An efficient and energy-saving method for producing hydrogen by electrolysis

Abstract

This invention provides a highly efficient and energy-saving method for producing hydrogen through electrolysis. The electrolysis hydrogen production system includes an electrolyzer, a separator, a vaporizer, a condenser, a raw water tank, a fresh water tank, a vacuum tank, and a vacuum pump. The electrolyte is transported from the bottom of the separator to the top of the vaporizer for heat exchange, and then flows back to the electrolyzer. Raw water enters the condenser, is preheated by steam from the vaporizer, and exits from the right side of the condenser. A small portion enters from the middle of the vaporizer, exchanges heat with the high-temperature electrolyte, and then vaporizes under vacuum. The vaporized steam enters the lower left side of the condenser, exchanges heat with the raw water, condenses into fresh water, and flows by gravity from the lower right side of the condenser into the fresh water tank. This electrolysis hydrogen production method achieves the separation and purification of raw water without the need for additional energy or a complex automatic control system, and saves the energy required for cooling the circulating electrolyte, resulting in significant energy savings. It also greatly expands the raw materials and application areas for hydrogen production.

Description

Technical Field

[0001] This invention belongs to the field of water electrolysis for hydrogen production technology, specifically relating to a highly efficient and energy-saving method for hydrogen production by electrolysis. Background Technology

[0002] Current hydrogen production systems using water electrolysis employ a process that uses alkaline solutions prepared with pure water. This process demands extremely high purity water, leading to high purification costs and consequently, high overall hydrogen production costs. Furthermore, the electrolysis process directly consumes some electrical energy, generating a significant amount of heat. This necessitates the use of large quantities of circulating cooling water to cool the electrolyte, especially during start-up and pressure maintenance after shutdown. Summary of the Invention

[0003] To address at least one of the aforementioned technical problems, this application utilizes vacuum decompression to reduce the vaporization boiling point of the feed water to a level significantly lower than the temperature of the circulating electrolyte. The heat generated during electrolysis is exchanged through the vaporization of the feed water, thereby lowering the temperature of the circulating electrolyte. The vaporized steam preheats the feed water and condenses it into fresh water that can be directly used for electrolysis, reducing the manufacturing cost of water for electrolysis and consequently lowering the production cost of hydrogen. This also saves energy for cooling the circulating electrolyte and significantly expands the raw materials and applications for hydrogen production. By incorporating electric heating and insulation measures during the electrolyte circulation process, heat is provided during start-up and pressure maintenance to rapidly increase the temperature of the electrolysis system.

[0004] The first aspect of the present invention provides a high-efficiency and energy-saving electrolytic hydrogen production system, the electrolytic hydrogen production system comprising: an electrolyzer 1, a separator 2, a circulating pump 3, a vaporizer 4, a condenser 5, a raw water tank 6, a fresh water tank 7, a vacuum pump 8, and a vacuum tank 9;

[0005] The electrolytic cell outlet 1-2 on the upper side of the electrolytic cell 1 is connected to the separator inlet 2-1 on the upper side of the separator 2 through a gas-liquid pipe 11, and the separator outlet 2-2 at the bottom of the separator 2 is connected to the circulation pump inlet 3-1 of the circulation pump 3 through a separation electrolyte pipe 12.

[0006] The circulation pump outlet 3-2 of the circulation pump 3 is connected to the vaporizer heating tube inlet 4-1 on the upper side of the vaporizer 4 through the cooling electrolyte pipe 13, and the vaporizer heating tube outlet 4-2 on the lower side of the vaporizer 4 is connected to the electrolytic cell inlet 1-1 on the lower side of the electrolytic cell 1 through the return electrolyte pipe 14.

[0007] The vaporizer steam outlet 4-4 at the top of the vaporizer 4 is connected to the condenser shell inlet 5-1 on the lower left side of the condenser 5 via a steam pipe 17, and the condenser shell outlet 5-2 on the lower right side of the condenser 5 is connected to the fresh water tank 7 via a fresh water pipe 18.

[0008] The raw water pipeline 15 is connected to the condenser tube inlet 5-3 at the left end of the condenser 5. The condenser tube outlet 5-4 at the right end of the condenser 5 is connected to the vaporizer raw material inlet 4-3 in the middle of the vaporizer 4 via the hot water pipeline 16. The condenser tube outlet 5-4 at the right end of the condenser 5 is also connected to the raw water tank 6 via the upstream part of the hot water pipeline 16-1 and the wastewater pipeline 19. The vaporizer residual liquid outlet 4-5 at the bottom of the vaporizer 4 is connected to the wastewater pipeline 19 via the vaporizer residual liquid outlet pipeline 23. The connection between the vaporizer residual liquid outlet pipeline 23 and the wastewater pipeline 19 is the upper end of the vaporizer residual liquid outlet pipeline 23. The upper end of the vaporizer residual liquid outlet pipeline 23 is lower than the lower end of the upstream part of the hot water pipeline 16-1.

