FIELD OF THE INVENTION
The present invention relates generally to drying systems. . More particularly, the present
invention relates to the field of energy efficient refrigeration type Hydrogen gas driers to
assure low humidity level inside a generator. The invention also rdates to a :Hydrogen glls
drier comprising of two heat exchangers and works on the principle that :at dew point
temperature the moisture present in gas condensates to water form and can be drained out.
The said drier is highly efficient and requires only 8 hours of service a day. The drier is
constructed in such a manner that any component can be taken out and replaced without
dismantling the other components.
BACKGROUND AND PRIOR ART OF THE INVENTION
As has long been appreciated, an effective cooling system for generators is essential since the
electrical output of the machine is limited substantially by the permissible rise in temperature
within the machine. There are numerous types of gas/gas heat exchangers and evaporators,
obtained with various technologies.
Air dryers are generally utilized to remove water vapor typi~ally from compressed air or gas.
Helium with a thermal-conductivity of 0.142 W/(m-K) was considered as coolant as well,
however its high cost hinders its adoption despite its non-flammability. For generators up to
1000 MW, air cooling can be used. In one such air-cooled systems, the generator stator is
pressed into a finned housing. Engine inlet air is then sucked over the fins, thus removing
heat from the generator, but directing the heated air into the engine inlet.
Fluid cooling systems have long been used to provide cooling mechanism within a generator.
The inventor recognized the disadvantage of fluid cooling generators is that it does not cool
the generator rotor shaft, is fairly complex, requiring a circulating pump and a radiator, and it
also has the potential to lea.k tluid and cause damage to the system.
2
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prior art DE 10311602 AI proposes a thermal accumulator to be provided in an edge area
of a gas-refrigerant area of a heat exchanger. Providing the thermal accumulator at the outer
sides of the heat exchanger, however, is comparably space-consuming and results in the heat.
exchanger operating at low energy efficiency.
The prior art DE19943109 Cl proposes another solution with r~spt>r.t to the problem of
pressure dew point fluctuations. According to DE 19943109 C 1, a "standard heat exchanger"
is proposed in conjunction with a circulating refrigerant fluid which is in tum cooled by
refrigerant circulation. An ice-water mixture is gener~ted by the refrigerant circuit. Storage
takes place within the refrigerant fluid. In this context, as well, the constructional expenditure
is not negligible due to the required second heat exchanger and a pump for pumping the icewater
mixture. Moreover, energy efficiency is reduced by the multiple heat transitions and the
use of the pump. On the one hand, the pump needs electric drive power and, on the other, the
heat input into the refrigerant fluid increases the required cooling capacity and consequently
the power consumption of the refrigerant compressor.
The prior art DE3233973 discloses a device for dehumidifying gases, in particular
compressed air, which comprises a multiplicity of neighbouring chambers combined into two
groups and having separating walls made of a gas-impermeable, extensible material which is
· a good heat conductor, the moist gas exchanging heat in the frrst group with the dried cold
gas, which is cooled with a coolant in the second group with removal of liquid and which has
a common collector over the other chamber of each group as a feed or outlet for the
corresponding stream of medium.
The prior art with application number PCT/GB2000/003529 discloses a gas drier that
includes a membrane located between an inlet and an outlet in the drier. Water vapour from
the gas passes through the membrane as it can permeate the membrane faster t.han the gas due
to relative permeability of the membrane. A cellulose acelate membrane is used in this drier.
The prior art CN204220003U discloses a split type explosion-proof freezing dryer. In this
utility model, the lleat exchanger is separated from the refrigerating system and th~
3
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electricity, so that the heat exchanger is not electrified and is put in the explosion-proof zone;
the refrigerating system and the elec):ricity are of a box body and are put in a non-explosionproof
area.
A common problem with refrigeration-type dryers is determining how to suspend cooling
(i.e., "de-enersize" the system) durin~ times of no lo~d or low load oonditions. Por eMm!Jlt::,
the demand for refrigeration is low or non-existent when little to no air is flowing through the
refrigerator dryer or when the incoming air is already cool. Typically, it is desirable to reduce
or discontinue cooling during such periods to avoid ice formation in the refrigerant system
that could affect operation of the refrigeration air dryer. Ice can plug the system so that it
does not continue drying the air, or it can plug the air passages stopping the flow of
compressed air.
