A seawater-based anion exchange membrane water electrolysis hydrogen production system and method

Abstract

The application discloses a seawater-based hydrogen production system for water electrolysis by an anion exchange membrane, comprising an anion exchange membrane electrolysis tank unit, a hydrogen gravity separation unit, a hydrogen washing unit, a hydrogen purification unit, an oxygen gravity separation unit, an oxygen washing unit, an oxygen gas-liquid separation unit, a weak alkali liquid circulation unit, a heat exchange unit, a flash evaporation unit, a seawater desalination unit, a vacuum pump unit, a seawater filtration and barge transportation unit and a fresh water storage and supply unit. The application can circulate fresh water between the flash evaporation unit and the heat exchange unit, realize the repeated use of fresh water, and heat the circulating fresh water by using the weak alkali liquid which needs to be cooled, and then flash evaporate the hot fresh water, generate steam as a heat source to heat seawater of the seawater desalination unit, and desalinate the seawater under a negative pressure environment to prepare fresh water which can be used as raw material fresh water of the anion exchange membrane electrolysis tank unit.

Description

A seawater-based anion exchange membrane water electrolysis hydrogen production system and method Technical Field

[0001] This invention relates to the technical field of hydrogen production by electrolysis, and more particularly to a system and method for hydrogen production by anion exchange membrane electrolysis of water based on seawater. Background Technology

[0002] Hydrogen is a zero-carbon emission new energy source and is considered an ideal fuel for addressing environmental and energy issues. Hydrogen production through water electrolysis using green electricity can achieve the goal of zero-carbon emission hydrogen production. Anion exchange membrane (EEM) water electrolysis technology combines the advantages of traditional alkaline water electrolysis and proton exchange membrane (PEM) water electrolysis. It avoids the extensive use of precious metals in an alkaline system, and the equipment cost is significantly lower than that of PEM water electrolysis, making it a very promising hydrogen production technology.

[0003] With the large-scale development of wind power, randomness and volatility are no longer the main problems limiting grid connection. Lagging grid construction can no longer meet the rapidly expanding wind power development. In order to promote the consumption of new energy sources and optimize the energy structure, developing supporting energy storage facilities is conducive to achieving efficient utilization of wind resources. Offshore wind power hydrogen production has become the best choice for developing hydrogen energy at present due to its huge available wind resources, no land occupation, and abundant seawater resources.

[0004] Therefore, developing an anion exchange membrane water electrolysis hydrogen production system and method based on seawater can not only produce hydrogen using offshore wind power, but also produce fresh water to meet the raw material fresh water demand for anion exchange membrane water electrolysis hydrogen production. This will help meet the application needs of distributed offshore wind power hydrogen production scenarios and improve the utilization efficiency of offshore wind power, which is of great strategic significance. Summary of the Invention

[0005] In response to the technical problems mentioned in the background section, this invention provides a seawater-based anion exchange membrane electrolysis water hydrogen production system and method. This system and method utilizes a cooled, weakly alkaline solution to heat circulating freshwater, which is then flash-evaporated. The resulting steam serves as a heat source to heat seawater in a seawater desalination unit. The seawater undergoes low-temperature desalination under negative pressure. The produced freshwater can be used as feedstock for anion exchange membrane electrolyzer units, making it suitable for distributed offshore wind power hydrogen production scenarios. This invention aims to provide technical support for the development of independently controllable seawater-based anion exchange membrane electrolysis water hydrogen production equipment.

[0006] The technical means employed in this invention are as follows:

[0007] A seawater-based anion exchange membrane water electrolysis hydrogen production system includes:

[0008] Anion exchange membrane electrolyzer unit, hydrogen gravity separation unit, hydrogen purification unit, oxygen gravity separation unit, oxygen-liquid separation unit, weak alkali solution circulation unit, heat exchange unit, flash evaporation unit, seawater desalination unit, vacuum pump unit, seawater filtration and transportation unit, and freshwater storage and supply unit.