[0009] The condenser vacuum outlet 5-5 on the upper right side of the condenser 5 is connected to the upper inlet of the vacuum tank 9 through the first vacuum pipe 21, and the lower outlet of the vacuum tank 9 is connected to the inlet of the vacuum pump 8 through the second vacuum pipe 22.

[0010] Preferably, the separator 2 is an oxygen-liquid separator or a hydrogen-liquid separator. Therefore, the gas discharged from the top of the separator 2 is oxygen or hydrogen.

[0011] Preferably, the wastewater pipe 19 is connected to the upstream portion 16-1 of the hot water pipe at a position higher than the vaporizer raw material inlet 4-3, and the vaporizer residual liquid outlet 4-5 is lower than the vaporizer raw material inlet 4-3.

[0012] Preferably, the height difference between the top of the vaporizer residual liquid outlet pipe 23 and the liquid surface of the raw water tank 6 is >5m, preferably 10.3m, so as to ensure that even if the shell side of the vaporizer 4 and the condenser 5 is in a vacuum state, the raw water in the tube side of the condenser 5 can flow smoothly into the vaporizer 4.

[0013] The height difference between the lowest point of the condenser 5 and the liquid surface of the freshwater tank 7 is >5m, preferably 10.3m, to ensure that even if the shell side of the condenser 5 is in a vacuum state, the condensate in the shell side of the condenser 5 can freely fall into the freshwater tank 7.

[0014] Preferably, a valve is installed at the raw material inlet 4-3 of the vaporizer. The valve opening is adjusted according to the system's heat exchange capacity. For example, the valve opening is adjusted according to the temperature and flow rate of the high-temperature electrolyte entering the vaporizer 4.

[0015] Preferably, the vaporizer 4 is also provided with a valve at the bottom for use as a drain valve during parking operations.

[0016] Preferably, the vaporizer 4 adopts a vertical design and is divided into three sections: upper, middle, and lower.

[0017] The upper part is an enlarged section used for vaporization separation and steam transportation;

[0018] The middle section is the heating section, which is used for circulating electrolyte and raw water to enter and complete heat exchange, or for the electrothermal insulation of the electrolyte before starting electrolysis;

[0019] The lower section is the residual liquid section, used for the collection and discharge of residual liquid after the raw material water is separated.

[0020] Preferably, the outer surface of the vaporizer 4 or separator 2 is provided with an insulation layer to prevent heat loss during start-up and shutdown pressure maintenance. The vaporizer 4 or separator 2 is provided with an electric heating device to provide heat during start-up and shutdown pressure maintenance to quickly raise the temperature of the electrolysis system.

[0021] A second aspect of the present invention provides a method for producing hydrogen by electrolysis, using the high-efficiency and energy-saving hydrogen electrolysis system described in the first aspect, the method comprising the following steps:

[0022] After electrolysis in the electrolytic cell 1, the electrolyte produces hydrogen and oxygen. A high-temperature gas-liquid mixture containing electrolyte and hydrogen or a high-temperature gas-liquid mixture containing electrolyte and oxygen flows from the electrolytic cell outlet 1-2 through the gas-liquid pipe 11 and the separator inlet 2-1 into the separator 2. The separated gas is discharged from the top of the separator 2.

[0023] The separated high-temperature electrolyte is transported from the separator outlet 2-2 through the separated electrolyte pipeline 12, the circulating pump 3, the cooling electrolyte pipeline 13, and the vaporizer heating tube inlet 4-1 to the heating tube of the vaporizer 4. After the electrolyte is cooled by heat exchange with the raw water in the vaporizer 4, it flows back to the electrolytic cell 1 from the vaporizer heating tube outlet 4-2 through the return electrolyte pipeline 14 and the electrolytic cell inlet 1-1. After the raw water in the vaporizer 4 exchanges heat with the high-temperature electrolyte in the heating tube of the vaporizer 4, steam is generated under vacuum and enters the shell side of the condenser 5 through the vaporizer steam outlet 4-4, the steam pipeline 17, and the condenser shell side inlet 5-1.

[0024] Raw water input from the outside enters the tube side of the condenser 5 through the raw water pipe 15 and the condenser tube side inlet 5-3. After being preheated by the steam in the shell side of the condenser 5, the raw water is discharged from the condenser tube side outlet 5-4. Part of the discharged raw water enters the vaporizer 4 through the hot water pipe 16 and the vaporizer raw material inlet 4-3, and then exchanges heat with the high-temperature electrolyte in the heating tube of the vaporizer 4 and vaporizes under vacuum to generate steam. Most of the discharged raw water flows into the raw water tank 6 through the upstream part 16-1 of the hot water pipe and the wastewater pipe 19.

