Hydrogen production system using alkaline electrolysis water

Abstract

This invention proposes an alkaline water electrolysis hydrogen production system. The alkaline water electrolysis hydrogen production system includes: an electrolyzer with a hydrogen outlet; and a hydrogen separator with a gas-liquid mixture inlet and a gas outlet. The gas-liquid mixture inlet is connected to the hydrogen outlet of the electrolyzer via a first pipe, and the gas outlet is connected to a first outlet pipe for supplying hydrogen gas. The alkaline water electrolysis hydrogen production system further includes a refrigeration system disposed at the first outlet pipe. The refrigeration system includes a compressor, a condenser, an expansion valve, and an evaporator connected sequentially in a closed system via pipes. A refrigerant circulates within the closed system. The first outlet pipe is connected to a second heat exchanger, and the evaporator of the refrigeration system is disposed in the second heat exchanger and configured to absorb heat from the hydrogen. The alkaline water electrolysis hydrogen production system according to the invention includes a refrigeration system located at the outlet pipe, which is capable of further cooling the generated hydrogen.

Description

Technical Field

[0001] This invention relates to hydrogen production technology via water electrolysis, and more specifically, to an alkaline water electrolysis hydrogen production system. Background Technology

[0002] Hydrogen energy, as the optimal energy choice for the low-carbon era, plays a crucial role in the current energy transition. Water electrolysis is a recognized method for producing green hydrogen. Currently, water electrolysis hydrogen production systems are in a phase of rapid development. Among them, alkaline water electrolysis hydrogen production systems are widely used due to their high technological maturity, low cost, long equipment lifespan, and strong adaptability. However, the high power and water consumption of alkaline water electrolysis hydrogen production systems hinders their further widespread application.

[0003] Seawater is one of the most abundant resources on Earth. Compared to finite fossil fuels, seawater provides an almost unlimited supply of water, making the use of seawater for hydrogen production highly renewable and sustainable. Moreover, wind and solar power, which are increasingly being developed for deep-sea applications, can provide substantial amounts of electricity at sea.

[0004] Therefore, how to organically combine offshore wind power and seawater resources with alkaline water electrolysis technology to form a new type of alkaline water electrolysis hydrogen production system, and provide core competitive technical support for large-scale hydrogen production from nearshore / offshore offshore wind power, is a topic that urgently needs to be studied by technical personnel. Summary of the Invention

[0005] This invention proposes an alkaline water electrolysis hydrogen production system, comprising: an electrolyzer including a hydrogen outlet; and a hydrogen separator including a gas-liquid mixture inlet and a gas outlet. The gas-liquid mixture inlet is connected to the hydrogen outlet of the electrolyzer via a first pipe, and the gas outlet is used to connect to a first outlet pipe for supplying hydrogen flow. The alkaline water electrolysis hydrogen production system further includes a refrigeration system disposed at the first outlet pipe. The refrigeration system includes a compressor, a condenser, an expansion valve, and an evaporator connected in sequence as a closed system via pipes. A refrigerant circulates within the closed system. The first outlet pipe is connected to a second heat exchanger, and the evaporator of the refrigeration system is disposed in the second heat exchanger and configured to absorb heat from the hydrogen.

[0006] The aforementioned alkaline water electrolysis hydrogen production system includes a refrigeration system located at the first outlet pipe, which can use seawater as a cooling medium to further cool and dry the generated hydrogen.

[0007] Furthermore, in a further preferred embodiment, the alkaline water electrolysis hydrogen production system integrates a high-temperature heat pump system and a seawater desalination system. The high-temperature heat pump system is configured to recover waste heat from the electrolyte, thereby providing heat to the seawater desalination system. This seawater desalination system uses seawater as the water source for the water electrolysis hydrogen production system, which not only makes full use of the Earth's abundant seawater resources but also reduces hydrogen production costs and environmental pollution, resulting in significant economic and environmental benefits. Furthermore, this alkaline water electrolysis hydrogen production system can be used on offshore hydrogen production platforms, utilizing electricity generated by offshore wind turbines to produce hydrogen and green ammonia on-site, avoiding transmission losses from long-distance power transmission, and can serve as a primary application method for future deep-sea renewable energy.

