PEM water electrolysis hydrogen production and waste heat utilization system based on refrigeration cycle

Abstract

The invention discloses a refrigeration cycle-based PEM water electrolysis hydrogen production and waste heat utilization system, which comprises a water electrolysis hydrogen production system, a refrigeration cycle system, a gas purification system and a waste heat utilization system, and is characterized in that the water electrolysis hydrogen production system is used for electrolyzing water to produce hydrogen and oxygen, carrying out steam-water separation, cooling gas and removing water; refrigerant of the refrigeration cycle system absorbs heat in the evaporator to cool water or gas, and releases heat in the condenser to heat water or gas. The gas purification system is used for drying the hydrogen to finally obtain high-purity hydrogen; the waste heat utilization system is used for heating alkali liquor at an inlet of the electrolytic bath in the circulation loop by using waste heat generated by electrolyzing water; the waste heat utilization in the PEM water electrolysis hydrogen production process is realized, the adaptability of the PEM electrolytic bath to the new energy power generation power fluctuation is further improved, the loss of water, heat and electric energy in the PEM water electrolysis process is reduced, the energy utilization rate of a PEM hydrogen production system is improved, the PEM water electrolysis hydrogen production cost is reduced, and the economic benefit is improved.

Description

Technical Field

[0001] This invention belongs to the field of water electrolysis for hydrogen production, specifically relating to a PEM water electrolysis hydrogen production and waste heat utilization system based on a refrigeration cycle. Background Technology

[0002] With the increasing severity of global environmental pollution and energy crises, the vigorous development of renewable energy and the acceleration of energy transition are urgently needed. Hydrogen energy has attracted widespread attention due to its advantages such as cleanliness, high efficiency, high calorific value, and wide availability of raw materials. In recent years, water electrolysis for green hydrogen production has become a very popular research area. Among the four water electrolysis hydrogen production technologies, PEM (proton exchange membrane) water electrolysis has advantages such as high hydrogen production efficiency, high purity of generated hydrogen, rapid start-up and shutdown, and high adaptability to fluctuations in renewable energy power generation, making it a currently very popular method. In addition, coupling renewable energy (such as wind and solar power) power generation with water electrolysis hydrogen production technology is also a very popular research area. Combining renewable energy power generation with water electrolysis hydrogen production, using renewable energy electricity to electrolyze water for hydrogen production, can achieve zero carbon dioxide emissions throughout the entire process.

[0003] The efficiency of PEM water electrolysis for hydrogen production is generally 75%–85%, and the optimal operating temperature of the electrolyzer during the hydrogen production process is around 70℃. Renewable energy power generation is characterized by intermittency, randomness, and volatility, and its power output is frequently affected by natural conditions. Although PEM water electrolysis for hydrogen production responds faster to fluctuations in renewable energy power generation and is more adaptable than alkaline water electrolysis, the wide power fluctuations in renewable energy generation still have a certain impact on the operation of the PEM electrolyzer, reducing its efficiency and lifespan.

[0004] In the PEM water electrolysis hydrogen production process, some electrical energy is converted into heat, causing the electrolyzer temperature to rise. This heat is carried out of the electrolyzer by the gas-liquid mixture at the outlet and is eventually carried away by cooling water or dissipated into the surrounding environment. Simultaneously, the adsorption of water by the molecular sieve in the hydrogen drying tower is physical adsorption. When adsorption becomes saturated, it requires a period of heating and regeneration before adsorption can resume; this process is called the desiccant regeneration process. When the drying tower is in regeneration mode, hydrogen is heated to 200°C by an electric heater within the tower, causing the water adsorbed by the molecular sieve to be released and carried out of the system. This process also consumes a significant amount of electrical energy, increasing the energy consumption and cost of the entire PEM hydrogen production system.

[0005] In addition, the temperature of the water in the deionizer will affect the deionization effect of the deionizer. The optimal temperature is 5-40℃, which is lower than the optimal operating temperature of the PEM electrolyzer. Therefore, the water temperature must be controlled to meet the operating requirements of the deionizer and the PEM electrolyzer.

[0006] In summary, existing PEM water electrolysis hydrogen production systems suffer from several problems, including the lack of comprehensive utilization of waste heat during operation, low heat recovery and utilization rate, poor adaptability to wide power fluctuations in new energy power generation, severe power consumption in the hydrogen purification system, and failure to consider the different optimal operating water temperatures of the deionizer and PEM electrolyzer. Summary of the Invention

[0007] In view of the problems existing in the above-mentioned PEM electrolysis water production technology, the purpose of this invention is to provide a PEM electrolysis water production and waste heat utilization system based on a refrigeration cycle, which reduces the loss of water, heat and electricity during water electrolysis, improves the system energy utilization rate, and reduces the cost of water electrolysis hydrogen production.

[0008] To achieve the above objectives, the present invention employs the following technical solution:

[0009] A PEM electrolysis water production and waste heat utilization system based on a refrigeration cycle includes a hydrogen production system, a gas purification system, a refrigeration cycle system, and a waste heat utilization system.

[0010] The hydrogen production system includes an electrolyzer. The cathode outlet of the electrolyzer is sequentially connected to a first hydrogen-side gas-liquid separator, a hydrogen-side evaporator, and a second hydrogen-side gas-liquid separator. The liquid outlet of the second hydrogen-side gas-liquid separator and the liquid outlet condensed from the hydrogen-side evaporator are both connected to the liquid inlet of the first hydrogen-side gas-liquid separator. The gas outlet of the second hydrogen-side gas-liquid separator is connected to a gas purification system. The anode outlet of the electrolyzer is sequentially connected to a first oxygen-side gas-liquid separator, an oxygen-side evaporator, a second oxygen-side gas-liquid separator, and an oxygen storage tank. The liquid outlet of the second oxygen-side gas-liquid separator and the liquid outlet condensed from the oxygen-side evaporator are both connected to the liquid inlet of the first oxygen-side gas-liquid separator. The liquid outlets of the first hydrogen-side gas-liquid separator and the first oxygen-side gas-liquid separator are both connected to the electrolyzer via pipelines, passing through a precision filter, a circulating pump, and a deionizer.

[0011] The gas purification system mainly includes a first drying tower, a second drying tower, and a third drying tower connected in parallel with the gas outlet of the second gas-liquid separator on the hydrogen side. The other side of the first drying tower, the second drying tower, and the third drying tower are connected to a hydrogen storage tank.

[0012] The refrigeration cycle system includes a hydrogen-side evaporator and an oxygen-side evaporator. The hydrogen-side evaporator is installed on the gas pipeline between the first and second hydrogen-side gas-liquid separators to condense and remove water from the hydrogen gas at the outlet of the first hydrogen-side gas-liquid separator. The oxygen-side evaporator is installed on the gas pipeline between the first and second oxygen-side gas-liquid separators to condense and remove water from the oxygen gas at the outlet of the first oxygen-side gas-liquid separator. A circulating evaporator is installed in parallel with the connecting pipeline between the circulating pump and the deionizer to heat the liquid entering the deionizer. The first, second, and third regeneration evaporators are respectively installed on the pipeline connecting the gas outlet of the second hydrogen-side gas-liquid separator to the first, second, and third drying towers to further cool the hydrogen gas entering each drying tower. The first, second, and third condensers are respectively installed on the gas outlet or gas inlet pipelines on the other side of the first, second, and third drying towers. The circulating condenser is installed on the heat exchanger circulation pipeline at the cathode outlet and anode outlet of the electrolytic cell.