[0025] After the steam in the shell side of the condenser 5 completes heat exchange with the raw water in the tube side, most of the steam is condensed into fresh water and flows into the fresh water tank 7 automatically through the condenser shell side outlet 5-2 and the fresh water pipe 18.

[0026] A small portion of the unvaporized raw water in the vaporizer 4, carrying impurities, is discharged into the bottom of the raw water tank 6 through the vaporizer residual liquid outlet 4-5, the vaporizer residual liquid outlet pipe 23, and the wastewater pipe 19.

[0027] A small amount of vapor in the shell side of the condenser 5 is drawn from the vacuum outlet 5-5 of the condenser into the vacuum tank 9, condenses into water, and is then discharged from the lower outlet of the vacuum tank 9 via the vacuum pump 8.

[0028] The above text mostly refers to a volume fraction of 80% or more, while a small portion refers to a volume fraction of 20% or less.

[0029] Preferably, when the system is initially running, the vacuum pump 8 is turned on, so that the vaporizer 4, the shell side of the condenser 5, the vacuum tank 9, the hot water pipe 16, the steam pipe 17, the fresh water pipe 18, the wastewater pipe 19, and the vaporizer residual liquid outlet pipe 23 are in a vacuum state.

[0030] The raw water tank 6 contains raw water, and some of the raw water rises into the fresh water pipe 18 to form a water column to balance the external atmospheric pressure. That is, during the operation of the system, the lower end of the fresh water pipe 18 is always kept below the liquid surface of the raw water tank 6.

[0031] The freshwater tank 7 contains pre-stored freshwater, and some of the freshwater rises into the wastewater pipe 19 to form a water column to balance the external atmospheric pressure. That is, during the operation of the system, the lower end of the freshwater pipe 18 is always kept below the liquid level of the original water tank 6.

[0032] During system operation, the vacuum pump 8 is turned off, the vacuum in the vaporizer 4 is consumed by vaporization, and the vacuum in the shell side of the condenser 5 is generated by condensation, thereby continuously maintaining the vacuum state in the vaporizer 4 and the shell side of the condenser 5.

[0033] If the vacuum state is depleted due to system sealing performance or other conditions during system operation, vacuum pump 8 can be started directly to replenish the vacuum.

[0034] Preferably, the vaporization temperature in the vaporizer 4 is reduced by increasing the vacuum level in the shell side of the vaporizer 4 and the condenser 5. To prevent the vacuum seal from being damaged by excessively high or rapid fluctuations in the system vacuum, the liquid seal height should be greater than 10.34 meters.

[0035] Preferably, by increasing the heating and vaporization of the vaporizer 4, the condensation of the condenser 5, and the vacuum suction of the vacuum pump 8, not only are inorganic salts, microorganisms, and mechanical impurities in the raw water separated, but also low-boiling components and non-condensable gases are removed.

[0036] Low-boiling components refer to components with a boiling point below 90°C under normal pressure, such as benzene, hexane, carbon dioxide, and methane.

[0037] The raw water referred to in this article is fresh water that is normally added to the system, including seawater, brine, and even wastewater. Fresh water refers to raw water that has been treated and can be used for electrolysis in an electrolytic cell. Electrolyte refers to fresh water mixed with electrolytes or catalysts and then used for electrolysis in an electrolytic cell.

[0038] The upper openings of the raw water tank 6 and the fresh water tank 7 are open.

[0039] Preferably, during the initial operation of the system, some raw water enters the vaporizer 4 and fills the vaporizer residual liquid outlet pipe 23, so that the liquid level in the vaporizer 4 and the liquid level in the vaporizer residual liquid outlet pipe 23 are parallel.

[0040] Preferably, the vaporization temperature in the vaporizer 4 is reduced by increasing the vacuum level in the shell side of the vaporizer 4 and the condenser 5.

[0041] Preferably, during the start-up and warm-up process or the shutdown and pressure maintenance process, the electric heating device of the vaporizer 4 or separator 2 is turned on to provide heat to raise the temperature of the electrolysis system as quickly as possible.

[0042] In this application, "vacuum" refers to a state where the absolute pressure is below one atmosphere.

[0043] Compared with the prior art, the present invention has the following beneficial effects:

[0044] 1. In this application, the waste heat generated during the electrolysis process is absorbed by the vaporization of the raw water, eliminating the need for a circulating cooling system to cool the electrolyte. This saves on equipment investment and reduces energy consumption. Under a high vacuum environment, the raw water vaporizes at low temperatures and then rapidly condenses back into liquid fresh water, achieving separation of fresh water and impurities from the raw water. This process does not consume the vacuum generated by the vacuum pump, meaning no energy is consumed. Therefore, this electrolytic hydrogen production system and method can achieve the separation and purification of raw water without adding energy or a complex automatic control system, saving the energy required for cooling the circulating electrolyte. The energy-saving effect is significant, and it also greatly expands the raw materials and application areas for hydrogen production.

