
H-cut (for heating mode): Sometimes the load may fall
sharply, due to which hot water temperature starts
rising. When the hot water temperature rises above hot
water out set point plus H cut differential set point, the
burner is switched off. The H - Cut is set from the Heat
mode control loop screen. This safety prevents further
temperature rise in hot water. The burner will start firing
at minimum firing after hot water outlet temperature
goes below the hot water out temperature plus H - Cut
differential minus the hysteresis.
l
L-cut: If the chilled water outlet temperature drops
below the L-cut set point, the refrigerant pump is
switched off, stopping the burner immediately. This
safety prevents any further temperature drop in the
chilled water. As the chilled water outlet temperature
rises above the L-cut set point plus the hysterisis set
point, the refrigerant pump restarts, which in turn
restarts the burner, depending on the PID controller.
l
Antifreeze: If the chilled water outlet temperature
drops below the internal antifreeze set point, the chiller
trips and the 'TOTAL SHUTDOWN' alarm sequence is
carried out. The alarm should be reset only after the
chilled water outlet temperature rises above the internal
antifreeze set point plus the hysterisis set point.
l
Chilled/ hot water pump interlock: Chilled water
flow is a prerequisite for chiller operation. A potential
free contact is to be wired from the chilled water pump
motor starter to the chiller panel to sense chilled water
pump ON/ OFF/ TRIP status. The chiller starts only
when the chilled water pump is ON. If the chilled water
pump stops/ trips during operation, the 'TOTAL
SHUTDOWN' alarm sequence is carried out.
l
Cooling water pump interlock: Cooling water flow
should be stopped immediately when the chilled water
flow stops in the chiller. So the cooling water pump
should be started through the start permissive of
cooling water pump.
l
Chilled/ hot water flow switch: If the chilled water
flow drops below 50% of the rated value, the chiller
trips and the 'TOTAL SHUTDOWN' alarm sequence is
carried out.
l
Chilled/ hot water differential pressure switch: If
the differential pressure across the chilled water inlet
and outlet lines drops below the rated value, the chiller
trips and the 'TOTAL SHUTDOWN' alarm sequence is
carried out.
Safety devices are:
- Chiller mounted safeties, located on the chiller
- Panel mounted safeties, in the control panel, and
- Field interlocks passing signals from the field to the
chiller
Chiller mounted
l Chilled/ hot water flow switch
Paddle type device mounted on the chilled water outlet
nozzle
l Chilled/ hot water Differential Pressure (DP) switch
Connected to the inlet and outlet chilled water nozzles
l Refrigerant level electrodes
Mounted in the refrigerant level box
l Generator level electrodes
Mounted in the high temperature generator level box
l Absorber level electrodes
Mounted in the absorbent level box
l Auto blow down solenoid valve
Mounted on refrigerant pump outlet tapping to
absorber.
l Temperature sensors mounted at various locations to
display temperatures.
l Furnace temperature sensor.
l Generator Pressure switch.
l Furnace pressure switch.
Panel Mounted
l Generator level controller
l Refrigerant level controller
l Absorbent level controller
l Absorbent pump overload relay / AC Drive
l Refrigerant pump overload relay
l Purge pump overload relay
Field interlocks
l Cooling tower start/ stop permissive contacts
l Cooling water pump/ shut off valve - permissive
l Chilled/ hot water pump - permissive.
Safety Functions
The safety functions of the chiller protect it against
abnormal conditions. The various safety functions
Antifreeze protection: To prevent the chilled water
from freezing in the evaporator tubes, the safety functions
31 / 32
l
Generator pressure switch: If the generator
pressure increases above 29.9 inch Hg, chiller trips
and 'DILUTION CYCLE' alarm sequence is carried
out.
l
Butterfly control valve in cooling water line: If all
the cooling water pumps can be stopped electrically
when the differential pressure switch or flow switch
shows less or no flow in chilled water, automatically
operated butterfly valve is not required. However,
when such arrangement can not be ensured, auto
butterfly valve needs to be provided by the customer
to stop the cooling water based on differential
pressure switch / flow switch signal.
l
l
l
l
Crystallization prevention: If the concentrated
absorbent solution, while returning to the Absorber
from the Low Temperature Generator is excessively
cooled, it crystallizes in the Low Temperature Heat
Exchanger, affecting the chiller operation.
