System and method for coupling hydrogen production by water electrolysis with seawater desalination.

Abstract

This invention discloses a system and method for coupling hydrogen production by water electrolysis with seawater desalination. The functional module for coupling hydrogen production by water electrolysis with seawater desalination mainly includes an alkaline electrolytic cell module, an oxygen separation module, a hydrogen separation module, an alkaline solution filtration and circulation module, a negative pressure seawater desalination module, a freshwater replenishment module, and a hydrogen purification module. This invention allows seawater under negative pressure to be heated by directly utilizing an alkaline solution that requires cooling. Not only is the alkaline solution cooled, but the heat released when the alkaline solution is cooled is also utilized to perform low-temperature seawater desalination, and the approved freshwater can be supplied to the alkaline electrolytic cell module as a raw material for water electrolysis. According to this invention, by adopting a negative pressure seawater desalination module and replacing the alkaline solution cooler and the associated cooling water system, it is possible to reduce the energy consumption of hydrogen production by water electrolysis and also reduce the dependence of hydrogen production by water electrolysis on freshwater resources. Furthermore, according to this invention, it is possible to expand the application scenarios for hydrogen production by alkaline water electrolysis, contribute to the widespread application of offshore green hydrogen production technology, and have extremely high applicability.

Description

Technical Field

[0001] The present invention relates to a method and system for hydrogen production by alkaline water electrolysis, and particularly to a system and method for coupling hydrogen production by water electrolysis with seawater desalination.

Background Art

[0002] The technology of hydrogen production by water electrolysis is the most promising technology for green hydrogen production. Among them, the technology of hydrogen production by alkaline water electrolysis is relatively the most mature, with the lowest cost, excellent economy, and is widely applied on a large scale. However, currently, all commercially used hydrogen production systems by water electrolysis use fresh water as a raw material. Since fresh water resources are extremely limited worldwide, the problem of fresh water resource shortage is exacerbated.

[0003] Although seawater resources are abundant, seawater contains a large amount of impurities such as ions, microorganisms, and particles. Therefore, the technology of directly electrolyzing seawater to produce hydrogen has problems such as many electrolysis by-products, easy inactivation of the catalyst, and easy clogging of the diaphragm. Therefore, this technology currently remains at the stage of technology research and development and verification.

[0004] Therefore, it has become an urgent problem to effectively construct an indirect hydrogen production technology using seawater by organically combining seawater desalination technology and hydrogen production technology by alkaline water electrolysis and adapting it to large-scale applications.

Summary of the Invention

Problems to be Solved by the Invention

[0005] This invention has been made in view of the above technical problems and provides a system and method for coupling hydrogen production by water electrolysis with seawater desalination. By organically combining a negative pressure seawater desalination module with hydrogen production by water electrolysis, seawater can be desalinized using the heat released when the alkaline solution is cooled, and the fresh water necessary for hydrogen production by alkaline water electrolysis can be supplied. This enables not only energy saving and emission reduction, but also large-scale hydrogen production using seawater. This aims to provide technical support for hydrogen production by water electrolysis using renewable energy at sea, expanding the application scenarios for hydrogen production by alkaline water electrolysis and contributing to the widespread application of offshore green hydrogen production technology. [Means for solving the problem]

[0006] To achieve the above objectives, the present invention employs the following technical means.

[0007] One aspect of the present invention is a system for coupling hydrogen production by water electrolysis with seawater desalination, comprising an alkaline electrolytic cell module, an oxygen separation module, a hydrogen separation module, a hydrogen purification module, an alkaline liquid filtration and circulation module, a negative pressure seawater desalination module, and a freshwater replenishment module. The negative pressure seawater desalination module heats seawater under negative pressure, causing it to boil at a low temperature to generate steam. After removing impurities from the steam, it condenses to produce fresh water. The freshwater supply module supplies raw freshwater to the alkaline electrolytic cell module. The alkaline electrolytic cell module uses DC power to electrolyze fresh water into hydrogen and oxygen. The hydrogen and alkaline solution then flow into the hydrogen separation module, and the oxygen and alkaline solution flow into the oxygen separation module. The alkaline liquid filtration and circulation module forcibly circulates the alkaline liquid between the alkaline electrolytic cell module, the hydrogen separation module, and the oxygen separation module. The negative pressure seawater desalination module uses the heat released during the process of cooling the high-temperature alkaline solution to the required temperature in the electrolytic cell as its energy source.

[0008] Furthermore, the freshwater in the alkaline electrolytic cell module is electrolyzed into hydrogen and oxygen by the action of DC power. The hydrogen outlet of the alkaline electrolytic cell module is connected to the hydrogen separation module, creating a passage through which hydrogen and alkaline solution flow into the hydrogen separation module. The oxygen outlet of the alkaline electrolytic cell module is connected to the oxygen separation module, creating a passage through which oxygen and alkaline solution flow into the oxygen separation module. The alkaline solution inlet of the alkaline electrolytic cell module is connected to the negative-pressure seawater desalination module, creating a passage through which the cooled alkaline solution flows into the alkaline electrolytic cell module.

[0009] Furthermore, the oxygen inlet of the oxygen separation module is connected to the oxygen outlet of the alkaline electrolytic cell module, and the oxygen separation module separates the incoming oxygen and alkaline liquid using a gas-liquid separation method. The alkaline liquid outlet of the oxygen separation module is connected to the alkaline liquid outlet of the hydrogen separation module, and after merging to form a main pipe, it is connected to the alkaline liquid filtration and circulation module, which provides high-temperature alkaline liquid that requires cooling. The oxygen outlet of the oxygen separation module can be extended to a safety area to release oxygen into the atmosphere, or connected to an oxygen storage module to transport oxygen to the outside. The hydrogen inlet of the hydrogen separation module is connected to the hydrogen outlet of the alkaline electrolytic cell module, and the hydrogen separation module separates the incoming hydrogen and alkaline liquid using a gas-liquid separation method. The hydrogen outlet of the hydrogen separation module is connected to the hydrogen purification module, creating a passage for supplying high-purity hydrogen. The freshwater inlet of the hydrogen separation module is connected to the freshwater supply module, forming a passage for supplying freshwater as a raw material for electrolysis, and also assisting in the washing and cooling of hydrogen.

[0010] Furthermore, the hydrogen purification module deoxygenates the incoming hydrogen, trace amounts of oxygen, and trace amounts of water through a catalytic reaction, and removes water and other impurities using the principle of molecular sieve adsorption, ultimately purifying the hydrogen to 99.999% purity. The hydrogen outlet of the hydrogen purification module is connected to the user or storage module.

[0011] Furthermore, the seawater inlet of the negative pressure seawater desalination module is a seawater supply passage. The alkaline liquid inlet of the negative pressure seawater desalination module is connected to the alkaline liquid filtration and circulation module, becoming a high-temperature alkaline liquid inlet passage. The alkaline liquid outlet of the negative pressure seawater desalination module is connected to the alkaline electrolytic cell module, becoming the outflow passage for the cooled alkaline liquid. The freshwater outlet of the negative pressure seawater desalination module is connected to the freshwater replenishment module, which serves as the outlet for the desalinized seawater.

[0012] Furthermore, the negative pressure seawater desalination module includes a negative pressure seawater desalination device, a vacuum gauge, a vacuum pump, a control valve, a salinity meter, a control valve, a thermometer, a water quality detector, and a seawater supply pump. The vacuum gauge monitors the vacuum level inside the negative pressure seawater desalination plant and controls the vacuum pump to maintain the vacuum level inside the negative pressure seawater desalination plant within a predetermined range. The seawater supply pump draws up seawater and supplies it to the condenser in the negative-pressure seawater desalination plant, where the steam is cooled into liquid freshwater. The heated seawater is then supplied to the evaporation chamber within the negative-pressure seawater desalination plant, while the other portion is discharged as excess seawater. The salinity meter monitors the salinity of seawater in the evaporation chamber of the negative-pressure seawater desalination plant, and based on the results, controls the control valve to adjust the flow rate of concentrated seawater discharged. The water quality detector monitors whether the quality of the produced freshwater is acceptable, and controls the system to allow acceptable freshwater to flow into the freshwater tank, while returning unacceptable freshwater to the negative-pressure seawater desalination plant for further desalination. The thermometer monitors the temperature of the cooled alkaline solution and controls the opening of the control valve based on the result to ensure that the alkaline solution flows into the alkaline electrolytic cell module within the appropriate temperature range.