Drying systems based on internally heated regenerative dryers are commonly used to remove
moisture from hydrogen gas. Such systems typically consist of a coalescing pre-filter, a loose
bed carbon absorber, a regenerative dryer, an after filter, and a blower.
One way to prevent excessive cooling and the resulting problem, is to use a cycling-type
refrigeration dryer. However, the number of cycles per hour is significant because frequent
cycling adds costs associated with wear and tear on the compressor, control systems, and
valves. As a result, the life without maintenance of the refrigeration system is drastically
. reduced. Accordingly, it .would be desirable to provide a refrigerant air dryer system and
method that extends the life of its refrigeration system. It is a well-known fact that lower
energy consumption has both cost and environmental benefits. Accordingly it would also be
desirable to provide a refrigeration dryer system and method that reduces the amount of
. energy consumed.
Further, the conventional driers suffer from a number of defects such as need to consistently
replace or regenerate silica gel. Further, the present driers consume a lot of energy and thus
are not energy efficient. Thus the driers used presently are not efficient in taking away
moisture from gas.
4
Hydrogen gas is used as a coolant for generators for two reasons. First, it has the best heat
transfer properties of any gas, with a specific heat of 3.4 Btu/lb-F at standard conditions. On a
mass basis, this makes it more than 14 times more efficient than dry air for removing heat.
Second, it has the lowest atomic weight of any known gas, which keeps wind resistance
losses within generators to a minimum. In other words, the wind resistance to generator rotors
turning at 3600 rpm is red~ced when using hydrogen ga£ rather thun otltct gast:S as a coohng
medium. A hydrogen-cooled generator can be significantly smaller, and therefore less
expensive, than an air-cooled one. Also, Hydrogen has very low viscosity, a favorable
property for reducing drag losses in the rotor; these losses can be significant, as the rotors
have large diameter and high rotational speed.
Hydrogen gas drier is used in the gas supply system of generators for controlling the moisture
level during operation. The existing system uses duplex gas drier, which is a twin tower
adsorption type gas drier using silica gel as a drying agent. A common heater and air bl~wer
type arrangement is provided for regeneration of adsorbent material. The adsorbent material
is desiccant type which uses hot air for regeneration. The system involves frequent
changeovers and regeneration cycles, involving manual interfaces~ careful handling and need
for regular maintenance.
As with all desiccant dryers, it is important to keep oil and liquid water out of the desiccant
beds. Liquid water can disable a desiccant bed; however, water can be regenerated so that the
desiccant can be used again. Conversely, turbine oil contamination from the generator will
coat the desiccant and ruin it so that it cannot be regenerated. When turbine oil contamination
occurs, the only solution is to replace the desiccant. A desiccant dryer is only as effective as
its ability to regenerate itself As one vessel is drying the hydrogen gas, the other vessel
regenerates itself by energizing the heaters within each desiccant chamber and by purging a
small amount of hydrogen gas across the desiccant to carry the moisture, and potentially other
contaminants, out of the system. Depending on ambient temperature and the amount of water ·
being removed from the generator; varying amounts of liquid water can condense in the purge
exhaust drain line. This drain location is an cxc:ellent place to gauge the effectiveness of the
hydrogen dryer. By measuring the amount of condensate at this location over . time, it is
possible to accurately calculate the amount of water contamination within a generator.
5
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Moreover, this calculation is conservative because the purge gas carries additional water out
of the system in a vapor state that does not condense into the purge ~::xhaust drain location.
All desiccant materials are abrasive and create dust over time. To keep desiccant fines from
being introduced into the generator, a particulate after filter is used. The final component in
the
hydrogen drying system IS a positive displacement, rotary lobe hlower thflt mntinually
circulates about 10 actual cubic feet per minute through the dryer system. This blower is
necessary to overcome pressure drop associated with the dryer, filtration system, and piping.
Further, one of the major disadvantages of the present system is that it requires continuous
service throughout the day.
The inventors of the present invention have made effort to produce a refrigeration· type
Hydrogen gas drier to assure low humidity level inside the generators. It is also used to
increase the prevention process of corrosion and stress in rotor retaining ring. The major
advantage of the present invention is that it is manufactured from the premium quality raw
materials and thus is highly reliable.
OBJECT OF THE INVENTION
The principal object of the present invention is to propose a refrigeration type Hydrogen gas
drier device which incorporates two heat exchangers to take away moisture from gas
efficiently and reduce stress on the system.
