99.999% purity 1800m3/h Hydrogen Generation Plant
Raw water (pure water) is delivered to water tank. It goes through
valve via the pipe and is fed to H2 and O2 tower by complementary
pump. Then it goes through H2 and O2 separator in lower part of the
pipe and through alkali liquid recycling pump , alkali liquid
filter to electrolyzing tank. H2 and H2 are obtained by
electrolyzing. O2 and H2 through pipe to alkali liquid for cooling
and H2 and O2 separator comprehensive column cooling and washing(H2
needs to be cooled further). Moisture is separated through
water-gas separator and goes through water discharger to be
drained. O2 through O2 pipe goes to adjusting pipe to be delivered
out. According to customer’s requirement to be vented or stored. H2
from H2 comprehensive column and delivered after adjusted.
Cooling water of system is mainly supplies electrolyzer , silicon
rectifier penal , and for water sealing purpose for the tank.
Instrument air resource separately supplies for primary instrument
and valves in frame I of electrolyzing equipment.(pneumatic
diaphragm adjusting valve, primary instrument valve in H2 purifier
4.2 Technology process for electrolyzing equipment:
4.2.1 H2 and O2 system:
Pure water in electrolyzing tank is decomposed under DC action. In
the cathode and anode plates in cabin H2 and O2 are created
separately which flow out of the two poles in electrolyzing tank in
the cabin with alkali liquid.
Through external pipes they go together and enters alkali liquid
separator. H2 an O2 in the middle of separator (under alkali liquid
surface) under gravity ,H2 (O2 ) and alkali liquid descends
separately to separate H2(O2) which is cooled on the upper part of
the separator and washed. H2,O2 remove the dropping liquid on the
top of the separator and O2 is vented to the atmosphere after
adjusted valve. H2 is further cooled through comprehensive column
to be saturated to gas-water separator for removal of dropping
liquid. It is adjusted by pneumatic valve to Frame I.
4.2.2 Alkali liquid recycling system (alkali liquid recycling )
H1 and O2 from electrolyzing tank in alkali liquid under gravity in
separator they separate into H2 and O2.IT is cooled down in lower
part of separator. They (two branches) flow into alkali liquid
recycling pump. Pump provides the energy for alkali liquid
recycling.. We adopt recycling pump to ensure the stable operation
for the whole system. Alkali liquid goes through filter which
removes the mechanical impurity by asbestos cloth to lower part of
electrolyzing tank. It goes evenly through pipes to be distributed
to each electrolyzing cabin. Electrolyzing liquid flows to each
small cabin (between two poles) from lower part to upper part to be
electrolyzed so that form inner recycling system in electrolyzing
4.2.3 Water complementary system:
Raw water is complemented by water supplementary pump to
comprehensive column through washing sector to wash H2 or O2.
Washing sector is water of sealed structure. Extra complementary
water through flooding pipe to lower part of separator with alkali
liquid to alkali liquid to alkali liquid recycling system to
achieve purpose of water supplementary. Water pump working is
interrupted which start and stop is controlled by alkali liquid
surface for H2 and O2 separation.
4. 2.4 Cooling water supply system
It is divided into two branches,one through pneumatic diaphragm
adjusting valve into H2 (O2) alkali liquid cooler cooling recycling
alkali liquid so as to control system working tempt. purpose and
another separately into H2(O2) comprehensive column to cool the
4.2.5 Nitrogen system
This equipment has nitrogen filling opening pipe, through valve in
alkali liquid conflux pipe of H2 and O2 separator to fill the
system with nitrogen for blowing out and gas tightness at starting.
Blow up and gas tightness test when the system first start and
Blow up and gas tightness test when H2 tank first start or after
4. 2.6 Drainage system
Drainage opening for electrolyzing tank, alkali filter, alkali
liquid tank and raw water tank, etc.
4. 2.7 Alkali entering (inlet water) system for H2 plant
H2 generating equipment consists of electrolyzing tank and Frame
I., alkali liquid after filtering is filled to electrolyzing tank.