[0008] Generally speaking, the various embodiments of the present invention can be combined and coupled in any possible manner within the scope of the invention. These and other aspects, features, and / or advantages of the invention will become apparent and will be elucidated with reference to the embodiments described below. Attached Figure Description

[0009] Embodiments of the invention will be described by way of example only with reference to the following accompanying drawings, in which:

[0010] Figure 1 An alkaline water electrolysis hydrogen production system according to an embodiment of the present disclosure is schematically illustrated.

[0011] It should be understood that the accompanying drawings only illustrate certain specific embodiments of the invention and should not be construed as limiting other possible embodiments falling within the scope of the appended claims. The scope of protection of the invention is defined only by the appended claims. Detailed Implementation

[0012] Figure 1 An alkaline water electrolysis hydrogen production system according to an embodiment of the present disclosure is schematically illustrated.

[0013] like Figure 1 As shown, the alkaline water electrolysis hydrogen production system may include an electrolyzer 10, a hydrogen separator 20, and an oxygen separator 30.

[0014] Electrolyzer 10 is the core component of the system, configured for electrolysis and including hydrogen and oxygen outlets. In one specific embodiment, electrolyzer 10 can be a bipolar pressure filter electrolyzer and may include multiple parallel electrolytic cells (chambers). These electrolytic cells are connected in series and powered by a single power source, sharing a common anode and cathode. Within these electrolytic cells, water is decomposed under the influence of direct current, generating hydrogen at the cathode and oxygen at the anode. To reduce water resistance and improve electrolysis efficiency, NaOH or KOH electrolyte must be added to the water to prepare an alkaline electrolyte of a certain concentration, which is then injected into electrolyzer 10. In the electrolysis reaction, one part water is decomposed into one part hydrogen and half a part oxygen (reaction formula: H₂O → H₂ + 1 / 2 O₂). The generated hydrogen and oxygen are collected in a hydrogen main pipe and an oxygen main pipe, respectively, and then the hydrogen outlet and oxygen outlet exit from electrolyzer 10.

[0015] Hydrogen escaping from electrolyzer 10 enters hydrogen separator 20 via first pipe 11, and oxygen escaping from electrolyzer 10 enters oxygen separator 30 via second pipe 12. When the hydrogen and oxygen produced by electrolysis escape from electrolyzer 10, they are often in the form of a gas-liquid mixture, containing a large amount of water vapor and extremely small water droplets of alkaline electrolyte. Therefore, they must be separated by hydrogen separator 20 and oxygen separator 30; otherwise, a large amount of condensate and alkaline electrolyte will be consumed, and the purity of the hydrogen will also be affected.

[0016] Figure 1 The general outlines of the hydrogen separator 20 and oxygen separator 30 are only schematically depicted. In one specific embodiment, the hydrogen separator 20 and oxygen separator 30 typically include a housing capable of withstanding a certain pressure, which may consist of a cylindrical body and upper and lower end caps. Inside the housing is a helical metal tube serving as an internal cooling water pipe. This internal cooling water pipe extends helically from the upper to the lower part of the housing and then from the lower to the upper part, with both ends connected to pipe openings on the housing. These openings are used to connect to external cooling water pipes. Additionally, there is a gas outlet at the top of the housing, a liquid outlet at the bottom, and a gas-liquid mixture inlet and a pure water inlet on the side of the housing. The gas-liquid mixture inlet of the hydrogen separator 20 is connected to the hydrogen outlet of the electrolyzer 10 via the aforementioned first pipe 11, and the gas-liquid mixture inlet of the oxygen separator 30 is connected to the oxygen outlet of the electrolyzer 10 via the aforementioned second pipe 12. Figure 1 The diagram only schematically depicts the pure water inlet on the side of the hydrogen separator 20 housing. However, it will be understood that the oxygen separator 30 housing may also have a pure water inlet on its side.