[0013] In the refrigeration cycle system, the refrigerant flows through the hydrogen-side evaporator, oxygen-side evaporator, circulating evaporator, first regeneration evaporator, second regeneration evaporator, and third regeneration evaporator to absorb heat before entering the compressor for compression. Then, it passes through the first condenser, second condenser, third condenser, and circulating condenser to release heat before entering the expansion valve. The refrigerant at the outlet of the expansion valve enters the evaporator to complete the refrigeration cycle.

[0014] The waste heat utilization system mainly includes a hydrogen-side heat exchanger and an oxygen-side heat exchanger. The hydrogen-side heat exchanger is installed on the connecting pipeline between the cathode outlet of the electrolytic cell and the first gas-liquid separator on the hydrogen side, and the oxygen-side heat exchanger is installed on the connecting pipeline between the anode outlet of the electrolytic cell and the first gas-liquid separator on the oxygen side. A water circulation heating loop is formed between the hydrogen-side heat exchanger, the oxygen-side heat exchanger, the circulating condenser, and the deionizer outlet pipeline. The hydrogen-side heat exchanger and the oxygen-side heat exchanger are used to exchange heat between the liquid at the deionizer outlet and the gas-liquid mixture at the electrolytic cell outlet, and at the same time, the heat from the circulating condenser is used to increase the water temperature entering the electrolytic cell.

[0015] Furthermore, the pure water tank is connected to the liquid inlet of the first gas-liquid separator on the hydrogen side via a water replenishment pump. The water in the pure water tank is pumped to the first gas-liquid separator on the hydrogen side to replenish the water consumed in the electrolysis process.

[0016] Furthermore, the system piping also includes control valves for regulating the flow of refrigerant, circulating water, or hydrogen;

[0017] The second, fifth, sixth, eighth, ninth, tenth, eleventh, twelfth, and thirteenth control valves are respectively installed on the refrigerant inlet pipes of the circulating evaporator, hydrogen-side evaporator, oxygen-side evaporator, first condenser, second condenser, third condenser, first regenerating evaporator, second regenerating evaporator, and third regenerating evaporator, and are used to change the direction and flow rate of the refrigerant.

[0018] Furthermore, the first control valve is a three-way valve, which is installed between the circulating pump and the deionizer and connected to the circulating evaporator. The circulating evaporator is connected in parallel with the connecting pipeline between the circulating pump and the deionizer.

[0019] Furthermore, the fourth control valve is installed on the connecting pipeline between the oxygen-side heat exchanger and the circulating condenser. A branch of the fourth control valve is led out from the oxygen-side heat exchanger and the circulating condenser through a three-way valve to form a parallel connection with the circulating condenser. The third control valve is installed on the connecting pipeline between the hydrogen-side heat exchanger and the deionizer. By adjusting the third control valve in the water circulation loop, the flow rate of water passing through the first heat exchanger on the hydrogen side and the first heat exchanger on the oxygen side can be changed. By adjusting the first control valve and the fourth control valve, the flow direction of water in the pipeline can be changed.

[0020] Furthermore, the seventh control valve of the three-way valve is installed on the connecting pipe on one side of the first condenser, the second condenser, and the third condenser, connecting the pipes on the same side of the first condenser, the second condenser, and the third condenser. The fourteenth control valve is installed on the connecting pipe on the same side of the first regenerating evaporator and the second regenerating evaporator, connecting the two to each other. The fifteenth control valve is installed on the connecting pipe on the same side of the second regenerating evaporator and the third regenerating evaporator, connecting the two to each other. The flow direction of hydrogen in the drying system can be changed by adjusting the seventh, fourteenth, and fifteenth control valves.

[0021] Furthermore, the first regenerating evaporator, the second regenerating evaporator, and the third regenerating evaporator are arranged in parallel, as are the first condenser, the second condenser, and the third condenser.

[0022] Furthermore, the liquid outlet separated by the hydrogen-side evaporator is connected to the liquid inlet of the first gas-liquid separator on the hydrogen side, and the liquid outlet separated by the oxygen-side evaporator is connected to the liquid inlet of the first gas-liquid separator on the oxygen side. The hydrogen gas entering the hydrogen-side evaporator and the liquid separated by the oxygen-side evaporator are finally collected in the precision filter for filtration and then flowed back to the electrolytic cell by the circulation pump.

[0023] Furthermore, the condensate outlets of the circulating evaporator, the first regenerating evaporator, the second regenerating evaporator, and the third regenerating evaporator are respectively connected to the liquid outlet pipelines of the first gas-liquid separator and the oxygen-side first gas-liquid separator via pipelines; the water separated from the circulating evaporator, the first regenerating evaporator, the second regenerating evaporator, and the third regenerating evaporator after condensing hydrogen is combined with the water from the outlets of the hydrogen-side first gas-liquid separator and the oxygen-side first gas-liquid separator and flows together into the precision filter for filtration.

[0024] Furthermore, the hydrogen-side first gas-liquid separator and the oxygen-side first gas-liquid separator are connected together.

[0025] As can be seen from the above technical solutions, the present invention has the following advantages:

[0026] 1. The gas-liquid mixture at the outlet of the electrolyzer is cooled by heat exchange and then enters the first gas-liquid separator on the hydrogen side for gas-liquid separation. The gas-liquid mixture in the gas-liquid separator has a lower temperature and a lower degree of liquid atomization, which is more conducive to gas-liquid separation and reduces the cooling cost in the gas-liquid separation process.

[0027] 2. After heat exchange, the water in the circulating loop and the gas-liquid mixture at the electrolyzer outlet increase in temperature. The flow rate of the alkali solution through the heat exchanger can be adjusted by regulating the valves in the alkali circulation loop according to actual operating conditions. Simultaneously, a circulating evaporator and a circulating condenser are installed in the circulation loop, allowing for flexible adjustment of the deionizer and electrolyzer inlet water temperatures based on the renewable energy power generation capacity. This improves temperature control accuracy, further enhances the electrolyzer's adaptability to wide power fluctuations, and better couples with renewable energy power generation. This reduces the loss of water, heat, and electricity during PEM water electrolysis, improves the energy utilization rate of the entire PEM hydrogen production system, lowers the cost of PEM water electrolysis hydrogen production, and increases economic efficiency.

[0028] 3. The gas is cooled by a compressed steam refrigeration cycle, which has a better condensation effect than cooling water and is more conducive to the condensation of water in the gas, thus reducing water loss during electrolysis.

