System for combining water electrolysis to produce hydrogen with seawater desalination (options) and method for desalination of seawater

Abstract

FIELD: hydrogen production.SUBSTANCE: method and system for producing hydrogen by alkaline electrolysis of water and, in particular, systems for combining water electrolysis for producing hydrogen with desalination of seawater and a method for desalination of seawater. The system comprises an alkaline electrolyzer module, an oxygen separation module, a hydrogen separation module, an alkaline solution filtration and circulation module, a negative pressure seawater desalination module, a fresh water supply module, and a hydrogen purification module. The alkaline solution to be cooled is directly used to heat seawater in a negative pressure environment, thus not only cooling the alkaline solution, but also using the heat dissipated during the cooling of the alkaline solution to achieve low-temperature desalination of seawater. Fresh water is used as a material for water electrolysis, intended to be fed into the alkaline electrolyzer module.EFFECT: energy savings and emission reductions, as well as facilitation of large-scale indirect hydrogen production from seawater.10 cl, 4 dwg

Description

FIELD OF TECHNOLOGY

[0001] The present invention relates to a method and system for producing hydrogen through alkaline electrolysis of water, and in particular to systems for combining water electrolysis to produce hydrogen with seawater desalination and a method for desalinating seawater.BACKGROUND

[0002] Hydrogen production through water electrolysis is the most promising technology for green hydrogen production. Hydrogen production through alkaline water electrolysis is relatively well-developed, cost-effective, and economically viable, and is widely used. However, all commercially used water electrolysis systems for hydrogen production currently use fresh water as a feedstock. Given the extremely limited global freshwater resources, this undoubtedly exacerbates the problem of freshwater shortage.

[0003] Although seawater is abundant, its high content of ions, microorganisms, and particulate impurities poses significant challenges to direct seawater electrolysis for hydrogen production, including the formation of numerous electrolysis byproducts, rapid catalyst deactivation, and frequent membrane fouling. Hydrogen production from seawater electrolysis is currently still in the technical research, development, and validation stages.

[0004] Therefore, how to combine seawater desalination technology with hydrogen production through alkaline water electrolysis to create an efficient seawater-based indirect hydrogen production technology suitable for large-scale application has become an urgent problem to be solved. SUMMARY OF THE INVENTION

[0005] To solve the above-described technical problems, the present invention provides a system and method for combining water electrolysis to produce hydrogen with seawater desalination. By effectively combining a negative pressure seawater desalination module with hydrogen production through water electrolysis, the present invention utilizes the heat from the alkaline solution to be cooled to desalinate seawater, thereby supplying fresh water required for hydrogen production through alkaline water electrolysis.The present invention not only contributes to energy conservation and emission reduction, but also facilitates large-scale indirect hydrogen production from seawater, which is expected to provide a technical basis for hydrogen production through water electrolysis based on coastal renewable energy, thereby expanding the application scenarios of hydrogen production through alkaline water electrolysis and promoting the application of coastal green hydrogen production technologies.

[0006] In order to achieve the above objects, the present invention uses the following technical ideas to solve the above technical problems

[0007] In the first aspect of the present invention, there is provided a system for combining water electrolysis to produce hydrogen with seawater desalination, comprising an alkaline electrolyzer module, an oxygen separation module, a hydrogen separation module, a hydrogen purification module, an alkaline solution filtration and circulation module, a negative pressure seawater desalination module and a fresh water supply module, wherein the negative pressure seawater desalination module is configured to heat seawater under negative pressure to cause the seawater to boil at low temperatures to generate steam, and impurities are removed from the steam, and the steam is condensed to produce fresh water; the fresh water supply module is configured to supply fresh water to the alkaline electrolyzer module;Fresh water in the alkaline electrolyzer module is decomposed into hydrogen and oxygen under the action of direct current, the hydrogen and alkaline solution obtained in the electrolyzer are fed to the hydrogen separation module, and the oxygen and alkaline solution obtained in the electrolyzer are fed to the oxygen separation module; the alkaline solution filtration and circulation module is designed to provide forced circulation of the alkaline solution in the alkaline electrolyzer module, the hydrogen separation module and the oxygen separation module; the energy source of the negative pressure seawater desalination module is the heat released when the alkaline solution is cooled to the temperature required by the electrolyzer.

[0008] In a preferred embodiment, the hydrogen outlet channel of the alkali electrolyzer module is connected to the hydrogen separation module, acting as a passage for introducing hydrogen and an alkaline solution into the hydrogen separation module; the oxygen outlet channel of the alkali electrolyzer module is connected to the oxygen separation module, acting as a passage for introducing oxygen and an alkaline solution into the oxygen separation module; and the alkaline solution inlet channel of the alkali electrolyzer module is connected to the negative pressure seawater desalination module, acting as a passage for introducing cooled alkaline solution into the alkali electrolyzer module.

[0009] In a preferred embodiment, the oxygen inlet channel of the oxygen separation module is connected to the oxygen outlet channel of the alkali electrolyzer module, and the oxygen separation module separates the incoming oxygen and alkaline solution by the gas-liquid separation method; the alkaline solution outlet channel of the oxygen separation module and the alkaline solution outlet channel of the hydrogen separation module converge into a main pipe, which is connected to the alkaline solution filtration and circulation module to supply the alkaline solution to be cooled; the oxygen outlet channel of the oxygen separation module extends to safe areas for discharging oxygen or is connected to oxygen storage modules to transport oxygen to the outside; the hydrogen inlet channel of the hydrogen separation module is connected to the hydrogen outlet channel of the alkali electrolyzer module, and the hydrogen separation module separates the incoming hydrogen and alkaline solution by the gas-liquid separation method;the hydrogen outlet channel of the hydrogen separation module is connected to the hydrogen purification module, acting as a passage for supplying hydrogen; the fresh water inlet channel of the hydrogen separation module is connected to the fresh water supply module, acting as a passage for supplying fresh water for supplying fresh water for electrolysis, while also contributing to the functions of purifying and cooling hydrogen.

[0010] In a preferred embodiment, the hydrogen purification module performs deoxygenation on incoming hydrogen, residual oxygen, and residual water through catalytic reactions and removes water and other impurities using the molecular sieve adsorption principle, ultimately purifying hydrogen to 99.999%; and the hydrogen outlet channel of the hydrogen purification module is connected to consumers or storage modules.

[0011] In a preferred embodiment, the seawater inlet channel of the negative pressure seawater desalination module is a passage for feeding seawater; the alkaline solution inlet channel of the negative pressure seawater desalination module is connected to the alkaline solution filtration and circulation module, acting as a passage for feeding the alkaline solution into the negative pressure seawater desalination module; the alkaline solution outlet channel of the negative pressure seawater desalination module is connected to the alkaline electrolyzer module, acting as an outlet passage for the cooled alkaline solution; the fresh water outlet channel of the negative pressure seawater desalination module is connected to the fresh water supply module, acting as an outlet passage for usable fresh water after desalination of seawater.