[0017] The hydrogen separator 20 and oxygen separator 30, with the above-described structure, achieve separation through gravity settling. As described above, when hydrogen and oxygen containing a large amount of water vapor and extremely small water droplets in the alkaline electrolyte enter the hydrogen separator 20 and oxygen separator 30, the liquid portion remains in the existing alkaline electrolyte at the bottom of the separator, while the gas portion bubbles out of the liquid and rises into the upper space. Since the rising gas portion still contains droplets and other mist-like liquid particles, further separation is required. For this purpose, the coolant in the internal cooling water pipes maintains a low temperature inside the separator, causing the mist-like liquid particles in the rising gas portion to condense into larger droplets. These larger droplets fall into the liquid at the bottom of the separator due to gravity, thus achieving further gas-liquid separation. The separated gas is output from the upper gas outlet.

[0018] It will be understood that the hydrogen separator 20 and oxygen separator 30 are installed higher than the electrolyzer 10, thereby ensuring that the gas generated by the electrolyzer 10 can rise into the air separator 20 and oxygen separator 30. In another embodiment according to this disclosure, the hydrogen separator 20 and oxygen separator 30 may include multiple sets of parallel-arranged internal cooling water pipes to increase the heat exchange area and improve the gas-liquid separation efficiency. Furthermore, multiple liquid level sampling ports may be provided on the sides of the hydrogen separator 20 and oxygen separator 30 for measuring the liquid level, so that electrolyte can be replenished in a timely manner when the liquid level drops.

[0019] The hydrogen separated from hydrogen separator 20 can then flow out from the first outlet pipe 14 and is subsequently stored in a hydrogen storage tank (not shown) for use. Alternatively, as Figure 1 As shown, the hydrogen gas can be further dried by a refrigeration system before entering the hydrogen storage tank, which will be described in more detail below. The oxygen separated from the oxygen separator 30, as a byproduct, can flow out from the second outlet pipe 15 and be directly discharged into the atmosphere. Alternatively, the separated oxygen can be stored in an oxygen cylinder (not shown) for use.

[0020] The liquid outlets at the bottom of the hydrogen separator 20 and oxygen separator 30 are connected via a U-shaped pipe 40, which is connected to the inlet of the electrolytic cell 10 via a third pipe 13. In this configuration, the hydrogen separator 20 and oxygen separator 30 are installed such that the liquid levels in the hydrogen separator 20 and oxygen separator 30 are approximately the same due to the connection of the U-shaped pipe 40, and are both higher than the liquid level in the electrolytic cell 10. This ensures that the alkaline electrolyte always fills the entire electrolytic cell 10 under gravity and circulates between the electrolytic cell 10 and the hydrogen separator 20 and oxygen separator 30. In an alternative embodiment, an electrolyte circulation pump 50 can be installed on the third pipe 13 between the U-shaped pipe 40 and the electrolytic cell 10. This electrolyte circulation pump 50 can be turned on to pump the electrolyte in the U-shaped pipe 40 into the electrolytic cell 10. This configuration allows for active control of the circulation of the alkaline electrolyte and facilitates the discharge of electrolytic gases, thereby improving electrolysis efficiency.

[0021] Alternatively, the U-shaped pipe 40 may not be provided. In this case, the hydrogen separator 20 and the oxygen separator 30 can be connected to the inlet of the electrolyzer 10 via separate pipes, so that the electrolyte in the hydrogen separator 20 and the oxygen separator 30 can be returned to the electrolyzer 10 separately.

[0022] The alkaline water electrolysis hydrogen production system described above forms the following electrolyte circulation loop: Electrolyzer 10 – First pipe 11 / Second pipe 12 – Hydrogen separator 20 / Oxygen separator 30 – U-tube 40 – Third pipe 13 – Electrolyte circulation pump 50 – Electrolyzer 10. During the operation of the alkaline water electrolysis hydrogen production system, the alkaline electrolyte flows within the above circulation loop.