[0045] 2. In this application, the vacuum of the vaporizer 4 and the condenser 5 is initially generated by the vacuum pump 8. During operation, vaporization consumes the vacuum and condensation generates the vacuum, so the vacuum pump 8 does not need to run continuously to generate the vacuum.

[0046] 3. In this application, the higher the vacuum level of the vaporizer 4 and the condenser 5, the lower the vaporization temperature and the better the heat transfer and separation effect.

[0047] 4. In this application, not only are inorganic salts, microorganisms and mechanical impurities separated from the raw water, but also low-boiling components and non-condensable gases such as carbon dioxide are removed.

[0048] 5. In this application, automatic control can be achieved without a complex automatic control system.

[0049] 6. During start-up and heating or shutdown and pressure maintenance, the circulating electrolyte temperature can quickly reach the process requirements to save energy consumption. Attached Figure Description

[0050] Figure 1 This is a flow chart of the water electrolysis hydrogen production system of the present invention.

[0051] Figure 1 In this context, A represents raw material water, and B represents oxygen or hydrogen.

[0052] List of reference numerals in the attached diagram:

[0053] 1. Electrolytic Cell, 1-1. Electrolytic Cell Inlet, 1-2. Electrolytic Cell Outlet; 2. Separator, 2-1. Separator Inlet, 2-2. Separator Outlet; 3. Circulating Pump, 3-1. Circulating Pump Inlet, 3-2. Circulating Pump Outlet; 4. Vaporizer, 4-1. Vaporizer Heating Tube Inlet, 4-2. Vaporizer Heating Tube Outlet, 4-3. Vaporizer Raw Material Inlet, 4-4. Vaporizer Steam Outlet, 4-5. Vaporizer Residual Liquid Outlet; 5. Condenser, 5-1. Condenser Shell-Side Inlet, 5-2. Condenser Shell-Side Outlet, 5-3. Condenser Tube-Side Inlet 5-4. Condenser tube outlet; 5-5. Condenser vacuum outlet; 6. Raw water tank; 7. Fresh water tank; 8. Vacuum pump; 9. Vacuum tank; 11. Gas-liquid pipeline; 12. Separating electrolyte pipeline; 13. Cooling electrolyte pipeline; 14. Return electrolyte pipeline; 15. Raw water pipeline; 16. Hot water pipeline; 16-1. Upstream section of hot water pipeline; 17. Steam pipeline; 18. Fresh water pipeline; 19. Wastewater pipeline; 20. Exhaust pipeline; 21. First vacuum pipeline; 22. Second vacuum pipeline; 23. Vaporizer residual liquid outlet pipeline. Detailed Implementation

[0054] The present invention will now be described in further detail with reference to the embodiments.

[0055] Those skilled in the art will understand that the following embodiments are for illustrative purposes only and should not be construed as limiting the scope of the invention. Where specific techniques or conditions are not specified in the embodiments, they are performed in accordance with the techniques or conditions described in the literature in the field or according to the product instructions. Materials or equipment whose manufacturers are not specified are all conventional products that can be obtained by purchase.

[0056] Those skilled in the art will understand that, unless specifically stated otherwise, the singular forms “a,” “an,” “the,” and “the” used herein may also include the plural forms. It should be further understood that the term “comprising” as used in this specification means the presence of the stated features, integers, steps, operations, elements, and / or components, but does not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups thereof. It should be understood that when we say an element is “coupled” to another element, it can be directly coupled to the other element, or there may be intermediate elements. Furthermore, the term “coupled” as used herein can include wireless coupling.

[0057] In the description of this invention, unless otherwise stated, "a plurality of" means two or more. The terms "inner," "upper," "lower," etc., indicate the orientation or state relationship based on the orientation or state relationship shown in the drawings, and are only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the invention.

[0058] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installed," "connected," and "equipped with" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium. Those skilled in the art will understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0059] It will be understood by those skilled in the art that, unless otherwise defined, all terms used herein, including technical and scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. It should also be understood that terms such as those defined in general dictionaries should be understood to have the meaning consistent with their meaning in the context of the prior art, and should not be interpreted in an idealized or overly formal sense unless defined as herein.

