Seawater electrolysis hydrogen production system and control method thereof

Abstract

The invention relates to a seawater electrolysis hydrogen production system and a control method thereof. The seawater electrolysis hydrogen production system comprises an electrolytic bath (16), an oxygen-liquid separator (1), a hydrogen-liquid separator (6), a seawater heat exchanger (28), a seawater condenser (32), an alkali liquor heat exchanger (12), a hardness-removed low-salt water storage tank (40), a separated salt storage tank (45), an alkali tank (20) and a water tank (18). According to the seawater electrolysis hydrogen production system, waste heat generated in the electrolysis process can be effectively utilized to remove ions easy to deposit in seawater, the concentration of monovalent ions in the seawater is reduced so that the monovalent ions can serve as raw water for water electrolysis hydrogen production, and meanwhile the content of accumulated salt in the hydrogen production system is reduced in the mode that the solvent is evaporated to separate out salt; the method is used for solving the adverse effect of ions in seawater on the performance of a seawater electrolysis hydrogen production system.

Description

Technical Field

[0001] The present invention relates to the technical field of hydrogen production by electrolysis of seawater, and in particular to a system for hydrogen production by electrolysis of water and a control method thereof, and is particularly suitable for a hydrogen production system by electrolysis of water using seawater as an electrolysis raw material. Background Art

[0002] As the global demand for clean energy continues to grow, seawater electrolysis hydrogen production technology, as a sustainable and pollution-free means of energy production, is of great significance for expanding the scope of application of water electrolysis hydrogen production, reducing the water cost of water electrolysis hydrogen production, increasing offshore energy utilization, and achieving the dual carbon goals. However, the complex chemical composition of seawater has brought many challenges to the industrial application of water electrolysis hydrogen production technology.

[0003] Specifically, seawater contains a large amount of easily deposited ions, such as Ca 2 +, Mg2+, etc. During the electrolysis process, these ions are easily deposited on the surface of the electrolytic cell electrode to form non-conductive deposits, which not only reduces the conductivity of the electrode, but also increases the resistance of the electrode, thereby reducing the electrode efficiency and affecting the efficiency and output of hydrogen production by electrolysis.

[0004] At the same time, monovalent ions in seawater, such as Cl-, will gradually accumulate in the hydrogen production system during the electrolysis process. When the ion concentration reaches saturation, salt crystals will precipitate, which may block the pipelines of the hydrogen production system, and in severe cases may even cause equipment shutdown or damage, posing a great hidden danger to the safe operation of the hydrogen production system.

[0005] In view of the problem of the accumulation of monovalent ion concentration on the electrode surface of the seawater easily deposited ions in the hydrogen production system, there is an urgent need for an electrolytic water hydrogen production system and a control method that can remove the easily deposited ions from seawater and reduce the concentration of monovalent ions. In order to solve the above problems, the commonly used method is to filter and remove the ions in seawater through multi-stage reverse osmosis membranes and EDI technology (continuous electrolytic desalination technology) before the seawater enters the electrolytic water hydrogen production system. However, this method requires additional energy to maintain high pressure, and requires frequent replacement of reverse osmosis membrane components, resulting in high energy consumption, frequent maintenance, and a large footprint, which is not conducive to large-scale use in offshore conditions. In addition, the waste heat generated by the electrolyzer during the electrolysis process is often ignored and cannot be effectively recycled, resulting in a waste of energy.

[0006] Therefore, developing a seawater electrolysis hydrogen production system and its control method that can utilize the waste heat generated by the electrolyzer, does not require additional energy to maintain high pressure, requires less maintenance, and occupies a small area is of great significance for improving the economic and environmental benefits of water electrolysis hydrogen production technology and promoting the industrial application of water electrolysis hydrogen production technology.

[0007] In order to solve the above problems, the present invention is proposed. Summary of the invention

[0008] The purpose of the present invention is to address the deficiencies of the prior art and provide a water electrolysis hydrogen production system and control method that can recycle the waste heat of the hydrogen production electrolyzer, does not require additional energy to maintain high pressure, requires less maintenance, occupies less space, removes easily deposited ions in seawater, and reduces the concentration of monovalent ions, so as to solve the adverse effects of ions in seawater on the performance of the seawater electrolysis hydrogen production system. The seawater electrolysis hydrogen production system of the present invention can effectively utilize the waste heat generated during the electrolysis process to remove easily deposited ions in seawater, and reduce the concentration of monovalent ions in seawater so that it can be used as raw water for water electrolysis hydrogen production. At the same time, the accumulated salt content in the hydrogen production system is reduced by evaporating the solvent to precipitate salt, so as to solve the adverse effects of ions in seawater on the performance of the seawater electrolysis hydrogen production system.

[0009] The present invention provides a seawater electrolysis hydrogen production system and a control method thereof, which mainly include: an oxygen liquid separator, a hydrogen gas-liquid separator, an alkali liquid circulation pump, an alkali liquid heat exchanger, an electrolyzer, a water tank, an alkali tank, an alkali replenishing pump, a seawater heat exchanger, a seawater condenser, a vacuum pump, a water pump, a hardness-removing low-salt water storage tank, a salt precipitation storage tank, and an alkali return pump; the alkali replenishing pump replenishes alkali liquid to the hydrogen production system, the electrolyzer manufactures oxygen and hydrogen, and heats the alkali liquid; the seawater heat exchanger uses hot alkali liquid to evaporate seawater to generate steam; the seawater condenser uses cooling water to condense seawater steam to generate hardness-removing low-concentration salt water as an electrolysis raw material; the salt precipitation storage tank heats and evaporates the high-salt concentration alkali liquid in the hydrogen production system, precipitates salt crystals, and reduces the salt content of the hydrogen production system. Through the technical solution provided by the present invention, it is possible to recover the waste heat of seawater electrolysis, reduce the hardness of seawater, and make it usable as an electrolysis raw material; at the same time, the salt content gradually accumulated in the seawater electrolysis hydrogen production system can be removed.