[0013] Furthermore, the negative pressure seawater desalination plant consists of a cylindrical body, a condenser, a water receiving plate, a screen separator, and a heat exchanger. The condenser uses seawater as a cooling medium to condense water vapor, and the seawater, which has absorbed heat and risen in temperature, is used as a water source for heating alkaline solutions. The water receiving plate has a certain incline to catch condensed water droplets. A screen separator separates large droplets and impurities from water vapor. The heat exchanger uses an alkaline solution as a heat source to heat seawater, ultimately achieving low-temperature seawater desalination under negative pressure.

[0014] Furthermore, the negative pressure seawater desalination module includes a seawater supply filtration module, an RO reverse osmosis module, and a negative pressure distillation module. The seawater supply filtration module pumps up seawater, filters out impurities initially, and provides the seawater source to the RO reverse osmosis module. RO reverse osmosis modules produce fresh water. The negative pressure distillation module also incorporates electric heat from offshore wind power generation as a heat source. The negative pressure distillation module utilizes cooled freshwater to absorb heat released during the hydrogen production process by alkaline water electrolysis and electric heat from offshore wind power generation, thereby purifying the freshwater and producing pure water. The power interface of the alkaline electrolytic cell module is connected to an offshore wind power plant, and the pure water inside the alkaline electrolytic cell module is decomposed into hydrogen and oxygen using electricity from the offshore wind power plant.

[0015] Furthermore, the present invention includes a hydrogen transport module and a pure water transport module. The hydrogen transport module includes a hydrogen compression module, a hydrogen high-pressure storage module, and a hydrogen replenishment module. The hydrogen compression module has its hydrogen inlet connected to the hydrogen purification module, and its hydrogen outlet connected to the high-pressure hydrogen storage module and the hydrogen refueling module. It compresses hydrogen to a predetermined pressure to replenish the high-pressure hydrogen storage module or supply refueling power to the hydrogen refueling module. The high-pressure hydrogen storage module has its high-pressure hydrogen inlet connected to the hydrogen compression module, stores high-pressure hydrogen, and can be removed and transported. The hydrogen refueling module has its hydrogen inlet connected to the hydrogen compression module and replenishes high-pressure hydrogen to hydrogen-powered ships. The pure water transport module includes a pure water storage and supply module and a pure water external transport module. The pure water storage and supply module has its pure water inlet connected to the pure water outlet of the vacuum distillation module. Its pure water outlet functions as the outlet of the fresh water supply module, stores the pure water produced by the vacuum distillation module, provides raw material pure water for electrolysis to the alkaline electrolyzer module, and also provides pure water to the pure water external transport module. The pure water external transport module has its pure water inlet connected to the pure water storage and supply module and transports the produced fresh water to the outside, such as nearby platforms or ships.

[0016] Another aspect of the present invention is a method for coupling hydrogen production by water electrolysis and seawater desalination, decomposing fresh water in the alkaline electrolyzer module into hydrogen and oxygen under the action of direct current power, transporting oxygen and alkaline liquid to the oxygen separation module through the oxygen outlet of the alkaline electrolyzer module for gas-liquid separation. The purified oxygen is guided to a safe area and released into the atmosphere or sent to the oxygen storage module. transporting hydrogen and alkaline liquid to the hydrogen separation module through the hydrogen outlet of the alkaline electrolyzer module for gas-liquid separation, flowing the initially purified hydrogen and a small amount of water into the hydrogen purification module, further purifying it so that the hydrogen content reaches 99.999%, and supplying the hydrogen to users or storage modules. The alkaline liquid filtration and circulation module extracts the alkaline liquid from the oxygen separation module and the hydrogen separation module, cools it in the negative pressure seawater desalination module, and finally transports it to the alkaline electrolytic cell module to complete the cooling and forced circulation of the alkaline liquid. The process involves using the heat released when an alkaline solution is cooled in a negative-pressure seawater desalination module to heat and boil seawater under negative pressure to produce fresh water. The approved fresh water flows into a freshwater replenishment module and is also transported to a hydrogen separation module to replenish it as raw material for electrolysis, and assists in the washing and cooling of hydrogen. [Effects of the Invention]

[0017] The present invention has the following advantages.

[0018] 1. This invention not only cools the alkaline solution that requires cooling by directly using it to heat seawater under negative pressure, but also enables low-temperature seawater desalination by utilizing the heat released during the cooling of the alkaline solution. Furthermore, since the negative-pressure seawater desalination module can replace the alkaline solution cooler and its associated cooling water system, it can reduce the energy consumption of hydrogen production by water electrolysis.

[0019] 2. The present invention utilizes the heat released during the cooling of an alkaline solution to desalinate seawater under negative pressure, and supplies the approved freshwater to the electrolytic cell module as a raw material for water electrolysis. This reduces dependence on freshwater resources, makes it suitable for large-scale applications, expands the usage scenarios for hydrogen production by alkaline water electrolysis, and is also advantageous for the widespread application of offshore green hydrogen production technology. [Brief explanation of the drawing]

[0020] To more clearly illustrate embodiments of the present invention or technical means in the prior art, the following drawings are briefly introduced, but the following drawings represent only some embodiments of the present invention, and it goes without saying that those skilled in the art can obtain other drawings based on these drawings without any creative work.

[0021] [Figure 1] This flowchart shows the main functions of the technology for coupling hydrogen production by alkaline water electrolysis with seawater desalination according to Example 1 of the present invention. [Figure 2] This is a flowchart of the process system according to Embodiment 1 of the present invention. [Figure 3] This is a front view of a negative pressure seawater desalination module according to Embodiment 1 of the present invention. [Figure 4] This is a flowchart of the main functions according to Embodiment 2 of the present invention. [Modes for carrying out the invention]

[0022] To further clarify the purpose, technical means, and merits of the embodiments of the present invention, the technical means in the embodiments of the present invention will be described clearly and completely below with reference to the drawings of the embodiments, and it goes without saying that the embodiments described are not all embodiments but only a selection of embodiments of the present invention. Any other embodiments that a person skilled in the art could obtain without creative work based on the embodiments of the present invention shall all be included within the scope of the present invention.

[0023] Example 1 In this invention, Figure 1 is a flowchart showing the main functions of a technical method and system for coupling hydrogen production by water electrolysis and seawater desalination, with the area within baseline 1 showing the technical method and system for coupling hydrogen production by water electrolysis and seawater desalination. According to the system and method for coupling hydrogen production by water electrolysis and seawater desalination of this invention, by directly utilizing the alkaline solution that requires cooling to heat seawater under a negative pressure environment, it is possible not only to cool the alkaline solution but also to achieve low-temperature seawater desalination by utilizing the heat released during the cooling of the alkaline solution. At the same time, the approved freshwater can be supplied to the electrolytic cell module as a raw material for water electrolysis, thereby reducing dependence on freshwater resources. The functional modules for realizing the technology for coupling hydrogen production by alkaline water electrolysis and seawater desalination mainly include an alkaline electrolytic cell module 2, an oxygen separation module 3, a hydrogen separation module 4, an alkaline solution filtration and circulation module 5, a negative pressure seawater desalination module 6, a freshwater supply module 7, and a hydrogen purification module 8.

[0024] Each functional module is connected and performs its function as follows:

[0025] Alkaline electrolytic cell module: In the alkaline electrolytic cell, fresh water is decomposed into 1 part hydrogen and 1 / 2 part oxygen by the action of DC power. The hydrogen outlet of the alkaline electrolytic cell module is connected to the hydrogen separation module, which serves as a passage for hydrogen and alkaline liquid into the hydrogen separation module. The oxygen outlet of the alkaline electrolytic cell module is connected to the oxygen separation module, which serves as a passage for oxygen and alkaline liquid into the oxygen separation module. The alkaline liquid inlet of the alkaline electrolytic cell module is connected to the negative pressure seawater desalination module, which serves as a passage for cooled alkaline liquid into the alkaline electrolytic cell.

[0026] Oxygen Separation Module: The oxygen inlet of the oxygen separation module is connected to the oxygen outlet of the alkaline electrolytic cell module. The oxygen separation module separates the incoming oxygen and alkaline liquid using a gas-liquid separation method. The alkaline liquid outlet of the oxygen separation module is connected to the alkaline liquid outlet of the hydrogen separation module. The two pipes merge to form a main pipe, which is then connected to the alkaline liquid filtration and circulation module, providing high-temperature alkaline liquid that requires cooling. The oxygen outlet extends to a safe area to release oxygen into the atmosphere, or connects to the oxygen storage module to transport oxygen to the outside.