[0023] It will be understood that water in the alkaline electrolyte is continuously consumed during electrolysis. Therefore, the alkaline water electrolysis hydrogen production system according to this disclosure may further include a water replenishment system connected to the purified water inlet of the hydrogen separator 20 and / or oxygen separator 30, for continuously replenishing purified water to the hydrogen separator 20 and / or oxygen separator 30 during operation of the water electrolysis hydrogen production system. The aforementioned water replenishment system (i.e., the seawater desalination system 100 mentioned below) will be described in further detail below. Furthermore, although theoretically the electrolyte is not consumed during electrolysis, if a decrease in the concentration of the alkaline electrolyte in the electrolyzer 10 is observed during electrolysis, electrolyte replenishment will be necessary. Therefore, the alkaline water electrolysis hydrogen production system according to this disclosure may further include an alkaline tank 70. This alkaline tank 70 may be connected to the inlet of the electrolyzer 10 to inject electrolyte into the electrolyzer 10, for example, under the action of the alkaline electrolyte circulation pump 50.

[0024] In a preferred embodiment according to this disclosure, the alkaline water electrolysis hydrogen production system includes a high-temperature heat pump system 80 disposed at the aforementioned third pipe 13. This high-temperature heat pump system 80, compared to a conventional heat pump, can provide a higher output temperature with higher efficiency. Those skilled in the art will understand that during the electrolysis process in the electrolyzer 10, a portion of the supplied electricity is used to decompose water molecules into hydrogen and oxygen, while another portion generates heat, causing the alkaline electrolyte within the electrolyzer 10 to rise to a temperature of approximately 80°C. The high-temperature heat pump system 80 is configured to cool the electrolyte within the aforementioned circulation loop. In other words, the high-temperature heat pump system 80 is configured, for example, based on the reverse Carnot cycle principle to recover waste heat from electrolysis, raising the electrolyte's relatively low temperature of approximately 80°C to a high-quality thermal energy of over 100°C.

[0025] like Figure 1 As shown, the high-temperature heat pump system 80 typically includes an evaporator 81, a compressor 82, a condenser 83, and an expansion valve (or throttle valve) 84. These are connected sequentially via pipes to form a closed system, within which the heat pump working fluid continuously circulates. Specifically, the outlet of the evaporator 81 is connected to the inlet of the compressor 82, the outlet of the compressor 82 is connected to the inlet of the condenser 83, the outlet of the condenser 83 is connected to the inlet of the expansion valve 84, and the outlet of the expansion valve 84 is connected to the inlet of the evaporator 81. The evaporator 81 of the high-temperature heat pump system 80 and a portion of the third pipe 13 are disposed in the first heat exchanger 90, allowing the electrolyte in the third pipe 13 to exchange heat with the working fluid in the high-temperature heat pump system 80 within the first heat exchanger 90. Furthermore, the condenser 83 of the high-temperature heat pump system 80 can be configured to supply heat to the seawater desalination system 100.

[0026] The working process of the aforementioned high-temperature heat pump system 80 is as follows: The electrolyte in the third pipe 13 flows through the first heat exchanger 90 and exchanges heat with the working fluid in the evaporator 81; the low-pressure, low-temperature heat pump working fluid vapor generated in the evaporator 81 is compressed by the compressor 82 to increase its pressure and temperature (to above 100°C) before being discharged into the condenser 83. In the condenser 83, the heat pump working fluid vapor exchanges heat with the seawater desalination system 100 under constant pressure, releasing heat and condensing into a liquid with higher temperature and pressure; the high-pressure liquid heat pump working fluid flows through the expansion valve 84, where its pressure and temperature decrease simultaneously before entering the evaporator 81; the low-pressure, low-temperature heat pump working fluid liquid continuously absorbs heat from the low-grade heat source (i.e., the electrolyte in the third pipe 13) under constant pressure and vaporizes into steam, which is then drawn into the compressor 82. In this way, the heat pump working fluid completes a complete heat pump cycle through four processes: compression, condensation, expansion, and vaporization within the system.