[0029] 4. By utilizing the heat released by the refrigerant in the condenser of the compressed steam refrigeration cycle system to heat the hydrogen, the temperature of the hydrogen at the inlet of the regeneration drying tower is increased. This temperature is then used for desiccant regeneration, reducing the power consumption of the electric heater in the regeneration drying tower and significantly lowering the regeneration cost of the gaseous desiccant. Simultaneously, the heat released by the condenser can also be used for heating and providing domestic hot water, improving thermal energy utilization. Attached Figure Description

[0030] Figure 1 This is a flow chart of the PEM water electrolysis and waste heat utilization system based on the compressed steam refrigeration cycle of the present invention;

[0031] In the diagram: 1-Pure water tank; 2-Electrolyzer; 3-Hydrogen-side heat exchanger; 4-Oxygen-side heat exchanger; 5-Hydrogen-side first gas-liquid separator; 6-Oxygen-side and hydrogen-side first gas-liquid separator; 7-Hydrogen-side evaporator; 8-Oxygen-side evaporator; 9-Hydrogen-side second gas-liquid separator; 10-Oxygen-side second gas-liquid separator; 11-Precision filter; 12-Deionizer; 13-Make-up water pump; 14-Circulation pump; 15-Circulation evaporator; 16-Circulation condenser; 17-First regeneration evaporator; 18-Second regeneration evaporator; 19-Third regeneration evaporator; 20-First drying tower; 21-Second drying tower; 22- 23-First condenser; 24-Second condenser; 25-Third condenser; 26-Compressor; 27-Throttle valve; 28-First control valve; 29-Second control valve; 30-Third control valve; 31-Fourth control valve; 32-Fifth control valve; 33-Sixth control valve; 34-Seventh control valve; 35-Eighth control valve; 36-Ninth control valve; 37-Tenth control valve; 38-Eleventh control valve; 39-Twelfth control valve; 40-Thirteenth control valve; 41-Fourteenth control valve; 42-Fifteenth control valve; 43-Oxygen storage tank; 44-Hydrogen storage tank. Detailed Implementation

[0032] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments.

[0033] See Figure 1 The present invention discloses a PEM water electrolysis hydrogen production and waste heat utilization system, comprising a hydrogen production system, a gas purification system, a refrigeration cycle system and a waste heat utilization system.

[0034] The hydrogen production system includes a pure water tank 1, a water replenishment pump 13, an electrolyzer 2, a hydrogen-side first gas-liquid separator 5, an oxygen-side first gas-liquid separator 6, a hydrogen-side evaporator 7, an oxygen-side evaporator 8, a hydrogen-side second gas-liquid separator 9, an oxygen-side second gas-liquid separator 10, a precision filter 11, and a deionizer 12; it is used to generate a gas-liquid mixture by electrolyzing water, to separate, cool, and remove water from the gas, and to filter and purify the inlet water of the electrolyzer.

[0035] The cathode outlet of the electrolytic cell 2 is sequentially connected to the first hydrogen-side gas-liquid separator 5, the hydrogen-side evaporator 7, and the second hydrogen-side gas-liquid separator 9. The pure water tank 1 is connected to the liquid inlet of the first hydrogen-side gas-liquid separator 5 via a water replenishment pump 13. Water from the pure water tank 1 is pumped to the first hydrogen-side gas-liquid separator 5 via the water replenishment pump 13 to replenish the water consumed during the electrolysis process. The liquid outlet of the second hydrogen-side gas-liquid separator 9 and the liquid outlet condensed from the hydrogen-side evaporator 7 are both connected to the liquid inlet of the first hydrogen-side gas-liquid separator 5. The gas outlet of the second hydrogen-side gas-liquid separator 9 is connected to the gas purification system. The anode outlet of the electrolytic cell 2 is sequentially connected to the first oxygen-side gas-liquid separator 6, the oxygen-side evaporator 8, the second oxygen-side gas-liquid separator 10, and the oxygen storage tank 43. The liquid outlet of the second oxygen-side gas-liquid separator 10 and the liquid outlet condensed from the oxygen-side evaporator 8 are both connected to the liquid inlet of the first oxygen-side gas-liquid separator 6. The hydrogen-side first gas-liquid separator 5 and the oxygen-side first gas-liquid separator 6 are connected. The liquid outlets of the hydrogen-side first gas-liquid separator 5 and the oxygen-side first gas-liquid separator 6 are connected to the electrolytic cell 2 via pipelines through a precision filter 11, a circulation pump 14, and a deionizer 12.

[0036] The water separated by the hydrogen-side first gas-liquid separator 5 and the oxygen-side first gas-liquid separator 6 flows through a circulation pipeline, passing through a precision filter 11 to filter impurities from the pure water, and then through a circulation pump 14 before directly entering the deionizer 12, or first flowing through a circulating evaporator 15 before entering the deionizer 12. The precision filter 11 can filter particles larger than 0.01 μm in diameter from the water. The deionizer is filled with an ion exchange resin bed for purifying the pure water and improving its quality.

[0037] The gas-liquid mixture at the cathode outlet of electrolytic cell 2 enters the first gas-liquid separator 5 on the hydrogen side for gas-liquid separation. The separated gas enters the hydrogen-side evaporator 7 for cooling. The cooled hydrogen gas from the hydrogen-side evaporator 7 enters the second gas-liquid separator 9 on the hydrogen side for gas-liquid separation. The liquid separated from the second gas-liquid separator 9 and the liquid condensed from the hydrogen-side evaporator 7 are collected back to the first gas-liquid separator 5 on the hydrogen side. The separated alkaline solution returns to electrolytic cell 2 via a circulation pipeline. The gas-liquid mixture at the anode outlet of electrolytic cell 2 enters the first gas-liquid separator 6 on the oxygen side for gas-liquid separation. The separated gas enters the oxygen-side evaporator 8 for cooling. The cooled oxygen enters the second gas-liquid separator 10 on the oxygen side for gas-liquid separation. The oxygen at the outlet of the second gas-liquid separator 10 enters the oxygen storage tank 43 or is vented. The liquid separated from the second gas-liquid separator 10 and the liquid condensed from the oxygen-side evaporator 8 are collected back to the first gas-liquid separator 6 on the oxygen side. The alkaline solution separated from the first gas-liquid separator 6 on the oxygen side returns to electrolytic cell 2 via a circulation pipeline.

[0038] The gas purification system mainly includes a first drying tower 20, a second drying tower 21, and a third drying tower 22 connected in parallel, used to dry hydrogen to produce high-purity, low-dew-point hydrogen. The first drying tower 20, the second drying tower 21, and the third drying tower 22 are connected to the gas outlet of the second gas-liquid separator 9 on the hydrogen side, and the other side of the first drying tower 20, the second drying tower 21, and the third drying tower 22 are connected to a hydrogen storage tank.

[0039] The refrigeration cycle system includes a hydrogen-side evaporator 7, an oxygen-side evaporator 8, a circulating evaporator 15, a first regeneration evaporator 17, a second regeneration evaporator 18, a third regeneration evaporator 19, a compressor 26, a first condenser 23, a second condenser 24, a third condenser 25, a circulating condenser 16, and a throttling valve 27. In the evaporators, the refrigerant absorbs heat to condense and remove water from the gas, lowering the inlet water temperature of the deionizer when the electrolyzer is operating at high load. In the condensers, the refrigerant releases heat to heat the hydrogen gas at the inlet of the regeneration drying tower, raising the inlet water temperature of the electrolyzer when it is operating at low load.