[0010] Specifically, the present invention is implemented through the following technical solutions:

[0011] The first aspect of the present invention provides a system for producing hydrogen by electrolyzing seawater, which comprises: an electrolytic cell 16, an oxygen liquid separator 1, a hydrogen gas-liquid separator 6, a seawater heat exchanger 28, a seawater condenser 32, an alkali liquid heat exchanger 12, a de-hardened low-salt water storage tank 40, a salt precipitation storage tank 45, an alkali tank 20, and a water tank 18;

[0012] The alkali tank 20 is connected to the oxygen liquid separator 1 and the hydrogen liquid separator 6 respectively through a first alkali liquid replenishing pipe 23, and the first alkali liquid replenishing pipe 23 is provided with an alkali replenishing pump 24;

[0013] The electrolytic cell 16 is connected to the hydrogen gas-liquid separator 6 through the hydrogen gas-liquid circulation pipe 5, and the hydrogen gas-liquid separator 6 is provided with a hydrogen discharge pipe 7; the electrolytic cell 16 is connected to the oxygen liquid separator 1 through the oxygen liquid circulation pipe 3, and the oxygen liquid separator 1 is provided with an oxygen discharge pipe 2; the hydrogen gas-liquid separator 6 and the oxygen liquid separator 1 are connected to the seawater heat exchanger 28 through the first alkali liquid circulation pipe 8 and the second alkali liquid circulation pipe 10, and the second alkali liquid circulation pipe 10 is provided with an alkali liquid circulation pump 9;

[0014] The seawater heat exchanger 28 is connected to the seawater condenser 32 through a steam interconnecting pipe 31, the seawater condenser 32 is connected to a first cooling water circulation pipeline 33, and the seawater condenser 32 is connected to the de-hardened low-salt water storage tank 40;

[0015] The seawater heat exchanger 28 is connected to the alkali liquid heat exchanger 12 through the third alkali liquid circulation pipe 11, the alkali liquid heat exchanger 12 is connected to the second cooling water circulation pipeline 52, and the alkali liquid heat exchanger 12 is connected to the electrolytic cell 16 through the fourth alkali liquid circulation pipe 14 and the fifth alkali liquid circulation pipe 15;

[0016] The de-hardened low-salt water storage tank 40 is connected to the water tank 18 via a pumping pipeline 39;

[0017] The salt precipitation storage tank 45 is connected to the fifth alkali solution circulation pipe 15 through the first alkali return pipeline 44, and the salt precipitation storage tank 45 is connected to the alkali tank 20 through the second alkali return pipeline 57. The salt precipitation storage tank 45 is connected to a salt discharge pipe 47, and the salt precipitation storage tank 45 is connected to the vacuum pump 35 through a vacuum pipe 51, and the vacuum pipe 51 has a twelfth ball valve 50.

[0018] Preferably, the first alkali solution replenishing pipe 23 is provided with a third ball valve 21 and an alkali solution replenishing pipe ball valve 25 , and the fifth alkali solution circulation pipe 15 is provided with a fourth ball valve 22 .

[0019] Preferably, the seawater heat exchanger 28 is connected to a seawater replenishment pipe 26 and a concentrated seawater discharge pipe 30 , the seawater replenishment pipe 26 is provided with a fifth ball valve 27 , and the concentrated seawater discharge pipe 30 is provided with a fourteenth ball valve 29 .

[0020] Preferably, the de-hardened low-salt water storage tank 40 is provided with a first liquid level gauge 41 .

[0021] Preferably, the water pumping pipeline 39 is provided with a second ball valve 19 , an eighth ball valve 37 and a water pump 38 .

[0022] Preferably, the salt discharge pipe 47 is provided with a tenth ball valve 46;

[0023] The first alkali return pipeline 44 is provided with the fifteenth ball valve 43, and the second alkali return pipeline 57 is provided with the thirteenth ball valve 55 and the alkali return pump 56;

[0024] The salt precipitation storage tank 45 is provided with a second liquid level gauge 48 .

[0025] Preferably, the seawater condenser 32 is connected to the vacuum pump 35 with a sixth ball valve 34 therebetween, and the air pressure in the seawater heat exchanger 28 and the seawater condenser 32 is reduced through the sixth ball valve 34 and the vacuum pump 35, thereby reducing the boiling point of seawater, so that the seawater can evaporate and condense at a lower temperature.

[0026] Preferably, the water tank 18 is connected to the first alkali solution replenishing pipe 23 through the first ball valve 17. When the liquid level in the oxygen liquid separator 1 and the hydrogen gas-liquid separator 6 drops, the first ball valve 17, the alkali replenishing pump 24 and the alkali solution replenishing pipe ball valve 25 are opened to replenish the water stored in the water tank 18 into the seawater electrolysis hydrogen production system.

[0027] The seawater electrolysis hydrogen production system further comprises:

[0028] A nitrogen filling pipe 4, which is connected to an external nitrogen source and the oxygen liquid separator 1 and the hydrogen liquid separator 6, and is a pipeline for the outside world to supplement nitrogen to the hydrogen production system;

[0029] A ninth ball valve 42, the ninth ball valve 42 is connected to the seawater condenser 32 and the de-hardened low-salt water storage tank 40;

[0030] The seventh ball valve 36 is connected to the outside air and the de-hardening low-salt water storage tank 40. When the water in the de-hardening low-salt water storage tank 40 needs to be discharged to the water tank 18 for storage, the ninth ball valve 42 needs to be closed first, and the seventh ball valve 36 needs to be opened to allow the de-hardening low-salt water storage tank 40 to reach normal pressure;

[0031] A fifteenth ball valve 43, the fifteenth ball valve 43 is located in the first alkali return pipeline 44, and is used to control the connection and disconnection between the salt precipitation storage tank 45 and the fifth alkali liquid circulation pipe 15 in the hydrogen production system;

[0032] The eleventh ball valve 49 connects the external air and the salt storage tank 45. When the alkali solution in the salt storage tank 45 needs to be returned to the alkali tank 20, the twelfth ball valve 50 needs to be closed to disconnect the salt storage tank 45 from the vacuum environment, and then the eleventh ball valve 49 is opened to connect the external air, so that the salt storage tank 45 reaches normal pressure;

[0033] A second cooling water circulation pipeline 52, wherein the second cooling water circulation pipeline 52 is connected to an external cooling water source and the alkali liquid heat exchanger 12;

[0034] A pneumatic regulating valve 53, wherein the pneumatic regulating valve 53 is located on the second cooling water circulation pipeline 52;

[0035] A temperature transmitter 54, wherein the temperature transmitter 54 is located in the fourth alkali solution circulation pipe 14;

[0036] Interlock 13, the interlock 13 connects the pneumatic control valve 53 and the temperature transmitter 54. When the temperature in the temperature transmitter 54 exceeds the set value, the interlock 13 controls the pneumatic control valve 53 to increase the flow rate of cooling water in the second cooling water circulation pipeline 52, thereby achieving the effect of increasing the heat exchange capacity and reducing the alkali solution temperature of the hydrogen production system.