Yet another objective of the present invention is to provide a drier device for extraction of
moisture from the Hydrogen of the generator by the principle that at dew point temperature,
the moisture present in gas condensates to water form and can be drained out.
Yet another object of the invention is to provide a refrigeration type Hydrogen gas drier
de:vice which is having modular construction such that any component can be taken out and
replaced without dismantling other components.
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The prior art consists of a number of gas driers using silica gel as a drying agent. However, it
is the object of the present invention to provide a Hydrogen gas drier device in which there is
no need to replace or regenerate the silica gel.
A further objective ·of the present invention is to solve the above drawbacks in the known art
in an extremely simple, economic and particularly functional way.
SUMMARY OF THE INVENTION
Accordingly the present invention relates to a refrigeration type Hydrogen gas drier device
comprising of two heat exchangers. The first heat-exchanger is a Hydrogen .shell tube type,
called pre-cooler (2) in which temperature of Hydrogen reduces to around 25 to 30°C. The
cooled Hydrogen then enters the second heat exchanger named evaporator or chiller (3).
Further cooling up to 0°C to 3°C is accomplished in this heat exchanger. The set Dew Point is
adjustable. The cooling coil inside the evaporator is propelled through a refrigeration system.
Due to low temperature in the evaporator, the moisture in Hydrogen condenses and converts
into water form. The water is collected in a well-protected condensate collector and can be
drained out when desired. Leaving the evaporator, the Hydrogen again travels to the precooler
where it has dual function:
(a) It cools the input Hydrogen gas temperature to some extent so that the heat load on
chiller is reduced.
(b) The temperature of th~ leaving Hydrogen gas rises to a safe temperature of about 25°
. to 40° .before entering the generator and unnecessary stress on the system is
eliminated.
The entire drier unit is housed in three compartments:
(a) The uppermost compartment where the pre-cooler and chiller are situated,
(b) The control panel containing the electrical components and
(c) The lowermost compartment containing the refrigeration circuit.
7
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In this respect, before explaining at least one embodiment of the invention in detail, it is to be
understood that the invention is not limited in its application to the details ofconstruction and
to the arrangements of the components set forth in the following description or illustrated in
the drawings. The invention is capable of other embodiments and of being practiced and
0 0
carried out in various ways. Also, it is to be understood that the phraseology and terminology
employed herein, as well as the abstract, ar·e for the purpose of description and should not be
regarded as limiting.
As such, those skilled in the art will appreciate that the conception upon which this disclosure
is based may readily be utilized as a basis for the designing of other structures, methods and
systems for carrying out the several purposes of the present invention. It is important,
therefore, that the claims be regarded as including such equivalent constructions insofar as
they do not depart from the spirit and scope of the present invention.
BRIEF DESCRIPTION OF FIGURES
The invention is illustrated in the accompanying drawings, throughout which like reference .
letters indicate corresponding parts in the various figures. The embodiments herein will be
better understood from the following description with reference to the drawings, in which:
Figure 1 shows a block diagram of a generator to gas drier interconnection with different pipe
sizes.
Figure 2 ·shows a schematic diagram of Refrigeration type Hydrogen gas drier device
according to the present invention.
Figure 3 shows the right section view of the Refrigeration type Hydrogen gas drier device as
proposed in the present invention.
Figure 4 shows the front section view of the Refrigeration type Hydrogen gas drier device as
proposed in the present invention.
8
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Figure 5 shows the left section view of the Refrigeration type Hydrogen gas drier device as
proposed in the present invention.
Figure 6 shows the back section view of the Refrigeration type Hydrogen gas drier device as
proposed in the present invention:
Figure 7 shows the top section view of the Refrigeration type Hydrogen gas drier device as
proposed in the present invention.
Figure 8 shows a bottom section view of the Refrigeration type Hydrogen gas drier device as
proposed in the present invention ..
Figure 9 shows _front panel controls of the Refrigeration type Hydrogen gas drier device as
proposed in the present invention.
DETAILED DESCRIPTION OF THE INVENTION
The structural and functional characteristics of the present invention and its advantages with
respect to the known art are evident and more clearly defined in the following description,
referring to the enclosed drawings which shows the heat exchangers for Hydrogen gas
refrigeration driers produced according to the innovative principles of the invention ·itself.