[0027] In the aforementioned high-temperature heat pump system 80, the evaporator 81 is the heat absorption device, where the heat pump working fluid absorbs heat from the low-temperature heat source to produce a cooling effect; the compressor 82 plays the role of compressing and transporting the heat pump working fluid vapor, and is the heart of the entire system; the condenser 83 is the heat release device, where the heat absorbed from the evaporator 81 and the heat converted from the work consumed by the compressor 82 are carried away by the heating medium (such as the seawater desalination system 100) in the condenser 83; and the expansion valve 84 throttles and reduces the pressure of the heat pump working fluid and regulates the flow rate of the heat pump working fluid entering the evaporator 81, serving as the boundary between the high and low pressure of the system. In the heat pump cycle, only after consuming a certain amount of energy (such as electrical energy) can the heat pump working fluid continuously transfer the heat absorbed from the low-temperature side to the high-temperature side, thereby realizing the reverse heat transfer. The working fluids used in the aforementioned high-temperature heat pump system 80 include R245fa, R134a, R11, R1336mzz(Z) and R1233zd(E), etc. These working fluids remain stable and have high thermal efficiency at high temperatures.

[0028] As described above, the working fluid at a temperature above 100°C in the condenser 83 of the high-temperature heat pump system 80 is used to heat the seawater desalination system 100, thereby heating the seawater to boiling and generating water vapor, which is then condensed to form pure water, used as a supplementary water source for the water electrolysis hydrogen production system. The seawater desalination system 100 can generally include a connected water vapor generation section 101 and a condensation section 102. The condenser 83 is disposed in the water vapor generation section 101, where the high-temperature working fluid serves as a heat source to heat the seawater, causing water vapor to form within the water vapor generation section 101. The condensation section 102 is configured to receive the water vapor from the water vapor generation section 101 and provide a low-temperature environment, allowing the water vapor to condense into pure water. The condensation section 102 can be connected to the pure water inlets of the aforementioned hydrogen separator 20 and oxygen separator 30 to supply pure water to them.

[0029] In a preferred embodiment, the cooling medium of the condenser section 102 is seawater. Further, the condenser section 102 includes a cooling water pipe 1021, in which the cooling medium is seawater, thereby condensing water vapor through the low temperature of the seawater. Since seawater is an inexhaustible low-temperature liquid, using it as a cooling medium is both energy-saving and environmentally friendly, while also improving cooling efficiency and stability. It will be understood that the working fluid above 100°C in the condenser 83 of the high-temperature heat pump system 80 can also be used for other purposes as needed, such as heating on offshore platforms.

[0030] The aforementioned seawater desalination system 100 can be a seawater desalination device employing distillation, such as a multi-stage flash distillation device, a multi-effect distillation device, or a vapor compression distillation device, which will be described in further detail below. Seawater flows into the seawater desalination system 100 through the inlet pipe, and the waste liquid formed after evaporation is discharged into the sea through the outlet pipe.