Crystallization occurs, either, when the concentration
of the absorbent (related to its temperature)
becomes too high or its temperature drops
excessively. The following safety functions prevent
the chiller from crystallizing:
Burner modulation on crystallization prevention
safety: The strong solution concentration and the
crystallization temperature corresponding to that
concentration are calculated in the PLC. The PLC
always tries to maintain the pre-set safe distance
between the crystallization temperature and strong
solution temperature of low temperature heat
exchanger outlet. If the distance is less than the preset safe distance, the PLC switches on/ off or
modulates the burner so that the strong solution will
never reach crystallization zone.
Absorber level safety: Minor crystallization in the
chiller can result in low absorber level. When the
absorber level falls below 25% of the sight glass, the
blow-down solenoid valve opens. It closes when the
absorber level goes above the 50% level of the sight
glass. The opening of the blow-down solenoid valve
allows the flow of refrigerant from refrigerant pump
to absorber. Burner modulation opens only when the
absorber level reaches the 50% level of the sight
glass. Adequate level ensures dilute solution supply
to generator thus preventing crystallization.
HTG high temperature safety: If the HTG
temperature exceeds the HTG high temperature set
point of 320°F, the 'DILUTION CYCLE' alarm
sequence is carried out. The chiller goes into the
dilution cycle immediately. The HTG high temperature
alarm cannot be reset until the HTG temperature drops
below the set point minus the hysterisis set value of
9°F.
l
HTG high pressure safety: If the HTG pressure
exceeds the HTG pressure switch setting, the
'DILUTION CYCLE' alarm sequence is carried out and
the chiller goes into the dilution cycle immediately. The
HTG high-pressure alarm cannot be reset until the HTG
pressure drops below the HTG pressure switch setting.
l
Stack high temperature safety: If the stack
temperature exceeds the stack high temperature set
point of 482°F, the 'DILUTION CYCLE' alarm sequence
is carried out and the chiller goes into the dilution cycle
immediately. Stack high temperature alarm cannot be
reset until the stack temperature drops below the set
point minus the hysterisis set value 9°F.
l
Cooling water low temperature safety: If the
cooling water inlet temperature drops below the
cooling water low temperature set point, the 'DILUTION
CYCLE' alarm sequence is carried out. The chiller goes
into the dilution cycle immediately. The alarm cannot
be reset until the cooling water inlet temperature rises
above the cooling water low temperature set point plus
hysterisis set value.
l
HTG Vapor saturation temperature high: If the HTG
vapor saturation temperature exceeds the high HTG
vapor temperature set point, the 'DILUTION CYCLE'
alarm sequence is carried out and the chiller goes into
the Dilution Cycle immediately. The alarm cannot be
reset until the HTG vapor temperature goes below the
HTG vapor temperature trip set point minus the set
hysterisis value.
l
Furnace pressure switch: If the furnace pressure
exceeds the set point, the 'DILUTION CYCLE' alarm
sequence is carried out and the chiller goes in to
Dilution cycle. The alarm can only be reset when the
when the furnace pressure goes bellow the furnace
pressure switch set point minus the set hysteresis
valve.
l
Furnace outlet temperature high: If the furnace
outlet temperature exceeds the furnace temperature
set point, the 'DILUTION CYCLE' alarm sequence is
carried out and the chiller goes in to Dilution cycle. The
alarm can only be reset only when the furnace
temperature goes bellow the Furnace Temperature Trip
set point minus the hysterisis value.
EcoChill Nxt
Direct Fired Vapor Absorption Chiller
33 / 34
Cavitation protection of refrigerant pump:
Burner trip: If the burner trips frequently just before
The refrigerant pump starts to cavitate, when the
refrigerant level in the evaporator pan falls below the set
level. To ensure minimum acceptable suction pressure,
the refrigerant level is not allowed to fall below a certain
level by means of three level electrodes and a level relay.
firing, then there is a possibility of fuel leakage into the
furnace without getting burnt. The leaked fuel will get
collected at the bottom of the furnace and it can get
instantaneously burnt (causing an explosion) when the
burner fires subsequently. This has to be prevented by all
means. The following safety function prevents this
hazard.
If the burner trips for more than 3 times within the pre-set
period in the PLC, say within 10 minutes, then the chiller
invariably goes into 'DILUTION CYCLE' alarm sequence
with an alarm 'check for fuel leakage in the furnace'. Until
the alarm is reset, the chiller cannot be re-started.
The three electrodes are mounted in the refrigerant level
box assembly present on the lower shell. The pump
starts when the level reaches the electrode that is
smallest in length. It stops when the level goes below the
longest electrode. When the level goes below the
intermediate electrode, a delay of 20 seconds is provided
before the pump can be switches off automatically.