The embodiments herein and the various features and advantages details therefor are
explained more fully with reference to the non-limiting embodiments that are illustrated in
the accompanying drawings and detailed in the following description. Description of wellknown
components and processing techniques are omitted so as to not unnecessarily obscure
the _embodiments herein. The examples used herein are intended merely to facilitate an
understanding of ways in which the embodiments herein may be practiced and to further
enable those of skill in·the art to practice the embodiments herein. Accordingly lhe examples
. .
should not be construed as limiting the scope of the embodiments herein.
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9
AB shown in the figures, the embodiments herein provide a hydrogen gas drier based on the
principle of moisture extraction from the generator using a refrigeration technique.
Figure 2 shows a gas drier according to the present invention. The moisture extraction from
the Hydrogen of the generator is accomplished in this system by the principle that at Dew
Point temperature the moisture present in the gas condensates to water form and can be
drained out.
The present system comprises of two heat exchangers. The first heat exchanger is a Hydrogen
to Hydrogen shell and tube type Heat Exchanger called pre-cooler (2) with cold gas passing
through pipe (20). The Hydrogen enters the pre-cooler (2) where the temperature of the gas
reduces by approximately 20° C. The cooled Hydrogen gas then enters the second Heat
Exchanger called evaporator or chiller (3). There is a temperature difference of about 50 %
between Input Hydrogen temperature and set Dew Point at chiller (3). In chiller, the cooling
of Hydrogen gas is accomplished to the extent that Hydrogen gas temperature goes down up
to the set Dew Point. The cooling pipes have Refrigerant gas as refrigerant propelled through
a compressor refrigerant system. One of the biggest advantages of the present invention is
that the set due point is adjustable. In the Evaporated heat exchanger the temperature of the
Hydrogen gas goes down to the Dew Point Temperature of around 3° C and moisture now
converts to water. The water thus collected is drained to condensate collector.
The Hydrogen gas while leaving the chiller (3) cools down to around 3 to 5° C and is dried.
After leaving the chiller the Hydrogen gas again enters the pre-cooler (2) where it has dual
functions: It cools the input Hydrogen gas temperature to some extent so that the heat load on
chiller (3) is reduced. Also, the temperature of the leaving Hydrogen gas rises to a safe
temperature of about 25° to 40° before entering the generator and thus unnecessary stress on
the system is eliminated.
The cooling circuit is a simple refrigerant system designed for long life avoiding stressful
operation thus over rated compressor (1 0) of 1.5 Ton is used. Rl34 N R22 gas is filled as a
refrigerant which has a lower pressure operation and hence lower risk of leakage. The Dew
Point display with dew point transmitter is provided to maintain the dew point of the
10
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Hydrogen gas with duplex temperature controller in the unit and to display the dew point of
incoming gas from generator and outgoing Hydrogen gas to turbo generator.
As indicated in figure 2 and 4, the drier comprises of three main compartments:
A. Uppermost compartment where pre-cooler (2) and evaporator/chiller (3) are situated.
The drain line coming out of chiller is also situated in this compartment. The
condensate holder, isolation valve (9) and drain valve (5) are also situated in this
compartment. The water from chiller {3) will flow down to condensate holder
through isolation valve (9).
B. Electrical components control panel. This is an isolated cubicle provided in the
middle compartment which occupies less than half width of middle component. The
incoming and outgoing cables are as follows:
B.l: 3 core mains input lead. Corning out of the cubical through a sealed cable gland
on left side of Drier to main Switch (3 0 MCB).
B.2: Wires to Fan Motor of refrigeration circuit from Control Panel.
B.3: Wires to compressor {1 0) from control panel.
B.4: One wire for earth.
B.S: The RTD Inputs are Fed through cables (3 in number) corning from RTDs
provided at top of the cubicle.
B.6: Cables ofRTD signal to CTBOl
B.7: 04-20 rnA current signal·cable corresponding to RTD's signal from CTBOI
11
--~ ";;
"·';-. nExcept
compressor (10) and fan (12) no electrical compon~nt is fitted outside the
control panel.
The back of the middle compartment is not is.olated with the uppermost compartment.
The said portion consists of a water tray having a drain pipe fitted with it. This tray is
meant to collect water that condenses at chiller pipe lines. In the said compartment,
the drain lines coming out of chiller are provided with shut off valves (9) and if
needed, the two pipes can be detached from the valves. The water from chiller (3)
flows down to condensate holder through these valves.