[0031] The aforementioned multi-stage flash evaporation equipment mainly consists of three parts: a heating device, a heat recovery heat exchanger, and a heat exchange unit. The raw seawater is first introduced into the heating device, which typically includes a heater, such as a seawater peak heater. Here, the seawater is heated to a certain temperature, usually provided by an external heat source such as low-pressure steam extraction from a thermal power plant. The heated seawater enters the heat recovery heat exchanger, where it exchanges heat with the outflowing seawater through a partitioned heat exchanger, achieving heat recovery. Part of the concentrated brine from the final stage is discharged, while the other part is mixed with the makeup seawater and returned to the heat recovery section as circulating brine. The seawater after heat recovery enters the flash chamber, which is the core part of the multi-stage flash evaporation equipment. The pressure in the flash chamber is controlled below the saturated vapor pressure corresponding to the temperature of the hot brine, causing the hot brine to rapidly partially vaporize upon entering the flash chamber. The resulting steam condenses to produce the desired fresh water. The number of flash chambers is called the number of stages. The raw seawater flows sequentially through several flash chambers with gradually decreasing pressure, evaporating and cooling stage by stage, while the brine also gradually becomes more concentrated. These three parts are interconnected by pipes and heat exchangers, forming a continuous process. Seawater is first heated in the heating section, then heat is recovered in the heat recovery section, and finally, freshwater is produced by step-by-step depressurization and flash evaporation in the heat exchange section through multi-stage flash chambers.

[0032] The aforementioned low-temperature multi-effect distillation equipment refers to desalination equipment where the maximum seawater temperature is below 70℃. Its characteristic feature is the series of horizontal tube spray falling film evaporators connected in series. Using a certain amount of steam input, through multiple evaporation and condensation processes, the evaporation temperature of each subsequent effect is lower than that of the preceding effect, thus obtaining a desalination process with a distillation water volume many times greater than the amount of steam. The feed seawater is preheated and degassed in the condenser and then divided into two streams. One stream is discharged back into the sea as cooling water, while the other stream becomes the feed liquid for the distillation process. After adding a scale inhibitor, the feed liquid is introduced into the group of evaporators with the lowest temperature. The spray system distributes the feed liquid onto the top row of tubes of each evaporator. During the downward flow, some of the seawater absorbs the latent heat of the condensed steam in the tubes and vaporizes. The remaining feed liquid is pumped into the next group of evaporator effects, where the operating temperature is higher than the previous group. The evaporation and spraying process is repeated in the new group. The remaining feed liquid continues forward, leaving as a concentrate in the group with the highest temperature. Fresh steam is introduced into the evaporator tube of the highest-temperature effect. While condensation occurs inside the tube, approximately the same amount of evaporation occurs outside. The secondary steam passes through a vapor-liquid separator and enters the heat transfer tube of the next effect, where the operating temperature and pressure are slightly lower than the first effect. This evaporation and condensation process repeats along the effects of a series of evaporators, with the steam from the last effect being condensed by seawater coolant in the condenser.

[0033] The aforementioned vapor compression distillation equipment is very similar to low-temperature multi-effect distillation equipment. Heating steam flows inside the heat transfer tubes while seawater flows downwards outside the tubes, partially evaporating after absorbing the latent heat of the steam. The resulting secondary steam has a relatively low temperature and pressure, making it unsuitable for direct heating of seawater. However, after simple mechanical or thermal compression, it can be used as heating steam, transported to the heat transfer tubes to heat the seawater, and simultaneously condensed to become product water. The difference between vapor compression distillation equipment and low-temperature multi-effect distillation equipment lies in the compression of the secondary steam generated after seawater vaporization to obtain relatively high-pressure steam, which is then transported to the heat transfer tubes to heat and evaporate the seawater outside the tubes. Therefore, vapor compression distillation for seawater desalination does not require external heating steam during normal operation.

[0034] The above only provides several possible implementations of the seawater desalination system 100 and is not intended to limit the specific type of the seawater desalination system 100.

[0035] In another preferred embodiment according to this disclosure, the alkaline water electrolysis hydrogen production system includes a refrigeration system 60 disposed at the aforementioned first outlet pipe 14. The refrigeration system 60 is configured to further condense water vapor contained in the hydrogen flowing out of the hydrogen separator 20, thereby further drying the hydrogen.