[0009] The offshore green electricity drives the anion exchange membrane electrolyzer unit to decompose freshwater into hydrogen and oxygen; hydrogen and weak alkaline solution undergo gas-liquid separation via the hydrogen gravity separation unit; oxygen and weak alkaline solution undergo gas-liquid separation via the oxygen gravity separation unit; the hot alkaline solution from the hydrogen gravity separation unit and the oxygen gravity separation unit is cooled by freshwater in the heat exchange unit and then circulated to the anion exchange membrane electrolyzer unit by the weak alkaline solution circulation unit; the freshwater in the heat exchange unit is heated by the hot weak alkaline solution and then enters the flash evaporation unit, where the generated water vapor enters the seawater desalination unit as a heat source for heating seawater; after heating, the seawater undergoes distillation and desalination in a vacuum environment, with seawater supplied by the seawater filtration and transfer unit, and the generated freshwater stored in the seawater storage and supply unit; the flash evaporation unit and the heat exchange unit circulate the freshwater.

[0010] Hydrogen and a small amount of water enter the hydrogen purification unit, where they are deoxygenated and dried to achieve high-purity hydrogen with a low dew point, which is then supplied to users.

[0011] Furthermore, the present invention also includes a method for producing hydrogen by anion exchange membrane electrolysis of water based on seawater, comprising the following steps:

[0012] Step 1: The anion exchange membrane electrolyzer unit is driven by offshore green electricity to decompose fresh water into hydrogen and oxygen;

[0013] Step 2: Hydrogen and weak alkaline solution are separated into gas and liquid by the hydrogen gravity separation unit; oxygen and weak alkaline solution are separated into gas and liquid by the oxygen gravity separation unit.

[0014] Step 3: The hot alkaline solutions from the hydrogen gravity separation unit and the oxygen gravity separation unit are cooled by fresh water in the heat exchange unit and then circulated to the anion exchange membrane electrolyzer unit by the weak alkaline solution circulation unit.

[0015] Step 4: The fresh water in the heat exchange unit is heated by a hot weak alkaline solution and then enters the flash evaporation unit. The water vapor generated enters the seawater desalination unit as a heat source for heating the seawater.

[0016] Step 5: After heating, the seawater is distilled and desalinated in a vacuum environment. The seawater is supplied by the seawater filtration and transfer unit, and the resulting freshwater is stored in the seawater storage and supply unit.

[0017] Step 6: The flash evaporation unit and the heat exchange unit circulate fresh water;

[0018] Step 7: Hydrogen and a small amount of water enter the hydrogen purification unit, where deoxygenation and drying are performed to achieve high-purity hydrogen with a low dew point, which is then supplied to the user.

[0019] Compared with the prior art, the present invention has the following advantages:

[0020] This invention enables freshwater circulation between the flash evaporation unit and the heat exchange unit, achieving reusable freshwater utilization. It also utilizes a cooled, weakly alkaline solution to heat the circulating freshwater, which is then flash-evaporated. The resulting steam serves as a heat source to heat the seawater in the seawater desalination unit. The seawater undergoes low-temperature desalination under negative pressure, and the produced freshwater can be used as feedstock for the anion exchange membrane electrolyzer unit. Therefore, this invention not only improves thermal energy utilization and increases the water production ratio but is also applicable to distributed offshore wind power hydrogen production scenarios, thus promoting the rapid development of offshore wind power hydrogen production. Attached Figure Description

[0021] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0022] Figure 1 is a flowchart of the main functions of the present invention.

[0023] Figure 2 is a process system flowchart of an embodiment of the present invention.