C. The lowest part houses complete refrigeration circuit components including
compressor (10), Refrigeration condenser {11), liquid receiver (15), HP/LP cutout
pressure switch (8), Accumulator (6), suction pressure gauge(?), discharge pressure·
gauge (18), Freon filter Drier (13), Freon indicator (16), charging line valve and
valve at the Output line of chiller. At the inlet, one solenoid valve (14) followed by a
capillary (19) is provided to control the refrigerant flow into the chiller in order to
avoid freezing in the refrigerant line. The capillary tube (19) is not situated in the
lower refrigeration compartment but is situated near to the chiller itself in the upper
most compartment. The two pressure gauges i.e. suction (7) and discharge (18) are
also available in the compartment. The gauges are readable from front of the drier
through a transparent partition. The lowest compartment is provided with louvers on
left, right and covers so that there is ample air available for proper fan operation. The
extra metal nets are also provided beneath the louvers. On the right side of the drier,
the water collector chamber or condensate holder is provided. This chamber is
situated inside the machine so that if it is required to clean the chamber, the same can
be done by removing the top cover of the chamber. This is bolte<:I cover and if it is
opened for cleaning the chamber, the gasket provided at the top should be replaced
while bolting the cover again. The bolts should be tightened properly and the system
should again be checked for pneumatic· test. Bt:fore opening the cover of the
condensate chamber it must be ensured that Hydrogen supply is cut off by the two
drain valve provided at drain line of chiller. The condensate chamber is provided
12
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with two number of valves at its output.
The chiller (3), the associated pipe lines, the chiller flanges and all the parts liable to
be cooled below ambient temperature are properly insulated with Polyurethane foam . .
sheet all over. This is to ensure that no ambient air can touch the cooler parts, to
avoid condensation of air at these· parts. However,' during service it is important to
ensure that the insulation is not stripped off. If damaged, re-insulation should be done
over the required part. All the flanges are provided with hi-tensile bolts along with
nut washer and spring washer. No switch is provided in the main line outside the
cover of the drier. It is important to ensure that from where the supply to drier is
tapped the same should be equipped with ON-OFF switch. A 15 Amp single phase
switch is sufficient. The back doors are provided with general screwed knobs.
The gas to be dried is passed through the drier and is cooled sufficiently to condense the
moisture from gaseous to liquid state with the help of the refrigeration device. The complete
refrigeration circuit is mounted on a platform. If a major repair is required, the complete
platform can be taken out of the drier simply by dismantling two input and output pipes from
the valves and no cutting of pipes is required. The two pressure gauges i.e. suction (7) and
discharge (18) are available on the platform need not be dismantled.
As indicated in Figure 9, the Drier Power supply is a 3 0 3 wire- 415 VAC and a MCB
operated main switch is provided at the left side of Drier. The total current drain of Drier is
up to 15 Amperes. The 3 phase supply is fed to compressor (10) and fan motor via 3 fuse for
each. A three phase to single phase (11 OV) step down transformer is used for all the control
components supply. One 3 0 MCB (MCB-1) of 16A is provided at incomer. One 1- 0 ·
(MCB-2) is provided for control supply. Miniature circuit breakers (two in number) of 10
Ampere capacity are used. The ON position is towards upward direction. In addition to
MCBs. in both line, HRC Fuses are also provided inside the chamber..
A DPDT switch is provided at the drier paneL To choose manual operation of the drier, the
13
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switch is pushed towards left side. The lighting of lamp B3 implies Manual operation of drier.
To choose Auto operation of the drier, the switch is pushed towards right side. The lighting of
lamp B2 implies Auto operation of drier. The system is to be started by a push button. When
this Push Button is pressed, the Motor starts immediately but compressor does not start. It . .
will start after tht:: time set at delay timer. The delay timer is in series with compressor start
circuit and delays the start of compressor by set time. This timer is factory set for 0.5 min.
delay.
A dew Point Display (13) for display the Hydrogen gas Dew Point in Inlet & Outlet Pipe Line
of the Drier.
A digital Voltmeter indicates input power supply voltage, used for compressor (10) and fan
motor.
A digital Ammeter indicated total drawn current of power supply. During compressor OFF
condition this should 0.8 Ampere. During compressor ON condition, the current will rise up
to 3.2 Ampere continuous. Any major deviation in valves of current is an indication of fault.
The cyclic timer is in working during AUTO operation. This has very wide range of ON and
OFF duration settings.
The chiller temperature controller is a digital temperature indicator having platinum RTD as
input sensor. The sensor senses the temperature of output Hydrogen immediately after it
leaves the evaporator (3). Hence it is an indication of temperature inside the evaporator. The
said controller has provision to set the temperature so that compressor (10) stops when during
cooling the temperature reaches the set value. This setting is done by left side potentiometer..