Cavitation protection of the absorbent
pump: The absorbent pump starts to cavitate when the
absorbent level in the absorber sump falls excessively. To
prevent the excess absorbent from being pumped out of
the absorber sump, the absorbent level in the HTG is not
allowed to rise above a certain level. This is done by
means of three level electrodes, and a level relay.
The three electrodes are mounted on the high
temperature generator level box. The absorbent level is to
be maintained below the smallest electrode. The longest
electrode acts as the reference electrode. When the level
reaches the smallest electrode, the pump stops after a
delay of 5 seconds. The pump restarts when the level
goes below the intermediate electrode.
Motor protection
l
Absorbent pump overload relay: If the absorbentpump motor draws more than its rated current, the
overload relay trips. The 'TOTAL SHUTDOWN' alarm
sequence is carried out. The alarm cannot be reset
until the absorbent pump overload relay (inside the
control panel) is manually reset.
l
Refrigerant pump overload relay: If the refrigerant
pump motor draws more than its rated current, the
overload relay trips and the 'DILUTION CYCLE' alarm
sequence is carried out. The alarm cannot be reset
until the refrigerant pump overload relay (inside the
control panel) is reset manually.
l
Purge pump overload relay: If the purge pump motor
draws more than its rated current, the overload relay
trips. The alarm cannot be reset until the purge pump
overload relay (inside the control panel) is reset
manually.
Machine Room Layout Considerations
vent, drain and sampling connections. It should have
minimum pressure drop and should be tested for
leaks.
Location: Unlike conventional electric chillers,
absorption chillers are characterized by their silent
operation and simpler foundation. Owing to this, they can
be located in basements or on terraces of buildings; the
location being ultimately decided by space availability
and ease of installation and maintenance.
l
In the connecting lines, the field instruments should be
installed adjacent to the chiller. Design and routing of
the piping should provide easy access to the field
instruments for effective maintenance.
l
The crossover piping from the absorber to the
condenser is a standard feature of Thermax absorption
chiller.
l
The piping should be adequately supported to prevent
any strain on the chiller nozzles and connecting
flanges.
l
Check whether the air-vent valves, drain valves and the
pressure gauges are provided on the chilled water,
cooling water, fuel and drain piping. The drain
connections should be at the lowest point, whereas the
air-vents should be at the highest point on the piping.
be less than 85%. High humidity can result in corrosion
and failure of electrical equipment. The chiller room
should be adequately ventilated.
l
The inlet chilled water line, hot water line and the inlet
cooling water line to the chiller should be flushed
clean, before connecting these to the chiller.
Drainage: All the discharge pipes and overflow pipes
l
Check the connective direction of the chilled water and
the cooling water piping.
l
Check the valve positions on the chilled water piping,
cooling water piping, fuel and drain piping.
l
Make sure that strainers are provided in the water
circuits.
l
If cooling water pump is not dedicated to individual
chiller, auto-operated butterfly valve is necessary in the
cooling water circuit.
Room Size: The machine room size should be
decided according to the dimensions of the chiller. A
provision of minimum 3.3 ft clearance space should be
made on all sides of the chiller. In addition, provision for
tube removal space should be made on either side of the
chiller. A clearance of 3.95 ft is recommended on the
panel side of the chiller and 0.7 ft is recommended on
the top of the chiller. For more details please refer to the
Dimensional Data given in this document.
Ambient Temperature: Temperature in the machine
room should be in the range of 4o F to
113oF.
Humidity: The humidity inside the chiller room should
should be routed to the drains. The drains should be
covered. The slope of the drainage system should be
such that there is no accumulation of water. In case the
chiller room is built in the basement, a water tank and
pump is required for proper drainage.
Piping Guidelines
Fuel (oil/ gas) piping should be designed and installed to
meet the prescribed safety standards. Pipe sizing should
be as per the required flow rates.
l
l
For oil-fired systems, the fuel tank should be equipped
with safety devices such as firetrap, level controls and
vent, drain connections. The fuel tank should not be
exposed to rain. Filters should be installed at the inlet
and outlet of the fuel tank. Depending on the elevation
of the fuel tank with respect to the burner, a day tank
may be required.
For gas-fired systems, the piping design pressure
should be higher than the working pressure. The piping
should be equipped with a stop valve, safety devices,
Electrical Guidelines
l
All field wiring should be in accordance with applicable
codes.
l
Use Copper conductors only.
l
All wiring should be checked regularly for any damage
and all terminal connections tested for tightness.
l
The power supply specifications should match those
on the unit nameplate. Voltage must be within 15% of
nameplate value.