[0040] The hydrogen-side evaporator 7 is installed on the gas pipeline between the first hydrogen-side gas-liquid separator 5 and the second hydrogen-side gas-liquid separator 9. Hydrogen gas from the outlet of the first hydrogen-side gas-liquid separator 5 enters the hydrogen-side evaporator 7 for condensation and water removal. The oxygen-side evaporator 8 is installed on the gas pipeline between the first oxygen-side gas-liquid separator 6 and the second oxygen-side gas-liquid separator 10. Oxygen gas from the outlet of the first oxygen-side gas-liquid separator 6 enters the oxygen-side evaporator 8 for condensation and water removal. The circulating evaporator 15 is installed in parallel with the connecting pipeline between the circulating pump 14 and the deionizer 12. The first regeneration evaporator... Unit 17, the second regenerating evaporator 18, and the third regenerating evaporator 19 are respectively installed on the pipeline connecting the gas outlet of the second gas-liquid separator 9 on the hydrogen side to the first drying tower 20, the second drying tower 21, and the third drying tower 22 to further cool the hydrogen entering each drying tower; the first condenser 23, the second condenser 24, and the third condenser 25 are respectively installed on the gas outlet or gas inlet pipeline on the other side of the first drying tower 20, the second drying tower 21, and the third drying tower 22; the circulating condenser 16 is installed on the heat exchanger circulation pipeline set at the cathode outlet and anode outlet of the electrolytic cell 2.

[0041] The refrigerant outlets of the hydrogen-side evaporator 7, oxygen-side evaporator 8, circulating evaporator 15, first regeneration evaporator 17, second regeneration evaporator 18, and third regeneration evaporator 19 are all connected to the refrigerant inlet of compressor 26 via pipelines. The refrigerant outlet of compressor 26 is connected to the refrigerant inlets of first condenser 23, second condenser 24, third condenser 25, and circulating condenser 16, respectively. The refrigerant outlets of first condenser 23, second condenser 24, third condenser 25, and circulating condenser 16 are all connected to the inlet of expansion valve 27 via pipelines. The outlet of expansion valve 27 is then connected to the refrigerant inlets of hydrogen-side evaporator 7, oxygen-side evaporator 8, circulating evaporator 15, first regeneration evaporator 17, second regeneration evaporator 18, and third regeneration evaporator 19 via pipelines. In the refrigeration cycle system, the refrigerant flows through the hydrogen-side evaporator 7, oxygen-side evaporator 8, circulating evaporator 15, first regeneration evaporator 17, second regeneration evaporator 18, and third regeneration evaporator 19, absorbing heat before entering the compressor 26 for compression. It then releases heat through the first condenser 23, second condenser 24, third condenser 25, and circulating condenser 16 before entering the expansion valve 27. The refrigerant at the outlet of the expansion valve 27 enters the evaporator to complete the refrigeration cycle. The evaporators and condensers are arranged in parallel. The refrigerant in the refrigeration cycle system can be any refrigerant that meets the requirements of the refrigeration cycle.

[0042] The liquid outlet separated by the hydrogen-side evaporator 7 is connected to the liquid inlet of the first gas-liquid separator 5 on the hydrogen side, and the liquid outlet separated by the oxygen-side evaporator 8 is connected to the liquid inlet of the first gas-liquid separator 6 on the oxygen side. The liquid separated by the hydrogen-side evaporator 7 and the oxygen-side evaporator 8 is finally collected in the precision filter 11 for filtration and then flows back to the electrolytic cell 2 via the circulation pump 14.

[0043] The condensate outlets of the circulating evaporator 15, the first regenerating evaporator 17, the second regenerating evaporator 18, and the third regenerating evaporator 19 are connected to the liquid outlet pipelines of the first gas-liquid separator 5 and the oxygen-side first gas-liquid separator 6, respectively, through pipelines. The water separated after the circulating evaporator 15, the first regenerating evaporator 17, the second regenerating evaporator 18, and the third regenerating evaporator 19 condenses hydrogen is combined with the water from the outlets of the hydrogen-side first gas-liquid separator 5 and the oxygen-side first gas-liquid separator 6 and flows together into the precision filter 11 for filtration.

[0044] The waste heat utilization system mainly includes a hydrogen-side heat exchanger 3 and an oxygen-side heat exchanger 4. The hydrogen-side heat exchanger 3 is installed on the connecting pipeline between the cathode outlet of the electrolytic cell 2 and the first hydrogen-side gas-liquid separator 5. The gas-liquid mixture at the cathode outlet of the electrolytic cell 2 enters the first hydrogen-side gas-liquid separator 5 after heat exchange through the hydrogen-side heat exchanger 3. The oxygen-side heat exchanger 4 is installed on the connecting pipeline between the anode outlet of the electrolytic cell 2 and the first oxygen-side gas-liquid separator 6. The gas-liquid mixture at the anode outlet of the electrolytic cell 2 enters the first oxygen-side gas-liquid separator 6 for gas-liquid separation after heat exchange through the first oxygen-side heat exchanger 4. A water circulation heating loop is formed between the hydrogen-side heat exchanger 3, the oxygen-side heat exchanger 4, the circulating condenser 16, and the outlet pipeline of the deionizer 12. The hydrogen-side heat exchanger 3 and the oxygen-side heat exchanger 4 are used to exchange heat between the liquid at the outlet of the deionizer 12 and the gas-liquid mixture at the outlet of the electrolyzer 5, thereby reducing the temperature of the gas-liquid mixture entering the hydrogen-side first gas-liquid separator 5 and the oxygen-side first gas-liquid separator 6. At the same time, the heat from the circulating condenser 16 is used to increase the water temperature entering the electrolyzer 2.

[0045] In addition, the system piping also includes control valves for regulating the flow of refrigerant, circulating water, or hydrogen. Second control valve 29, fifth control valve 32, sixth control valve 33, eighth control valve 35, ninth control valve 36, tenth control valve 37, eleventh control valve 38, twelfth control valve 39, and thirteenth control valve 40 are respectively installed on the refrigerant inlet pipes of the circulating evaporator 15, hydrogen-side evaporator 7, oxygen-side evaporator 8, first condenser 23, second condenser 24, third condenser 25, first regenerator evaporator 17, second regenerator evaporator 18, and third regenerator evaporator 19. During electrolysis, the second control valve 29, fifth control valve 32, sixth control valve 33, eighth control valve 35, ninth control valve 36, tenth control valve 37, eleventh control valve 38, twelfth control valve 39, and thirteenth control valve 40 at the evaporator and condenser inlets need to be adjusted according to the actual situation to change the refrigerant flow direction and flow rate.