The set value can be read by pressing set push button. The higher side set point is set by right
side potentiometer but cannot be read by set push button. The lowest position of
potentiometer gives around 2°C and highest right position gives around 7°C z~ne. The chiller
temperature controller maintains the temperature within the set· value, hence avoiding
freezing of the refrigerant.
14
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The sensor has the following specification:
•2x100% RTD PT-100, 3 wire Simplex 100 ohm at 0°C ..
• Accuracy+ 0.1% as per IS 2848
• Process connection: 1/2" BSP.
• Thermowell: stainless steel. .
The sensor is located inside the Thermowell and can be replaced, if desired. The location of
sensor is at outlet of evaporator in 50 NB pipe.
The Hydrogen input and output temperature indications are separate digital temperature
indications with 3 digit 25 mm LED display. The range is from 0 to 99.9°C having 0.1 °C
·resolution. The sensor is 4 wire Duplex RTD ofPt-100 ohm having 100 at 0°C with 0.1%
accuracy. These measurements are wired to the remote control system (DCS). The RTD
sensor is conducted in bulb of size with M18 process connection. The Thermowell are fitted
in input and output line of Hydrogen circuit.
Indicating lamps of 110 VAC supply (8 in number) and of 415 VAC (3 in number) are
installed on control panel. These lamps are replaceable from outside the panel by unscrewing
the cover of bulbs. The bulbs should be kept as spares in good quantity.
The described of bulbs is as follows:
B1: MAINS ON INDICATOR: This is ON if Pqwer supply is available to the system after
main switch is ON.
B2:.AUTO: Lights when AUTO/Manual Switch is in AUTO mode.
B3: MANUAL: tights Auto/Manual Switch is in Mariual mode.
B4: FAN ON: Lights when Refrigeration circuit FAN is ON.
15
BS: COMPRESSOR ON: Lights when Compressor is in ON cbndition.
B6: COMPRESSOR OFF: Lights when Compressor is in OFF condition ..
B7: FAN MOTOR OVERLOAD: Lights when fan Motor gets ov~rln;~ded.
B8: COMPRESSOR OVERLOAD: Lights when Compressor gets overloaded.
Ll: R PHASE: Lights when R-Phase of Mains is supplied.
L2: Y PHASE: Lights when Y-Phase of Mains is supplied.
L3: B PHASE: Lights when B-Phase of Mains is supplied.
Additional Lamps:
1. U-LED (DOOR LIGHT): Lights upper portion when control panel door opens.
2. L-LED: Light lower portion.
Further, two separate Buzzers are installed for alarms in case of overloading of Compressor
or Fan Motor. The 3 Phase wiring are in Delta connection.
To achieve the best mode, the following technical specifications of the proposed invention
should be adopted:
Hydrogen Gas· Flow Rate: 4.0-60 Nm3/Hr
Temperature of Hydrogen Gas at Inlet:
Temperature of Hydrogen Gas at Outlet:
16
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Pressure Of Hydrogen Gas at Inlet: 5 KG/cm3
Compressor Capacity: 3225 KCAL/Hr (Min.)
Design Pressure: · 10 KG/Cm3
Dew Point at Evaporator: 3°C TO 5°C (ADJUST ABLE)
Flange connection: NB50
Power point at evaporator: 415 V AC 50 HZ-30
Design for maximum ambient temperature: 60°C
Total Pressure Drop in Drier H2 Circuit: 8 MM Wg.
Power Consumption: 2.5 KW (MAX)
Colour Shade: As per requirement
A number of tests were carried out to ensure smooth working of the Drier device. They are as
follows:·
1. HYDRAULIC TEST
Hydraulic test is performed on the pre-cooler and chiller units of the drier separately at the
manufacturing stage before final assembly of the drier to check for leakage in the Pre cooler
or chiller unit.
17
:; ... ;. r~
Pre cooler
There are two kinds of hydraulic tests conducted on pre-cooler. They are
(a) Shell side
(b) Tube Side
(a) Shell side test:
• This test is conducted on the pre-cooler capsule to check for leakage in the shell part
of the pre cooler.
• The tubes are expanded.
• The inlet of the pre-cooler unit is pumped with water using a hydraulic pump system.