[0037] The second aspect of the present invention provides a control method for the seawater electrolysis hydrogen production system according to the first aspect of the present invention, comprising:

[0038] The alkali liquid in the alkali tank 20 is pumped into the oxygen liquid separator 1 and the hydrogen liquid separator 6 through the first alkali liquid replenishing pipe 23 by the alkali replenishing pump 24 until the target liquid level is reached.

[0039] The alkali liquid circulation pump 9 is turned on, and the electrolytic cell 16 is powered on to start electrolysis. The high-temperature mixed fluid of hydrogen and alkali liquid generated by electrolysis of water in the electrolytic cell 16 enters the hydrogen gas-liquid separator 6 through the hydrogen gas-liquid circulation pipe 5 for gas-liquid separation. The separated hydrogen is discharged through the hydrogen discharge pipe 7. The separated high-temperature alkali liquid enters the alkali liquid circulation pump 9 through the first alkali liquid circulation pipe 8 to enter the next alkali liquid circulation;

[0040] The high-temperature mixed fluid of oxygen and alkali liquid generated by electrolysis of water in the electrolytic cell 16 enters the oxygen-liquid separator 1 through the oxygen-liquid circulation pipe 3 for gas-liquid separation, the separated oxygen is discharged through the oxygen discharge pipe 2, and the separated high-temperature alkali liquid enters the alkali liquid circulation pump 9 through the first alkali liquid circulation pipe 8 to enter the next alkali liquid circulation;

[0041] The high-temperature alkali solution passes through the second alkali solution circulation pipe 10 and enters the seawater heat exchanger 28 to heat and evaporate the seawater. The generated seawater vapor passes through the steam interconnection pipe 31 and enters the seawater condenser 32 to exchange heat with the cooling water in the first cooling water circulation pipeline 33 to generate condensed water. At this time, the condensed water has a lower concentration of easily deposited ions and monovalent ions than the original seawater, and serves as the electrolysis raw water of the electrolysis seawater hydrogen production system.

[0042] The condensed water flows into the de-hardening low-salt water storage tank 40 for standby use by way of natural overflow;

[0043] After heat exchange in the seawater heat exchanger 28, the high-temperature alkali liquid enters the alkali liquid heat exchanger 12 through the third alkali liquid circulation pipe 11 to exchange heat and cool with the cooling water in the second cooling water circulation pipeline 52, and then returns to the electrolytic cell 16 through the fourth alkali liquid circulation pipe 14 and the fifth alkali liquid circulation pipe 15 to carry out a new round of water electrolysis hydrogen production process.

[0044] Preferably, before the seawater heat exchanger 28 and the seawater condenser 32 work, it is necessary to close the twelfth ball valve 50, the eighth ball valve 37, the seventh ball valve 36, the fourteenth ball valve 29, and the fifth ball valve 27, and open the sixth ball valve 34 and the vacuum pump 35 to reduce the air pressure in the seawater heat exchanger 28 and the seawater condenser 32, thereby reducing the boiling point of seawater and allowing seawater to evaporate and condense at a lower temperature.

[0045] Preferably, the fifth ball valve 27 is opened, and raw seawater is replenished to the seawater heat exchanger 28 through the seawater replenishment pipe 26. After the seawater replenishment is completed, the fifth ball valve 27 is closed to maintain the vacuum state in the seawater heat exchanger 28. When the raw seawater stored in the seawater heat exchanger 28 is consumed to the target liquid level, the fourteenth ball valve 29 is opened, and the concentrated seawater after evaporation is discharged through the concentrated seawater drain pipe 30, and then the fourteenth ball valve 29 is closed to maintain the vacuum state in the seawater heat exchanger 28.

[0046] Preferably, the water reserve in the de-hardening low-salt water storage tank 40 is observed by the first liquid level gauge 41. When the de-hardening low-salt water storage tank 40 is full, the ninth ball valve 42 is closed to isolate the de-hardening low-salt water storage tank 40 from the vacuum environment in the seawater heat exchanger 28 and the seawater condenser 32, and then the seventh ball valve 36 is opened to restore the de-hardening low-salt water storage tank 40 to normal pressure, and then the eighth ball valve 37, the pump 38 and the second ball valve 19 are opened to pump the water in the de-hardening low-salt water storage tank 40 through the pumping pipeline 39 into the water tank 18 as electrolysis raw water for the electrolysis seawater hydrogen production system.

[0047] Preferably, as the electrolyzer 16 consumes water in the hydrogen production system by electrolysis of seawater, when the liquid levels in the oxygen-liquid separator 1 and the hydrogen-gas-liquid separator 6 decrease, the first ball valve 17, the alkali replenishing pump 24, and the alkali solution replenishing pipe ball valve 25 are opened to replenish the water stored in the water tank 18 into the hydrogen production system by electrolysis of seawater. After the replenishment is completed, the first ball valve 17, the alkali replenishing pump 24, and the alkali solution replenishing pipe ball valve 25 are closed.

[0048] Preferably, the salt storage tank 45 has a heating function, the fourth ball valve 22 and the fifteenth ball valve 43 are normally closed valves, and when the accumulated salt concentration in the electrolysis seawater hydrogen production system is close to saturation, the fifteenth ball valve 43 is opened to allow the high salt concentration alkali solution to enter the salt storage tank 45, and then the fifteenth ball valve 43 is closed; the eleventh ball valve 49 and the tenth ball valve 46 are closed, the twelfth ball valve 50 and the vacuum pump 35 are opened to put the salt storage tank 45 in a vacuum state, and the heating of the salt storage tank 45 is started. The thermal function evaporates and precipitates salt from the alkali solution with high salt concentration. After the second liquid level gauge 48 observes that the liquid level in the salt precipitation storage tank 45 drops to the target liquid level, the twelfth ball valve 50 and the vacuum pump 35 are closed, and the eleventh ball valve 49 is opened to restore the salt precipitation storage tank 45 to normal pressure. Then, the tenth ball valve 46 is opened to discharge salt crystals through the salt discharge pipe 47. At the same time, the thirteenth ball valve 55 and the alkali return pump 56 are opened to pump the remaining alkali solution into the alkali tank 20 through the second alkali return pipeline 57 for standby use.