[0036] exist Figure 1In the specific embodiment shown, the refrigeration system 60 is a vapor compression refrigeration machine and includes a compressor 61, a condenser 62, an expansion valve (or throttle valve) 63, and an evaporator 64. These devices are connected sequentially by pipes to form a closed system, within which the refrigerant continuously circulates. Specifically, the outlet of the compressor 61 is connected to the inlet of the condenser 62, the outlet of the condenser 62 is connected to the inlet of the expansion valve 63, the outlet of the expansion valve 63 is connected to the inlet of the evaporator 64, and the outlet of the evaporator 64 is connected to the inlet of the compressor 61. The aforementioned first outlet pipe 14 is connected to the second heat exchanger 110 to deliver hydrogen containing water vapor to the second heat exchanger 110. The evaporator 64 of the refrigeration system 60 is disposed in the second heat exchanger 110 and configured to absorb heat from the hydrogen, causing the water vapor in the hydrogen to further condense and flow back to the hydrogen separator 20. The dried hydrogen is then discharged via the third outlet pipe 16 of the second heat exchanger 110, for example, flowing into a hydrogen storage tank. Furthermore, the condenser 62 of the refrigeration system 60 and the external cooling water pipe 65 are located in the third heat exchanger 120. The cooling medium in the external cooling water pipe 65 is seawater, thus using the low temperature of the seawater to dissipate heat from the condenser 62. As described above, using seawater as the cooling medium is both energy-saving and environmentally friendly, while also improving cooling efficiency and stability.

[0037] The working process of the refrigeration system 60 is as follows: The compressor 61 draws the low-temperature, low-pressure refrigerant vapor generated in the evaporator 64 into the cylinder. After being compressed by the compressor 61, the pressure and temperature of the refrigerant vapor increase. Then, the high-temperature, high-pressure refrigerant vapor is discharged into the condenser 62. In the condenser 62, the high-temperature, high-pressure refrigerant vapor exchanges heat with the cooler seawater (seawater in the external cooling water pipe 65), transferring heat to the seawater. The refrigerant itself releases heat and condenses from a gas into a liquid. This high-pressure refrigerant liquid passes through the expansion valve 63 for throttling, pressure reduction, and temperature reduction before entering the evaporator 64. In the evaporator 64, the low-temperature, low-pressure refrigerant liquid absorbs heat from the hydrogen in the first outlet pipe 14 and vaporizes, while the water vapor in the hydrogen is cooled. The refrigerant vapor generated in the evaporator 64 is then drawn away by the compressor 61. In this way, the refrigerant undergoes four processes in the system: compression, condensation, throttling, and vaporization (evaporation), thus completing one refrigeration cycle.

[0038] In a preferred embodiment, the evaporator 64 of the refrigeration system 60 lowers the temperature of the hydrogen from the first outlet pipe 14 to below 0°C. In this way, water vapor in the hydrogen can condense into ice and fall back into the hydrogen separator 20 under gravity, which further enhances the cooling effect on the hydrogen.

[0039] The alkaline water electrolysis hydrogen production system described above organically combines offshore wind power and seawater resources with alkaline water electrolysis technology. This not only fully utilizes the Earth's abundant seawater resources but also reduces hydrogen production costs and environmental pollution, resulting in significant economic and environmental benefits. Furthermore, this alkaline water electrolysis hydrogen production system can be used on offshore hydrogen production platforms, utilizing electricity generated by offshore wind turbines to produce hydrogen and green ammonia on-site, avoiding transmission losses associated with long-distance power transmission. It can serve as a primary application method for future deep-sea renewable energy.

[0040] Although the invention has been described in conjunction with the specific embodiments described above, it should not be construed as limiting it in any way to the examples presented. The scope of the invention is defined by the appended claims. In the context of the claims, the terms "comprising" or "including" do not exclude other possible elements or steps. Furthermore, references such as "a" or "an" should not be construed as excluding multiple elements. The use of reference numerals for elements shown in the figures in the claims should also not be construed as limiting the scope of the invention. Moreover, various features mentioned in different claims may be advantageously combined, and mentioning these features in different claims does not preclude the impossibility and advantage of such combinations. Furthermore, the terms "first," "second," "third," "fourth," etc., used in this invention are merely for distinguishing related components and are not intended to assign them any attribute of priority.