[0027] Hydrogen Separation Module: The hydrogen inlet of the hydrogen separation module is connected to the hydrogen outlet of the alkaline electrolytic cell module. The hydrogen separation module separates the incoming hydrogen and alkaline liquid using a gas-liquid separation method. The hydrogen outlet of the hydrogen separation module is connected to the hydrogen purification module, which serves as a passage for supplying high-purity hydrogen. The alkaline liquid outlet of the hydrogen separation module is connected to the alkaline liquid outlet of the oxygen separation module, where they merge to form a total alkaline liquid pipe. This pipe is then connected to the alkaline liquid filtration and circulation module, which provides high-temperature alkaline liquid that requires cooling. The freshwater inlet of the hydrogen separation module is connected to the freshwater supply module, which serves as a passage for supplying freshwater as raw material for electrolysis, as well as assisting functions such as hydrogen washing and cooling.

[0028] Hydrogen Purification Module: The hydrogen inlet of the hydrogen purification module is connected to the hydrogen outlet of the hydrogen separation module. The hydrogen purification module deoxygenates the incoming hydrogen, trace amounts of oxygen, and trace amounts of water through a catalytic reaction, and removes water and other impurities using the principle of molecular sieve adsorption, ultimately purifying the hydrogen to 99.999% purity. The hydrogen outlet of the hydrogen purification module is connected to the user or storage module.

[0029] Alkaline Solution Filtration and Circulation Module: The alkaline solution inlet of the alkaline solution filtration and circulation module is connected to the total alkaline solution pipe where the alkaline solution outlets of the hydrogen separation module and the oxygen separation module merge. The alkaline solution outlet of the alkaline solution filtration and circulation module is connected to the negative pressure freshwater production module. The alkaline solution filtration and circulation module forcibly circulates the alkaline solution between the alkaline electrolytic cell module, the hydrogen separation module, and the oxygen separation module, removing impurities from the alkaline solution.

[0030] Negative pressure seawater desalination module: The seawater inlet of the negative pressure seawater desalination module is a seawater supply passage, the alkaline solution inlet of the negative pressure seawater desalination module is connected to an alkaline solution filtration and circulation module and becomes a high-temperature alkaline solution inlet passage, the alkaline solution outlet of the negative pressure seawater desalination module is connected to an alkaline electrolytic cell module and becomes a cooled alkaline solution outlet passage, and the freshwater outlet of the negative pressure seawater desalination module is connected to a freshwater replenishment module and becomes a freshwater outlet passage for the desalination-approved freshwater. The negative pressure seawater desalination module uses the heat released in the process of cooling the high-temperature alkaline solution to the required temperature in the electrolytic cell to heat the seawater under negative pressure, causing the seawater to boil at a low temperature and generate steam. Impurities are removed from the steam in a screen separator and condensed in a condenser to produce freshwater. The approved freshwater enters the freshwater replenishment module and is supplied to the alkaline electrolytic cell module as raw freshwater via a hydrogen separation module, and the unapproved freshwater is re-evaporated to produce freshwater.

[0031] Freshwater replenishment module: The freshwater inlet of the freshwater replenishment module is connected to the negative pressure seawater desalination module, and the freshwater outlet of the freshwater replenishment module is connected to the hydrogen separation module. The freshwater replenishment module stores the approved freshwater produced in the negative pressure seawater desalination module and replenishes the raw freshwater to the alkaline electrolytic cell module.

[0032] The specific flow of the technology and system that couples hydrogen production by water electrolysis with seawater desalination is as follows: Freshwater in alkaline electrolytic cell module 2 is decomposed into 1 part hydrogen and 1 / 2 part oxygen by the action of DC power. The oxygen and alkaline liquid are transported to oxygen separation module 3 via the oxygen outlet of the alkaline electrolytic cell module for gas-liquid separation. The purified oxygen is guided to a safety area and released into the atmosphere, or sent to an oxygen storage module. The hydrogen outlet of the alkaline electrolytic cell module transports the hydrogen and alkaline liquid to hydrogen separation module 4 for gas-liquid separation. The initially purified hydrogen and a small amount of water are further purified in hydrogen purification module 8 to a hydrogen content of 99.999%, and the hydrogen is finally supplied to the user. Alternatively, the alkaline solution is supplied to the storage module, and the alkaline solution filtration and circulation module 5 extracts the alkaline solution from the oxygen separation module 3 and the hydrogen separation module 4, cools it in the negative pressure seawater desalination module 6, and finally transports it to the alkaline electrolytic cell module 2, thereby completing the cooling and forced circulation of the alkaline solution. The heat released when the alkaline solution is cooled in the negative pressure seawater desalination module 6 is used to heat the seawater under negative pressure, boiling the seawater to produce fresh water. The approved fresh water enters the fresh water supply module 7 and is supplied to the hydrogen separation module 4 as raw material fresh water for electrolysis, while simultaneously assisting in the washing and cooling of hydrogen. Therefore, the present invention is advantageous in reducing the dependence of hydrogen production by alkaline water electrolysis on fresh water resources by directly utilizing the alkaline solution that needs to be cooled to heat seawater under negative pressure to perform low-temperature seawater desalination, and supplying the approved fresh water to the electrolytic cell module as raw material for water electrolysis.

[0033] Figure 2 is a flowchart of a process system according to an embodiment of the present invention. As shown in Figure 2, the oxygen separation module 3 consists of an oxygen gravity separator 31, an oxygen washing cooler 32, a gas-liquid separator 33, a pressure transmitter 34, and a control valve 35. It separates oxygen and alkaline liquid into gas-liquid and gas-liquid to produce high-purity oxygen. The pressure transmitter 34 controls the opening of the control valve 35 based on the measured pressure of the oxygen gravity separator 31 to maintain a constant pressure in the hydrogen production system by water electrolysis. The hydrogen separation module 4 consists of a hydrogen gravity separator 41, a hydrogen washing cooler 42, a gas-liquid separator 43, a level difference transmitter 44, and a control valve 45. It separates oxygen and alkaline liquid into gas-liquid and further purifies the hydrogen in the hydrogen purification module 8. The hydrogen purification module 8 consists of a deoxygenation tower, a drying tower, a condenser, and a gas-liquid separator. The level difference transmitter 44 controls the opening of the control valve 45 based on the measured level difference between the oxygen gravity separator 31 and the hydrogen gravity separator 41 to maintain level balance.The alkaline liquid filtration and circulation module 5 consists of an alkaline liquid filter 51 and an alkaline liquid circulation pump 52. The negative pressure seawater desalination module 6 consists of a negative pressure seawater desalination device 61, a vacuum gauge 62, a vacuum pump 63, a control valve 64, a salinity meter 65, a control valve 66, a thermometer 67, a water quality detector 68, and a seawater supply pump 69. Among these, the vacuum gauge 62 monitors the vacuum level inside the negative pressure seawater desalination device 61 and controls the vacuum pump 63 to control the negative pressure seawater desalination device. Maintaining a reasonable vacuum within 61, the seawater supply pump 69 pumps up seawater and supplies it to the condenser in the negative pressure seawater desalination plant 61, cooling the steam into liquid freshwater. Then, the heated seawater is supplied to the evaporation chamber in the negative pressure seawater desalination plant 61, with one portion being replenished and the other being discharged as excess seawater. The salinity meter 65 controls the control valve 66 based on the measured salinity of the seawater in the evaporation chamber in the negative pressure seawater desalination plant 61 to control the discharged concentration. The flow rate of the compressed seawater is adjusted, and the water quality detector 68 monitors whether the quality of the produced freshwater is acceptable. Based on the monitoring results, it controls the system so that acceptable freshwater enters the freshwater tank 71 and unacceptable freshwater is further desalined in the negative pressure seawater desalination device 61. The thermometer 67 monitors the temperature of the cooled alkaline solution and controls the opening of the control valve 64 based on the monitoring results to ensure that the alkaline solution flows into the alkaline electrolytic cell module 2 (the alkaline electrolytic cell module consists of an alkaline electrolytic cell powered by a DC power supply) within a reasonable temperature range. The freshwater replenishment module 7 consists of a freshwater tank 71 and a freshwater replenishment pump 72. Acceptable freshwater produced by the negative pressure seawater desalination device 61 enters the freshwater tank 71 and is transported by the freshwater replenishment pump 72 to the hydrogen washing cooler 42, where it replenishes the freshwater that is the raw material for electrolysis and can also assist in functions such as hydrogen washing and cooling.