[0049] Compared with the prior art, the present invention has the following beneficial effects:

[0050] 1. The present invention uses vacuum to reduce the boiling point of seawater, uses the seawater heat exchanger 28 to evaporate seawater to generate steam, and uses the seawater condenser 32 to generate seawater condensed water to remove hardness and reduce salt in the original seawater, which is used as electrolytic raw water for the electrolytic water hydrogen production system. The waste heat generated by the electrolytic cell during the electrolysis process reduces the easily deposited ions in the electrolytic raw water.

[0051] 2. The present invention uses vacuum to reduce the boiling point of high-salt concentration alkali solution, and uses the salt precipitation storage tank 45 to evaporate the high-salt concentration alkali solution for salt precipitation, thereby avoiding the problem that these salt crystals block the pipeline of the hydrogen production system, which may even cause equipment shutdown or damage in severe cases. BRIEF DESCRIPTION OF THE DRAWINGS

[0052] Figure 1 The process flow chart of the hydrogen production system by electrolyzing seawater of the present invention is shown in FIG.

[0053] Names of the accompanying drawings in the accompanying drawings: 1. oxygen liquid separator, 2. oxygen discharge pipe, 3. oxygen liquid circulation pipe, 4. nitrogen filling pipe, 5. hydrogen liquid circulation pipe, 6. hydrogen liquid separator, 7. hydrogen discharge pipe, 8. first alkali liquid circulation pipe, 9. alkali liquid circulation pump, 10. second alkali liquid circulation pipe, 11. third alkali liquid circulation pipe, 12. alkali liquid heat exchanger, 13. interlock, 14. fourth alkali liquid circulation pipe, 15. fifth alkali liquid circulation pipe, 16. electrolytic cell, 17. first ball valve, 18. water tank, 19. second ball valve, 20. alkali tank, 21. third ball valve, 22. fourth ball valve, 23. first alkali liquid replenishing pipe, 24. alkali replenishing pump, 25. second alkali liquid replenishing pipe, 26. seawater replenishing pipe, 27. fifth ball valve, 28. seawater heat exchanger, 2 9. The fourteenth ball valve, 30. The concentrated seawater drain pipe, 31. The steam interconnecting pipe, 32. The seawater condenser, 33. The first cooling water circulation pipeline, 34. The sixth ball valve, 35. The vacuum pump, 36. The seventh ball valve, 37. The eighth ball valve, 38. The water pump, 39. The water pumping pipeline, 40. The hard low brine storage tank, 41. The first liquid level gauge, 42. The ninth ball valve, 43. The fifteenth ball valve, 44. The first alkali return pipeline, 45. The salt separation tank, 46. The tenth ball valve, 47. The salt discharge pipe, 48. The second liquid level gauge, 49. The eleventh ball valve, 50. The twelfth ball valve, 51. The vacuum tube, 52. The second cooling water circulation pipeline, 53. The pneumatic regulating valve, 54. The temperature transmitter, 55. The thirteenth ball valve, 56. The alkali return pump, 57. The second alkali return pipeline. DETAILED DESCRIPTION

[0054] The present invention is further described in detail below in conjunction with embodiments.

[0055] Those skilled in the art will appreciate that the following examples are only used to illustrate the present invention and should not be considered to limit the scope of the present invention. If no specific techniques or conditions are specified in the examples, the techniques or conditions described in the literature in the art or the product specifications are used. If the manufacturer of the materials or equipment used is not specified, they are all conventional products that can be purchased.

[0056] Those skilled in the art will appreciate that, unless expressly stated otherwise, the singular forms "a", "an", "said" and "the" used herein may also include plural forms. It should be further understood that the term "comprising" used in the specification of the present invention refers to the presence of the 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 refer to an element as being "connected" to another element, it may be directly connected to the other element, or there may be intermediate elements. In addition, the "connection" used herein may include wireless connections.

[0057] In the description of the present invention, unless otherwise specified, "plurality" means two or more than two. The terms "inside", "upper", "lower", etc., indicating positions or state relationships, are based on the positions or state relationships shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific position, be constructed and operate in a specific position, and therefore cannot be understood as limiting the present invention.

[0058] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "provided with" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium. For ordinary technicians in this field, the specific meanings of the above terms in the present invention will be understood according to 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 those generally understood by those skilled in the art in the art to which the present invention belongs. It should also be understood that terms such as those defined in common dictionaries should be understood to have meanings consistent with the meanings in the context of the prior art, and will not be interpreted with idealized or overly formal meanings unless defined as herein.

[0060] Example

[0061] like Figure 1 As shown, the electrolytic seawater hydrogen production system of this embodiment includes: an electrolytic cell 16, an oxygen liquid separator 1, a hydrogen gas-liquid separator 6, a seawater heat exchanger 28, a seawater condenser 32, an alkali liquid heat exchanger 12, a de-hardening low-salt water storage tank 40, a salt precipitation storage tank 45, an alkali tank 20, and a water tank 18;

[0062] The alkali tank 20 is connected to the oxygen liquid separator 1 and the hydrogen liquid separator 6 respectively through a first alkali liquid replenishing pipe 23, and the first alkali liquid replenishing pipe 23 is provided with an alkali replenishing pump 24;

[0063] The electrolytic cell 16 is connected to the hydrogen gas-liquid separator 6 through the hydrogen gas-liquid circulation pipe 5, and the hydrogen gas-liquid separator 6 is provided with a hydrogen discharge pipe 7; the electrolytic cell 16 is connected to the oxygen liquid separator 1 through the oxygen liquid circulation pipe 3, and the oxygen liquid separator 1 is provided with an oxygen discharge pipe 2; the hydrogen gas-liquid separator 6 and the oxygen liquid separator 1 are connected to the seawater heat exchanger 28 through the first alkali liquid circulation pipe 8 and the second alkali liquid circulation pipe 10, and the second alkali liquid circulation pipe 10 is provided with an alkali liquid circulation pump 9;