[0012] In a preferred embodiment, the negative pressure seawater desalination module comprises a negative pressure seawater desalination device, a vacuum gauge, a vacuum pump, a control valve, a salinity meter, a temperature sensor, a water quality detector and a seawater supply pump, wherein the vacuum gauge is configured to monitor the vacuum level inside the negative pressure seawater desalination device and control the vacuum pump to maintain the vacuum level inside the negative pressure seawater desalination device within a predetermined range;The seawater feeding pump draws in seawater and supplies it to the condenser of the negative pressure seawater desalination device to cool the water vapor to the state of liquid fresh water, then the first flow of heated seawater is supplied to the evaporation chamber of the negative pressure seawater desalination device, and the second flow of heated seawater is discharged; the salinity meter regulates and controls the flow rate of the discharged concentrated seawater through the regulating valve according to the monitored salinity of the seawater inside the evaporation chamber of the negative pressure seawater desalination device; the water quality detector controls the entry of suitable fresh water into the fresh water tank and the return of unsuitable fresh water to the negative pressure seawater desalination device for further desalination according to the monitored water quality of the produced fresh water;The temperature sensor controls the opening degree of the control valve according to the monitored temperature of the cooled alkaline solution, ensuring that the alkaline solution enters the alkaline electrolyzer module within the allowable temperature range.

[0013] In a preferred embodiment, the negative pressure seawater desalination device comprises a cylindrical body for desalinating seawater under negative pressure, a condenser, a collecting plate, a mesh separator and a heat exchanger, wherein the condenser condenses water vapor using seawater as a cooling medium, and then the seawater that has absorbed heat and is heated acts as a heat source for heating an alkaline solution; the collecting plate is configured to collect condensed water droplets and has a certain inclination; the mesh separator is configured to separate liquid droplets and impurities from water vapor; and the heat exchanger heats seawater using the heated alkaline solution as a heat source, ultimately performing the function of low-temperature desalination of seawater under negative pressure.

[0014] In a second aspect of the present invention, a system for combining water electrolysis to produce hydrogen with seawater desalination is provided, comprising a negative pressure seawater desalination module, which comprises a seawater supply and filtration module, a reverse osmosis (RO) module and a negative pressure distillation module, wherein the seawater supply and filtration module is configured to draw in seawater and pre-filter impurities to provide seawater for the RO module; the RO module is configured to prepare fresh water;The heat source of the negative pressure distillation module provides electric heating from offshore wind power, and the negative pressure distillation module is configured to purify fresh water to obtain purified water using cooling fresh water to absorb heat generated during the production of hydrogen through alkaline electrolysis of water, as well as electric heating from offshore wind power; and the power interface of the alkaline electrolyzer module is connected to the offshore wind power, and the fresh water in the alkaline electrolyzer module is decomposed into hydrogen and oxygen under the action of the energy of the offshore wind power.

[0015] In a preferred embodiment, said system further comprises a hydrogen delivery module that comprises a hydrogen compression module, a high-pressure hydrogen storage module and a hydrogen filling module, wherein the hydrogen inlet channel of the hydrogen compression module is connected to the hydrogen purification module, the hydrogen outlet channel of the hydrogen compression module is connected to the high-pressure hydrogen storage module and the hydrogen filling module, and the hydrogen compression module is configured to compress hydrogen to a required pressure and fill the high-pressure hydrogen storage module with it or provide filling energy for the hydrogen filling module; the high-pressure hydrogen inlet channel of the high-pressure hydrogen storage module is connected to the hydrogen compression module, and the high-pressure hydrogen storage module is configured to store high-pressure hydrogen and can be unloaded for transportation;and the hydrogen inlet channel of the hydrogen filling module is connected to the hydrogen compression module and is configured to fill high-pressure hydrogen into hydrogen-powered vessels; and;

[0016] The system further comprises a purified water delivery module, which comprises a purified water storage and supply module and a purified water output module, wherein the inlet channel for pure water of the purified water storage and supply module is connected to the outlet channel for purified water of the negative pressure distillation module, and the outlet channel for purified water of the purified water storage and supply module acts as the outlet channel of the fresh water supply module; the purified water storage and supply module is configured to store the purified water produced by the negative pressure distillation module, replenish the purified water for electrolysis in the alkaline electrolyzer and supply the purified water to the purified water output module; and the inlet channel for purified water of the purified water output module is connected to the purified water storage and supply module, supplying the produced fresh water to nearby platforms or vessels that need it.

[0017] In a third aspect of the present invention, there is provided a method for desalinating seawater using a system for combining water electrolysis to produce hydrogen with seawater desalination as described above, comprising:

[0018] Decomposition of fresh water in an alkaline electrolyzer module into hydrogen and oxygen under the action of direct current;

[0019] transporting oxygen and an alkaline solution from the oxygen outlet channel of the alkaline electrolyzer module to the oxygen separation module for separating gas and liquid, wherein the purified oxygen is sent to a safe area for unloading or introduced into the oxygen storage module;

[0020] transporting hydrogen and alkaline solution from the hydrogen outlet channel of the alkali electrolyzer module to the hydrogen separation module for gas-liquid separation, the pre-purified hydrogen together with water enters the hydrogen purification module for further purification until the hydrogen content reaches 99.999%, and then the hydrogen is finally supplied to consumers or storage modules;

[0021] Pulling the alkaline solution from the oxygen separation module and the hydrogen separation module through the alkaline solution filtration and circulation module, cooling the alkaline solution through the negative pressure seawater desalination module, and finally transporting the alkaline solution to the alkaline electrolysis module, performing cooling and forced circulation of the alkaline solution; and

[0022] Using the heat generated during cooling of the alkali solution in the negative pressure seawater desalination module to heat seawater under negative pressure for boiling evaporation to obtain fresh water, the suitable fresh water is supplied to the fresh water supply module and transported to the hydrogen separation module to supply fresh water used for electrolysis and promote the purification and cooling of hydrogen.

[0023] The present invention has the following advantages.

[0024] 1. The present invention directly utilizes an alkaline solution requiring cooling to heat seawater under negative pressure. This not only cools the alkaline solution but also utilizes the heat released during cooling of the alkaline solution to achieve low-temperature seawater desalination. Furthermore, the negative pressure seawater desalination module replaces the alkaline solution cooling device and auxiliary water cooling system, reducing energy consumption in hydrogen production through water electrolysis.

[0025] 2. The present invention utilizes the heat released during the cooling of the alkaline solution to desalinate seawater under negative pressure, and the suitable fresh water is supplied as raw material to the alkaline electrolyzer module for water electrolysis, which not only reduces the dependence on fresh water resources but also supports large-scale application. The present invention expands the application scenarios of hydrogen production through alkaline water electrolysis and promotes the application of coastal green hydrogen production technologies. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] The graphical materials used in the embodiments or prior art will be briefly described herein to more clearly describe the embodiments of the present application or the technical solutions of the prior art. Obviously, the following graphical materials described represent only some embodiments of the present invention. For those of ordinary skill in the art, other graphical materials can also be obtained according to the provided graphical materials without creative efforts.

[0027] Fig. 1 is a functional block diagram of a technology for producing hydrogen by alkaline water electrolysis coupled with seawater desalination according to Embodiment 1 of the present invention.

[0028] Fig. 2 is a block diagram of a process system according to Embodiment 1 of the present invention.