• A Pressure gauge is fitted at the outlet of the pre-cooler. Water is pumped till the
gauge reads 15 Kg/cm3 pressure. At this pressure, the pump is removed and the input
is sealed with a valve.
• The setup is left at this pressure for 30 minutes.
• A maintained reading of 15 Kg/cm3 at the pressure gauge after 30 minutes ensures no
leakage in the shell of the pre-cooler.
(b) Tube Side Test
• This test is conducted on the tube circuit of the pre-cooler to check for leakage in the
tube circuit of the pre cooler.
• The tubes are expanded.
• The inlet of the pre-cooler unit is pumped with water using a hydraulic pump system. .
• A Pressure gauge is fitted at the outlet of the pre-cooler. Water is ~pumped till the·
gauge reads 15 Kg/cm3 pressure. At this pressure, the pump is removed and the input
is sealed with a valve.
• The setup is left at this pressure for· 30 minutes.
• A maintained reading of 15 Kg/cm3 at the pressure gauge after 30 minutes ensures no
leakage in the tube circuit of the pre-cooler.
18
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.----------------------------- ---- --------------------------
Chiller Unit
• This test is conducted on the chiller to check for leakage in the tube circuit of chiller.
• The tubes are expanded ..
• The inlet of the chiller unit is pumped with water using a hydraulic pump system.
• · A Pressure gauge is fitted at the outlet of the chiller. Water 1s pumped till the gauge
reads 1~ Kg/cm3
pressnre. At this prP.5'Hrre, the _pump is removod and the i11put is
sealed with a valve.
• The setup is left at this pressure for 30 minutes.
• A maintained reading of 15 Kg/cm3 at the pressure gauge after 30 minutes ensures no
leakage in the tube circuit of the chiller.
2. PNEUMATIC TEST
Pneumatic test is performed on the pre-cooler and chiller units of the drier separately at
manufacturing stage before the final assembly of the drier to check for leakage in the precooler
or chiller unit.
Pre cooler
• This test is conducted on the pre-cooler capsule to check for leakage in the shell and
tubes of the pre cooler.
• The tubes are expanded.
• The inlet of the pre-cooler unit is pumped with air.
• A Press·ure gauge is fitted at the outlet of the pre-cooler. Air is pumped till the gauge
reads 10 Kg/cm3 pressure. At this pressure, the pump is removed an~ the input is
sealed with a valve.
• The setup is left at this pressure for 8 hours.
• A maintained reading of 10 Kg/cm3 at the pressure gauge after 8 hrs ensures no
leakage in the shell of the pre-cooler:
19
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Chiller Unit
• This test is conducted on the chiller to check for leakage in the tube circuit of chiller.
• The tubes are expanded.
· • The inlet of th~ r.hillp,r unit i~ p1.1mped with aiL
• A Pressure gauge is fitted at the outlet of the chiller. Air is pumped till the gauge
reads 10 Kg/cm3 pressure. At this pressure, the pump is removed and the input is
sealed with a valve.
• The setup is left at this pressure for 8 hours.
• A maintained reading of 10 Kg/cm3 at the pressure gauge after 8 hrs ensures no
leakage in the tube circuit of the chiller.
Pneumatic test is also performed separately on the H2 Circuit after assembly.
Air is pumped through the valve below drain chamber to the chiller and pre-cooler. Pressure
gauge is connected at the pre-cooler. Air is pumped till this pressure gauge reads 10 Kg/cm3
•
The Hydrogen gas circuit is maintained at this pressure for 8 hours. to ensure there is no
leakage.
No change in the reading of the pressure gauge after 8 hours reflects no leakage in the circuit.
3. ·PERFORMANCE I FUNCTION TEST (ON HOT AIR)
Manual operation- The ToggJe switch on the control panel is pushed to left side for
operation in Manual Mode. In this mode, the cyclic timer is not functional and the drier can
be switched ON and OFF by the PUSH BUTTONS on the Drier Panel. The drier has
. . .
provision. to operate manually i.e. without Cyclic Timer (Time Switch}
20
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In this condition the system is to be started by· a push button provided [PUSH TO START].
When this PB is pressed, the Motor of Fan starts immediately but compressor does not start,
it will-start after the time set at delay timer. The delay timer is Factory set at 0.5 minutes. If
any other setting is required that can be set. After the compressor starts working the . .
evaporator heat exchanger starts to cool. The cooling continues till set Dew Point is attained.