[0064] The seawater heat exchanger 28 is connected to the seawater condenser 32 through a steam interconnecting pipe 31, the seawater condenser 32 is connected to a first cooling water circulation pipeline 33, and the seawater condenser 32 is connected to the de-hardened low-salt water storage tank 40;

[0065] The seawater heat exchanger 28 is connected to the alkali liquid heat exchanger 12 through the third alkali liquid circulation pipe 11, the alkali liquid heat exchanger 12 is connected to the second cooling water circulation pipeline 52, and the alkali liquid heat exchanger 12 is connected to the electrolytic cell 16 through the fourth alkali liquid circulation pipe 14 and the fifth alkali liquid circulation pipe 15;

[0066] The de-hardened low-salt water storage tank 40 is connected to the water tank 18 via a pumping pipeline 39;

[0067] The salt precipitation storage tank 45 is connected to the fifth alkali solution circulation pipe 15 through the first alkali return pipeline 44, and the salt precipitation storage tank 45 is connected to the alkali tank 20 through the second alkali return pipeline 57. The salt precipitation storage tank 45 is connected to a salt discharge pipe 47, and the salt precipitation storage tank 45 is connected to the vacuum pump 35 through a vacuum pipe 51, and the vacuum pipe 51 has a twelfth ball valve 50.

[0068] The first alkali solution replenishing pipe 23 is provided with a third ball valve 21 and an alkali solution replenishing pipe ball valve 25 , and the fifth alkali solution circulating pipe 15 is provided with a fourth ball valve 22 .

[0069] The seawater heat exchanger 28 is connected to a seawater replenishment pipe 26 and a concentrated seawater discharge pipe 30 . The seawater replenishment pipe 26 is provided with a fifth ball valve 27 , and the concentrated seawater discharge pipe 30 is provided with a fourteenth ball valve 29 .

[0070] The de-hardened low-salt water storage tank 40 is provided with a first liquid level gauge 41 .

[0071] The water pumping pipeline 39 is provided with a second ball valve 19 , an eighth ball valve 37 and a water pump 38 .

[0072] The salt discharge pipe 47 is provided with a tenth ball valve 46;

[0073] The first alkali return pipeline 44 is provided with the fifteenth ball valve 43, and the second alkali return pipeline 57 is provided with the thirteenth ball valve 55 and the alkali return pump 56;

[0074] The salt precipitation storage tank 45 is provided with a second liquid level gauge 48 .

[0075] The seawater condenser 32 is connected to the vacuum pump 35, with a sixth ball valve 34 therebetween. The sixth ball valve 34 and the vacuum pump 35 are used to reduce the air pressure in the seawater heat exchanger 28 and the seawater condenser 32, thereby reducing the boiling point of seawater, so that the seawater can evaporate and condense at a lower temperature.

[0076] The water tank 18 is connected to the first alkali solution replenishing pipe 23 through the first ball valve 17. When the liquid levels in the oxygen liquid separator 1 and the hydrogen gas-liquid separator 6 decrease, the first ball valve 17, the alkali replenishing pump 24 and the alkali solution replenishing pipe ball valve 25 are opened to replenish the water stored in the water tank 18 to the seawater electrolysis hydrogen production system.

[0077] The seawater electrolysis hydrogen production system further comprises:

[0078] A nitrogen filling pipe 4, which is connected to an external nitrogen source and the oxygen liquid separator 1 and the hydrogen liquid separator 6, and is a pipeline for the outside world to supplement nitrogen to the hydrogen production system;

[0079] A ninth ball valve 42, the ninth ball valve 42 is connected to the seawater condenser 32 and the de-hardened low-salt water storage tank 40;

[0080] The seventh ball valve 36 is connected to the outside air and the de-hardening low-salt water storage tank 40. When the water in the de-hardening low-salt water storage tank 40 needs to be discharged to the water tank 18 for storage, the ninth ball valve 42 needs to be closed first, and the seventh ball valve 36 needs to be opened to allow the de-hardening low-salt water storage tank 40 to reach normal pressure;

[0081] A fifteenth ball valve 43, the fifteenth ball valve 43 is located in the first alkali return pipeline 44, and is used to control the connection and disconnection between the salt precipitation storage tank 45 and the fifth alkali liquid circulation pipe 15 in the hydrogen production system;

[0082] The eleventh ball valve 49 connects the external air and the salt storage tank 45. When the alkali solution in the salt storage tank 45 needs to be returned to the alkali tank 20, the twelfth ball valve 50 needs to be closed to disconnect the salt storage tank 45 from the vacuum environment, and then the eleventh ball valve 49 is opened to connect the external air, so that the salt storage tank 45 reaches normal pressure;

[0083] A second cooling water circulation pipeline 52, wherein the second cooling water circulation pipeline 52 is connected to an external cooling water source and the alkali liquid heat exchanger 12;

[0084] A pneumatic regulating valve 53, wherein the pneumatic regulating valve 53 is located on the second cooling water circulation pipeline 52;

[0085] A temperature transmitter 54, wherein the temperature transmitter 54 is located in the fourth alkali solution circulation pipe 14;

[0086] Interlock 13, the interlock 13 connects the pneumatic control valve 53 and the temperature transmitter 54. When the temperature in the temperature transmitter 54 exceeds the set value, the interlock 13 controls the pneumatic control valve 53 to increase the flow rate of cooling water in the second cooling water circulation pipeline 52, thereby achieving the effect of increasing the heat exchange capacity and reducing the alkali solution temperature of the hydrogen production system.

[0087] The control method of the seawater electrolysis hydrogen production system comprises:

[0088] The alkali liquid in the alkali tank 20 is pumped into the oxygen liquid separator 1 and the hydrogen liquid separator 6 through the first alkali liquid replenishing pipe 23 by the alkali replenishing pump 24 until the target liquid level is reached.

