Composition of hydrogen production system by electrolysis of water
Composition of hydrogen production system by electrolysis of water – Electrolyzer Coatings – Cheersonic
1. Water supply system
Raw water first enters the desalinated water preparation device, and after ultrafiltration + two-stage reverse osmosis treatment, it enters the lye tank, alkali distribution tank and cooling device water tank. The water entering the lye tank and the lye distribution tank is prepared into lye, which is pumped by the lye distribution into the inlet liquid separation device and enters the lye circulation system to replenish lye for the lye circulation system; enters the water tank of the demineralized water cooling device The water, under the output of the circulating water pump, flows through the water-water heat exchanger, enters the multiple coolers in the gas-liquid separation device and the hydrogen purification device, and returns to the water tank of the cooling device.
2. Alkaline circulation system
There are two electrolytes coming out of the electrolytic cell: one is rich in hydrogen, and the other is rich in oxygen. They respectively enter the hydrogen separator and oxygen separator in the gas-liquid separation device. After the hydrogen and oxygen are separated, the two The caustic soda is combined, filtered by the caustic filter, then cooled by the caustic cooler, enters the caustic circulating pump, pressurized by the pump and returns to the electrolytic cell, so as to realize the caustic circulation in the hydrogen production system.
3. Electrolyzer
The lye in the lye circulation system enters the electrolytic cell, and the water begins to decompose under the action of direct current, and hydrogen and oxygen are generated on the cathode and anode plates of the electrolysis chamber respectively. The hydrogen and oxygen flow out from both ends of the electrolytic cell together with the electrolyte and enter the gas-liquid separation device.
The reaction equation in the electrolytic cell is as follows:
electrolysis
2H2O ======= 2 H2↑ + O2 ↑
KOH (electrolyte)
4. Gas-liquid separation device
The gas-liquid separation device is equipped with hydrogen separation scrubber, oxygen separator, hydrogen cooler, gas-water separator, lye circulation pump and other equipment. The electrolyte containing hydrogen and oxygen passes through the hydrogen and oxygen separators respectively, and is separated from the electrolytic alkali solution under the action of gravity, and the separated oxygen is discharged to the outside, and the hydrogen is further washed, cooled, and separated to remove the liquid droplets in the separation device. Then enter the hydrogen purification unit.
5. Hydrogen purification device
In the hydrogen purification device, the hydrogen is catalyzed by the catalyst to react with the residual oxygen in the hydrogen as follows: 2H2+O2=2H2O,
After cooling, adsorption, and separation, high-purity hydrogen with a purity of 99.999% is obtained.
6. Hydrogen storage equipment
The high-purity hydrogen is distributed to each hydrogen storage tank for storage after the pressure is balanced by the hydrogen confluence rack.
7. Hydrogen supply system
At present, there are three main ways of transporting hydrogen storage abroad, hydrogen cylinder racks, long-tube trailers, and solid-state hydrogen storage devices. Because solid-state hydrogen storage devices are rarely used in China and are still in the research and development stage in China, hydrogen cylinders are generally considered. and long tube trailers as the main mode of transportation.
The main technological process of the hydrogen supply system is as follows:
Hydrogen storage tank→hydrogen busbar→hydrogen buffer tank→hydrogen compressor→hydrogen filling busbar (or filling device)→hydrogen bottle set (or long tube trailer).
8. Auxiliary system
The hydrogen production auxiliary system mainly includes: demineralized water preparation system, refrigeration heat exchange system, compressed air supply system, lye storage system and nitrogen sweeping system. Each system is described as follows:
1) Demineralized water preparation system
The demineralized water preparation system adopts conventional filtration, ultrafiltration, and two-stage reverse osmosis treatment processes to meet the water quality requirements of the hydrogen production system, as follows:
Conductivity: <1μs/cm (25°C);
Ca2+: <5ppm;
Na+: <50ppb;
Fe2+: <3ppb;
SiO2: <50ppb.
The process flow of the desalination system is as follows:
Deep well water (with pressure)→disc filter→ultrafiltration device→ultrafiltration water tank→first-stage reverse osmosis high-pressure pump→first-stage reverse osmosis device→two-stage reverse osmosis high-pressure pump→two-stage reverse osmosis device→demineralized water tank → Demineralized water pump → to each water point of the hydrogen production system.
2) Refrigeration heat exchange system
Refrigeration and heat exchange system equipment mainly includes buffer water tank, circulation pump and compression refrigerator.
3) Compressed air supply system
Compressed air supply system equipment mainly includes air compressors, filters, dryers and compressed air storage tanks. This project is equipped with a set of instrument air source devices to meet the instrument air source of the entire hydrogen station. The equipment includes air compressors, air storage tanks etc., to meet the gas requirements for hydrogen production system instruments.
4) Alkaline storage system
The lye storage system equipment mainly includes alkali storage tanks and lye delivery pumps. This system mainly realizes the loading and unloading of external lye, the configuration of dilute lye, and the recovery of waste lye, etc., to meet the distribution needs of the electrolytic solution for the hydrogen production system.
5) Nitrogen purging system
The nitrogen purge system equipment mainly includes nitrogen cylinder racks and nitrogen confluence racks, which provide inert gas replacement and purge functions for the hydrogen production system equipment to ensure the safe operation of the hydrogen production system.
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