[0046] The first control valve 28, the fourth control valve 31, and the seventh control valve 34 are all three-way valves. The first control valve 28 is installed between the circulation pump 14 and the deionizer 12 and is connected to the circulation evaporator 15 through the first control valve 28. The connection pipeline between the circulation evaporator 15 and the circulation pump 14 and the deionizer 12 is in parallel; the fourth control valve 31 is installed on the connection pipeline between the oxygen-side heat exchanger 4 and the circulation condenser 16. A branch is led out from between the oxygen-side heat exchanger 4 and the circulation condenser 16 through the fourth control valve 31 to form a parallel connection with the circulation condenser 16. The third control valve 30 is installed on the connection pipeline between the hydrogen-side heat exchanger 3 and the deionizer 12. By adjusting the third control valve 30 in the water circulation loop in real time according to the actual operating load of the electrolytic cell, the flow rate of water passing through the first heat exchanger 3 on the hydrogen side and the first heat exchanger 4 on the oxygen side can be changed. During different operating loads of the electrolytic cell, the first control valve 28 and the fourth control valve 31 can be adjusted to change the flow direction of water in the pipeline.

[0047] The seventh control valve 34 is installed on the connection pipeline on one side of the first condenser 23, the second condenser 24, and the third condenser 25, and the same-side pipelines of the first condenser 23, the second condenser 24, and the third condenser 25 are connected through the seventh control valve 34. The fourteenth control valve 41 is installed on the connection pipeline on the same side of the first regeneration evaporator 17 and the second regeneration evaporator 18 to connect them to each other. The fifteenth control valve 42 is installed on the connection pipeline on the same side of the second regeneration evaporator 18 and the third regeneration evaporator 19 to connect them to each other; by adjusting the seventh control valve 34, the fourteenth control valve 41, and the fifteenth control valve 42, the flow direction of hydrogen in the drying system can be changed.

[0048] The drying tower uses molecular sieve as an adsorbent, allowing non-polar molecules such as hydrogen to pass through, but having a strong affinity for highly polar molecules such as water. The adsorption of the molecular sieve is physical adsorption. When the adsorption is saturated, it takes some time to be heated and regenerated to remove the moisture in the molecular sieve before it can adsorb again. The hydrogen drying adopts a three-tower联动 drying process. In one cycle, the first drying tower 20, the second drying tower 21, and the third drying tower 22 all sequentially experience the main working, regeneration, and sub-working states.

[0049] When the first drying tower 20, second drying tower 21, and third drying tower 22 are in main operation, regeneration, and secondary operation states, respectively, the second condenser 24 is activated by adjusting the valves, and no refrigerant passes through the first condenser 23 and third condenser 25. Hydrogen gas from the outlet of the second gas-liquid separator 9 on the hydrogen side flows sequentially through the first regeneration evaporator 17 and the first drying tower 20, where it is cooled and dried respectively. After passing through the first condenser 23, the hydrogen gas enters the second condenser 24. Heated by the refrigerant in the second condenser 24, the hydrogen gas enters the second drying tower 21, where it is electrically heated to 200°C, desorbing the water adsorbed in the molecular sieve. The high-temperature hydrogen gas, carrying the water desorbed from the molecular sieve in the second drying tower 21, enters the second regeneration evaporator 18 for cooling. Finally, the hydrogen gas sequentially enters the third regeneration evaporator 19 and the third drying tower 22, where it is cooled and dried again. The dried hydrogen gas then enters the third condenser 25, and the high-purity hydrogen gas obtained from the outlet of the third condenser 25 is stored in the hydrogen storage tank 44. Figure 1 The gas drying process is only shown when the first drying tower 20, the second drying tower 21, and the third drying tower 22 are in the main working, regeneration, and secondary working states, respectively. When the first drying tower 20, the second drying tower 21, and the third drying tower 22 are in other working states, the gas drying process needs to be changed accordingly.

[0050] Example 1

[0051] When the electrolyzer is operating at low load, the gas-liquid mixture at the anode outlet of electrolyzer 2 is cooled by the oxygen-side heat exchanger 4 and then enters the first oxygen-side gas-liquid separator 6 for gas-liquid separation. The sixth control valve 33 is opened to allow refrigerant to pass through the oxygen-side evaporator 8. The gas separated by the first oxygen-side gas-liquid separator 6 enters the oxygen-side evaporator 8 for cooling, and then enters the second oxygen-side gas-liquid separator 10 for further gas-liquid separation. The separated oxygen is either vented or stored in the oxygen storage tank 43. The gas-liquid mixture at the cathode outlet of electrolyzer 2 is cooled by the hydrogen-side heat exchanger 3 and then enters the first hydrogen-side gas-liquid separator 5 for gas-liquid separation. The fifth control valve 32 is opened to allow refrigerant to pass through the hydrogen-side evaporator 7. The gas separated by the first hydrogen-side gas-liquid separator 5 enters the hydrogen-side evaporator 7 for cooling, and then enters the second hydrogen-side gas-liquid separator 9 for further gas-liquid separation. The separated hydrogen enters the gas purification system for drying. Water separated by the hydrogen-side first gas-liquid separator 5 and the oxygen-side first gas-liquid separator 6 passes through a precision filter 11 to remove particles larger than 0.01 μm in diameter. Adjusting the first control valve 28 allows the water from the outlet of the precision filter 11 to directly enter the deionizer 12 after passing through the circulation pump 14. Since the electrolyzer 2 is operating at a low load, adjusting the third control valve 30 and the fourth control valve 31 sequentially sends the purified water from the deionizer 12 to the hydrogen-side heat exchanger 3, the oxygen-side heat exchanger 4, and the circulating condenser 16 for heat exchange and temperature increase. The heated water then flows back into the electrolyzer 2. During electrolysis, the pure water in the pure water tank 1 is pumped by the makeup water pump 13 to the hydrogen-side first gas-liquid separator 5 and the oxygen-side first gas-liquid separator 6 to replenish the water consumed during electrolysis. Hydrogen enters the gas purification system. The openings of control valves 11 (38), 12 (39), and 13 (40) are adjusted according to actual condensation requirements. Opening control valves 11 (38), 12 (39), and 13 (40) allows refrigerant to pass through the first regenerator evaporator 17, the second regenerator evaporator 18, and the third regenerator evaporator 19, respectively. The first drying tower 20, the second drying tower 21, and the third drying tower 22 sequentially experience main operating, regeneration, and secondary operating states within one cycle. Only the operating procedures when the first drying tower 20, the second drying tower 21, and the third drying tower 22 are in the main operating, regeneration, and secondary operating states, respectively, are described here. Control valve 9 (36) is opened to put the second condenser 24 into operation. Control valves 8 (35) and 10 (37) are closed to prevent refrigerant from passing through the first condenser 23 and the third condenser 25. Control valve 14 (41) is closed, and the hydrogen from the outlet of the second gas-liquid separator 9 on the hydrogen side flows sequentially through the first regenerator evaporator 17 and the first drying tower 20, where it is cooled and dried, respectively. Adjusting the seventh control valve 34, hydrogen gas passes through the first condenser 23 and then enters the second condenser 24. Heated by the refrigerant in the second condenser 24, the hydrogen gas enters the second drying tower 21, where it is electrically heated to 200°C, desorbing the water adsorbed in the molecular sieve. The high-temperature hydrogen gas, carrying the water desorbed from the molecular sieve in the second drying tower 21, enters the second regenerating evaporator 18 for cooling.The fifteenth control valve 42 is opened, and the hydrogen gas sequentially enters the third regenerating evaporator 19 and the third drying tower 22, where it is cooled and dried again. The dried hydrogen gas then enters the third condenser 25, and the high-purity hydrogen gas obtained from the outlet of the third condenser 25 enters the hydrogen storage tank 44 for storage. The water obtained from cooling the hydrogen gas in the circulating evaporator 15, the first regenerating evaporator 17, the second regenerating evaporator 18, and the third regenerating evaporator 19 is mixed with the water separated by the first gas-liquid separator 5 on the hydrogen side and the first gas-liquid separator 6 on the oxygen side, and finally flows into the electrolyzer 2 together.