[0024] In the diagram: 1 is the baseline; 2 is the anion exchange membrane electrolyzer unit; 3 is the hydrogen gravity separation unit; 4 is the hydrogen washing unit; 5 is the hydrogen purification unit; 6 is the oxygen gravity separation unit; 7 is the oxygen washing unit; 8 is the oxygen-liquid separation unit; 9 is the weak alkali solution circulation unit; 10 is the heat exchange unit; 11 is the flash evaporation unit; 12 is the seawater desalination unit; 13 is the vacuum pump unit; 14 is the seawater filtration and transfer unit; 15 is the freshwater storage and supply unit; 21 is the anion exchange membrane electrolyzer; 31 is the hydrogen horizontal gravity separator; 41 is the hydrogen washing tower; 51 is the hydrogen purification module; 61 is the oxygen horizontal gravity separator; 71 is... The oxygen scrubbing tower includes: 81 oxygen-liquid separator, 91 weak alkali circulating pump, 92 weak alkali filter, 101 heat exchanger, 102 freshwater circulating pump, 103 pressure reducing valve, 111 flash evaporator, 112 vacuum instrument, 113 remote control valve, 121 seawater desalination unit, 122 thermometer, 123 remote control valve, 124 salinity meter, 125 remote control valve, 126 flow meter, 131 vacuum pump, 132 vacuum instrument, 141 seawater pump, 142 multi-media filter, 143 activated carbon filter, 144 precision filter, 151 freshwater storage tank, and 152 freshwater supply pump. Detailed Implementation

[0025] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.

[0026] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this invention are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of the invention described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover a non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0027] Figure 1 of this invention is a main functional flow diagram of a seawater-based anion exchange membrane electrolysis water hydrogen production system and method. Baseline 1 represents a seawater-based anion exchange membrane electrolysis water hydrogen production system and method. The functional implementation units of the seawater-based anion exchange membrane electrolysis water hydrogen production system and method of this invention mainly include: anion exchange membrane electrolyzer unit 2, hydrogen gravity separation unit 3, hydrogen washing unit 4, hydrogen purification unit 5, oxygen gravity separation unit 6, oxygen washing unit 7, oxygen-liquid separation unit 8, weak alkali solution circulation unit 9, heat exchange unit 10, flash evaporation unit 11, seawater desalination unit 12, vacuum pump unit 13, seawater filtration and transportation unit 14, and freshwater storage and supply unit 15.

[0028] In a preferred embodiment, in this application, the power interface of the anion exchange membrane electrolyzer unit 1 is connected to green electricity such as offshore wind power; the hydrogen outlet of the anion exchange membrane electrolyzer unit 1 is connected to the hydrogen gravity separation unit 3; the oxygen outlet of the anion exchange membrane electrolyzer unit 1 is connected to the oxygen gravity separation unit 6; and the low-temperature weak alkaline solution inlet of the anion exchange membrane electrolyzer unit is connected to the outlet of the weak alkaline solution circulation unit. The fresh water in the anion exchange membrane electrolyzer unit is decomposed into hydrogen and oxygen by the green electricity generated by offshore wind power, etc. The hydrogen and hot weak alkaline solution enter the hydrogen gravity separation unit, while the oxygen and hot weak alkaline solution enter the oxygen gravity separation unit.

[0029] The hydrogen inlet of the hydrogen gravity separation unit 3 is connected to the hydrogen outlet of the anion exchange membrane electrolyzer unit; the hydrogen outlet of the hydrogen gravity separation unit is connected to the hydrogen inlet of the hydrogen washing unit; the hot weak alkali liquid outlet of the hydrogen gravity separation unit is connected to the heat exchange unit; and the weak alkali liquid reflux port of the hydrogen gravity separation unit is connected to the weak alkali liquid outlet of the hydrogen washing unit.

[0030] The hydrogen inlet of hydrogen washing unit 4 is connected to the hydrogen outlet of the hydrogen gravity separation unit; the hydrogen outlet of the hydrogen washing unit is connected to the hydrogen purification unit; the fresh water inlet of the hydrogen washing unit is connected to the fresh water storage and supply unit; and the weak alkali liquid outlet of the hydrogen washing unit is connected to the weak alkali liquid reflux port of the hydrogen gravity separation unit. Its main functions are: washing the weak alkali from the hydrogen, cooling the hydrogen gas, and replenishing the anion exchange membrane electrolyzer unit with fresh water.

[0031] The inlet of hydrogen purification unit 5 is connected to the hydrogen washing unit; the outlet of the hydrogen purification unit can be connected to a hydrogen user or storage device. It removes trace amounts of oxygen from hydrogen, reducing its moisture content and ensuring the outlet hydrogen is high-purity, low-dew-point hydrogen.