[0029] Fig. 3 is a front view of a negative pressure seawater desalination module according to Embodiment 1 of the present invention.

[0030] Fig. 4 is a block diagram of the main functions according to Embodiment 2 of the present invention.

[0031] 1 - Basic configuration, 2 - Alkaline electrolyzer module, 3 - Oxygen separation module, 4 - Hydrogen separation module, 5 - Alkaline solution filtration and circulation module, 6 - Negative pressure seawater desalination module, 7 - Fresh water supply module, 8 - Hydrogen purification module, 31 - Gravity oxygen separator, 32 - Oxygen purifier and cooler, 33 - Gas-liquid separator, 34 - Pressure sensor, 35 - Control valve, 41 - Gravity hydrogen separator, 42 - Hydrogen purifier and cooler, 43 - Gas-liquid separator, 44 - Differential level sensor, 45 - Control valve, 51 - Alkaline solution filter, 52 - Alkaline solution circulation pump, 61 - Negative pressure seawater desalination device, 62 - Vacuum pressure gauge, 63 - vacuum pump, 64 - control valve, 65 - salinity meter, 66 - control valve, 67 - temperature sensor, 68 - water quality detector,69 - seawater supply pump, 71 - fresh water tank, 72 - fresh water supply pump, 611 - cylindrical body of the negative pressure seawater desalination device, 612 - condenser, 613 - water collection plate, 614 - mesh separator, 615 - heat exchanger.DETAILED DESCRIPTION OF IMPLEMENTATION OPTIONS,

[0032] In order to make the objectives, technical solutions and advantages of the embodiments of the present invention more obvious, the technical solutions according to the present invention will be clearly and completely described below in combination with the accompanying drawings in the embodiments of the present invention, and of course, the described embodiments are some, not all, embodiments of the present invention. The following description of at least one exemplary embodiment is itself only illustrative and is in no way intended to limit the present invention, its application or use. All other embodiments obtained by persons of ordinary skill in the art based on the embodiments of the present invention without creative efforts are included in the protection scope of the present invention. Embodiment 1

[0033] Fig. 1 of the present invention is a functional block diagram of a method and system for producing hydrogen through water electrolysis combined with seawater desalination. The method and systems for producing hydrogen through water electrolysis combined with seawater desalination are shown in the region within the basic configuration 1. The system and method for producing hydrogen through water electrolysis combined with seawater desalination according to the present invention directly use an alkaline solution that requires cooling to heat seawater under negative pressure, which not only cools the alkaline solution, but also uses the heat released during cooling of the alkaline solution to achieve low-temperature desalination of seawater. Moreover, the obtained suitable fresh water is supplied as raw material to the alkaline electrolyzer module for water electrolysis, reducing the dependence on fresh water resources.The functional modules for implementing the technology for producing hydrogen through alkaline water electrolysis combined with seawater desalination mainly include: alkaline electrolyzer module 2, oxygen separation module 3, hydrogen separation module 4, alkaline solution filtration and circulation module 5, seawater desalination module 6 under negative pressure, fresh water supply module 7, and hydrogen purification module 8.

[0034] The connections and functions between modules are as follows:

[0035] Alkaline electrolysis module: Fresh water in the alkaline electrolysis module is decomposed into one part hydrogen and half part oxygen by the action of direct current; the hydrogen outlet channel of the alkaline electrolysis module is connected to the hydrogen separation module, acting as a passage for the hydrogen and alkaline solution to enter the hydrogen separation module; the oxygen outlet channel of the alkaline electrolysis module is connected to the oxygen separation module, acting as a passage for the oxygen and alkaline solution to enter the oxygen separation module; and the alkaline solution inlet channel of the alkaline electrolysis module is connected to the negative pressure seawater desalination module, acting as a passage for the cooled alkaline solution to enter the alkaline electrolysis module.

[0036] Oxygen separation module: The oxygen inlet channel of the oxygen separation module is connected to the oxygen outlet channel of the alkali electrolyzer module, and the oxygen separation module separates the incoming oxygen and alkaline solution through gas-liquid separation; the alkaline solution outlet channel of the oxygen separation module and the alkaline solution outlet channel of the hydrogen separation module converge into a main pipe, which is connected to the alkaline solution filtration and circulation module to supply high-temperature alkaline solution to be cooled; the oxygen outlet channel of the oxygen separation module passes to safe areas for oxygen discharge or is connected to oxygen storage modules to transport oxygen to the outside.

[0037] Hydrogen separation module: The hydrogen inlet channel of the hydrogen separation module is connected to the hydrogen outlet channel of the alkali electrolyzer module, and the hydrogen separation module separates the incoming hydrogen and alkaline solution by gas-liquid separation; the hydrogen outlet channel of the hydrogen separation module is connected to the hydrogen purification module, acting as a passage for supplying relatively high-purity hydrogen; the alkaline solution outlet channel of the hydrogen separation module and the alkaline solution outlet channel of the oxygen separation module converge into a main pipe, which is connected to the alkaline solution filtration and circulation module to supply high-temperature alkaline solution to be cooled; the fresh water inlet channel of the hydrogen separation module is connected to the fresh water supply module, acting as a fresh water supply passage for supplying fresh water for electrolysis, while also contributing to the functions of hydrogen purification and cooling.

[0038] Hydrogen Purification Module: The hydrogen inlet channel of the hydrogen purification module is connected to the hydrogen outlet channel of the hydrogen separation module; the hydrogen purification module performs deoxygenation of the inlet hydrogen, residual oxygen, and residual water through catalytic reactions, and removes water and other impurities using the principle of molecular sieve adsorption, ultimately purifying hydrogen to 99.999%; and the hydrogen outlet channel of the hydrogen purification module is connected to consumers or storage modules.

[0039] Alkaline Solution Filtration and Circulation Module: The alkaline solution inlet of the alkaline solution filtration and circulation module is connected to the main pipe, into which the alkaline solution outlet of the hydrogen separation module and the alkaline solution outlet of the oxygen separation module converge; the alkaline solution outlet of the alkaline solution filtration and circulation module is connected to the negative pressure seawater desalination module. The alkaline solution filtration and circulation module has the functions of forcibly circulating the alkaline solution in the alkaline electrolyzer module, hydrogen separation module, and oxygen separation module, while filtering out impurities from the alkaline solution.

[0040] Negative pressure seawater desalination module: the seawater inlet channel of the negative pressure seawater desalination module is a passage for feeding seawater; the alkaline solution inlet channel of the negative pressure seawater desalination module is connected to the alkaline solution filtration and circulation module, acting as a passage for feeding high-temperature alkaline solution into the negative pressure seawater desalination module; the alkaline solution outlet channel of the negative pressure seawater desalination module is connected to the alkaline electrolyzer module, acting as an outlet passage for the cooled alkaline solution; and the fresh water outlet channel of the negative pressure seawater desalination module is connected to the fresh water supply module, acting as an outlet passage for suitable fresh water after desalination of seawater.The negative pressure seawater desalination module utilizes the heat released during cooling of the high-temperature alkaline solution to the required electrolyzer temperature to heat seawater under negative pressure. The seawater is then boiled at a low temperature, generating steam. The steam then passes through a mesh separator to remove impurities, followed by condensation in a condenser to produce fresh water. Suitable fresh water enters the fresh water supply module and, after passing through the hydrogen separation module, replenishes the alkaline electrolyzer module with fresh water. Unsuitable fresh water is re-evaporated to produce fresh water.