[0052] Example 2

[0053] During normal operation of the electrolyzer, the gas-liquid mixture at the anode outlet of electrolyzer 2 is cooled by the oxygen-side heat exchanger 4 and then enters the first oxygen-side gas-liquid separator 6 for gas-liquid separation. Opening the sixth control valve 33 allows the refrigerant to pass through the oxygen-side evaporator 8. The gas separated by the first oxygen-side gas-liquid separator 6 enters the oxygen-side evaporator 8 for cooling, and then enters the second oxygen-side gas-liquid separator 10 for further gas-liquid separation. The separated oxygen is either vented or stored in the oxygen storage tank 43. The gas-liquid mixture at the cathode outlet of electrolyzer 2 is cooled by the hydrogen-side heat exchanger 3 and then enters the first hydrogen-side gas-liquid separator 5 for gas-liquid separation. Opening the fifth control valve 32 allows the refrigerant to pass through the hydrogen-side evaporator 7. The gas separated by the first hydrogen-side gas-liquid separator 5 enters the hydrogen-side evaporator 7 for cooling, and then enters the second hydrogen-side gas-liquid separator 9 for further gas-liquid separation. The separated hydrogen enters the gas purification system for drying. Water separated by the hydrogen-side first gas-liquid separator 5 and the oxygen-side first gas-liquid separator 6 passes through a precision filter 11 to remove particles larger than 0.01 μm in diameter. Adjusting the first control valve 28 allows the water from the outlet of the precision filter 11 to directly enter the deionizer 12 after passing through the circulation pump 14. Since the electrolyzer is in normal operation, adjusting the third control valve 30 allows the purified water from the deionizer 12 to be sequentially fed into the hydrogen-side heat exchanger 3 and the oxygen-side heat exchanger 4 for heat exchange and temperature increase. Closing the fourth control valve 31 allows the purified water from the outlet of the oxygen-side heat exchanger 4 to flow directly into the electrolyzer 2. During electrolysis, the purified water in the pure water tank 1 is pumped by the water replenishment pump 13 to the hydrogen-side first gas-liquid separator 5 and the oxygen-side first gas-liquid separator 6 to replenish the water consumed during electrolysis. Hydrogen enters the gas purification system. The openings of control valves 11 (38), 12 (39), and 13 (40) are adjusted according to actual condensation requirements. Opening control valves 11 (38), 12 (39), and 13 (40) allows refrigerant to pass through the first regenerator evaporator 17, the second regenerator evaporator 18, and the third regenerator evaporator 19, respectively. The first drying tower 20, the second drying tower 21, and the third drying tower 22 sequentially experience main operating, regeneration, and secondary operating states within one cycle. Only the operating procedures when the first drying tower 20, the second drying tower 21, and the third drying tower 22 are in the main operating, regeneration, and secondary operating states, respectively, are described here. Control valve 9 (36) is opened to put the second condenser 24 into operation. Control valves 8 (35) and 10 (37) are closed to prevent refrigerant from passing through the first condenser 23 and the third condenser 25. Control valve 14 (41) is closed, and the hydrogen from the outlet of the second gas-liquid separator 9 on the hydrogen side flows sequentially through the first regenerator evaporator 17 and the first drying tower 20, where it is cooled and dried, respectively. Adjusting the seventh control valve 34, hydrogen gas passes through the first condenser 23 and then enters the second condenser 24. Heated by the refrigerant in the second condenser 24, the hydrogen gas enters the second drying tower 21, where it is electrically heated to 200°C, desorbing the water adsorbed in the molecular sieve. The high-temperature hydrogen gas, carrying the water desorbed from the molecular sieve in the second drying tower 21, enters the second regenerating evaporator 18 for cooling.The fifteenth control valve 42 is opened, and the hydrogen gas sequentially enters the third regenerating evaporator 19 and the third drying tower 22, where it is cooled and dried again. The dried hydrogen gas then enters the third condenser 25, and the high-purity hydrogen gas obtained from the outlet of the third condenser 25 enters the hydrogen storage tank 44 for storage. The water obtained from cooling the hydrogen gas in the circulating evaporator 15, the first regenerating evaporator 17, the second regenerating evaporator 18, and the third regenerating evaporator 19 is mixed with the water separated by the first gas-liquid separator 5 on the hydrogen side and the first gas-liquid separator 6 on the oxygen side, and finally flows into the electrolyzer 2 together.