EcoChill Nxt
Direct Fired Vapor Absorption Chiller
l
For minimum circuit ampacity and maximum fuse size,
see the unit nameplate.
l
Wiring to the chiller control panel should be proper.
l
Proper wiring should be provided from the chiller
control panel to the control valve.
l
Proper interlocking of chilled water and cooling water
with the chiller control panel should be provided.
Insulation Guidelines
l
Use adhesive agents, iron wires and bounds to mount
insulation material. These should not be fixed/
mounted using tapping screws or rivets.
l
Use non-combustible insulation material. This could be
wool or polystyrene foam in case of cold surfaces, and
glass wool in case of hot surfaces.
l
The insulation should not cover the cap of the damper,
sight glass, handle of the refrigerant lowdown valve,
refrigerant pump motor, refrigerant level electrode box
cover, HTG level electrode level box cover and the
service valves.
l
For effective in-tube cleaning, the evaporator header
should be removable.
l
To assist in-tube inspection, the HTG headers should
be removable.
l
In addition to this, following components should also
have removable insulation:
Ø
Chilled water flow switch
Ø
Chilled water freeze protection thermostat
Ø
Chilled water temperature sensor
Flue Gas Duct Guidelines
l
The flue gas duct and chimney should be designed
and installed to comply with prescribed specification
and safety standards.
l
The flue gas duct and chimney should be designed so
that the outlet pressure is slightly negative. The outlet
pressure can be maintained by using dampers in the
flue gas duct, especially when multiple chillers are
connected to the same chimney.
l
Sharp bends and other fittings causing back pressure
should be avoided. The chimney height should be
based on the sharp bends and the horizontal length of
the duct.
35 / 36
l
The machine room should have adequate ventilation
for sufficient burner make-up air and for effective flue
gas removal. The machine room pressure should never
fall below the flue gas outlet pressure. The chimney
location should depend on the atmospheric conditions
and the position of the cooling tower and vents.
l
Soot should be removed from the system. Heat
resistant material should be used for its construction.
Ducts should be properly insulated. The chimney
should have lightning arresters with proper earthing
connections. It should have effective protection from
rain, wind and snow. Expansion joints should be
provided to limit thermal stresses.
Site Unloading And Installation
Unloading instructions
l
For unloading purposes, use the lifting shackles
provided on the chiller. Rigging from any other point on
the chiller can damage the unit and cause personal
injury.
l
Use proper sized hooks/ slings and approved methods
for lifting the chiller.
l
Lift the chiller simultaneously from all four corners,
while keeping the unit level with the ground.
l
Proper care should be taken while hooking up the
shackles near the pipes. (Refer figure)
l
Every care should be taken to prevent damage to
interconnecting pipes, control panel and chiller
mounted panel.
PLACE THE HOOK AS SHOWN
TO AVOID DAMAGE TO THE PIPES
Hanger Plate
Rigging and shifting to the foundation
To avoid any damage, the chiller should be rigged with
care to its ultimate location. A plate should be placed
beneath the saddles of the chiller and castors or rollers
placed below this plate. The chiller should be pulled
gradually from one side using a winch. The wire rope
used for pulling should be tied to the saddle.
Leveling of chiller
Before hooking up the chiller to the external piping, it is
very important to level it based on the procedure given
below. Proper leveling of the chiller is essential to
achieve the rated capacity of the unit. Allowable
tolerance (both lengthwise and side-wise) is less than or
equal to 1/16 inch per 5 ft.
Unloading & Installation of Machine (Single
piece)
As a standard feature, the chiller is shipped as a single
piece. All piping should be adequately supported and
fitted to prevent any strain on nozzles and connecting
flanges. During installation, sizes of cooling and chilled
water lines should match with those of the connecting
nozzles. Their inlet connections should be flushed clean,
and the electrical wiring should be verified. The sketch
shown below indicates the unloading of a single piece
chiller.
Note: This is only a diagrammatic representation of the
general appearance of the chiller. The actual chiller may
be different than what has been shown here.
There are four leveling checkpoints provided on the
heater. Labeled as A, B, C and D in the figure below,
these check points are designated by three punch
marks on the tube sheet or shell of the lower shell of the
chiller.
Procedure for leveling
Fill a clear vinyl hose (diameter of the hose 3/8”) with
water, ensuring that there are no air bubbles in it. Using
point 'A' as reference point, measure the difference in
the water level at the other points (i.e. B, C and D).