[0041] Fresh Water Supply Module: The fresh water inlet of the fresh water supply module is connected to the negative pressure seawater desalination module, and the fresh water outlet of the fresh water supply module is connected to the hydrogen separation module. The fresh water supply module is configured to store suitable fresh water produced by the negative pressure seawater desalination module and supply fresh water to the alkaline electrolyzer module.

[0042] The process of the method and system for producing hydrogen through water electrolysis combined with seawater desalination is as follows: fresh water in the alkali electrolyzer module 2 is decomposed into one part hydrogen and half a part oxygen by the action of direct current; from the oxygen outlet channel of the alkali electrolyzer module, the oxygen and the alkaline solution are transported to the oxygen separation module 3 for gas-liquid separation, and the purified oxygen is sent to a safe area for discharge or storage in the oxygen storage module; from the hydrogen outlet channel of the alkali electrolyzer module, the hydrogen and the alkaline solution are transported to the hydrogen separation module 4 for gas-liquid separation, and the pre-purified hydrogen together with a small amount of water is entered into the hydrogen purification module 8 for further purification until the hydrogen content reaches 99.999%, and then the hydrogen is finally supplied to consumers or storage modules;the alkaline solution filtration and circulation module 5 draws out the alkaline solution from the oxygen separation module 3 and the hydrogen separation module 4, then the alkaline solution is cooled by the seawater desalination module 6 under negative pressure, and finally transported to the alkaline electrolyzer module 2 to complete the cooling and forced circulation of the alkaline solution;and the heat released during cooling of the alkaline solution in the seawater desalination module 6 under negative pressure is used to heat seawater under negative pressure for evaporation by boiling to produce fresh water, then the suitable fresh water is supplied to the fresh water supply module 7, and it is transported to the hydrogen separation module 4 to supply fresh water used for electrolysis and to facilitate the purification and cooling of hydrogen. Therefore, the present invention provides direct use of the alkaline solution that requires cooling for heating seawater under negative pressure for low-temperature seawater desalination, supplies suitable fresh water as a raw material to the alkaline electrolyzer module for water electrolysis, helping to reduce the dependence of hydrogen production through alkaline electrolysis of water on fresh water resources.

[0043] Fig. 2 is a structural diagram of a process system according to an embodiment of the present invention. As shown in the figure, the oxygen separation module 3 includes a gravity oxygen separator 31, an oxygen purifier-cooler 32, a gas-liquid separator 33, a pressure sensor 34, and a control valve 35, which mainly provide gas-liquid separation of oxygen and an alkaline solution to produce high-purity oxygen. The pressure sensor 34 controls the opening degree of the control valve 35 based on the measured pressure of the gravity oxygen separator 31, ensuring a stable pressure in the system during the process of producing hydrogen through water electrolysis.The hydrogen separation module 4 comprises a gravity hydrogen separator 41, a hydrogen purifier-cooler 42, a gas-liquid separator 43, a differential level sensor 44, and a control valve 45, which primarily ensures gas-liquid separation of oxygen and an alkaline solution, providing the basis for further hydrogen purification in the hydrogen purification module 8. The hydrogen purification module 8 comprises a deoxygenation tower, a drying tower, a condenser, and a gas-liquid separator. The differential level sensor 44 regulates the opening degree of the control valve 45 based on the measured difference in liquid levels between the gravity oxygen separator 31 and the gravity hydrogen separator 41, ensuring a balance of liquid levels. The alkaline solution filtration and circulation module 5 comprises an alkaline solution filter 51 and an alkaline solution circulation pump 52.The module 6 for desalinating seawater under negative pressure comprises a device 61 for desalinating seawater under negative pressure, a vacuum pressure gauge 62, a vacuum pump 63, a control valve 64, a salinity meter 65, a control valve 66, a temperature sensor 67, a water quality detector 68, and a pump 69 for supplying seawater. The vacuum pressure gauge 62 is configured to monitor the vacuum level inside the device 61 for desalinating seawater under negative pressure and to control the vacuum pump 63 to maintain the vacuum level inside the device 61 for desalinating seawater under negative pressure within an acceptable range.The seawater supply pump 69 draws seawater and supplies it to the condenser in the seawater desalination device 61 under negative pressure to condense water vapor into liquid fresh water. A portion of the heated seawater after condensation is supplied to the evaporation chamber in the seawater desalination device 61 under negative pressure as a replenishment, while the excess is discharged. The salinity meter 65 adjusts the control valve 66 based on monitoring the salinity of the seawater in the evaporation chamber of the seawater desalination device 61 under negative pressure to regulate and control the flow rate of the discharged concentrated seawater.The water quality detector 68 controls, based on monitoring the quality of the received fresh water, the discharge of suitable fresh water into the fresh water tank 71, while returning unsuitable fresh water back to the seawater desalination device 61 under negative pressure for additional desalination. The temperature sensor 67 controls, based on monitoring the temperature of the cooled alkaline solution, the degree of opening of the control valve 64 to ensure that the alkaline solution enters the alkaline electrolyzer module 2 within the permissible temperature range (the alkaline electrolyzer module contains an alkaline electrolyzer powered by a DC source). The fresh water supply module 7 contains the fresh water tank 71 and the fresh water supply pump 72.Suitable fresh water produced by the negative pressure seawater desalination device 61 is sent to the fresh water tank 71 and then transported to the hydrogen purifier-cooler 42 via the fresh water supply pump 72, which serves to replenish fresh water for electrolysis, while also facilitating the purification and cooling of hydrogen.

[0044] Fig. 3 is a front view of a negative pressure seawater desalination module according to an embodiment of the present invention. As shown in the figure, the negative pressure seawater desalination device 61 includes a cylindrical body 611 of the negative pressure seawater desalination device, a condenser 612, a water collecting plate 613, a mesh separator 614, and a heat exchanger 615. The condenser 612 uses seawater as a cooling medium to condense water vapor. The seawater that has absorbed heat and become warm can be used as a heat source to heat an alkaline solution, promoting the efficient use of thermal energy. The water collecting plate 613 is configured to collect condensed water droplets and has a certain inclination, which facilitates the discharge of fresh water.The mesh separator is designed to separate larger liquid droplets and impurities from water vapor, ensuring the quality of fresh water. Heat exchanger 615 uses an alkaline solution as a heat source to heat seawater, ultimately enabling low-temperature seawater desalination under negative pressure.

[0045] The present invention directly utilizes an alkaline solution requiring cooling to heat seawater under negative pressure. This not only cools the alkaline solution but also utilizes the heat released during cooling to achieve low-temperature seawater desalination. The resulting usable fresh water is then fed to an alkaline electrolyzer module for water electrolysis, reducing dependence on freshwater resources. Furthermore, the negative pressure seawater desalination module replaces the alkaline solution cooling devices and their associated water cooling systems, reducing energy consumption in hydrogen production through water electrolysis.Moreover, the method and system for producing hydrogen through water electrolysis combined with seawater desalination according to the present invention are suitable for large-scale application, which not only expands the application scenarios of hydrogen production through alkaline water electrolysis, but also promotes the application of marine green hydrogen production technologies. Embodiment 2.