[0032] The oxygen inlet of the oxygen gravity separation unit 6 is connected to the oxygen outlet of the anion exchange membrane electrolyzer unit; the oxygen outlet of the oxygen gravity separation unit is connected to the oxygen inlet of the oxygen scrubbing unit; the hot weak alkali solution outlet of the oxygen gravity separation unit is connected to the heat exchange unit; and the weak alkali solution reflux port of the oxygen gravity separation unit is connected to the weak alkali solution outlet of the oxygen scrubbing unit. This system separates oxygen and alkali solution and can replenish the anion exchange membrane electrolyzer unit with fresh water.

[0033] The oxygen inlet of oxygen scrubbing unit 7 is connected to the oxygen outlet of the oxygen gravity separation unit; the oxygen outlet of oxygen scrubbing unit is connected to the oxygen-liquid separation unit; the fresh water inlet of oxygen scrubbing unit is connected to the fresh water storage and supply unit; and the weak alkali liquid outlet of oxygen scrubbing unit is connected to the weak alkali liquid reflux port of the oxygen gravity separation unit. Its main functions are: to scrub the weak alkali in the oxygen and to cool the hydrogen gas.

[0034] The oxygen inlet of the oxygen-liquid separation unit 8 is connected to the oxygen outlet of the oxygen scrubbing unit; the oxygen outlet of the oxygen-liquid separation unit is led to a safe area for discharge. Its main function is to achieve gas-liquid separation of oxygen, thereby improving oxygen purity.

[0035] The inlet of the weak alkali solution circulation unit 9 is connected to the weak alkali solution outlet of the heat exchange unit; the outlet of the weak alkali solution circulation unit is connected to the low-temperature weak alkali solution inlet of the anion exchange membrane electrolyzer unit. Its main function is to provide power for the circulation of the weak alkali solution.

[0036] The weak alkaline solution inlet of heat exchange unit 10 is connected to the hot weak alkaline solution outlets of the hydrogen gravity separation unit and the oxygen gravity separation unit, respectively; the low-temperature weak alkaline solution outlet of the heat exchange unit is connected to the inlet of the weak alkaline solution circulation unit; the freshwater inlet of the heat exchange unit is connected to the circulating water outlet of the flash evaporation unit and the circulating freshwater outlet of the seawater desalination unit, respectively; the hot freshwater outlet of the heat exchange unit is connected to the freshwater inlet of the flash evaporation unit. Its main function is to cool the hot weak alkaline solution with freshwater and increase the freshwater temperature to facilitate flash evaporation treatment.

[0037] The freshwater inlet of flash evaporation unit 11 is connected to the hot freshwater outlet of the heat exchange unit; the vacuum outlet of the flash evaporation unit is connected to the vacuum pump unit; the circulating water outlet of the flash evaporation unit is connected to the freshwater inlet of the heat exchange unit; and the steam outlet of the flash evaporation unit is connected to the seawater desalination unit. Its main function is to flash-evaporate the freshwater heated by the heat exchange unit and then use the steam as a heat source to supply the seawater desalination unit.

[0038] The steam inlet of the seawater desalination unit 12 is connected to the steam outlet of the flash evaporation unit; the circulating freshwater outlet of the seawater desalination unit is connected to the freshwater inlet of the heat exchange unit; the vacuum outlet of the seawater desalination unit is connected to the vacuum pump unit; the seawater inlet of the seawater desalination unit is connected to the seawater filtration and transportation unit; and the freshwater outlet of the seawater desalination unit is connected to the freshwater storage and supply unit. Its main function is to heat seawater using steam as a heat source under negative pressure to achieve low-temperature seawater desalination.

[0039] The inlet of vacuum pump unit 13 is connected to the vacuum outlet of both the flash evaporation unit and the seawater desalination unit; the outlet of the vacuum pump unit is led to a safe area for venting. Its main function is to provide a vacuum environment for the flash evaporation unit and the seawater desalination unit.