A
B
VAPOR ABSORPTION
CHILLER
C
D
EcoChill Nxt
Direct Fired Vapor Absorption Chiller
37 / 38
Optional Multi-sectional Shipment
C
A
The chiller can be shipped in three sections viz. the lower
shell assembly, upper shell assembly and the HTG
assembly. This is done when there are indications that
the chiller's dimensions as a single piece may cause
rigging problems (particularly for retrofit jobs).
D
B
CLEAR VINYL HOSE
A
0 inch
B
inch
C
inch
D
inch
1. LOWER SHELL ASSEMBLY
Leveling calculations are as shown below:
A - B=C - D
L
L
A - D=B - C
L
L
A - C= B - D
W
W
Where L= Length of the heater
W= Width of the heater
In case the tolerance is not met, it can be achieved by
inserting a metal shim between the chiller frame and
foundation. Metal shim size could be 2” width X 3”
length, whereas the thickness of the shims should be in
the range of 0.024” to 0.354”.
2. UPPER SHELL ASSEMBLY
After making adjustments, confirm the leveling of the
machine by taking a new set of readings.
Procedure for grouting
After leveling the chiller, it is required to be grouted before
the external piping can be connected to it.
This is done by fixing the anchor bolts, by welding washer
to the chiller frame and by tightening the bolts.
Storage of the unit
In case the unit is not to be installed immediately, it
should be kept covered until its installation. It is
recommended to keep the chiller indoors during this
period to prevent any damage to it. Nitrogen should not
be removed from the heater unit. All the accessories
supplied along with the unit should be kept in the same
place.
3. HTG ASSEMBLY
Notes
Sustainable Solutions in
Energy & Environment
COOLING & HEATING DIVISION
Thermax Ltd., India
D-13 MIDC Industrial Area, R.D. Aga Road,
Chinchwad, Pune 411 019, India.
Tel : 00-91-20-27475941, Fax : 00-91-20-27475907
www.thermaxindia.com
Thermax Inc, USA
Tel : 00-1-248-4743050, Fax : 00-1-248-4745790
Email: [email protected], [email protected]
www.thermax-usa.com
Thermax Europe Ltd., UK
Tel : 00-44-1908-378-914, Fax : 00-44-1908-379-487
Email: [email protected]
www.thermax-europe.com
Thermax (Zhejiang)
Cooling & Heating Engg. Co. Ltd., China
Tel : 00-86-21-64483996, Fax : 00-86-21-64483997
Email: [email protected]
www.thermax-china.com
Thermax do Brasil
Tel : 00-55-21-25169227, Fax : 00-55-21-25169226 Email:
[email protected]
www.thermaxdobrasil.com.br
Thermax Rus Ltd., Russia
Tel : 00-7-095-9350490 / 91, Fax : 00-7-095-1347410
Email: [email protected]
Thermax Ltd., UAE
Tel : 00-971-4-8816481, Fax : 00-971-4-8816039
Email: [email protected], [email protected]
Thermax Ltd., Saudi Arabia
Tel : 00-966-3-8575056, Fax : 00-966-3-8575068
Email: [email protected]
Thermax Ltd., Kenya
Tel: 00-254-204440233, Fax : 00-254-204451919
Email: [email protected]
Thermax Ltd, Nigeria
Tel: 00-234-8022908770, Fax : 00-234-14936187
Email: [email protected]
Thermax Ltd., Thailand
Tel : 00-66-2-6555790, Fax : 00-66-2-6555791
Email: [email protected]
Thermax Ltd., Malaysia
Tel : 00-60-3-21669801, Fax : 00-60-3-21669802
Email: [email protected]
Thermax Ltd., Indonesia
Tel : 00-62-21-83793259, Fax : 00-62-21-83793258
Email: [email protected]
Thermax Ltd., Philippines
Tel : 00-63-2-9296964, Fax : 00-63-2-9296982
Email: [email protected]
Thermax Ltd., Bangladesh
Telefax : 00-880-29885823, Mob : 00-880-1912008882
Email: [email protected]
Thermax Ltd., Srilanka
Tel: 00-94-777769126, Fax : 00-94-112533217
Email: [email protected]
www.thermaxindia.com
In view of our constant endeavour to improve the quality of our products, we reserve the
right to alter or change specifications without prior notice. All photographs shown in this
publication are representative in purpose, and to be used for reference only. For actual
details and specifications, please refer to Thermax offer document

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