[0060] A high-efficiency and energy-saving electrolytic hydrogen production system, the electrolytic hydrogen production system comprising: an electrolyzer 1, a separator 2, a circulating pump 3, a vaporizer 4, a condenser 5, a raw water tank 6, a fresh water tank 7, a vacuum pump 8, and a vacuum tank 9;

[0061] The electrolytic cell outlet 1-2 on the upper side of the electrolytic cell 1 is connected to the separator inlet 2-1 on the upper side of the separator 2 through a gas-liquid pipe 11, and the separator outlet 2-2 at the bottom of the separator 2 is connected to the circulation pump inlet 3-1 of the circulation pump 3 through a separation electrolyte pipe 12.

[0062] The circulation pump outlet 3-2 of the circulation pump 3 is connected to the vaporizer heating tube inlet 4-1 on the upper side of the vaporizer 4 through the cooling electrolyte pipe 13, and the vaporizer heating tube outlet 4-2 on the lower side of the vaporizer 4 is connected to the electrolytic cell inlet 1-1 on the lower side of the electrolytic cell 1 through the return electrolyte pipe 14.

[0063] The vaporizer steam outlet 4-4 at the top of the vaporizer 4 is connected to the condenser shell inlet 5-1 on the lower left side of the condenser 5 via a steam pipe 17, and the condenser shell outlet 5-2 on the lower right side of the condenser 5 is connected to the fresh water tank 7 via a fresh water pipe 18.

[0064] The raw water pipeline 15 is connected to the condenser tube inlet 5-3 at the left end of the condenser 5. The condenser tube outlet 5-4 at the right end of the condenser 5 is connected to the vaporizer raw material inlet 4-3 in the middle of the vaporizer 4 via the hot water pipeline 16. The condenser tube outlet 5-4 at the right end of the condenser 5 is also connected to the raw water tank 6 via the upstream part of the hot water pipeline 16-1 and the wastewater pipeline 19. The vaporizer residual liquid outlet 4-5 at the bottom of the vaporizer 4 is connected to the wastewater pipeline 19 via the vaporizer residual liquid outlet pipeline 23. The connection between the vaporizer residual liquid outlet pipeline 23 and the wastewater pipeline 19 is the upper end of the vaporizer residual liquid outlet pipeline 23. The upper end of the vaporizer residual liquid outlet pipeline 23 is lower than the lower end of the upstream part of the hot water pipeline 16-1.

[0065] The condenser vacuum outlet 5-5 on the upper right side of the condenser 5 is connected to the upper inlet of the vacuum tank 9 through the first vacuum pipe 21, and the lower outlet of the vacuum tank 9 is connected to the inlet of the vacuum pump 8 through the second vacuum pipe 22.

[0066] Preferably, the separator 2 is an oxygen-liquid separator or a hydrogen-liquid separator. Therefore, the gas discharged from the top of the separator 2 is oxygen or hydrogen.

[0067] The wastewater pipe 19 is connected to the upstream part 16-1 of the hot water pipe at a position higher than the raw material inlet 4-3 of the vaporizer, and the residual liquid outlet 4-5 of the vaporizer is lower than the raw material inlet 4-3 of the vaporizer.

[0068] The height difference between the top of the vaporizer residual liquid outlet pipe 23 and the liquid surface of the raw water tank 6 is >5m, preferably 10.3m, to ensure that even if the shell side of the vaporizer 4 and the condenser 5 is in a vacuum state, the raw water in the tube side of the condenser 5 can flow smoothly into the vaporizer 4.

[0069] The height difference between the lowest point of the condenser 5 and the liquid surface of the freshwater tank 7 is >5m, preferably 10.3m, to ensure that even if the shell side of the condenser 5 is in a vacuum state, the condensate in the shell side of the condenser 5 can freely fall into the freshwater tank 7.

[0070] The vertical height of the freshwater pipe 18 above the liquid level in the freshwater tank 7 is greater than 10.3m, so that the freshwater pipe 18 can withstand a water column of up to 10.3m.

[0071] The vertical height of the wastewater pipe 19 above the liquid level of the original water tank 6 is greater than 10.3m, so that the wastewater pipe 19 can withstand a water column of up to 10.3m.

[0072] A valve is installed at the raw material inlet 4-3 of the vaporizer. The valve opening is adjusted according to the system's heat exchange capacity. For example, the valve opening is adjusted according to the temperature and flow rate of the high-temperature electrolyte entering the vaporizer 4. A valve is also installed at the bottom of the vaporizer 4 for draining wastewater during shutdown operations.

[0073] An electrolytic hydrogen production method, using the high-efficiency and energy-saving electrolytic hydrogen production system described in the first aspect, the electrolytic hydrogen production method comprising the following steps:

[0074] After electrolysis in the electrolytic cell 1, the electrolyte produces hydrogen and oxygen. A high-temperature gas-liquid mixture containing electrolyte and hydrogen or a high-temperature gas-liquid mixture containing electrolyte and oxygen flows from the electrolytic cell outlet 1-2 through the gas-liquid pipe 11 and the separator inlet 2-1 into the separator 2. The separated gas is discharged from the top of the separator 2.