[0040] The seawater inlet of the seawater filtration and transport unit 14 is connected to a seawater source; the outlet of the seawater filtration and transport unit is connected to the seawater desalination unit. Its main function is to pre-treat seawater to provide seawater for the desalination unit.

[0041] The freshwater inlet of the freshwater storage and supply unit 15 is connected to the seawater desalination unit; the outlet of the freshwater storage and supply unit is connected to the freshwater inlets and outlets of the hydrogen washing unit and oxygen washing unit, respectively. Its main functions are: to store freshwater produced by seawater desalination, to provide washing water for the washing unit, and to replenish freshwater feedstock for the anion exchange membrane electrolyzer unit; additional freshwater can be supplied externally.

[0042] As a preferred method, a seawater-based anion exchange membrane electrolysis method for hydrogen production includes the following steps: A marine-powered anion exchange membrane electrolyzer unit 2 decomposes fresh water into hydrogen and oxygen; hydrogen and a weak alkaline solution undergo gas-liquid separation in a hydrogen gravity separation unit 3; then, hydrogen and a small amount of alkaline solution enter a hydrogen washing unit 4 for further alkaline removal, wherein the alkaline solution from the hydrogen washing unit 4 can be returned to the hydrogen gravity separation unit 3; finally, hydrogen and a small amount of water enter a hydrogen purification unit 5, where high-purity, low-dew-point hydrogen is achieved through deoxygenation and drying, and then supplied to users; Additionally, oxygen and a weak alkaline solution undergo gas-liquid separation in an oxygen gravity separation unit 6; then, oxygen and a small amount of alkaline solution enter an oxygen washing unit 7 for further alkaline removal, wherein the alkaline solution from the oxygen washing unit 7 can be returned to the oxygen gravity separation unit 6; finally, oxygen and a small amount of water enter an oxygen-liquid separation unit 8, thereby obtaining oxygen with higher purity. The hot alkaline solutions from the hydrogen gravity separation unit 3 and the oxygen gravity separation unit 6 are cooled by fresh water in the heat exchange unit 10 and then circulated to the anion exchange membrane electrolyzer unit 2 by the weak alkaline solution circulation unit 9. The fresh water in the heat exchange unit 10 is heated by the hot weak alkaline solution and then enters the flash evaporation unit 11. The generated water vapor enters the seawater desalination unit 12 as a heat source for heating the seawater. The vacuum pump unit 13 maintains the vacuum level of the flash evaporation unit 11 and the seawater desalination unit 12. After heating, the seawater is distilled and desalinated in a vacuum environment. The seawater is supplied by the seawater filtration and transfer unit 14. The generated fresh water is stored in the seawater storage and supply unit 15 and can be replenished to the anion exchange membrane electrolyzer unit 2 by the hydrogen washing unit 4 and the oxygen washing unit 7. The flash evaporation unit 11 and the heat exchange unit 10 circulate fresh water, which can be replenished by the fresh water from the seawater desalination, realizing the reusability of fresh water.