Claims

1. An alkaline water electrolysis hydrogen production system, the alkaline water electrolysis hydrogen production system comprising: An electrolytic cell (10) includes a hydrogen outlet; and Hydrogen separator (20) includes a gas-liquid mixture inlet and a gas outlet. The gas-liquid mixture inlet is connected to the hydrogen outlet of the electrolyzer (10) via a first pipe (11). The gas outlet is used to connect to a first gas outlet pipe (14) for supplying hydrogen flow. The alkaline water electrolysis hydrogen production system is characterized in that it further includes a refrigeration system (60) disposed at the first outlet pipe (14). The refrigeration system (60) includes a compressor (61), a condenser (62), an expansion valve (63), and an evaporator (64) connected in sequence to form a closed system through pipes. The refrigerant circulates within the closed system. The first outlet pipe (14) is connected to a second heat exchanger (110). The evaporator (64) of the refrigeration system (60) is disposed in the second heat exchanger (110) and is configured to absorb the heat of hydrogen.

2. The hydrogen generation system by alkaline electrolysis of water according to claim 1, characterized in that, The condenser (62) and the external cooling water pipe (65) are installed in the third heat exchanger (120), and the cooling medium in the external cooling water pipe (65) is seawater.

3. The hydrogen generation system by alkaline electrolysis of water according to claim 1 or 2, characterized in that, The evaporator (64) lowers the temperature of the hydrogen to below 0°C.

4. The hydrogen generation system by alkaline electrolysis of water according to claim 1 or 2, characterized by, The second heat exchanger (110) includes a third outlet pipe (16) through which dried hydrogen gas is discharged from the second heat exchanger (110).

5. The alkaline water electrolysis hydrogen production system according to claim 1, characterized in that, The electrolytic cell (10) further includes a liquid inlet, and the hydrogen separator (20) further includes a liquid outlet, the liquid outlet of which is connected to the liquid inlet of the electrolytic cell (10) via a third pipe (13). The alkaline water electrolysis hydrogen production system also includes a high-temperature heat pump system (80) installed at the third pipeline (13).

6. The hydrogen generation system by alkaline electrolysis of water according to claim 5, characterized in that, The high-temperature heat pump system (80) includes an evaporator (81), a compressor (82), a condenser (83), and an expansion valve (84) connected in sequence by pipes to form a closed system. The heat pump working fluid circulates within the closed system. The evaporator (81) and a portion of the third pipe (13) are located in the first heat exchanger (90).

7. The hydrogen generation system by alkaline electrolysis of water according to claim 6, characterized in that, The high-temperature heat pump system (80) is configured to increase the thermal energy of the electrolyte in the third pipe (13) from about 80°C to over 100°C.

8. The hydrogen generation system by alkaline electrolysis of water according to claim 7, characterized in that, The alkaline water electrolysis hydrogen production system also includes a seawater desalination system (100), the condenser (83) of the high-temperature heat pump system (80) is configured to heat the seawater desalination system (100), and the seawater desalination system (100) is configured to supply purified water to the hydrogen separator (20).

9. The hydrogen generation system by alkaline electrolysis of water according to claim 8, characterized in that, The seawater desalination system (100) includes a water vapor generating section (101) and a condensing section (102) connected together. The condenser (83) of the high-temperature heat pump system (80) is disposed in the water vapor generating section (101) for heating the seawater in the water vapor generating section (101) to form water vapor. The condensing section (102) is configured to condense the water vapor to form pure water.

10. The hydrogen generation system by alkaline electrolysis of water according to claim 9, characterized in that, The condensation section (102) includes a cooling water pipe (1021), and the cooling medium in the cooling water pipe (1021) is seawater.

11. The hydrogen generation system by alkaline electrolysis of water according to claim 8, characterized by, The seawater desalination system (100) includes a multi-stage flash distillation device, a multi-effect distillation device, or a vapor compression distillation device.

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