[0075] The separated high-temperature electrolyte is transported from the separator outlet 2-2 through the separated electrolyte pipeline 12, the circulating pump 3, the cooling electrolyte pipeline 13, and the vaporizer heating tube inlet 4-1 to the heating tube of the vaporizer 4. After the electrolyte is cooled by heat exchange with the raw water in the vaporizer 4, it flows back to the electrolytic cell 1 from the vaporizer heating tube outlet 4-2 through the return electrolyte pipeline 14 and the electrolytic cell inlet 1-1. After the raw water in the vaporizer 4 exchanges heat with the high-temperature electrolyte in the heating tube of the vaporizer 4, steam is generated under vacuum and enters the shell side of the condenser 5 through the vaporizer steam outlet 4-4, the steam pipeline 17, and the condenser shell side inlet 5-1.

[0076] Raw water input from the outside enters the tube side of the condenser 5 through the raw water pipe 15 and the condenser tube side inlet 5-3. After being preheated by the steam in the shell side of the condenser 5, the raw water is discharged from the condenser tube side outlet 5-4. Part of the discharged raw water enters the vaporizer 4 through the hot water pipe 16 and the vaporizer raw material inlet 4-3, and then exchanges heat with the high-temperature electrolyte in the heating tube of the vaporizer 4 and vaporizes under vacuum to generate steam. Most of the discharged raw water flows into the raw water tank 6 through the upstream part 16-1 of the hot water pipe and the wastewater pipe 19.

[0077] After the steam in the shell side of the condenser 5 completes heat exchange with the raw water in the tube side, most of the steam is condensed into fresh water and flows into the fresh water tank 7 automatically through the condenser shell side outlet 5-2 and the fresh water pipe 18.

[0078] A small portion of the unvaporized raw water in the vaporizer 4, carrying impurities, is discharged into the bottom of the raw water tank 6 through the vaporizer residual liquid outlet 4-5, the vaporizer residual liquid outlet pipe 23, and the wastewater pipe 19.

[0079] A small amount of vapor in the shell side of the condenser 5 is drawn from the vacuum outlet 5-5 of the condenser into the vacuum tank 9, condenses into water, and is then discharged from the lower outlet of the vacuum tank 9 via the vacuum pump 8.

[0080] Preferably, when the system is initially running, the vacuum pump 8 is turned on, so that the vaporizer 4, the shell side of the condenser 5, the vacuum tank 9, the hot water pipe 16, the steam pipe 17, the fresh water pipe 18, the wastewater pipe 19, and the vaporizer residual liquid outlet pipe 23 are in a vacuum state.

[0081] The raw water tank 6 contains raw water, and some of the raw water rises into the fresh water pipe 18 to form a water column to balance the external atmospheric pressure. That is, during the operation of the system, the lower end of the fresh water pipe 18 is always kept below the liquid surface of the raw water tank 6.

[0082] The freshwater tank 7 contains pre-stored freshwater, and some of the freshwater rises into the wastewater pipe 19 to form a water column to balance the external atmospheric pressure. That is, during the operation of the system, the lower end of the freshwater pipe 18 is always kept below the liquid level of the original water tank 6.

[0083] During system operation, the vacuum pump 8 is turned off, the vacuum in the vaporizer 4 is consumed by vaporization, and the vacuum in the shell side of the condenser 5 is generated by condensation, thereby continuously maintaining the vacuum state in the vaporizer 4 and the shell side of the condenser 5.

[0084] Preferably, the vaporization temperature in the vaporizer 4 is reduced by increasing the vacuum level in the shell side of the vaporizer 4 and the condenser 5.

[0085] The vaporizer 4 of this application adopts the principle of pressure reduction distillation. Under high vacuum, the boiling point of the raw water is reduced. Through the heating of the high-temperature electrolyte, a large amount of water is vaporized and then condensed into clean water, thereby achieving the separation of water and impurities in the raw water. At the same time, the temperature of the circulating electrolyte is reduced by evaporation.

[0086] In a specific embodiment, the vaporizer 4 or separator 2 is insulated to prevent heat loss during start-up and pressure maintenance. The vaporizer 4 is vertically designed, with vaporization divided into three sections: the upper section is an expansion section for vaporization separation and steam transport; the middle section is a heating section for circulating electrolyte and raw water to enter and complete heat exchange, or for electrothermal insulation of the electrolyte before start-up electrolysis; and the lower section is a residual liquid section for collecting and discharging residual liquid after raw water separation. The three sections are connected by flanges, and the lower section can be easily removed if necessary to clean the scale accumulated in the heating plate pipes.