[0046] Based on Embodiment 1, this embodiment combines hydrogen production with seawater desalination using offshore wind power into a new system for large-scale co-production of hydrogen and fresh water, thereby achieving a transition from onshore electricity transmission to onshore hydrogen delivery. In this embodiment, an electric heating method using waste heat generated during hydrogen production through alkaline water electrolysis and supplemented by offshore wind power is used to perform negative pressure distillation of fresh water prepared from seawater through reverse osmosis (RO).This method enables the large-scale production of purified water, which not only meets the feedstock (purified water) needed for hydrogen production through alkaline water electrolysis powered by offshore wind energy, but can also supply purified water to supporting platforms, nearby work platforms, or vessels. Furthermore, hydrogen produced through alkaline water electrolysis powered by offshore wind energy can not only be supplied to onshore consumers but also fuel moored hydrogen-powered vessels. Therefore, the present invention not only enables the combined production of hydrogen and fresh water using offshore wind energy but also contributes to energy savings and emission reductions.This method provides technical support for the development of an autonomous and controllable technological system for the combined production of hydrogen and fresh water using offshore wind energy, solving the problem of large-scale offshore wind energy deployment while significantly reducing the investment costs of offshore wind farms. This method offers the opportunity to develop offshore wind energy to address the bottleneck in energy transmission channels, making it an environmentally friendly and high-quality strategic energy source.

[0047] In an embodiment of the present invention, a system and method for co-producing hydrogen and clean water based on offshore wind energy are provided, the functional modules of which include the following.

[0048] Alkaline electrolysis module: The power interface of the alkaline electrolysis module is connected to the offshore wind power system; the alkaline solution inlet channel of the alkaline electrolysis module is connected to the alkaline solution outlet channel of the negative pressure distillation module; the hydrogen outlet channel of the alkaline electrolysis module is connected to the hydrogen separation and cooling module; and the oxygen outlet channel of the alkaline electrolysis module is connected to the oxygen separation and cooling module. The main function of the alkaline electrolysis module is to decompose purified water in the alkaline electrolysis module into hydrogen and oxygen under the action of offshore wind power. The resulting hydrogen and alkaline solution enter the hydrogen separation and cooling module, and the resulting oxygen and alkaline solution enter the oxygen separation and cooling module.

[0049] Oxygen separation and cooling module: the oxygen inlet channel of the oxygen separation and cooling module is connected to the oxygen outlet channel of the alkali electrolyzer module, and the oxygen outlet channel of the oxygen separation and cooling module is directed to a safe area for oxygen discharge; the alkali solution outlet channel of the oxygen separation and cooling module and the alkali solution outlet channel of the hydrogen separation and cooling module converge into a main pipe, which is connected to the alkali solution filtration and circulation module; the cooling fresh water inlet channel of the oxygen separation and cooling module is connected to the cooling fresh water inlet channel of the hydrogen separation and cooling module, and then connected to the cooling fresh water outlet channel of the hydrogen purification and cooling module;and the outlet channel for the cooling fresh water of the oxygen separation and cooling module is connected to the outlet channel for the cooling fresh water of the hydrogen separation and cooling module, and then connected to the inlet channel for the heat source fresh water of the negative pressure distillation module. The main function of the oxygen separation and cooling module is to perform gas-liquid separation, purification and cooling of the oxygen and alkaline solution entering the oxygen separation and cooling module from the alkaline electrolyzer module, thereby increasing the purity of the oxygen.

[0050] Hydrogen separation and cooling module: the hydrogen inlet channel of the hydrogen separation and cooling module is connected to the hydrogen outlet channel of the alkali electrolyzer module, the hydrogen outlet channel of the hydrogen separation and cooling module is connected to the hydrogen purification module, and the alkali solution outlet channel of the hydrogen separation and cooling module and the alkali solution outlet channel of the oxygen separation and cooling module converge into a main pipe, which is connected to the alkali solution filtration and circulation module; the cooling fresh water inlet channel of the hydrogen separation and cooling module is connected to the cooling fresh water inlet channel of the oxygen separation and cooling module, and then connected to the cooling fresh water outlet channel of the hydrogen purification and cooling module;the outlet channel for cooling fresh water of the hydrogen separation and cooling module is connected to the outlet channel for cooling fresh water of the oxygen separation and cooling module and then connected to the inlet channel for the heat source fresh water of the negative pressure distillation module; and the inlet channel for purified water of the hydrogen separation and cooling module is connected to the purified water storage and supply module;Specifically, the cooling fresh water first enters the hydrogen purification and cooling module to absorb heat, and then the fresh water is divided into two streams entering the hydrogen separation and cooling module and the oxygen separation and cooling module to absorb heat, respectively. The main function of the hydrogen separation and cooling module is to perform gas-liquid separation, and purification and cooling are performed on the hydrogen and alkaline solution entering the hydrogen separation and cooling module from the alkali electrolyzer module to remove the alkaline solution from the hydrogen; and the hydrogen separation and cooling module also acts as a passage for feeding purified water to the alkali electrolyzer module, and facilitates the functions of hydrogen purification and cooling;and, in particular, the purified water is fed into the hydrogen separation and cooling module, then enters the electrolyzer through the alkaline solution filtration and circulation module and the negative pressure distillation module, completing the cycle.;

[0051] Hydrogen Purification and Cooling Module: The hydrogen inlet of the hydrogen purification and cooling module is connected to the hydrogen outlet of the hydrogen separation and cooling module, the hydrogen outlet of the hydrogen purification and cooling module is connected to the hydrogen compression module, and the cooling fresh water outlet of the hydrogen purification and cooling module is connected to the cooling fresh water outlet of the oxygen separation and cooling module and the cooling fresh water inlet of the hydrogen separation and cooling module. The main function of the hydrogen purification and cooling module is to remove oxygen, water, and other impurities from hydrogen through catalytic reactions, cooling, and adsorption on a molecular sieve, ultimately achieving a hydrogen purification rate of up to 99.999%.

[0052] Hydrogen compression module: The hydrogen inlet of the hydrogen compression module is connected to the hydrogen purification and cooling module, and the hydrogen outlet of the hydrogen compression module is connected to the high-pressure hydrogen storage module and the hydrogen refueling module. The main function of the hydrogen compression module is to compress hydrogen to the required pressure, fill the high-pressure hydrogen storage module with hydrogen, and supply refueling energy to the hydrogen refueling module.

[0053] High-pressure hydrogen storage module: The high-pressure hydrogen inlet of the high-pressure hydrogen storage module is connected to the hydrogen compression module. The main function of the high-pressure hydrogen storage module is to store high-pressure hydrogen and can be unloaded for transportation.

[0054] Hydrogen Refueling Module: The hydrogen inlet channel of the hydrogen refueling module is connected to the hydrogen compression module and supplies high-pressure hydrogen to hydrogen-powered ships.