[0089] The alkali liquid circulation pump 9 is turned on, and the electrolytic cell 16 is powered on to start electrolysis. The high-temperature mixed fluid of hydrogen and alkali liquid generated by electrolysis of water in the electrolytic cell 16 enters the hydrogen gas-liquid separator 6 through the hydrogen gas-liquid circulation pipe 5 for gas-liquid separation. The separated hydrogen is discharged through the hydrogen discharge pipe 7. The separated high-temperature alkali liquid enters the alkali liquid circulation pump 9 through the first alkali liquid circulation pipe 8 to enter the next alkali liquid circulation;

[0090] The high-temperature mixed fluid of oxygen and alkali liquid generated by electrolysis of water in the electrolytic cell 16 enters the oxygen-liquid separator 1 through the oxygen-liquid circulation pipe 3 for gas-liquid separation, the separated oxygen is discharged through the oxygen discharge pipe 2, and the separated high-temperature alkali liquid enters the alkali liquid circulation pump 9 through the first alkali liquid circulation pipe 8 to enter the next alkali liquid circulation;

[0091] The high-temperature alkali solution passes through the second alkali solution circulation pipe 10 and enters the seawater heat exchanger 28 to heat and evaporate the seawater. The generated seawater vapor passes through the steam interconnection pipe 31 and enters the seawater condenser 32 to exchange heat with the cooling water in the first cooling water circulation pipeline 33 to generate condensed water. At this time, the condensed water has a lower concentration of easily deposited ions and monovalent ions than the original seawater, and serves as the electrolysis raw water of the electrolysis seawater hydrogen production system.

[0092] The condensed water flows into the de-hardening low-salt water storage tank 40 for standby use by way of natural overflow;

[0093] After heat exchange in the seawater heat exchanger 28, the high-temperature alkali liquid enters the alkali liquid heat exchanger 12 through the third alkali liquid circulation pipe 11 to exchange heat and cool with the cooling water in the second cooling water circulation pipeline 52, and then returns to the electrolytic cell 16 through the fourth alkali liquid circulation pipe 14 and the fifth alkali liquid circulation pipe 15 to carry out a new round of water electrolysis hydrogen production process.

[0094] Before the seawater heat exchanger 28 and the seawater condenser 32 are operated, it is necessary to close the twelfth ball valve 50, the eighth ball valve 37, the seventh ball valve 36, the fourteenth ball valve 29, and the fifth ball valve 27, and open the sixth ball valve 34 and the vacuum pump 35 to reduce the air pressure in the seawater heat exchanger 28 and the seawater condenser 32, thereby reducing the boiling point of seawater and allowing the seawater to evaporate and condense at a lower temperature.

[0095] The fifth ball valve 27 is opened, and raw seawater is replenished to the seawater heat exchanger 28 through the seawater replenishment pipe 26. After the seawater replenishment is completed, the fifth ball valve 27 is closed to maintain the vacuum state in the seawater heat exchanger 28. When the raw seawater stored in the seawater heat exchanger 28 is consumed to the target liquid level, the fourteenth ball valve 29 is opened, and the concentrated seawater after evaporation is discharged through the concentrated seawater drain pipe 30, and then the fourteenth ball valve 29 is closed to maintain the vacuum state in the seawater heat exchanger 28.

[0096] The water reserve in the de-hardening low-salt water storage tank 40 is observed by the first liquid level gauge 41. When the de-hardening low-salt water storage tank 40 is full, the ninth ball valve 42 is closed to isolate the de-hardening low-salt water storage tank 40 from the vacuum environment in the seawater heat exchanger 28 and the seawater condenser 32, and then the seventh ball valve 36 is opened to restore the de-hardening low-salt water storage tank 40 to normal pressure, and then the eighth ball valve 37, the pump 38 and the second ball valve 19 are opened to pump the water in the de-hardening low-salt water storage tank 40 into the water tank 18 through the pumping pipeline 39 as electrolysis raw water for the electrolysis seawater hydrogen production system.

[0097] As the electrolyzer 16 consumes water in the hydrogen production system by electrolysis of seawater, when the liquid levels in the oxygen-liquid separator 1 and the hydrogen-gas-liquid separator 6 decrease, the first ball valve 17, the alkali replenishing pump 24, and the alkali liquid replenishing pipe ball valve 25 are opened to replenish the water stored in the water tank 18 into the hydrogen production system by electrolysis of seawater. After the replenishment is completed, the first ball valve 17, the alkali replenishing pump 24, and the alkali liquid replenishing pipe ball valve 25 are closed.

[0098] The salt storage tank 45 has a heating function. The fourth ball valve 22 and the fifteenth ball valve 43 are normally closed valves. When the accumulated salt concentration in the electrolysis seawater hydrogen production system is close to saturation, the fifteenth ball valve 43 is opened to allow the high salt concentration alkali solution to enter the salt storage tank 45, and then the fifteenth ball valve 43 is closed; the eleventh ball valve 49 and the tenth ball valve 46 are closed, and the twelfth ball valve 50 and the vacuum pump 35 are opened to put the salt storage tank 45 in a vacuum state, and the heating function of the salt storage tank 45 is started. The high-salt concentration alkali solution can be evaporated and salt is precipitated. After the second liquid level meter 48 observes that the liquid level in the salt precipitation storage tank 45 drops to the target liquid level, the twelfth ball valve 50 and the vacuum pump 35 are closed, and the eleventh ball valve 49 is opened to restore the salt precipitation storage tank 45 to normal pressure, and then the tenth ball valve 46 is opened to discharge salt crystals through the salt discharge pipe 47. At the same time, the thirteenth ball valve 55 and the alkali return pump 56 are opened to pump the remaining alkali solution into the alkali tank 20 through the second alkali return pipeline 57 for standby use.