[0043] Figure 2 is a process system flow chart of an embodiment of the present invention. As shown in the figure, the anion exchange membrane electrolyzer 21 realizes the electrolysis of water to produce hydrogen and oxygen using green electricity; the hydrogen horizontal gravity separator 31 realizes the gas-liquid separation of hydrogen and alkaline solution; the hydrogen washing tower 41 washes away a small amount of alkaline solution in the hydrogen and can replenish fresh water to the anion exchange membrane electrolyzer 21; the hydrogen purification module 51 achieves high purity and low dew point of hydrogen through deoxygenation, drying, etc.; the oxygen horizontal gravity separator 61 realizes the gas-liquid separation of oxygen and alkaline solution; the oxygen washing tower 71 washes away a small amount of alkaline solution in the oxygen and can replenish fresh water to the anion exchange membrane electrolyzer 21; the oxygen-liquid separator 81 realizes the gas-liquid separation of hydrogen and water to improve oxygen purity; the weak alkaline solution circulation unit 9 consists of a weak alkaline solution circulation pump 91 and a weak alkaline solution filter 92, which provides power for alkaline solution circulation and filters impurities; the heat exchange unit 10 consists of a heat exchanger 101 and a fresh water circulation pump. 102 and 103 are composed of a pressure reducing valve; heat exchanger 101 realizes heat exchange between hot weak alkaline solution and fresh water; fresh water circulation pump 102 provides power for fresh water circulation; pressure reducing valve 103 enhances fresh water flash evaporation; flash evaporation unit 11 consists of flash evaporator 111, vacuum instrument 112, and remote control valve 113; flash evaporator 111 is used to generate steam from fresh water flash evaporation; vacuum instrument 112 regulates the flow rate by controlling the opening of remote control valve 113 to ensure the vacuum requirement of flash evaporator 111; desalination unit 12 consists of seawater desalination unit 121, thermometer 122, and remote control valve 113. The system comprises a control valve 123, a salinity meter 124, a remote control valve 125, and a flow meter 126. The seawater desalination unit 121 is used to achieve negative pressure, low-temperature desalination of seawater. The temperature meter 122 controls the opening of the remote control valve 123 based on the seawater temperature signal within the desalination unit 121 to regulate the seawater intake. The salinity meter 124 controls the opening and closing of the remote control valve 125 based on the seawater concentration within the desalination unit 121 to timely discharge concentrated seawater. The flow meter 126 measures the amount of freshwater produced. The vacuum pump unit 13 consists of a vacuum pump 131 and a vacuum meter 132. The vacuum instrument 132 controls the operating power of the vacuum pump 131 by sending a vacuum degree signal inside the seawater desalination unit 121 to keep the vacuum degree within a reasonable range. The seawater filtration and transfer unit 14 consists of a seawater pump 141, a multi-media filter 142, an activated carbon filter 143, and a precision filter 144. The seawater pump 141 provides seawater to the seawater desalination unit, while the multi-media filter 142, activated carbon filter 143, and precision filter 144 mainly pre-treat the seawater. The freshwater storage and supply unit 15 consists of a freshwater storage tank 151 and a freshwater supply pump 152. The freshwater storage tank 151 stores the freshwater prepared by seawater desalination, while the freshwater supply pump 152 delivers washing water to the washing unit and can also replenish the freshwater raw material for the anion exchange membrane electrolyzer unit.

[0044] This invention enables freshwater circulation between the flash evaporation unit and the heat exchange unit, achieving reusable freshwater utilization. It also utilizes a cooled, weakly alkaline solution to heat the circulating freshwater, which is then flash-evaporated. The resulting steam serves as a heat source to heat the seawater in the seawater desalination unit. The seawater undergoes low-temperature desalination under negative pressure, and the produced freshwater can be used as feedstock for the anion exchange membrane electrolyzer unit. Therefore, this invention not only improves thermal energy utilization and increases the water production ratio but is also applicable to distributed offshore wind power hydrogen production scenarios, thus promoting the rapid development of offshore wind power hydrogen production.

[0045] The sequence numbers of the above embodiments of the present invention are for descriptive purposes only and do not represent the superiority or inferiority of the embodiments. In the above embodiments of the present invention, the descriptions of each embodiment have their own emphasis; parts not described in detail in a certain embodiment can be referred to in the relevant descriptions of other embodiments. It should be understood that the disclosed technical content in the several embodiments provided in this application can be implemented in other ways.