The Evaporator temperature starts to rise and when it reaches the set limit say 5°C, the fan
starts but compressor will start after set time of 0.5"to 1.5 minutes delay timer. In this time of
0.5 minutes, the dew point may further rise 1 or 2°C. Thus 7°C or 8°C is shown at Evaporator
temp indicator. After start of compressor cooling again commences and Dew points start
receding. The 3°C value may be available within 3 to 5 minutes.
For Example:
Compressor on time- I minute
Compressor off time- 2 minutes (more than 2 minutes for better performance)
The exact time depends upon various factors:
a) Inlet H2 Temperature
b) Inlet H2 flow rate
c) Atmospheric Temperature
The operation thus continues and compressor will start or stop according to EV Temperature
reached (factory set at 3°C). As soon as EV Te-mperature is attended the compressor and fan
stops, and temperature will remain within the specified zone.
Auto operation- The Toggle switch on the control panel is pushed to right side for operation
in Auto Mode. In this mode, the cyclic timer is functional and the drier cannot be switched
ON and OFF by the PUSH BUTTONS on the Drier Panel. In the Auto mode, the operation of
cyclic timer (Time. Switch) comes into picture and total supply of system is gener~ted by ONOFF
Cycle set at this timer. The total ON time is 8 hours in a day.
21
Alarm Test- Two buzzers have been installed in the drier for sounding on overloading of the
compressor and fan motor separately.
Performance test of the drier is performed on the drier at the time of final inspection.
4. HIGH VOLTAGE AND INSULATION RESISTANCE TEST
High voltage test of compressor and fan motor performed to check for leakage· current. A
high voltage of 2 KV is applied .to the fan motor and compressor supply points separately for
1 minute to check for any leakage faults. Insulation Resistance of the connecting wires of fan
motor and compressor is also checked by supplying the supply points of fan motor and
compressor separately by 500V by a Megger. The resistance should be greater than and equal
to 10 Mega Ohm to ensure proper insulation resistance.
The forms, as also the materials, of the he~t exchangers for refrigeration type Hydrogen gas drier
of the invention can naturally be different from that provided, as an illustrative but non-limiting
example, in the drawings.
Modifications and improvements may be made to the foregoing without departing from the
scope of the present invention.

STATEMENT OF CLAIMS
WE CLAIM:
1. A modular refrigeration type Hydrogen gas drier device comprising:
a gas-to-gas pre-cooler (2) for reducing the temperature of the incumbent Hydrogen
gas;
a gas-to-refrigerant evaporator (3) for receiving pre-cooled Hydrogen gas for further
cooling the gas up to the set dew point;
an electrical components control panel for housing incoming and outgoing cables
which connect the device components; and
a refrigeration system compartment for housing the cooling circuit components.
2. A refrigeration type Hydrogen gas drier device as claimed in claim 1, wherein the
pre-cooler (2) is a shell and tube type heat exchanger.
3. A refrigeration type Hydrogen gas drier device as claimed in claim 1, wherein the
evaporator (3) is a shell and tube type heat exchanger.
4. A refrigeration type Hydrogen gas drier device as claimed in claim 1, wherein the
said refrigeration system comprises of a compressor (10} for compressing and
cooling the gas; refrigeration condenser ·(11) for supplying refrigerant to the
evaporator (3); a condensate collector(17) for collection of excess moisture
discharged by Hydrogen gas, the cold Hydrogen gas being recirculated , to attain a
temperature below the inlet gas before being fed into the generator; liquid receiver
(15); HP/LP cut out pressure switch (8); Accumulator (6); suction pressure gauge
23

(7); discharge pressure gauge (18); Freon filter drier (13); Freon indicator (16);
charging line valve and valves at the input and output line of the evaporator (3).
5. A refrigeration system as claimed in claim 4, wherein the compressor used weighs at
least 1.5 tons.
6. A refrigeration system as claimed in claim 4, wherein the gas used as a refrigerant is
Rl34AIR22.
7. A refrigeration type Hydrogen gas drier device as claimed in claim 1, wherein the
device is started by a push button.
8. A refrigeration type Hydrogen gas drier device as claimed in any of the proceeding
claims, wherein the complete refrigeration circuit is mounted on a platform to
achieve a modular system.
9. A refrigeration type Hydrogen gas drier device as claimed in any of the proceeding
claims, comprising a plurality of indicator means.
IO. A refrigeration type Hydrogen gas drier device as herein described and illustrated in
the figures of the accompanying drawings.