[0055] Negative pressure distillation module: the cooling fresh water inlet of the negative pressure distillation module is connected with the reverse osmosis (RO) module, the cooling fresh water outlet of the negative pressure distillation module is connected with the cooling fresh water inlet of the hydrogen purification and cooling module, the purified water outlet of the negative pressure distillation module is connected with the purified water storage and supply module, the heat source fresh water inlet of the negative pressure distillation module is connected to the cooling fresh water outlet channels of the hydrogen separation and cooling module and the oxygen separation and cooling module, the alkaline solution inlet of the negative pressure distillation module is connected with the alkaline solution filtration and circulation module,The alkaline solution outlet channel of the negative pressure distillation module is connected to the alkaline electrolyzer module, and the electric heating interface of the negative pressure distillation module is connected to the offshore wind power system. The main function of the negative pressure distillation module is to use cooling fresh water to absorb the heat generated during hydrogen production through alkaline water electrolysis and the heat from the electricity generated by the offshore wind power to purify fresh water, enabling large-scale production of purified water.

[0056] Alkali Solution Filtration and Circulation Module: The alkali solution inlet of the alkali solution filtration and circulation module is connected to the main pipe into which the alkali solution outlet channels of the hydrogen separation and cooling module and the oxygen separation and cooling module converge. The alkali solution outlet channel of the alkali solution filtration and circulation module is connected to the negative pressure distillation module. The main function of the alkali solution filtration and circulation module is to enable forced circulation of the alkali solution in the alkali electrolyzer module, hydrogen separation and cooling module, and oxygen separation and cooling module, and to filter out impurities from the alkali solution.

[0057] Purified Water Storage and Supply Module: The purified water inlet of the purified water storage and supply module is connected to the purified water outlet of the negative pressure distillation module, and the purified water outlet of the purified water storage and supply module is connected to the purified water inlet of the hydrogen separation and cooling module and the purified water output module. The main function of the purified water storage and supply module is to store the purified water obtained by the negative pressure distillation module, supply the purified water to the alkaline electrolyzer for electrolysis, and supply the purified water to the purified water output module.

[0058] Purified Water Output Module: The purified water inlet of the purified water output module is connected to the purified water storage and supply module, allowing the produced fresh water to be distributed to nearby platforms or vessels that need it.

[0059] Seawater Supply and Filtration Module: The seawater outlet of the seawater supply and filtration module is connected to the RO module, and the seawater inlet of the seawater supply and filtration module can be located below sea level. The main function of the purified water outlet module is to extract seawater, perform pre-filtration of impurities, and provide seawater to the RO module.

[0060] RO Module: The seawater inlet of the RO module is connected to the seawater supply and filtration module, and the freshwater outlet of the RO module is connected to the freshwater cooling inlet of the negative pressure distillation module. The main function of the RO module is to process seawater through RO to produce fresh water.

[0061] Fig. 4 is a block diagram of the main functions of the method and system for co-producing hydrogen and purified water based on offshore wind energy. The method and system for co-producing hydrogen and purified water based on offshore wind energy are shown in the area inside the basic configuration and mainly include the following functional implementation modules: an alkaline electrolyzer module, an oxygen separation and cooling module, a hydrogen separation and cooling module, a hydrogen purification and cooling module, a hydrogen compression module, a high-pressure hydrogen storage module, a hydrogen filling module, a negative pressure distillation module, an alkaline solution filtration and circulation module, a purified water storage and supply module, a purified water output module,seawater supply and filtration module and RO module. The functional diagram of the method and system for the joint production of hydrogen and pure water based on offshore wind energy is as follows: purified water in the alkaline electrolyzer module is decomposed into hydrogen and oxygen under the action of direct current supplied by offshore wind energy; the oxygen produced by the alkaline electrolyzer module and the alkaline solution are transported through its oxygen outlet channel to the oxygen separation and cooling module for gas-liquid separation, purification and cooling, and the oxygen after removing the alkaline solution can be sent to a safe area for discharge; the hydrogen produced by the alkaline electrolyzer module and the alkaline solution are transported through its hydrogen outlet channel to the hydrogen separation and cooling module for gas-liquid separation, purification and cooling to remove the alkaline solution,Then the hydrogen together with a small amount of water enters the hydrogen purification and cooling module for further purification until the hydrogen content reaches 99.999%, and then the hydrogen is compressed to the required pressure by the hydrogen compression module and supplied to the high-pressure hydrogen storage module or the hydrogen filling module at any time; the alkaline solution filtration and circulation module draws the alkaline solution from the hydrogen separation and cooling module and the oxygen separation and cooling module, then the alkaline solution is finally transported to the alkali electrolyzer module after being cooled by the negative pressure distillation module, completing the cooling and forced circulation of the alkaline solution; the seawater supply and filtration module draws seawater from the sea and supplies it after filtration to the RO module to obtain fresh water, and then the obtained fresh water, acting as cooling fresh water (cooling medium),Enters the negative pressure distillation module, then enters the hydrogen purification and cooling module to absorb heat, then enters the oxygen separation and cooling module and the hydrogen separation and cooling module to absorb heat, and finally enters the negative pressure distillation module as heat source fresh water, which undergoes negative pressure distillation to obtain purified water through heating with an alkaline solution and auxiliary electric heating from offshore wind power; and the purified water obtained by the negative pressure distillation module enters the hydrogen separation and cooling module through the purified water storage and supply module to supply purified water for alkaline electrolysis, which can also enter the purified water output module for external distribution of purified water.

[0062] Alkaline electrolyzer module enables the production of hydrogen and oxygen through the electrolysis of purified water using offshore wind energy. The oxygen separation and cooling module contains a gravity oxygen separator, an oxygen purifier and cooler, and a gas-liquid separator, enabling gas-liquid separation and cooling of the oxygen and alkaline solution, and the oxygen is sent to a safe area for discharge. The hydrogen separation and cooling module contains a gravity hydrogen separator, an oxygen purifier and cooler, and a gas-liquid separator, enabling gas-liquid separation and cooling of the hydrogen and alkaline solution. The hydrogen purification and cooling module purifies hydrogen to 99.999% purity through deoxygenation, cooling,adsorption on a molecular sieve; and the purified hydrogen is compressed to a required pressure by a hydrogen compression module (providing a compressor and a hydrogen buffer tank) and supplied to a high-pressure hydrogen storage module (providing a high-pressure storage tank and a safety valve); the purified hydrogen can also be supplied at any time to a hydrogen filling module (providing a filling switching ball valve, a flow meter and a check valve) for external hydrogen filling. The negative pressure distillation module comprises a negative pressure distillation device, a vacuum gauge, a vacuum pump, a temperature sensor, a water quality detector and a brine temperature regulating valve, among which the negative pressure distillation device uses the waste heat generated during the process of producing hydrogen through alkaline electrolysis of water,supplemented by auxiliary electric heating from offshore wind power to perform negative pressure distillation on fresh water obtained from seawater through reverse osmosis (RO), enabling large-scale production of purified water; a vacuum gauge measures a vacuum level of the negative pressure distillation device and controls a vacuum pump to maintain a stable vacuum level of the negative pressure distillation device; a temperature sensor is configured to measure the temperature of the heat source fresh water in the negative pressure distillation device and control the flow rate of the booster pump to regulate the temperature; a water quality detector is configured to monitor the quality of the heat source fresh water in the negative pressure distillation device and control the opening degree of the brine temperature regulating valve,to maintain the quality of the seawater, which is a heat source. The alkaline solution filtration and circulation module comprises an alkaline solution filter and an alkaline solution circulation pump, among which the alkaline solution filter is configured to remove impurities from the alkaline solution, and the alkaline solution circulation pump provides energy for forced circulation of the alkaline solution. The purified water storage and supply module comprises a purified water tank and a purified water supply pump, among which the purified water tank is configured to store purified water obtained by the distillation device under negative pressure and supply the purified water to both the purified water supply pump and the purified water output module (providing a drain hose, a flow meter and a quick-release shut-off valve); and the purified water supply pump supplies the purified water to the oxygen purifier-cooler,To meet the need for purified water for hydrogen production through alkaline water electrolysis. The seawater supply and filtration module comprises a seawater lift pump, a mixed-bed filter, an activated carbon filter, and a precision filter. The seawater lift pump draws nearby seawater to supply it to the distillation device under negative pressure; and the mixed-bed filter, the activated carbon filter, and the precision filter remove impurities from the seawater, extending the service life of the RO device. The RO module comprises a booster pump and the RO device. The booster pump provides energy for feeding filtered seawater to the RO device to produce fresh water.