Claims

1. A system for producing hydrogen by electrolysis of seawater, characterized in that: It includes: Electrolyzer (16), oxygen liquid separator (1), hydrogen gas liquid separator (6), seawater heat exchanger (28), seawater condenser (32), alkali liquid heat exchanger (12), de-hardening low-salt water storage tank (40), salt precipitation storage tank (45), alkali tank (20), water tank (18); The alkali tank (20) is connected to the oxygen liquid separator (1) and the hydrogen liquid separator (6) respectively through a first alkali liquid replenishing pipe (23), and the first alkali liquid replenishing pipe (23) is provided with an alkali replenishing pump (24); The electrolytic cell (16) is connected to the hydrogen gas-liquid separator (6) via a hydrogen gas-liquid circulation pipe (5), and the hydrogen gas-liquid separator (6) is provided with a hydrogen discharge pipe (7); the electrolytic cell (16) is connected to the oxygen liquid separator (1) via an oxygen liquid circulation pipe (3), and the oxygen liquid separator (1) is provided with an oxygen discharge pipe (2); the hydrogen gas-liquid separator (6) and the oxygen liquid separator (1) are connected to the seawater heat exchanger (28) via a first alkali liquid circulation pipe (8) and a second alkali liquid circulation pipe (10), and the second alkali liquid circulation pipe (10) is provided with an alkali liquid circulation pump (9); The seawater heat exchanger (28) is in communication with the seawater condenser (32) via a steam interconnecting pipe (31); the seawater condenser (32) is connected to a first cooling water circulation pipeline (33); and the seawater condenser (32) is in communication with the de-hardened low-salt water storage tank (40); The seawater heat exchanger (28) is connected to the alkali liquid heat exchanger (12) via a third alkali liquid circulation pipe (11), the alkali liquid heat exchanger (12) is connected to the second cooling water circulation pipeline (52), and the alkali liquid heat exchanger (12) is connected to the electrolytic cell (16) via a fourth alkali liquid circulation pipe (14) and a fifth alkali liquid circulation pipe (15); The de-hardened low-salt water storage tank (40) is connected to the water tank (18) via a pumping pipeline (39); The salt precipitation storage tank (45) is connected to the fifth alkali solution circulation pipe (15) via a first alkali return pipeline (44), the salt precipitation storage tank (45) is connected to the alkali tank (20) via a second alkali return pipeline (57), the salt precipitation storage tank (45) is connected to a salt discharge pipe (47), the salt precipitation storage tank (45) is connected to a vacuum pump (35) via a vacuum pipe (51), and the vacuum pipe (51) is provided with a twelfth ball valve (50).

2. The system for producing hydrogen by electrolysis of seawater according to claim 1, characterized in that: The first alkali solution replenishing pipe (23) is provided with a third ball valve (21) and an alkali solution replenishing pipe ball valve (25), and the fifth alkali solution circulation pipe (15) is provided with a fourth ball valve (22). The seawater heat exchanger (28) is connected to a seawater replenishment pipe (26) and a concentrated seawater discharge pipe (30), the seawater replenishment pipe (26) is provided with a fifth ball valve (27), and the concentrated seawater discharge pipe (30) is provided with a fourteenth ball valve (29); The de-hardened low-salt water storage tank (40) is provided with a first liquid level gauge (41); The water pumping pipeline (39) is provided with a second ball valve (19), an eighth ball valve (37) and a water pump (38); The salt discharge pipe (47) is provided with a tenth ball valve (46); The first alkali return pipeline (44) is provided with the fifteenth ball valve (43), and the second alkali return pipeline (57) is provided with a thirteenth ball valve (55) and an alkali return pump (56); The salt precipitation storage tank (45) is provided with a second liquid level gauge (48).

3. The system for producing hydrogen by electrolysis of seawater according to claim 1, characterized in that: The seawater condenser (32) is connected to the vacuum pump (35), with a sixth ball valve (34) therebetween. The sixth ball valve (34) and the vacuum pump (35) are used to reduce the air pressure in the seawater heat exchanger (28) and the seawater condenser (32), thereby reducing the boiling point of the seawater, so that the seawater can evaporate and condense at a lower temperature.

4. The system for producing hydrogen by electrolysis of seawater according to claim 1, characterized in that: The water tank (18) is connected to the first alkali solution replenishment pipe (23) through a first ball valve (17). When the liquid level in the oxygen liquid separator (1) and the hydrogen liquid separator (6) decreases, the first ball valve (17), the alkali replenishment pump (24) and the alkali solution replenishment pipe ball valve (25) are opened to replenish the water stored in the water tank (18) into the seawater electrolysis hydrogen production system.

5. The system for producing hydrogen by electrolysis of seawater according to claim 1, characterized in that: The seawater electrolysis hydrogen production system further comprises: A nitrogen filling pipe (4), the nitrogen filling pipe (4) is connected to an external nitrogen source and the oxygen liquid separator (1) and the hydrogen liquid separator (6), and is a pipeline for the outside world to supplement nitrogen to the hydrogen production system; a ninth ball valve (42), the ninth ball valve (42) being connected to the seawater condenser (32) and the de-hardened low-salt water storage tank (40); a seventh ball valve (36), wherein the seventh ball valve (36) is connected to the outside air and the de-hardening low-salt water storage tank (40); when the water in the de-hardening low-salt water storage tank (40) needs to be discharged into the water tank (18) for storage, the ninth ball valve (42) needs to be closed first, and the seventh ball valve (36) needs to be opened, so that the de-hardening low-salt water storage tank (40) reaches normal pressure; A fifteenth ball valve (43), the fifteenth ball valve (43) is located in the first alkali return pipeline (44), and is used to control the connection and disconnection between the salt precipitation storage tank (45) and the fifth alkali liquid circulation pipe (15) in the hydrogen production system; an eleventh ball valve (49), the eleventh ball valve (49) connecting the external air and the salt precipitation storage tank (45), and when the alkali solution in the salt precipitation storage tank (45) needs to be returned to the alkali tank (20), the twelfth ball valve (50) needs to be closed to disconnect the salt precipitation storage tank (45) from the vacuum environment, and then the eleventh ball valve (49) is opened to connect the external air, so that the salt precipitation storage tank (45) reaches normal pressure; A second cooling water circulation pipeline (52), wherein the second cooling water circulation pipeline (52) is connected to an external cooling water source and the alkali liquid heat exchanger (12); a pneumatic regulating valve (53), the pneumatic regulating valve (53) being located on the second cooling water circulation pipeline (52); A temperature transmitter (54), wherein the temperature transmitter (54) is located in the fourth alkali solution circulation pipe (14); An interlock (13) is provided, wherein the interlock (13) is connected to the pneumatic control valve (53) and the temperature transmitter (54). When the temperature in the temperature transmitter (54) exceeds a set value, the interlock (13) controls the pneumatic control valve (53) to increase the flow rate of cooling water in the second cooling water circulation pipeline (52), thereby achieving the effect of increasing the heat exchange amount and reducing the temperature of the alkali solution in the hydrogen production system.