[0054] Example 3

[0055] When the electrolyzer is operating under high load, the gas-liquid mixture at the anode outlet of electrolyzer 2 is cooled by the oxygen-side heat exchanger 4 and then enters the first oxygen-side gas-liquid separator 6 for gas-liquid separation. The sixth control valve 33 is opened to allow refrigerant to pass through the oxygen-side evaporator 8. The gas separated by the first oxygen-side gas-liquid separator 6 enters the oxygen-side evaporator 8 for cooling, and then enters the second oxygen-side gas-liquid separator 10 for further gas-liquid separation. The separated oxygen is either vented or stored in the oxygen storage tank 43. The gas-liquid mixture at the cathode outlet of electrolyzer 2 is cooled by the hydrogen-side heat exchanger 3 and then enters the first hydrogen-side gas-liquid separator 5 for gas-liquid separation. The fifth control valve 32 is opened to allow refrigerant to pass through the hydrogen-side evaporator 7. The gas separated by the first hydrogen-side gas-liquid separator 5 enters the hydrogen-side evaporator 7 for cooling, and then enters the second hydrogen-side gas-liquid separator 9 for further gas-liquid separation. The separated hydrogen enters the gas purification system for drying. Water separated by the hydrogen-side first gas-liquid separator 5 and the oxygen-side first gas-liquid separator 6 passes through a precision filter 11 to remove particles larger than 0.01 μm in diameter. Since the electrolyzer is operating under high load, the first control valve 28 is adjusted so that the pure water from the outlet of the precision filter 11 enters the circulating evaporator 15 via the circulating pump 14, cooling the pure water temperature to below 40°C. The pure water from the outlet of the circulating evaporator 15 enters the deionizer 12. The third control valve 30 is adjusted so that the purified water from the deionizer 12 is sequentially fed into the hydrogen-side heat exchanger 3 and the oxygen-side heat exchanger 4 for heat exchange and temperature increase. The fourth control valve 31 is closed, and the pure water from the outlet of the oxygen-side heat exchanger 4 flows directly into the electrolyzer 2. During electrolysis, the pure water in the pure water tank 1 is pumped by the makeup water pump 13 to the hydrogen-side first gas-liquid separator 5 and the oxygen-side first gas-liquid separator 6 to replenish the water consumed during electrolysis. Hydrogen enters the gas purification system. The openings of control valves 11 (38), 12 (39), and 13 (40) are adjusted according to actual condensation requirements. Opening control valves 11 (38), 12 (39), and 13 (40) allows refrigerant to pass through the first regenerator evaporator 17, the second regenerator evaporator 18, and the third regenerator evaporator 19, respectively. The first drying tower 20, the second drying tower 21, and the third drying tower 22 sequentially experience main operating, regeneration, and secondary operating states within one cycle. Only the operating procedures when the first drying tower 20, the second drying tower 21, and the third drying tower 22 are in the main operating, regeneration, and secondary operating states, respectively, are described here. Control valve 9 (36) is opened to put the second condenser 24 into operation. Control valves 8 (35) and 10 (37) are closed to prevent refrigerant from passing through the first condenser 23 and the third condenser 25. Control valve 14 (41) is closed, and the hydrogen from the outlet of the second gas-liquid separator 9 on the hydrogen side flows sequentially through the first regenerator evaporator 17 and the first drying tower 20, where it is cooled and dried, respectively. Adjusting the seventh control valve 34, hydrogen gas passes through the first condenser 23 and then enters the second condenser 24. After being heated by the refrigerant in the second condenser 24, the hydrogen gas enters the second drying tower 21. In the second drying tower 21, the hydrogen gas is electrically heated to 200°C, causing the adsorbed water in the molecular sieve to be desorbed.High-temperature hydrogen gas, carrying water desorbed from the molecular sieve in the second drying tower 21, enters the second regenerating evaporator 18 for cooling. The fifteenth control valve 42 is opened, and the hydrogen gas sequentially enters the third regenerating evaporator 19 and the third drying tower 22, where it is cooled and dried again. The dried hydrogen gas then enters the third condenser 25, and the high-purity hydrogen gas exiting the third condenser 25 is stored in the hydrogen storage tank 44. The water obtained from cooling the hydrogen gas in the circulating evaporator 15, the first regenerating evaporator 17, the second regenerating evaporator 18, and the third regenerating evaporator 19 is mixed with the water separated by the first gas-liquid separator 5 on the hydrogen side and the first gas-liquid separator 6 on the oxygen side, and finally flows into the electrolyzer 2.

[0056] Compared to existing technologies, this invention involves a gas-liquid mixture at the electrolyzer outlet undergoing heat exchange and cooling before entering the first gas-liquid separator on the hydrogen side for gas-liquid separation. The lower temperature and reduced liquid atomization in the separator facilitate gas-liquid separation and reduce cooling costs during the process. In the circulating loop, the water temperature rises after heat exchange with the gas-liquid mixture at the electrolyzer outlet. The flow rate of the alkali solution through the heat exchanger can be adjusted by regulating the valves in the alkali solution circulating loop according to actual operating conditions. Furthermore, a circulating evaporator and a circulating condenser are incorporated into the circulating loop, allowing for flexible adjustments based on the power generation capacity of the new energy source. By varying the inlet water temperature of the deionizer and electrolyzer, the accuracy of temperature control is improved, further enhancing the electrolyzer's adaptability to wide power fluctuations and better coupling with renewable energy power generation. Utilizing a compressed steam refrigeration cycle to cool the gas provides better condensation than cooling water, facilitating water condensation in the gas and reducing water loss during electrolysis. The heat released by the refrigerant in the condenser of the compressed steam refrigeration cycle system is used to heat hydrogen, increasing the inlet hydrogen temperature of the regeneration drying tower for desiccant regeneration. This reduces the power consumption of the electric heater in the regeneration drying tower, significantly lowering the regeneration cost of the gaseous desiccant. Simultaneously, the heat released by the condenser can also provide heating and domestic hot water, improving thermal energy utilization.

Claims

1. A PEM electrolysis water production and waste heat utilization system based on a refrigeration cycle, characterized in that: This includes a hydrogen production system, a gas purification system, a refrigeration cycle system, and a waste heat recovery system; The hydrogen production system includes an electrolyzer (2). The cathode outlet of the electrolyzer (2) is sequentially connected to a hydrogen-side first gas-liquid separator (5), a hydrogen-side evaporator (7), and a hydrogen-side second gas-liquid separator (9). The liquid outlet of the hydrogen-side second gas-liquid separator (9) and the liquid outlet condensed from the hydrogen-side evaporator (7) are both connected to the liquid inlet of the hydrogen-side first gas-liquid separator (5). The gas outlet of the hydrogen-side second gas-liquid separator (9) is connected to a gas purification system. The anode outlet of the electrolyzer (2) is sequentially connected to an oxygen-side first gas-liquid separator (5). The system includes a gas-liquid separator (6), an oxygen-side evaporator (8), an oxygen-side second gas-liquid separator (10), and an oxygen storage tank (43). The liquid outlet of the oxygen-side second gas-liquid separator (10) and the liquid outlet condensed from the oxygen-side evaporator (8) are both connected to the liquid inlet of the oxygen-side first gas-liquid separator (6). The liquid outlets of the hydrogen-side first gas-liquid separator (5) and the oxygen-side first gas-liquid separator (6) are connected to the electrolytic cell (2) via pipelines through a precision filter (11), a circulation pump (14), and a deionizer (12). The gas purification system mainly includes a first drying tower (20), a second drying tower (21), and a third drying tower (22) connected in parallel with the gas outlet of the second gas-liquid separator (9) on the hydrogen side. The other side of the first drying tower (20), the second drying tower (21), and the third drying tower (22) are connected to a hydrogen storage tank. The refrigeration cycle system includes a hydrogen-side evaporator (7) and an oxygen-side evaporator (8). The hydrogen-side evaporator (7) is installed on the gas pipeline between the first hydrogen-side gas-liquid separator (5) and the second hydrogen-side gas-liquid separator (9) for condensing and removing water from the hydrogen gas at the outlet of the first hydrogen-side gas-liquid separator (5). The oxygen-side evaporator (8) is installed on the gas pipeline between the first oxygen-side gas-liquid separator (6) and the second oxygen-side gas-liquid separator (10) for condensing and removing water from the oxygen gas at the outlet of the first oxygen-side gas-liquid separator (6). The circulating evaporator (15) is installed between the circulating pump (14) and the deionizer (12) and connected in parallel with the connecting pipeline between the circulating pump (14) and the deionizer (12) for condensing and removing water from the oxygen gas entering the deionizer (12). The liquid is heated; the first regenerating evaporator (17), the second regenerating evaporator (18), and the third regenerating evaporator (19) are respectively installed on the pipeline connecting the gas outlet of the second gas-liquid separator (9) on the hydrogen side to the first drying tower (20), the second drying tower (21), and the third drying tower (22) to further cool the hydrogen entering each drying tower; the first condenser (23), the second condenser (24), and the third condenser (25) are respectively installed on the gas outlet or gas inlet pipeline on the other side of the first drying tower (20), the second drying tower (21), and the third drying tower (22); the circulating condenser (16) is installed on the heat exchanger circulating pipeline set at the cathode outlet and anode outlet of the electrolytic cell (2); In the refrigeration cycle system, the refrigerant flows through the hydrogen-side evaporator (7), oxygen-side evaporator (8), circulating evaporator (15), first regeneration evaporator (17), second regeneration evaporator (18), and third regeneration evaporator (19) to absorb heat before entering the compressor (26) for compression. Then, it passes through the first condenser (23), second condenser (24), third condenser (25), and circulating condenser (16) to release heat before entering the expansion valve (27). The refrigerant at the outlet of the expansion valve (27) enters the evaporator to complete the refrigeration cycle. The waste heat utilization system mainly includes a hydrogen-side heat exchanger (3) and an oxygen-side heat exchanger (4). The hydrogen-side heat exchanger (3) is installed on the connecting pipe between the cathode outlet of the electrolytic cell (2) and the first gas-liquid separator (5) on the hydrogen side. The oxygen-side heat exchanger (4) is installed on the connecting pipe between the anode outlet of the electrolytic cell (2) and the first gas-liquid separator (6) on the oxygen side. A water circulation heating loop is formed between the hydrogen-side heat exchanger (3), the oxygen-side heat exchanger (4), the circulating condenser (16), and the outlet pipe of the deionizer (12). The hydrogen-side heat exchanger (3) and the oxygen-side heat exchanger (4) are used to exchange heat between the liquid at the outlet of the deionizer (12) and the gas-liquid mixture at the outlet of the electrolytic cell 5. At the same time, the heat from the circulating condenser (16) is used to increase the water temperature entering the electrolytic cell (2).