[0063] This embodiment utilizes waste heat generated in producing hydrogen through alkaline water electrolysis, in combination with auxiliary electric heating from offshore wind power, to perform negative pressure distillation on fresh water produced from seawater by reverse osmosis (RO), enabling large-scale production of purified water, which not only satisfies the need for purified water for producing hydrogen through alkaline water electrolysis using offshore wind power, but also supplies purified water to carrier platforms, nearby work platforms, or ships.

[0064] In this embodiment, fresh water obtained through the RO, acting as cooling fresh water (cooling medium), enters the distillation module under negative pressure, then enters the hydrogen purification and cooling module to absorb heat, then enters the hydrogen separation and cooling module and the oxygen separation and cooling module to absorb heat, and finally enters the distillation module under negative pressure as fresh water as a heat source. The alkaline solution from the alkaline solution filtration and circulation module, together with auxiliary electric heating from offshore wind power, is used to heat and distill the fresh water as a heat source for purification.

[0065] In this embodiment, offshore wind power and on-site seawater are used to produce hydrogen through alkaline water electrolysis, and the resulting hydrogen can be stored. The produced hydrogen can be transported to shore via a filled, high-pressure hydrogen storage module as a single unit on barges, and can also be sent to moored hydrogen-powered vessels for refueling at any time via a hydrogen refueling station. This not only enables the development of offshore wind power to overcome the bottleneck in energy transmission channels, but also significantly reduces the investment costs of offshore wind farms.

[0066] In this embodiment, fresh water is used as a medium to ensure heat transfer in producing hydrogen through alkaline water electrolysis and a negative pressure distillation module, which places low requirements on the materials of the system and equipment and demonstrates good economic feasibility.

[0067] Offshore wind power auxiliary electric heating allows for large fluctuations in wind power output, with strong adaptability and is conducive to on-site consumption and utilization of offshore wind power.

[0068] By combining offshore wind power with hydrogen production through alkaline water electrolysis and seawater desalination, this embodiment enables large-scale co-production of hydrogen and purified water, which not only promotes energy efficiency but also helps solve the problem of large-scale offshore wind power application.

[0069] In summary, this embodiment enables large-scale co-production of hydrogen and purified water by combining offshore wind power with hydrogen production through alkaline water electrolysis and seawater desalination. By satisfying the need for purified water for hydrogen production through alkaline water electrolysis using offshore wind power, the present invention provides purified water for supporting platforms, nearby work platforms, or vessels. The resulting hydrogen can be stored under high pressure or used to fuel hydrogen-powered vessels.The present invention promotes the efficient use of energy, enables the development of offshore wind power to eliminate the bottleneck of power transmission channels, significantly reduces the investment cost of offshore wind power plants, and helps solve the problem of applying large-scale offshore wind power.

[0070] Finally, it should be noted that the above various embodiments are only for illustrating the technical solution of the present invention, and not for limiting it; although the present invention has been described in detail with reference to the above embodiments, it should be understood by those of ordinary skill in the art that the technical solutions described in the above embodiments can be modified, or some or all of their technical features can be replaced with equivalents; and such modification or replacement does not cause the essence of the corresponding technical solution to deviate from the scope of the technical solution according to each embodiment of the present invention.

Claims

1. A system for combining water electrolysis for producing hydrogen with seawater desalination, comprising: an alkaline electrolyzer module, an oxygen separation module, a hydrogen separation module, a hydrogen purification module, an alkaline solution filtration and circulation module, a negative pressure seawater desalination module, and a fresh water supply module, wherein the negative pressure seawater desalination module is configured to heat seawater under negative pressure to cause the seawater to boil at low temperatures to create steam, and impurities are removed from the steam, and the steam is condensed to produce fresh water; the fresh water supply module is configured to supply fresh water to the alkaline electrolyzer module;Fresh water in the alkaline electrolyzer module is decomposed into hydrogen and oxygen under the action of direct current, the hydrogen and alkaline solution obtained in the electrolyzer are fed to the hydrogen separation module, and the oxygen and alkaline solution obtained in the electrolyzer are fed to the oxygen separation module; the alkaline solution filtration and circulation module is configured to provide forced circulation of the alkaline solution in the alkaline electrolyzer module, the hydrogen separation module and the oxygen separation module; and the energy source of the negative pressure seawater desalination module is the heat released when the alkaline solution is cooled to the temperature required by the electrolyzer.

2. The system according to claim 1, characterized in that the hydrogen outlet channel of the alkaline electrolyzer module is connected to the hydrogen separation module, acting as a passage for the supply of hydrogen and an alkaline solution to the hydrogen separation module; the oxygen outlet channel of the alkaline electrolyzer module is connected to the oxygen separation module, acting as a passage for the supply of oxygen and an alkaline solution to the oxygen separation module; and the alkaline solution inlet channel of the alkaline electrolyzer module is connected to the negative pressure seawater desalination module, acting as a passage for the supply of cooled alkaline solution to the alkaline electrolyzer module.

3. The system according to claim 1, characterized in that the oxygen inlet channel of the oxygen separation module is connected to the oxygen outlet channel of the alkaline electrolyzer module, and the oxygen separation module separates the incoming oxygen and alkaline solution by the gas-liquid separation method; the alkaline solution outlet channel of the oxygen separation module and the alkaline solution outlet channel of the hydrogen separation module converge into a main pipe, which is connected to the alkaline solution filtration and circulation module to supply the alkaline solution to be cooled; the oxygen outlet channel of the oxygen separation module passes into safe areas for releasing oxygen or is connected to oxygen storage modules for transporting oxygen to the outside; the hydrogen inlet channel of the hydrogen separation module is connected to the hydrogen outlet channel of the alkaline electrolyzer module, and the hydrogen separation module separates the incoming hydrogen and alkaline solution by the gas-liquid separation method;the hydrogen outlet channel of the hydrogen separation module is connected to the hydrogen purification module, acting as a passage for supplying hydrogen; the fresh water inlet channel of the hydrogen separation module is connected to the fresh water supply module, acting as a passage for supplying fresh water for supplying fresh water for electrolysis, while also contributing to the functions of purifying and cooling hydrogen.