[0087] The vaporizer 4 is made of corrosion-resistant materials such as titanium. The diameter of the expansion section is twice that of the heating section. The heating section uses coil heating or electric heating, and multiple coil sections or multiple electric heating sections can be installed. After heat exchange in the heating section, the raw water temperature rises and boils under vacuum, rapidly expanding in volume. After separation from impurities in the raw water in the expansion section, water vapor mixed with low-boiling-point components and non-condensable gases is drawn into the condenser, while excess unvaporized raw water carrying impurities flows out from the bottom.

Claims

1. A method for producing hydrogen by electrolysis, characterized in that, The following high-efficiency and energy-saving electrolytic hydrogen production system is used, which includes: an electrolyzer (1), a separator (2), a circulating pump (3), a vaporizer (4), a condenser (5), a raw water tank (6), a fresh water tank (7), a vacuum pump (8), and a vacuum tank (9). The electrolytic cell outlet (1-2) on the upper side of the electrolytic cell (1) is connected to the separator inlet (2-1) on the upper side of the separator (2) through a gas-liquid pipe (11); the separator outlet (2-2) at the bottom of the separator (2) is connected to the circulation pump inlet (3-1) of the circulation pump (3) through a separation electrolyte pipe (12). The circulation pump outlet (3-2) of the circulation pump (3) is connected to the vaporizer heating tube inlet (4-1) on the upper side of the vaporizer (4) through the cooling electrolyte pipe (13); the vaporizer heating tube outlet (4-2) on the lower side of the vaporizer (4) is connected to the electrolytic cell inlet (1-1) on the lower side of the electrolytic cell (1) through the return electrolyte pipe (14); The vaporizer steam outlet (4-4) at the top of the vaporizer (4) is connected to the condenser shell inlet (5-1) on the lower left side of the condenser (5) via a steam pipe (17), and the condenser shell outlet (5-2) on the lower right side of the condenser (5) is connected to the fresh water tank (7) via a fresh water pipe (18). The raw water pipe (15) is connected to the condenser tube inlet (5-3) at the left end of the condenser (5). The condenser tube outlet (5-4) at the right end of the condenser (5) is connected to the vaporizer raw material inlet (4-3) in the middle of the vaporizer (4) through the hot water pipe (16). The condenser tube outlet (5-4) at the right end of the condenser (5) is also connected to the raw water tank (6) through the upstream part of the hot water pipe (16-1) and the wastewater pipe (19) in sequence. The vaporizer residual liquid outlet (4-5) at the bottom of the vaporizer (4) is connected to the wastewater pipe (19) through the vaporizer residual liquid outlet pipe (23). The connection between the vaporizer residual liquid outlet pipe (23) and the wastewater pipe (19) is the upper end of the vaporizer residual liquid outlet pipe (23). The upper end of the vaporizer residual liquid outlet pipe (23) is lower than the lower end of the upstream part of the hot water pipe (16-1). The condenser vacuum outlet (5-5) on the upper right side of the condenser (5) is connected to the upper inlet of the vacuum tank (9) through the first vacuum pipe (21), and the lower outlet of the vacuum tank (9) is connected to the inlet of the vacuum pump (8) through the second vacuum pipe (22). The electrolytic hydrogen production method includes the following steps: After the electrolyte is electrolyzed in the electrolytic cell (1), hydrogen and oxygen are produced. A high-temperature gas-liquid mixture containing electrolyte and hydrogen or a high-temperature gas-liquid mixture containing electrolyte and oxygen flows from the outlet (1-2) of the electrolytic cell through the gas-liquid pipe (11) and the separator inlet (2-1) into the separator (2). The separated gas is discharged from the top of the separator (2). The separated high-temperature electrolyte is transported from the separator outlet (2-2) through the separated electrolyte pipeline (12), the circulating pump (3), the cooling electrolyte pipeline (13), and the vaporizer heating tube inlet (4-1) to the heating tube of the vaporizer (4). After the electrolyte is cooled by heat exchange with the raw water in the vaporizer (4), it flows back to the electrolytic cell (1) from the vaporizer heating tube outlet (4-2) through the return electrolyte pipeline (14) and the electrolytic cell inlet (1-1). After the raw water in the vaporizer (4) exchanges heat with the high-temperature electrolyte in the heating tube of the vaporizer (4), steam is generated under vacuum and enters the shell side of the condenser (5) through the vaporizer steam outlet (4-4), the steam pipeline (17), and the condenser shell side inlet (5-1). Raw water input from the outside enters the tube side of the condenser (5) through the raw water pipe (15) and the condenser tube side inlet (5-3). After being preheated by the steam in the shell side of the condenser (5), the raw water is discharged from the condenser tube side outlet (5-4). Part of the discharged raw water enters the vaporizer (4) through the hot water pipe (16) and the vaporizer raw material inlet (4-3), and then undergoes heat exchange with the high-temperature electrolyte of the heating tube of the vaporizer (4) and vaporizes under vacuum to generate steam. Most of the discharged raw water flows into the raw water tank (6) through the upstream part of the hot water pipe (16-1) and the wastewater pipe (19). After the steam in the shell side of the condenser (5) and the raw water in the tube side complete the heat exchange, most of the steam is condensed into fresh water and flows into the fresh water tank (7) automatically through the condenser shell side outlet (5-2) and the fresh water pipe (18). A small portion of the unvaporized raw water in the vaporizer (4) carries impurities and is discharged into the bottom of the raw water tank (6) through the vaporizer residual liquid outlet (4-5), the vaporizer residual liquid outlet pipe (23), and the wastewater pipe (19). A small amount of vapor in the shell side of the condenser (5) is drawn from the vacuum outlet (5-5) of the condenser into the vacuum tank (9), condenses into water, and is then discharged from the lower outlet of the vacuum tank (9) via the vacuum pump (8).