[0034] Figure 3 is a front view of a negative pressure seawater desalination module according to an embodiment of the present invention. As shown in Figure 3, the negative pressure seawater desalination apparatus 61 consists of a cylindrical body 611, a condenser 612, a water receiving plate 613, a screen separator 614, and a heat exchanger 615. The condenser 612 uses seawater as a cooling medium to condense water vapor, and the seawater then absorbs heat and rises in temperature, becoming a heat source for heating the alkaline solution, thus contributing to the effective utilization of heat. The water receiving plate 613 has a certain incline and is used to receive condensed water droplets, which is advantageous for the discharge of fresh water. The screen separator separates large droplets and impurities in the water vapor to ensure the mass of fresh water. The heat exchanger 615 uses the alkaline solution as a heat source to heat the seawater, ultimately achieving low-temperature seawater desalination under negative pressure.

[0035] This invention not only cools the alkaline solution that requires cooling by directly using it to heat seawater under negative pressure, but also enables low-temperature seawater desalination by utilizing the heat released during the cooling of the alkaline solution. The approved freshwater can then be supplied to the electrolytic cell module as a raw material for water electrolysis, reducing dependence on freshwater resources. At the same time, the negative-pressure seawater desalination module replaces the alkaline solution cooler and its associated cooling water system, thereby reducing the energy consumption of hydrogen production by water electrolysis. Furthermore, the technology and system of coupling hydrogen production by water electrolysis and seawater desalination according to this invention are suitable for large-scale applications, thus expanding the use cases for hydrogen production by alkaline water electrolysis and also being advantageous for the widespread application of offshore green hydrogen production technology.

[0036] Example 2 Based on Example 1, this embodiment forms a new system by coupling hydrogen production and seawater desalination based on offshore wind power generation, thereby achieving large-scale simultaneous production of hydrogen and freshwater, and shifting from a system that transmits electricity to land to a system that transports hydrogen to land. In this embodiment, waste heat generated in the hydrogen production process by alkaline water electrolysis and auxiliary electric heating from offshore wind power generation are used to negative-pressure distillation of freshwater obtained from seawater by RO reverse osmosis, realizing large-scale pure water production. This not only satisfies the demand for pure water as a raw material for hydrogen production by alkaline water electrolysis using offshore wind power generation, but can also supply pure water to the onboard platform, nearby work platform, or vessel. Furthermore, the hydrogen produced by electrolyzing alkaline water using offshore wind power generation can be supplied not only to land but also to refuel hydrogen-powered vessels at anchor. Therefore, the present invention not only realizes simultaneous production of hydrogen and freshwater based on offshore wind power generation, but also contributes to energy saving and emission reduction. This is expected to provide technical support for the development of equipment for autonomous and controllable offshore wind power-based simultaneous hydrogen and freshwater production systems. This will not only solve challenges in large-scale offshore wind power applications but also significantly reduce the cost of offshore wind farms, enabling the development of offshore wind power beyond power transmission routes to become a green, high-quality strategic energy source.

[0037] Embodiments of the present invention provide a system and method for the simultaneous production of hydrogen and pure water using offshore wind power generation, and include the following functional modules.

[0038] Alkaline electrolytic cell module: The power interface of the alkaline electrolytic cell module is connected to the offshore wind power generation system. The alkaline liquid inlet of the alkaline electrolytic cell module is connected to the alkaline liquid outlet of the negative pressure distillation module. The hydrogen outlet of the alkaline electrolytic cell module is connected to the hydrogen separation cooling module. The oxygen outlet of the alkaline electrolytic cell module is connected to the oxygen separation cooling module. The offshore wind power generation system decomposes the pure water in the alkaline electrolytic cell module into hydrogen and oxygen. The hydrogen and alkaline liquid enter the hydrogen separation cooling module, and the oxygen and alkaline liquid enter the oxygen separation cooling module.

[0039] Oxygen Separation Cooling Module: The oxygen inlet of the oxygen separation cooling module is connected to the oxygen outlet of the alkaline electrolytic cell module, and the oxygen outlet of the oxygen separation cooling module is extended to a safety area for exhaust. The alkaline liquid outlet of the oxygen separation cooling module is connected to the alkaline liquid outlet of the hydrogen separation cooling module, and after merging to form a main pipe, it is connected to the alkaline liquid filtration and circulation module. The cooling freshwater inlet of the oxygen separation cooling module is connected to the cooling freshwater inlet of the hydrogen separation cooling module and then to the cooling freshwater outlet of the hydrogen purification cooling module. The cooling freshwater outlet of the oxygen separation cooling module is connected to the cooling freshwater outlet of the hydrogen separation cooling module and then to the heat source freshwater inlet of the negative pressure distillation module. Main Function: The oxygen separation cooling module improves the purity of oxygen by performing gas-liquid separation, washing, and cooling on the oxygen and alkaline liquid that enters the oxygen separation cooling module from the alkaline electrolytic cell module.

[0040] Hydrogen separation cooling module: The hydrogen inlet of the hydrogen separation cooling module is connected to the hydrogen outlet of the alkaline electrolytic cell module, the hydrogen outlet of the hydrogen separation cooling module is connected to the hydrogen purification cooling module, the alkaline liquid outlet of the hydrogen separation cooling module is connected to the alkaline liquid outlet of the oxygen separation cooling module, and after merging to form a main pipe, it is connected to the alkaline liquid filtration circulation module, the cooling freshwater inlet of the hydrogen separation cooling module is connected to the cooling freshwater inlet of the oxygen separation cooling module and then to the cooling freshwater outlet of the hydrogen purification cooling module, the cooling freshwater outlet of the hydrogen separation cooling module is connected to the cooling freshwater outlet of the oxygen separation cooling module and then to the heat source freshwater inlet of the negative pressure distillation module, and the pure water inlet of the hydrogen separation cooling module is connected to the pure water storage replenishment module. Specifically, the cooling freshwater first passes through the hydrogen purification cooling module to absorb heat, then branches into two paths and continues to flow into the hydrogen separation cooling module and the oxygen separation cooling module respectively to absorb heat. Main function: The hydrogen and alkaline liquid that enter the hydrogen separation and cooling module from the alkaline electrolytic cell module are subjected to gas-liquid separation, washing, and cooling. The alkaline liquid contained in the hydrogen is removed and supplied as pure water to the passages of the alkaline electrolytic cell module, assisting in functions such as washing and cooling of the hydrogen. Specifically, after being supplied to the hydrogen separation and cooling module, it enters the electrolytic cell and circulates through the alkaline liquid filtration and circulation module and the negative pressure distillation module.

[0041] Hydrogen Purification Cooling Module: The hydrogen inlet of the hydrogen purification cooling module is connected to the hydrogen outlet of the hydrogen separation cooling module, the hydrogen outlet of the hydrogen purification cooling module is connected to the hydrogen compression module, and the cooled freshwater outlet of the hydrogen purification cooling module is connected to the cooled freshwater outlet of the oxygen separation cooling module and the cooled freshwater inlet of the hydrogen separation cooling module. Main Function: Removes oxygen, water, and other impurities through catalytic reaction, cooling, and molecular sieve adsorption, ultimately purifying hydrogen to 99.999%.

[0042] 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 hydrogen high-pressure storage module and the hydrogen replenishment module. Main Function: Not only can it compress hydrogen to a predetermined pressure and replenish the hydrogen high-pressure storage module, but it can also supply replenishment power to the hydrogen replenishment module.

[0043] High-pressure hydrogen storage module: The high-pressure hydrogen inlet of the high-pressure hydrogen storage module is connected to the hydrogen compression module. High-pressure hydrogen can be stored and then removed for transport.

[0044] Hydrogen replenishment module: The hydrogen inlet of the hydrogen replenishment module is connected to the hydrogen compression module, allowing for the replenishment of high-pressure hydrogen into hydrogen-powered vessels.