4. The system according to claim 1, characterized in that the hydrogen purification module performs deoxygenation of incoming hydrogen, residual oxygen and residual water through catalytic reactions and removes water and other impurities using the principle of adsorption on a molecular sieve, ultimately purifying hydrogen to 99.999%; and the hydrogen outlet channel of the hydrogen purification module is connected to consumers or storage modules.

5. The system according to claim 1, characterized in that the inlet channel for seawater of the negative pressure seawater desalination module is a passage for feeding seawater; the inlet channel for the alkaline solution of the negative pressure seawater desalination module is connected to the alkaline solution filtration and circulation module, acting as a passage for feeding the alkaline solution into the negative pressure seawater desalination module; the outlet channel for the alkaline solution of the negative pressure seawater desalination module is connected to the alkaline electrolyzer module, acting as an outlet passage for the cooled alkaline solution; and the outlet channel for fresh water of the negative pressure seawater desalination module is connected to the fresh water supply module, acting as an outlet passage for suitable fresh water after desalination of seawater.

6. The system according to claim 1, characterized in that the module for desalination of sea water under negative pressure comprises a device for desalination of sea water under negative pressure, a vacuum pressure gauge, a vacuum pump, a control valve, a salinity meter, a temperature sensor, a water quality detector and a pump for supplying sea water, wherein the vacuum pressure gauge is configured to monitor the vacuum level inside the device for desalination of sea water under negative pressure and to control the vacuum pump to maintain the vacuum level inside the device for desalination of sea water under negative pressure within a predetermined range;The seawater feeding pump draws in seawater and supplies it to the condenser of the negative pressure seawater desalination device to cool the water vapor to the state of liquid fresh water, then the first flow of heated seawater is supplied to the evaporation chamber of the negative pressure seawater desalination device, and the second flow of heated seawater is discharged; the salinity meter regulates and controls the flow rate of the discharged concentrated seawater through the regulating valve according to the monitored salinity of the seawater inside the evaporation chamber of the negative pressure seawater desalination device; the water quality detector controls the entry of suitable fresh water into the fresh water tank and the return of unsuitable fresh water to the negative pressure seawater desalination device for further desalination according to the monitored water quality of the produced fresh water;and the temperature sensor controls the opening degree of the regulating valve according to the monitored temperature of the cooled alkaline solution, ensuring that the alkaline solution enters the alkaline electrolyzer module within the allowable temperature range.

7. The system according to claim 1, characterized in that the device for desalinating seawater under negative pressure comprises a cylindrical body for desalinating seawater under negative pressure, a condenser, a collecting plate, a mesh separator and a heat exchanger, wherein the condenser condenses water vapor using seawater as a cooling medium, and then the seawater, which has absorbed heat and is heated, acts as a heat source for heating an alkaline solution; the collecting plate is configured to collect condensed water droplets and has a certain slope; the mesh separator is configured to separate liquid droplets and impurities from water vapor; and the heat exchanger heats the seawater using the heated alkaline solution as a heat source, ultimately performing the function of low-temperature desalination of seawater under negative pressure.

8. A system for combining water electrolysis for hydrogen production with seawater desalination, comprising a negative pressure seawater desalination module, which comprises a seawater supply and filtration module, a reverse osmosis (RO) module, and a negative pressure distillation module, wherein the seawater supply and filtration module is configured to draw in seawater and pre-filter impurities to provide seawater for the RO module; the RO module is configured to prepare fresh water;The heat source of the negative pressure distillation module provides electric heating from offshore wind power, and the negative pressure distillation module is configured to purify fresh water to obtain purified water using cooling fresh water to absorb heat generated during the production of hydrogen through alkaline electrolysis of water, as well as electric heating from offshore wind power; and the power interface of the alkaline electrolyzer module is connected to the offshore wind power, and the fresh water in the alkaline electrolyzer module is decomposed into hydrogen and oxygen under the action of the energy of the offshore wind power.

9. The system according to claim 8, characterized in that it further comprises a hydrogen delivery module, which comprises a hydrogen compression module, a high-pressure hydrogen storage module and a hydrogen filling module, wherein the hydrogen inlet channel of the hydrogen compression module is connected to the hydrogen purification module, the hydrogen outlet channel of the hydrogen compression module is connected to the high-pressure hydrogen storage module and the hydrogen filling module, and the hydrogen compression module is configured to compress hydrogen to the required pressure and fill the high-pressure hydrogen storage module with it or provide filling energy for the hydrogen filling module; the high-pressure hydrogen inlet channel of the high-pressure hydrogen storage module is connected to the hydrogen compression module, and the high-pressure hydrogen storage module is configured to store high-pressure hydrogen and can be unloaded for transportation;and the hydrogen inlet channel of the hydrogen filling module is connected to the hydrogen compression module and is configured to fill high-pressure hydrogen into hydrogen-powered vessels; and; The system further comprises a purified water delivery module, which comprises a purified water storage and supply module and a purified water output module, wherein the inlet channel for pure water of the purified water storage and supply module is connected to the outlet channel for purified water of the negative pressure distillation module, and the outlet channel for purified water of the purified water storage and supply module acts as the outlet channel of the fresh water supply module; the purified water storage and supply module is configured to store purified water produced by the negative pressure distillation module, replenish purified water for electrolysis in an alkaline electrolyzer and supply purified water to the purified water output module; and the inlet channel for purified water of the purified water output module is connected to the purified water storage and supply module, supplying the produced fresh water to nearby platforms or vessels that need it.

10. A method for desalinating seawater using a system for combining water electrolysis to produce hydrogen with seawater desalination according to any one of paragraphs 1-7, comprising: decomposition of fresh water in an alkaline electrolyzer module into hydrogen and oxygen under the influence of direct current; transporting oxygen and an alkaline solution from the oxygen outlet channel of the alkaline electrolyzer module to the oxygen separation module for separating gas and liquid, wherein the purified oxygen is directed to a safe area for unloading or introduced into the oxygen storage module; transporting hydrogen and an alkaline solution from the hydrogen outlet channel of the alkaline electrolyzer module to the hydrogen separation module for separating gas and liquid, wherein the pre-purified hydrogen together with water enters the hydrogen purification module for further purification until the hydrogen content reaches 99.999%, and then the hydrogen is finally supplied to consumers or storage modules; drawing the alkaline solution from the oxygen separation module and the hydrogen separation module through the alkaline solution filtration and circulation module, cooling the alkaline solution through the seawater desalination module under negative pressure, and finally transporting the alkaline solution to the alkaline electrolyzer module, performing cooling and forced circulation of the alkaline solution; and using the heat released during cooling of the alkaline solution in the seawater desalination module under negative pressure to heat seawater under negative pressure for boiling evaporation to obtain fresh water, wherein the suitable fresh water is supplied to the fresh water supply module and is transported to the hydrogen separation module to supply fresh water used for electrolysis and facilitate the purification and cooling of hydrogen.

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