6. A control method for a hydrogen production system by electrolysis of seawater according to any one of claims 1 to 5, characterized in that: It includes: The alkali liquid in the alkali tank (20) is pumped into the oxygen liquid separator (1) and the hydrogen liquid separator (6) through the first alkali liquid replenishing pipe (23) by the alkali replenishing pump (24) until the target liquid level is reached. The alkali liquid circulation pump (9) is turned on, and the electrolytic cell (16) is powered on to start electrolysis. The high-temperature mixed fluid of hydrogen and alkali liquid generated by the electrolysis of water in the electrolytic cell (16) enters the hydrogen gas-liquid separator (6) through the hydrogen gas-liquid circulation pipe (5) for gas-liquid separation. The separated hydrogen is discharged through the hydrogen discharge pipe (7). The separated high-temperature alkali liquid enters the alkali liquid circulation pump (9) through the first alkali liquid circulation pipe (8) to enter the next alkali liquid circulation. The high-temperature mixed fluid of oxygen and alkali liquid generated by the electrolysis of water in the electrolytic cell (16) enters the oxygen-liquid separator (1) through the oxygen-liquid circulation pipe (3) for gas-liquid separation, the separated oxygen is discharged through the oxygen discharge pipe (2), and the separated high-temperature alkali liquid enters the alkali liquid circulation pump (9) through the first alkali liquid circulation pipe (8) to enter the next alkali liquid circulation; The high-temperature alkali solution passes through the second alkali solution circulation pipe (10) and enters the seawater heat exchanger (28) to heat and evaporate the seawater. The generated seawater vapor passes through the steam interconnection pipe (31) and enters the seawater condenser (32) to exchange heat with the cooling water in the first cooling water circulation pipeline (33) to generate condensed water. At this time, the condensed water has a lower concentration of easily deposited ions and monovalent ions than the original seawater, and is used as the electrolysis raw water of the seawater electrolysis hydrogen production system. The condensed water flows into the de-hardening low-salt water storage tank (40) by way of natural overflow for standby use; After the high-temperature alkali liquid has been heat exchanged in the seawater heat exchanger (28), it enters the alkali liquid heat exchanger (12) through the third alkali liquid circulation pipe (11) to exchange heat with the cooling water in the second cooling water circulation pipe (52), and then returns to the electrolytic cell (16) through the fourth alkali liquid circulation pipe (14) and the fifth alkali liquid circulation pipe (15) to carry out a new round of water electrolysis hydrogen production process.

7. The control method according to claim 6 is characterized in that, before the seawater heat exchanger (28) and the seawater condenser (32) are operated, the twelfth ball valve (50), the eighth ball valve (37), the seventh ball valve (36), the fourteenth ball valve (29), and the fifth ball valve (27) are closed, and the sixth ball valve (34) and the vacuum pump (35) are opened to reduce the air pressure in the seawater heat exchanger (28) and the seawater condenser (32), thereby reducing the boiling point of seawater, so that seawater can evaporate and condense at a lower temperature; The fifth ball valve (27) is opened, and raw seawater is replenished into the seawater heat exchanger (28) through the seawater replenishment pipe (26). After the seawater replenishment is completed, the fifth ball valve (27) is closed to maintain the vacuum state in the seawater heat exchanger (28); when the raw seawater stored in the seawater heat exchanger (28) is consumed to the target liquid level, the fourteenth ball valve (29) is opened, and concentrated seawater after evaporation is discharged through the concentrated seawater drainage pipe (30), and then the fourteenth ball valve (29) is closed to maintain the vacuum state in the seawater heat exchanger (28).

8. The control method according to claim 6 is characterized in that the water reserve in the de-hardening low-salt water storage tank (40) is observed by the first liquid level gauge (41). When the de-hardening low-salt water storage tank (40) is full, the ninth ball valve (42) is closed to isolate the de-hardening low-salt water storage tank (40) from the vacuum environment in the seawater heat exchanger (28) and the seawater condenser (32), and then the seventh ball valve (36) is opened to restore the de-hardening low-salt water storage tank (40) to normal pressure, and then the eighth ball valve (37) and the pump (38) and the second ball valve (19) are opened to pump the water in the de-hardening low-salt water storage tank (40) through the pumping pipeline (39) into the water tank (18) as electrolysis raw water for the electrolysis seawater hydrogen production system.

9. The control method according to claim 6 is characterized in that, as the electrolytic cell (16) consumes water in the electrolytic seawater hydrogen production system, when the liquid levels in the oxygen liquid separator (1) and the hydrogen gas-liquid separator (6) decrease, the first ball valve (17), the alkali replenishing pump (24), and the alkali solution replenishing pipe ball valve (25) are opened to replenish the water stored in the water tank (18) into the electrolytic seawater hydrogen production system, and the first ball valve (17), the alkali replenishing pump (24), and the alkali solution replenishing pipe ball valve (25) are closed after the replenishment is completed.

10. The control method according to claim 6 is characterized in that the salt precipitation storage tank (45) has a self-heating function, the fourth ball valve (22) and the fifteenth ball valve (43) are normally closed valves, and when the accumulated salt concentration in the electrolysis seawater hydrogen production system is close to saturation, the fifteenth ball valve (43) is opened to allow the high salt concentration alkali solution to enter the salt precipitation storage tank (45), and then the fifteenth ball valve (43) is closed; the eleventh ball valve (49) and the tenth ball valve (46) are closed, the twelfth ball valve (50) and the vacuum pump (35) are opened to put the salt precipitation storage tank (45) in a vacuum state, and the vacuum pump (35) is started. The heating function of the salt precipitation storage tank (45) is used to evaporate and precipitate salt from the alkali solution with a high salt concentration. After the second liquid level meter (48) observes that the liquid level in the salt precipitation storage tank (45) has dropped to the target liquid level, the twelfth ball valve (50) and the vacuum pump (35) are closed, the eleventh ball valve (49) is opened to restore the pressure in the salt precipitation storage tank (45) to normal pressure, and then the tenth ball valve (46) is opened to discharge the salt crystals through the salt discharge pipe (47). At the same time, the thirteenth ball valve (55) and the alkali return pump (56) are opened to pump the remaining alkali solution through the second alkali return pipeline (57) into the alkali tank (20) for standby use.

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