[0045] Negative Pressure Distillation Module: The cooling freshwater inlet of the negative pressure distillation module is connected to the RO reverse osmosis module, the cooling freshwater outlet of the negative pressure distillation module is connected to the cooling freshwater inlet of the hydrogen purification cooling module, the pure water outlet of the negative pressure distillation module is connected to the pure water storage and replenishment module, the heat source freshwater inlet of the negative pressure distillation module is connected to the cooling freshwater outlet of the hydrogen separation cooling module and the cooling freshwater outlet of the oxygen separation cooling module, the alkaline liquid inlet of the negative pressure distillation module is connected to the alkaline liquid filtration and circulation module, the alkaline liquid outlet of the negative pressure distillation module is connected to the alkaline electrolytic cell module, and the electric heating interface of the negative pressure distillation module is connected to offshore wind power generation. Main Function: Using cooled freshwater, the module absorbs the heat released in the hydrogen production process by alkaline water electrolysis and electric heat from offshore wind power generation to purify freshwater and produce pure water on a large scale.

[0046] Alkaline Solution Filtration and Circulation Module: The alkaline solution inlet of the alkaline solution filtration and circulation module is connected to a total alkaline solution pipe formed by the confluence of the alkaline solution outlets of the hydrogen separation and cooling module and the oxygen separation and cooling module. The alkaline solution outlet of the alkaline solution filtration and circulation module is connected to the negative pressure distillation module. Main Function: It enables forced circulation of alkaline solution between the alkaline electrolytic cell module, the hydrogen separation and cooling module, and the oxygen separation and cooling module, and can filter out impurities from the alkaline solution.

[0047] Pure Water Storage and Replenishment Module: The pure water inlet of the pure water storage and replenishment module is connected to the pure water outlet of the negative pressure distillation module, and the pure water outlet of the pure water storage and replenishment module is connected to the pure water inlet of the hydrogen separation and cooling module and the inlet of the pure water external transport module. Main Functions: It stores the pure water produced by the negative pressure distillation module, can replenish the alkaline electrolytic cell with pure water for electrolysis, and can also supply pure water to the pure water external transport module.

[0048] Pure Water External Transport Module: The pure water inlet of the pure water external transport module is connected to the pure water storage and replenishment module, allowing the produced fresh water to be transported externally to nearby platforms or vessels where there is demand.

[0049] Seawater supply filtration module: The seawater outlet of the seawater supply filtration module is connected to the RO reverse osmosis module, and the seawater inlet of the seawater supply filtration module extends below the sea surface. Main function: It can pump up seawater, filter out impurities initially, and provide a seawater source to the RO reverse osmosis module.

[0050] RO Reverse Osmosis Module: The seawater inlet of the RO reverse osmosis module is connected to the seawater supply filtration module, and the freshwater outlet of the RO reverse osmosis module is connected to the cooled freshwater inlet of the negative pressure distillation module. Main function: Produces fresh water by treating seawater with RO reverse osmosis.

[0051] Figure 4 is a flowchart showing the main functions of the simultaneous hydrogen and pure water production method and system using offshore wind power generation, with the area within the baseline showing the simultaneous hydrogen and pure water production method and system using offshore wind power generation. The modules that realize the functions of the simultaneous hydrogen and pure water production method and system using offshore wind power generation of the present invention mainly include an alkaline electrolytic cell 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 replenishment module, a negative pressure distillation module, an alkaline liquid filtration and circulation module, a pure water storage and replenishment module, a pure water external transport module, a seawater supply filtration module, and an RO reverse osmosis module. The specific flow of the simultaneous hydrogen and pure water production method and system using offshore wind power generation is as follows: The pure water in the alkaline electrolytic cell module is decomposed into hydrogen and oxygen by the DC action of the offshore wind power generation, and the oxygen and alkaline liquid are transported to the oxygen separation and cooling module via the oxygen outlet of the alkaline electrolytic cell module for gas-liquid separation, washing, and cooling. The oxygen after the alkaline liquid has been removed is guided to a safe area and released into the atmosphere. Hydrogen and alkaline liquid are transported to the hydrogen separation and cooling module via the hydrogen outlet of the alkaline electrolytic cell module for gas-liquid separation, washing, and cooling. After the alkaline liquid is removed, hydrogen and a small amount of water enter the hydrogen purification and cooling module, where they are further purified to a hydrogen content of 99.999%. The hydrogen is then pressurized to the required pressure by the hydrogen compression module and supplied to the hydrogen high-pressure storage module, and can also be supplied to the hydrogen replenishment module as needed. The alkaline liquid filtration and circulation module extracts the alkaline liquid from the hydrogen separation and cooling module and the oxygen separation and cooling module, cools it via the negative pressure distillation module, and finally transports it to the alkaline electrolytic cell module to complete the cooling and forced circulation of the alkaline liquid.The seawater supply filtration module pumps up seawater from the sea, filters it, and supplies it to the RO reverse osmosis module to produce fresh water. The cooled fresh water then enters the negative pressure distillation module, where it is cooled as a condensation medium. It then enters the hydrogen purification cooling module to absorb heat, and then enters the oxygen separation cooling module and the hydrogen separation cooling module to absorb heat. Finally, the heat source freshwater enters the negative pressure distillation module, where negative pressure distillation of the freshwater is performed by heating with an alkaline solution and auxiliary electric heating from offshore wind power generation to produce pure water. The pure water produced by the negative pressure distillation module may then enter the hydrogen separation cooling module via the pure water storage and replenishment module to replenish the pure water raw material for alkaline electrolyzed water, and then enter the pure water external transport module to supply the pure water to the outside.

[0052] The alkaline electrolytic cell module uses offshore wind power to electrolyze pure water to produce hydrogen and oxygen. The oxygen separation and cooling module consists of an oxygen gravity separator, an oxygen scrubbing cooler, and a gas-liquid separator, achieving gas-liquid separation and cooling of oxygen and alkaline liquid, and guiding the separated oxygen to a safe area for exhaust. The hydrogen separation and cooling module consists of a hydrogen gravity separator, an oxygen scrubbing cooler, and a gas-liquid separator, achieving gas-liquid separation and cooling of hydrogen and alkaline liquid. The hydrogen purification and cooling module uses deoxygenation reactions, cooling, and molecular sieve adsorption to produce hydrogen with a content of 99%.The hydrogen is purified to 999%, then pressurized to the required pressure by a hydrogen compression module (consisting of a compressor and a hydrogen tank) and supplied to a high-pressure hydrogen storage module (consisting of a high-pressure tank and a safety valve). It is also supplied as needed to a hydrogen replenishment module (consisting of a replenishment on / off ball valve, a flow meter, and a check valve) to replenish hydrogen to the outside. The negative pressure distillation module consists of a negative pressure distillation apparatus, a vacuum gauge, a vacuum pump, a thermometer, a water quality monitor, and a brine temperature control valve. The negative pressure distillation apparatus produces hydrogen by alkaline water electrolysis. By utilizing the waste heat generated during the process and the auxiliary electric heating method of offshore wind power generation, fresh water obtained from seawater by RO reverse osmosis can be distilled under negative pressure to produce pure water on a large scale. A vacuum gauge measures the vacuum level of the negative pressure distillation apparatus and controls the vacuum pump to maintain a constant vacuum level within the apparatus. A thermometer measures the temperature of the heat source fresh water within the negative pressure distillation apparatus and adjusts the flow rate of the booster pump to regulate the temperature. A water quality monitor measures the water quality of the heat source fresh water within the negative pressure distillation apparatus and controls the opening of the saltwater temperature control valve to maintain the water quality of the heat source seawater. An alkaline liquid filtration circulation module... The system consists of a filter and an alkaline solution circulation pump. The alkaline solution filter removes impurities from the alkaline solution, and the alkaline solution circulation pump provides the power to circulate the alkaline solution. The pure water storage and replenishment module consists of a pure water tank and a pure water replenishment pump. The pure water tank stores the pure water produced by the negative pressure distillation apparatus and supplies pure water to the pure water replenishment pump and the pure water external transport module (consisting of an external transport hose, flow meter, and quick-coupling shut-off valve). The pure water replenishment pump can supply pure water to the oxygen washing and cooling unit, thereby supplying alkaline water power. This system can meet the demand for pure water necessary for hydrogen production through decongestion. The seawater supply filtration module consists of a seawater pump, a multi-media filter, an activated carbon filter, and a microfilter. The seawater pump draws seawater from nearby sources and supplies it to the negative pressure distillation unit. The multi-media filter, activated carbon filter, and microfilter remove some impurities from the seawater, extending the lifespan of the RO reverse osmosis unit. The RO reverse osmosis module consists of a booster pump and an RO reverse osmosis unit. The booster pump powers the RO reverse osmosis unit to produce fresh water from the filtered seawater.