[0046] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A seawater-based anion exchange membrane water electrolysis hydrogen production system, characterized in that, include: Anion exchange membrane electrolyzer unit (2), hydrogen gravity separation unit (3), hydrogen purification unit (5), oxygen gravity separation unit (6), oxygen-liquid separation unit (8), weak alkaline solution circulation unit (9), heat exchange unit (10), flash evaporation unit (11), seawater desalination unit (12), vacuum pump unit (13), seawater filtration and transportation unit (14), freshwater storage and supply unit (15); the anion exchange membrane electrolyzer unit (2) is driven by marine green electricity to decompose freshwater into hydrogen and oxygen; hydrogen and weak alkaline solution are separated into gas and liquid by the hydrogen gravity separation unit (3); oxygen and weak alkaline solution are separated into gas and liquid by the oxygen gravity separation unit (6); the heat of the hydrogen gravity separation unit (3) and the oxygen gravity separation unit (6) After being cooled by fresh water in the heat exchange unit (10), the alkaline solution is circulated to the anion exchange membrane electrolyzer unit (2) by the weak alkaline solution circulation unit (9); the fresh water in the heat exchange unit (10) is heated by hot weak alkaline solution and then enters the flash evaporation unit (11), and the generated water vapor enters the seawater desalination unit (12) as a heat source for heating seawater; after heating, the seawater is distilled and desalinated in a vacuum environment, and the seawater is provided by the seawater filtration and transfer unit (14), and the generated fresh water is stored in the seawater storage and supply unit (15); the flash evaporation unit (11) and the heat exchange unit (10) circulate fresh water; hydrogen and a small amount of water enter the hydrogen purification unit (5) to achieve high purity and low dew point hydrogen through deoxygenation and drying, and then supply it to the user.

2. The seawater-based anion exchange membrane water electrolysis hydrogen production system according to claim 1, characterized in that, The system also has a hydrogen washing unit (4); the hydrogen gas after gas-liquid separation enters the hydrogen washing unit (4) to remove the alkaline solution.

3. The seawater-based anion exchange membrane water electrolysis hydrogen production system according to claim 1, characterized in that, The system also includes an oxygen scrubbing unit (7); the oxygen after gas-liquid separation enters the oxygen scrubbing unit (7) to remove the alkaline solution.

4. The seawater-based anion exchange membrane water electrolysis hydrogen production system according to claim 2, characterized in that, The alkaline solution in the hydrogen washing unit (4) can be returned to the hydrogen gravity separation unit (3); at the same time, the raw material fresh water is replenished to the anion exchange membrane electrolyzer unit (2) through the hydrogen washing unit (4).

5. A seawater-based anion exchange membrane water electrolysis hydrogen production system according to claim 3, characterized in that, The alkaline solution in the oxygen washing unit (7) can be returned to the oxygen gravity separation unit (6); at the same time, the raw material fresh water is replenished to the anion exchange membrane electrolyzer unit (2) through the oxygen washing unit (7).

6. The seawater-based anion exchange membrane water electrolysis hydrogen production system according to claim 1, characterized in that, The system also has an oxygen-liquid separation unit (8); oxygen and a small amount of water enter the oxygen-liquid separation unit (8) to obtain oxygen with higher purity, which is then led to a safe area for venting.

7. The seawater-based anion exchange membrane water electrolysis hydrogen production system according to claim 1, characterized in that, The system also has a vacuum pump unit (13); the vacuum pump unit (13) maintains the vacuum level of the flash evaporation unit (11) and the seawater desalination unit (12).

8. A method for producing hydrogen by anion exchange membrane electrolysis of seawater, characterized in that, The process includes the following steps: Step 1: The offshore green electricity-driven anion exchange membrane electrolyzer unit decomposes freshwater into hydrogen and oxygen; Step 2: Hydrogen and weak alkaline solution undergo gas-liquid separation via a hydrogen gravity separation unit; oxygen and weak alkaline solution undergo gas-liquid separation via an oxygen gravity separation unit; Step 3: The hot alkaline solution from the hydrogen gravity separation unit and the oxygen gravity separation unit is cooled by freshwater in the heat exchange unit and then circulated to the anion exchange membrane electrolyzer unit by the weak alkaline solution circulation unit; Step 4: The freshwater in the heat exchange unit is heated by hot weak alkaline solution and then enters the flash evaporation unit. The generated water vapor enters the seawater desalination unit as a heat source for heating seawater; Step 5: After heating, the seawater is distilled and desalinated in a vacuum environment. The seawater is supplied by the seawater filtration and transport unit, and the generated freshwater is stored in the seawater storage and supply unit; Step 6: The flash evaporation unit and the heat exchange unit circulate the freshwater; Step 7: Hydrogen and a small amount of water enter the hydrogen purification unit, where deoxygenation and drying are performed to achieve high-purity hydrogen with a low dew point, which is then supplied to the user.

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