2. The method for producing hydrogen by electrolysis according to claim 1, characterized in that, The wastewater pipe (19) is connected to the upstream part (16-1) of the hot water pipe at a position higher than the raw material inlet (4-3) of the vaporizer, and the residual liquid outlet (4-5) of the vaporizer is lower than the raw material inlet (4-3) of the vaporizer.

3. The method for producing hydrogen by electrolysis according to claim 1, characterized in that, The height difference between the top of the vaporizer residual liquid outlet pipe (23) and the liquid surface of the original water tank (6) is >5m; The height difference between the lowest point of the condenser (5) and the liquid surface of the freshwater tank (7) is >5m.

4. The method for producing hydrogen by electrolysis according to claim 1, characterized in that, A valve is installed at the raw material inlet (4-3) of the vaporizer.

5. The method for producing hydrogen by electrolysis according to claim 1, characterized in that, The vaporizer (4) adopts a vertical design and is divided into three sections: upper, middle and lower. The upper part is an enlarged section used for vaporization separation and steam transportation; The middle section is the heating section, which is used for circulating electrolyte and raw water to enter and complete heat exchange, or for the electrothermal insulation of the electrolyte before starting electrolysis; The lower section is the residual liquid section, used for the collection and discharge of residual liquid after the raw material water is separated.

6. The method for producing hydrogen by electrolysis according to claim 1, characterized in that, The vaporizer (4) or separator (2) is provided with an insulation layer on its outer surface to prevent heat loss during start-up and shutdown pressure maintenance. The vaporizer (4) or separator (2) is provided with an electric heating device to provide heat during start-up and shutdown pressure maintenance to quickly raise the temperature of the electrolysis system.

7. The method for producing hydrogen by electrolysis according to claim 1, characterized in that, When the system is initially running, the vacuum pump (8) is turned on, so that the vaporizer (4), the shell side of the condenser (5), the vacuum tank (9), the hot water pipe (16), the steam pipe (17), the fresh water pipe (18), the wastewater pipe (19), and the vaporizer residual liquid outlet pipe (23) are in a vacuum state; The raw water tank (6) contains raw water, and some of the raw water rises into the fresh water pipe (18) to form a water column to balance the external atmospheric pressure, that is, the lower end of the fresh water pipe (18) is always kept below the liquid surface of the raw water tank (6). The fresh water tank (7) contains fresh water, and some of the fresh water rises into the wastewater pipe (19) to form a water column to balance the external atmospheric pressure, that is, the lower end of the fresh water pipe (18) is always kept below the liquid surface of the original water tank (6). During system operation, the vacuum pump (8) is turned off, the vacuum in the vaporizer (4) is consumed by vaporization, and the vacuum in the shell side of the condenser (5) is generated by condensation, so as to continuously maintain the vacuum state in the shell side of the vaporizer (4) and the condenser (5).

8. The method for producing hydrogen by electrolysis according to claim 1, characterized in that, The vaporization temperature in the vaporizer (4) is reduced by increasing the vacuum level in the shell side of the vaporizer (4) and the condenser (5).

9. The method for producing hydrogen by electrolysis according to claim 1, characterized in that, By increasing the heating and vaporization of the vaporizer (4), the condensation of the condenser (5), and the vacuum suction of the vacuum pump (8), not only are inorganic salts, microorganisms and mechanical impurities in the raw water separated, but also low-boiling components and non-condensable gases are removed.

10. The method for producing hydrogen by electrolysis according to claim 6, characterized in that, During the start-up and warm-up or shutdown and pressure maintenance process, the electric heating device of the vaporizer (4) or separator (2) is turned on to provide heat to raise the temperature of the electrolysis system as quickly as possible.

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