When it is full, alkali liquid goes to H2(O2) separator. It is fit
Raw water is sucked with alkali liquid. It is fit when the system
is under washing. 4.1.8 Alkali dosage system
Raw water in alkali tank is recycled by alkali pump. It goes
through alkali filter, valve to be switched to alkali tank. During
raw water recycling, add potassium hydroxide regularly which is not
easy to be solved so that dosing alkali recycling(outside
recycling) is formed. This work is executed when the equipment
4.3. Description of the control system:
4.3.1,The supplier will provide PLC for hydrogen production system with
full automatic operation. Which has auto stop and auto inspection
and control. Each stage has warning, interlock function. It has one
button to auto level. It also has manual operation function. When
PLC has fault, system manual operation ensures the system to
produce the hydrogen continuously.
4.3.2 Control system circuit and parameter collect point for
4.2.3. Pressure control system
Through pressure transformer at O2 separator side, pressure is
measured and translated to DC signal of 4~20 mA to LC,by comparison
with set value and PID calculation, and by electrical switcher to
revert to 0.02～0.1MPa electric signal so as to control the opening
of pneumatic diaphragm valve to obtain pressure stability of the
system. System pressure is set on man-machine screen.
4.2.4 Liquid level control system
a. H2 separator level control
In process of electrolyzing, raw water is continuously consumed so
that the level of water at O2 separator is continuously reduced.
Thus it must be complemented by water complementary pump so as to
satisfy the consumption of water.
Liquid level is measured through pressure differential transformer
at the H2 side which is translated to standard 4～20mA electric
signal to PLC； Through comparison of set upper and lower liquid
level limitations for warning and interlock to create signal to
control start and stop, and interlock warning of the complementary
pump. Upper and lower liquid level limitations for warning and
interlock can be set on man-machine screen.
b. Pressure differential control at H2 and O2 sides
This system can control pressure balance at H2 and O2 sides.
Pressure differential of gas and liquid phases is measured by
pressure differential transformers at the O2 separator side and at
the H2 separator side. Two 4～20mA measured signal are transferred
to PLC and through PID calculation (P:proportion,I:integral
D:differential coefficient(selectable)normal operation)The
operation result is inputted to electric reverser to 0.02～0.1MPa
electric signal to control the opening of the pneumatic adjusting
valve on H2 outlet pipe so as to control the pressure balance at
the two sides.
Control frame process diagram :
4.2.5 Tank tempt. control system
Working tempt. of electrolyzing tank is a important parameter for
the equipment. It is approved that when gas output, environment
tempt. and alkali quantity is fixed, the tempt. of electrolyzing
tank is in proportion to recycling alkali tempt. We could adjust
the recycling alkali tempt. to control the tank tempt. The tempt.
transformer is installed on O2 separator side and the output signal
is transformed to PLC,and is compared with tank set value in PLC
and is calculated by reaction PID operation. Then signal is
transferred to electric reverser to create 0.02～0.1MPa signal to
adjust the opening of the cooling water pipe so as to control
recycling alkali liquid tempt.. We use our control method in
accordance with our year’s experience to adopt tandem PID control
method of H2 production system tempt. contrl.
4.2.6 Important parameter measuring points of hydrogen production
Pressure in the system
O2 liquid level
H2 liquid level
H2 and O2 tempt. differential
O2 tank tempt.
H2 tank tempt.
Alkali liquid recycling capacity
H2 content in O2 out of electrolyzing tank
O2 content in H2 out of the electrolyzing tank
Rectification panel current
PLC is matured technology with stable operation from German SIEMENS
or Japanese OMRON products. It consists of CPU, input and output
module for simulation, power supply module (E2PROM,separation transformer ), etc.
Hydrogen output: 1800m3/h
working pressure: 1.6Mpa
Hydrogen purity: ≥99.999%
Moisture contained in product hydrogen:
Dew point ≤-70℃
4.3 Utility and consumption
3-phase, 3 wires, no neutral, line to line voltage is 220 Volts
Single phase, line to line voltage 220volts.
No neutral wire
Requirement:Pressure:0.3-0.4MPa Tempt.:≤32℃ Hardness＜4 degree
For each equipment
Production of H2 & purifying
KOH dosage for electrolyzing liquid.
Potassium hydroxide consumption :2000Kg (prepared by seller with
4.4. Instrument air
Quality :Oil content ＜5mg/m3 Dust ＜20μm Dew point 10℃ lower than ambient tempt. Using nitrogen