2. The PEM electrolysis water production and waste heat utilization system based on a refrigeration cycle as described in claim 1, characterized in that: The pure water tank (1) is connected to the liquid inlet of the first gas-liquid separator (5) on the hydrogen side via a water replenishment pump (13). The water in the pure water tank (1) is sent to the first gas-liquid separator (5) on the hydrogen side via the water replenishment pump (13) to replenish the water consumed in the electrolysis process.

3. The PEM electrolysis water production and waste heat utilization system based on a refrigeration cycle as described in claim 2, characterized in that: The system piping also includes control valves for regulating the flow of refrigerant, circulating water, or hydrogen; The second control valve (29), the fifth control valve (32), the sixth control valve (33), the eighth control valve (35), the ninth control valve (36), the tenth control valve (37), the eleventh control valve (38), the twelfth control valve (39), and the thirteenth control valve (40) are respectively installed on the refrigerant inlet pipes of the circulating evaporator (15), the hydrogen-side evaporator (7), the oxygen-side evaporator (8), the first condenser (23), the second condenser (24), the third condenser (25), the first regenerating evaporator (17), the second regenerating evaporator (18), and the third regenerating evaporator (19) to change the direction and flow rate of the refrigerant.

4. The PEM electrolysis water production and waste heat utilization system based on a refrigeration cycle as described in claim 3, characterized in that: The first control valve (28) is a three-way valve. The first control valve (28) is installed between the circulating pump (14) and the deionizer (12) and is connected to the circulating evaporator (15) through the first control valve (28). The connecting pipeline between the circulating evaporator (15) and the circulating pump (14) and the deionizer (12) is connected in parallel.

5. The PEM electrolysis water production and waste heat utilization system based on a refrigeration cycle as described in claim 4, characterized in that: The fourth control valve (31) is installed on the connecting pipe between the oxygen-side heat exchanger (4) and the circulating condenser (16). A branch is drawn from the oxygen-side heat exchanger (4) and the circulating condenser (16) through the three-way valve (31) to form a parallel connection with the circulating condenser (16). The third control valve (30) is installed on the connecting pipe between the hydrogen-side heat exchanger (3) and the deionizer (12). The flow rate of water through the hydrogen-side first heat exchanger (3) and the oxygen-side first heat exchanger (4) can be changed by adjusting the third control valve (30) in the water circulation loop. The direction of water flow in the pipeline can be changed by adjusting the first control valve (28) and the fourth control valve (31).

6. The PEM electrolysis water production and waste heat utilization system based on a refrigeration cycle as described in claim 1, characterized in that: The seven control valve (34) of the three-way valve is installed on the connecting pipe on one side of the first condenser (23), the second condenser (24), and the third condenser (25). The pipes on the same side of the first condenser (23), the second condenser (24), and the third condenser (25) are connected through the seven control valve (34). The fourteenth control valve (41) is installed on the connecting pipe on the same side of the first regenerating evaporator (17) and the second regenerating evaporator (18) to connect the two. The fifteenth control valve (42) is installed on the connecting pipe on the same side of the second regenerating evaporator (18) and the third regenerating evaporator (19) to connect the two. The flow direction of hydrogen in the drying system is changed by adjusting the seven control valve (34), the fourteenth control valve (41), and the fifteenth control valve (42).

7. The PEM electrolysis water production and waste heat utilization system based on a refrigeration cycle as described in any one of claims 1-6, characterized in that: The first regenerating evaporator (17), the second regenerating evaporator (18), and the third regenerating evaporator (19) are arranged in parallel, and the first condenser (23), the second condenser (24), and the third condenser (25) are arranged in parallel.

8. The PEM electrolysis water production and waste heat utilization system based on a refrigeration cycle as described in any one of claims 1-6, characterized in that: The liquid outlet separated by the hydrogen-side evaporator (7) is connected to the liquid inlet of the first gas-liquid separator (5) on the hydrogen side, and the liquid outlet separated by the oxygen-side evaporator (8) is connected to the liquid inlet of the first gas-liquid separator (6) on the oxygen side. The liquid separated by the hydrogen-side evaporator (7) and the oxygen-side evaporator (8) is finally collected in the precision filter (11) for filtration and then flows back to the electrolytic cell (2) through the circulation pump (14).

9. The PEM electrolysis water production and waste heat utilization system based on a refrigeration cycle as described in any one of claims 1-6, characterized in that: The condensate outlets of the circulating evaporator (15), the first regenerating evaporator (17), the second regenerating evaporator (18), and the third regenerating evaporator (19) are connected to the liquid outlet pipelines of the first gas-liquid separator (5) and the oxygen-side first gas-liquid separator (6) respectively through pipelines. The water separated from the circulating evaporator (15), the first regenerating evaporator (17), the second regenerating evaporator (18), and the third regenerating evaporator (19) after condensing hydrogen is combined with the water from the outlets of the hydrogen-side first gas-liquid separator (5) and the oxygen-side first gas-liquid separator (6) and flows together into the precision filter (11) for filtration.

10. The PEM electrolysis water production and waste heat utilization system based on a refrigeration cycle as described in any one of claims 1-6, characterized in that: The hydrogen-side first gas-liquid separator (5) and the oxygen-side first gas-liquid separator (6) are connected.

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