[0053] In this embodiment, waste heat generated in the hydrogen production process by alkaline water electrolysis and an auxiliary electric heating method from offshore wind power generation are employed to perform negative pressure distillation on fresh water obtained from seawater by RO reverse osmosis, enabling the large-scale production of pure water. This not only meets the demand for raw material pure water necessary for hydrogen production by alkaline water electrolysis using offshore wind power generation, but also allows for the supply of pure water to the onboard platform, nearby work platforms, or vessels.

[0054] In this embodiment, the freshwater produced by RO reverse osmosis enters the negative pressure distillation module as cooled freshwater, where it functions as a condensing medium. Subsequently, it enters the hydrogen purification cooling module to absorb heat, and then enters the hydrogen separation cooling module and the oxygen separation cooling module to absorb further heat. After that, it enters the negative pressure distillation module as heat source freshwater. The alkaline liquid from the alkaline liquid filtration circulation module flows in and, with the assistance of electric heating from offshore wind power generation, heats the heat source seawater for distillation purification treatment.

[0055] In this embodiment, hydrogen can be produced by alkaline water electrolysis using offshore wind power and local seawater. The hydrogen can be stored, and the entire full high-pressure hydrogen storage module can be transported to land by barge, allowing for on-demand replenishment of hydrogen-powered vessels at anchor via hydrogen replenishment stations. This not only allows offshore wind power development to transcend existing power transmission routes, but also significantly reduces the investment costs of offshore wind power plants.

[0056] In this embodiment, fresh water is used as a medium to achieve heat transfer between the waste heat from the hydrogen production process by alkaline water electrolysis and the negative pressure distillation module, resulting in low material requirements for the system equipment and excellent cost-effectiveness.

[0057] In this embodiment, the auxiliary electric heating for offshore wind power generation can cope even with large fluctuations in wind power generation, demonstrating excellent adaptability, and is also advantageous for local consumption of offshore wind power.

[0058] In this embodiment, by coupling offshore wind power generation, hydrogen production by alkaline water electrolysis, and seawater desalination, large-scale simultaneous production of hydrogen and pure water can be achieved. This not only contributes to the efficient use of energy but also helps to solve application challenges of large-scale offshore wind power generation.

[0059] As described above, this embodiment not only enables large-scale simultaneous production of hydrogen and pure water by coupling offshore wind power generation, hydrogen production by alkaline water electrolysis, and seawater desalination, but also allows for the supply of pure water to the onboard platform, nearby work platforms, or vessels, based on meeting the pure water demand required for hydrogen production by alkaline water electrolysis using offshore wind power generation. Furthermore, the produced hydrogen can be stored under high pressure and used to replenish hydrogen-powered vessels, contributing to the efficient use of energy. The development of offshore wind power generation goes beyond the route of power transmission, significantly reduces the investment costs of offshore wind power plants, and helps solve the application challenges of large-scale offshore wind power generation.

[0060] Finally, the following should be explained: The above embodiments are merely for illustrating, and not limiting, the technical means of the present invention. Although the present invention has been described in detail with reference to the embodiments described above, it is possible to modify the technical means described in the embodiments above, or to make equivalent substitutions to some or all of their technical features, and it will be understood by those skilled in the art that such modifications or substitutions do not cause the essence of the corresponding technical means to deviate from the scope of the technical means of the embodiments of the present invention.

[0061] (Note) (Note 1) A system for coupling hydrogen production by water electrolysis with seawater desalination, comprising an alkaline electrolytic cell module, an oxygen separation module, a hydrogen separation module, a hydrogen purification module, an alkaline liquid filtration and circulation module, a negative pressure seawater desalination module, and a freshwater supply module, The negative pressure seawater desalination module heats seawater under negative pressure, causes the seawater to boil at a low temperature to generate steam, removes impurities from the steam, and then condenses it to produce fresh water. The freshwater supply module supplies raw freshwater to the alkaline electrolytic cell module. The alkaline electrolytic cell module, by the action of DC power, electrolyzes the fresh water inside the alkaline electrolytic cell module into hydrogen and oxygen, causing the hydrogen and alkaline solution to flow into the hydrogen separation module, and the oxygen and alkaline solution to flow into the oxygen separation module. The alkaline liquid filtration and circulation module forcibly circulates the alkaline liquid between the alkaline electrolytic cell module, the hydrogen separation module, and the oxygen separation module. The negative pressure seawater desalination module is a system for coupling hydrogen production by water electrolysis with seawater desalination, characterized in that it uses the heat released in the process of cooling a high-temperature alkaline solution to the required temperature of the electrolytic cell as an energy source.

[0062] (Note 2) The freshwater in the aforementioned alkaline electrolytic cell module is electrolyzed into hydrogen and oxygen by the action of DC power. The hydrogen outlet of the alkaline electrolytic cell module is connected to the hydrogen separation module, creating a passage through which hydrogen and alkaline solution flow into the hydrogen separation module. The oxygen outlet of the alkaline electrolytic cell module is connected to the oxygen separation module, creating a passage through which oxygen and alkaline solution flow into the oxygen separation module. A system for coupling hydrogen production by water electrolysis and seawater desalination as described in Appendix 1, characterized in that the alkaline liquid inlet of the alkaline electrolytic cell module is connected to a negative pressure seawater desalination module, and the cooled alkaline liquid flows into the alkaline electrolytic cell module through this connection.

[0063] (Note 3) The oxygen inlet of the oxygen separation module is connected to the oxygen outlet of the alkaline electrolytic cell module, and the oxygen separation module separates the incoming oxygen and alkaline liquid using a gas-liquid separation method. The alkaline liquid outlets of the oxygen separation module and the hydrogen separation module are connected and merged to form a main pipe, which is then connected to the alkaline liquid filtration and circulation module, providing high-temperature alkaline liquid that requires cooling. The oxygen outlet of the oxygen separation module extends to a safety area to release oxygen into the atmosphere, or it is connected to an oxygen storage module to transport oxygen to the outside. The hydrogen inlet of the hydrogen separation module is connected to the hydrogen outlet of the alkaline electrolytic cell module, and the hydrogen separation module separates the incoming hydrogen and alkaline liquid using a gas-liquid separation method. The hydrogen outlet of the hydrogen separation module is connected to the hydrogen purification module, forming a passage for supplying high-purity hydrogen. A system for coupling hydrogen production by water electrolysis and seawater desalination as described in Appendix 1, characterized in that the freshwater inlet of the hydrogen separation module is connected to a freshwater supply module, forming a passage for supplying freshwater as a raw material for electrolysis, and assisting in the washing and cooling of hydrogen.

[0064] (Note 4) The hydrogen purification module deoxygenates the incoming hydrogen, trace amounts of oxygen, and trace amounts of water through a catalytic reaction, and removes water and other impurities using the principle of molecular sieve adsorption, ultimately purifying the hydrogen to a purity of 99.999%. The system for coupling hydrogen production by water electrolysis with seawater desalination, as described in Appendix 1, characterized in that the hydrogen outlet of the hydrogen purification module is connected to a user or storage module.

[0065] (Note 5) The seawater inlet of the negative pressure seawater desalination module is a seawater supply passage. The alkaline liquid inlet of the negative pressure seawater desalination module is connected to the alkaline liquid filtration and circulation module, becoming a high-temperature alkaline liquid inlet passage. The alkaline liquid outlet of the negative pressure seawater desalination module is connected to the alkaline electrolytic cell module, becoming the outflow passage for the cooled alkaline liquid. A system for coupling hydrogen production by water electrolysis and seawater desalination as described in Appendix 1, characterized in that the freshwater outlet of a negative pressure seawater desalination module is connected to a freshwater replenishment module, which serves as a freshwater outlet for the desalination-treated seawater.

[0066] (Note 6) The negative pressure seawater desalination module includes a negative pressure seawater desalination device, a vacuum gauge, a vacuum pump, a control valve, a salinity meter, a control valve, a thermometer, a water quality detector, and a seawater supply pump. The vacuum gauge monitors the vacuum level inside the negative pressure seawater desalination plant and controls the vacuum pump to maintain the vacuum level inside the negative pressure seawater desalination plant within a predetermined range. The seawater supply pump pumps up seawater and supplies it to the condenser in the negative-pressure seawater desalination plant to cool the steam into liquid freshwater. Then, one portion of the heated seawater is supplied to the evaporation chamber in the negative-pressure seawater desalination plant, and the other portion is discharged as excess seawater. The salinity meter monitors the salinity of seawater in the evaporation chamber of the negative pressure seawater desalination plant, and controls the control valve based on the results to adjust the flow rate of concentrated seawater to be discharged. The water quality detector monitors whether the quality of the produced freshwater is acceptable, and controls the system to allow acceptable freshwater to flow into the freshwater tank, while returning unacceptable freshwater to the negative-pressure seawater desalination plant for further desalination treatment. The system for coupling hydrogen production by water electrolysis and seawater desalination as described in Appendix 1, characterized in that the thermometer monitors the temperature of the cooled alkaline solution, controls the opening of the control valve based on the result, and allows the alkaline solution to flow into the alkaline electrolytic cell module within an appropriate temperature range.

[0067] (Note 7) The negative pressure seawater desalination apparatus comprises a cylindrical body, a condenser, a water receiving plate, a screen separator, and a heat exchanger. The aforementioned condenser uses seawater as a cooling medium to condense water vapor, and the seawater, which has absorbed heat and been heated, is used as a water source for heating the alkaline solution. The water receiving plate has a certain incline and receives condensed water droplets. The aforementioned screen separator separates large droplets and impurities from the water vapor. The system for coupling hydrogen production by water electrolysis and seawater desalination as described in Appendix 1, characterized in that the heat exchanger heats seawater using an alkaline solution as a heat source and ultimately achieves a low-temperature seawater desalination function under negative pressure.

[0068] (Note 8) The negative pressure seawater desalination module includes a seawater supply filtration module, an RO reverse osmosis module, and a negative pressure distillation module. The aforementioned seawater supply filtration module pumps up seawater, filters out impurities initially, and provides a seawater source to the RO reverse osmosis module. The aforementioned RO reverse osmosis module generates fresh water, The negative pressure distillation module further includes electric heat from offshore wind power generation as a heat source, and the negative pressure distillation module uses cooled freshwater to absorb the heat released in the hydrogen production process by alkaline water electrolysis and electric heat from offshore wind power generation to purify the freshwater and produce pure water. The system for coupling hydrogen production by water electrolysis and seawater desalination as described in Appendix 1, characterized in that the power interface of the alkaline electrolytic cell module is connected to an offshore wind power generation facility, and the pure water in the alkaline electrolytic cell module is decomposed into hydrogen and oxygen using electricity from the offshore wind power generation facility.

[0069] (Note 9) It further includes a hydrogen transport module and a pure water transport module, The hydrogen transport module includes a hydrogen compression module, a high-pressure hydrogen storage module, and a hydrogen replenishment module. The hydrogen compression module is configured such that its hydrogen inlet is connected to a hydrogen purification module, its hydrogen outlet is connected to a hydrogen high-pressure storage module and a hydrogen replenishment module, and it compresses hydrogen to a predetermined pressure to replenish the hydrogen high-pressure storage module or to supply replenishment power to the hydrogen replenishment module. The aforementioned high-pressure hydrogen storage module is configured such that its high-pressure hydrogen inlet is connected to a hydrogen compression module, allowing it to store and detach high-pressure hydrogen for transport. The hydrogen replenishment module is configured such that its hydrogen inlet is connected to a hydrogen compression module, and it replenishes a powered vessel with high-pressure hydrogen. The pure water transport module includes a pure water storage and replenishment module and a pure water external transport module. The aforementioned pure water storage and replenishment module is configured such that its pure water inlet is connected to the pure water outlet of the negative pressure distillation module, functioning as the outlet of the fresh water replenishment module, storing the pure water produced in the negative pressure distillation module, supplying the alkaline electrolytic cell module with pure water for electrolysis, and supplying pure water to the pure water external transport module. The system for coupling hydrogen production by water electrolysis and seawater desalination as described in Appendix 8, characterized in that the pure water external transport module has its pure water inlet connected to a pure water storage and replenishment module, and transports the produced fresh water to a nearby platform or vessel.

[0070] (Note 10) The freshwater in the alkaline electrolytic cell module is decomposed into hydrogen and oxygen by the action of DC power. Oxygen and alkaline liquid are transported to the oxygen separation module via the oxygen outlet of the alkaline electrolytic cell module for gas-liquid separation. The purified oxygen is then guided to a safety area and released into the atmosphere, or sent to the oxygen storage module. Hydrogen and alkaline liquid are transported to the hydrogen separation module via the hydrogen outlet of the alkaline electrolytic cell module for gas-liquid separation. The initially purified hydrogen and a small amount of water are then fed into the hydrogen purification module for further purification to a hydrogen content of 99.999%, and the hydrogen is finally supplied to the user or storage module. The aforementioned alkaline liquid filtration and circulation module extracts the alkaline liquid from the oxygen separation module and the hydrogen separation module, cools it in the negative pressure seawater desalination module, and finally transports it to the alkaline electrolytic cell module to complete the cooling and forced circulation of the alkaline liquid. A seawater desalination method for a system for coupling hydrogen production by water electrolysis and seawater desalination, as described in any one of Appendix 1 to 7, characterized in that the heat released when an alkaline solution is cooled in a negative-pressure seawater desalination module is used to heat seawater under negative pressure, causing it to boil and evaporate to produce fresh water, the approved fresh water flows into a freshwater supply module, and is transported to a hydrogen separation module to be supplied as raw material freshwater for use in electrolysis, and also includes assisting in the washing and cooling of hydrogen. [Explanation of Symbols]

[0071] 1 Baseline, 2 Alkaline electrolytic cell module, 3 Oxygen separation module, 4 Hydrogen separation module, 5 Alkaline liquid filtration and circulation module, 6 Negative pressure seawater desalination module, 7 Freshwater supply module, 8 Hydrogen purification module, 31 Oxygen gravity separator, 32 Oxygen washing cooler, 33 Gas-liquid separator, 34 Pressure transmitter, 35 Control valve, 41 Hydrogen gravity separator, 42 Hydrogen washing cooler, 43 Gas-liquid separator, 44 Level difference transmitter, 45 Control valve, 51 Alkaline liquid filter, 52 Alkaline liquid circulation pump, 61 Negative pressure seawater desalination unit, 62 Vacuum gauge, 63 Vacuum pump, 64 Control valve, 65 Salinity meter, 66 Control valve, 67 Thermometer, 68 Water quality detector, 69 Seawater supply pump, 71 Freshwater tank, 72 Freshwater supply pump, 611 Cylinder, 612 Condenser, 613 Water receiving plate, 614 Screen separator, 615 Heat exchanger.

Claims

1. A system for coupling hydrogen production by water electrolysis with seawater desalination, comprising an alkaline electrolytic cell module, an oxygen separation module, a hydrogen separation module, a hydrogen purification module, an alkaline liquid filtration and circulation module, a negative pressure seawater desalination module, and a freshwater supply module, The negative pressure seawater desalination module heats seawater under negative pressure, causes the seawater to boil at a low temperature to generate steam, removes impurities from the steam, and then condenses it to produce fresh water. The freshwater supply module supplies raw freshwater to the alkaline electrolytic cell module. The alkaline electrolytic cell module, by the action of DC power, electrolyzes the fresh water inside the alkaline electrolytic cell module into hydrogen and oxygen, causing the hydrogen and alkaline solution to flow into the hydrogen separation module, and the oxygen and alkaline solution to flow into the oxygen separation module. The alkaline liquid filtration and circulation module forcibly circulates the alkaline liquid between the alkaline electrolytic cell module, the hydrogen separation module, and the oxygen separation module. The negative pressure seawater desalination module is a system for coupling hydrogen production by water electrolysis with seawater desalination, characterized in that it uses the heat released in the process of cooling a high-temperature alkaline solution to the required temperature of the electrolytic cell as an energy source.

2. The freshwater in the aforementioned alkaline electrolytic cell module is electrolyzed into hydrogen and oxygen by the action of DC power. The hydrogen outlet of the alkaline electrolytic cell module is connected to the hydrogen separation module, creating a passage through which hydrogen and alkaline solution flow into the hydrogen separation module. The oxygen outlet of the alkaline electrolytic cell module is connected to the oxygen separation module, creating a passage through which oxygen and alkaline solution flow into the oxygen separation module. The system for coupling hydrogen production by water electrolysis and seawater desalination according to claim 1, characterized in that the alkaline liquid inlet of the alkaline electrolytic cell module is connected to a negative pressure seawater desalination module, and the cooled alkaline liquid flows into the alkaline electrolytic cell module through this passage.

3. The oxygen inlet of the oxygen separation module is connected to the oxygen outlet of the alkaline electrolytic cell module, and the oxygen separation module separates the incoming oxygen and alkaline liquid using a gas-liquid separation method. The alkaline liquid outlets of the oxygen separation module and the hydrogen separation module are connected and merged to form a main pipe, which is then connected to the alkaline liquid filtration and circulation module, providing high-temperature alkaline liquid that requires cooling. The oxygen outlet of the oxygen separation module extends to a safety area to release oxygen into the atmosphere, or it is connected to an oxygen storage module to transport oxygen to the outside. The hydrogen inlet of the hydrogen separation module is connected to the hydrogen outlet of the alkaline electrolytic cell module, and the hydrogen separation module separates the incoming hydrogen and alkaline liquid using a gas-liquid separation method. The hydrogen outlet of the hydrogen separation module is connected to the hydrogen purification module, forming a passage for supplying high-purity hydrogen. The system for coupling hydrogen production by water electrolysis with seawater desalination according to claim 1, characterized in that the freshwater inlet of the hydrogen separation module is connected to a freshwater supply module, forming a passage for supplying freshwater as a raw material for electrolysis, and assisting in the washing and cooling of hydrogen.

4. The hydrogen purification module deoxygenates the incoming hydrogen, trace amounts of oxygen, and trace amounts of water through a catalytic reaction, and removes water and other impurities using the principle of molecular sieve adsorption, ultimately purifying the hydrogen to a purity of 99.999%. The system for coupling hydrogen production by water electrolysis with seawater desalination according to claim 1, characterized in that the hydrogen outlet of the hydrogen purification module is connected to a user or storage module.

5. The seawater inlet of the negative pressure seawater desalination module is a seawater supply passage. The alkaline liquid inlet of the negative pressure seawater desalination module is connected to the alkaline liquid filtration and circulation module, becoming a high-temperature alkaline liquid inlet passage. The alkaline liquid outlet of the negative pressure seawater desalination module is connected to the alkaline electrolytic cell module, becoming the outflow passage for the cooled alkaline liquid. The system for coupling hydrogen production by water electrolysis with seawater desalination according to claim 1, characterized in that the freshwater outlet of the negative pressure seawater desalination module is connected to a freshwater replenishment module, which serves as a freshwater outlet for the desalination-treated seawater.

6. The negative pressure seawater desalination module includes a negative pressure seawater desalination device, a vacuum gauge, a vacuum pump, a control valve, a salinity meter, a control valve, a thermometer, a water quality detector, and a seawater supply pump. The vacuum gauge monitors the vacuum level inside the negative pressure seawater desalination plant and controls the vacuum pump to maintain the vacuum level inside the negative pressure seawater desalination plant within a predetermined range. The seawater supply pump pumps up seawater and supplies it to the condenser in the negative-pressure seawater desalination plant to cool the steam into liquid freshwater. Then, one portion of the heated seawater is supplied to the evaporation chamber in the negative-pressure seawater desalination plant, and the other portion is discharged as excess seawater. The salinity meter monitors the salinity of seawater in the evaporation chamber of the negative pressure seawater desalination plant, and controls the control valve based on the results to adjust the flow rate of concentrated seawater to be discharged. The water quality detector monitors whether the quality of the produced freshwater is acceptable, and controls the system to allow acceptable freshwater to flow into the freshwater tank, while returning unacceptable freshwater to the negative-pressure seawater desalination plant for further desalination treatment. The system for coupling hydrogen production by water electrolysis with seawater desalination according to claim 1, characterized in that the thermometer monitors the temperature of the cooled alkaline solution, controls the opening of the control valve based on the result, and allows the alkaline solution to flow into the alkaline electrolytic cell module within an appropriate temperature range.

7. The negative pressure seawater desalination apparatus comprises a cylindrical body, a condenser, a water receiving plate, a screen separator, and a heat exchanger. The aforementioned condenser uses seawater as a cooling medium to condense water vapor, and the seawater, which has absorbed heat and been heated, is used as a water source for heating the alkaline solution. The water receiving plate has a certain incline and receives condensed water droplets. The aforementioned screen separator separates large droplets and impurities from the water vapor. The system for coupling hydrogen production by water electrolysis and seawater desalination according to claim 1, characterized in that the heat exchanger heats seawater using an alkaline solution as a heat source and ultimately achieves a low-temperature seawater desalination function under negative pressure.

8. The negative pressure seawater desalination module includes a seawater supply filtration module, an RO reverse osmosis module, and a negative pressure distillation module. The aforementioned seawater supply filtration module pumps up seawater, filters out impurities initially, and provides a seawater source to the RO reverse osmosis module. The aforementioned RO reverse osmosis module generates fresh water, The negative pressure distillation module further includes electric heat from offshore wind power generation as a heat source, and the negative pressure distillation module uses cooled freshwater to absorb the heat released in the hydrogen production process by alkaline water electrolysis and electric heat from offshore wind power generation to purify the freshwater and produce pure water. The system for coupling hydrogen production by water electrolysis with seawater desalination according to claim 1, characterized in that the power interface of the alkaline electrolytic cell module is connected to an offshore wind power generation facility, and the pure water in the alkaline electrolytic cell module is decomposed into hydrogen and oxygen using electricity from the offshore wind power generation facility.

9. It further includes a hydrogen transport module and a pure water transport module, The hydrogen transport module includes a hydrogen compression module, a hydrogen high-pressure storage module, and a hydrogen replenishment module. The hydrogen compression module is configured such that its hydrogen inlet is connected to a hydrogen purification module, its hydrogen outlet is connected to a hydrogen high-pressure storage module and a hydrogen replenishment module, and it compresses hydrogen to a predetermined pressure to replenish the hydrogen high-pressure storage module or to supply replenishment power to the hydrogen replenishment module. The aforementioned high-pressure hydrogen storage module is configured such that its high-pressure hydrogen inlet is connected to a hydrogen compression module, allowing it to store and detach high-pressure hydrogen for transport. The hydrogen replenishment module is configured such that its hydrogen inlet is connected to a hydrogen compression module, and it replenishes a powered vessel with high-pressure hydrogen. The pure water transport module includes a pure water storage and replenishment module and a pure water external transport module. The aforementioned pure water storage and replenishment module is configured such that its pure water inlet is connected to the pure water outlet of the negative pressure distillation module, functioning as the outlet of the fresh water replenishment module, storing the pure water produced in the negative pressure distillation module, supplying the alkaline electrolytic cell module with pure water for electrolysis, and supplying pure water to the pure water external transport module. The system for coupling hydrogen production by water electrolysis with seawater desalination according to claim 8, characterized in that the pure water external transport module has its pure water inlet connected to a pure water storage and replenishment module, and transports the produced fresh water to a nearby platform or vessel.

10. The freshwater in the alkaline electrolytic cell module is decomposed into hydrogen and oxygen by the action of DC power. Oxygen and alkaline liquid are transported to the oxygen separation module via the oxygen outlet of the alkaline electrolytic cell module for gas-liquid separation. The purified oxygen is then guided to a safety area and released into the atmosphere, or sent to the oxygen storage module. Hydrogen and alkaline liquid are transported to a hydrogen separation module via the hydrogen outlet of the alkaline electrolytic cell module for gas-liquid separation. The initially purified hydrogen and a small amount of water are then fed into a hydrogen purification module to further purify it to a hydrogen content of 99.999%, and the hydrogen is finally supplied to the user or storage module. The aforementioned alkaline liquid filtration and circulation module extracts the alkaline liquid from the oxygen separation module and the hydrogen separation module, cools it in the negative pressure seawater desalination module, and finally transports it to the alkaline electrolytic cell module to complete the cooling and forced circulation of the alkaline liquid. A seawater desalination method for a system for coupling hydrogen production by water electrolysis and seawater desalination according to any one of claims 1 to 7, characterized in that the heat released when an alkaline solution is cooled in a negative-pressure seawater desalination module is used to heat seawater under negative pressure, causing it to boil and evaporate to produce fresh water, the approved fresh water flows into a freshwater supply module, and is transported to a hydrogen separation module to be supplied as raw material freshwater for use in electrolysis, and also includes assisting in the washing and cooling of hydrogen.

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