Seawater electrolysis hydrogen production system and control method thereof

Abstract

The invention discloses a seawater electrolysis hydrogen production system and a control method thereof. The system comprises a seawater treatment system, an electrolytic bath, an alkali liquor circulation system, a salt precipitation system, a gas-liquid separation system and a gas cooling device, the seawater treatment system is used for purifying seawater to supplement moisture in the alkali liquor circulation system and washing gas separated by the gas-liquid separation system; the gas-liquid separation system and the alkali liquor circulation system are used for carrying out gas and alkali liquor separation on a gas-liquid mixture generated by electrolytic hydrogen production of the electrolytic bath and recovering the alkali liquor to the electrolytic bath; the salting-out system inputs part of the alkali liquor into the salting-out system for desalination treatment and sends the alkali liquor back to the gas-liquid separation system so as to control the salt concentration of the alkali liquor; and the gas cooling device is used for cooling the gas separated by the gas-liquid separation system. The method can effectively solve the problems of calcium and magnesium ion scaling and sodium chloride precipitation due to too high concentration in the long-time operation process of the direct seawater electrolysis hydrogen production system, and improves the efficiency and long-time operation stability of the seawater electrolysis hydrogen production system.

Description

Technical Field

[0001] This invention belongs to the field of water electrolysis hydrogen production technology, and relates to a seawater electrolysis hydrogen production system and its control method. Background Technology

[0002] my country has abundant seawater and offshore wind and solar resources. Offshore wind and solar power has low utilization and transportation efficiency due to its strong volatility and harsh environment. However, using offshore renewable energy to electrolyze seawater to produce hydrogen can not only produce "green hydrogen" cheaply and efficiently, but also promote the local consumption of offshore renewable energy.

[0003] Currently, seawater electrolysis for hydrogen production has developed into two directions: hydrogen production after seawater purification and direct seawater electrolysis. Among these, the seawater purification technology is the most mature. It utilizes reverse osmosis membranes to purify seawater, which is then fed into an electrolyzer to produce hydrogen. This technology has relatively low requirements for the electrolyzer system and its materials, but seawater purification plants require large land areas, and the energy consumption and cost of seawater purification are high, increasing the cost of hydrogen production. Direct seawater electrolysis for hydrogen production eliminates the need for a prior seawater desalination process and can be directly coupled with offshore wind and solar power, potentially achieving sustainable, low-cost hydrogen production.

[0004] However, direct seawater electrolysis for hydrogen production still faces many challenges. For example, the complex ionic composition of seawater can cause ion precipitates to clog the membrane and active sites. , During electrolysis, these ions gradually accumulate, causing an increase in the electrolyte salt concentration. When the concentration of these ions reaches saturation, salt crystals easily precipitate. These precipitated salt crystals can cause blockages or damage to system pipes, valves, pumps, etc., and may even clog the active sites of the electrolyzer, severely affecting electrolysis efficiency and electrolyzer lifespan. This poses a significant safety hazard to the long-term operation of the hydrogen production system. Therefore, developing a hydrogen production system process that is energy-efficient, easy to maintain, requires a small footprint, and is suitable for direct seawater electrolysis is a pressing problem that needs to be solved to achieve the industrialization of seawater-based hydrogen production. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention provides a seawater electrolysis hydrogen production system and its control method, which can effectively solve the problems of calcium and magnesium ion scaling and excessive sodium chloride precipitation during long-term operation of direct seawater electrolysis hydrogen production systems, thereby improving the efficiency and long-term operational stability of the seawater electrolysis hydrogen production system.

[0006] The present invention adopts the following technical solution.

[0007] The first aspect of this invention provides a seawater electrolysis hydrogen production system, comprising a seawater treatment system, an electrolyzer, an alkaline solution circulation system, a salt precipitation system, a gas-liquid separation system, and a gas cooling device; The outlet of the seawater treatment system is connected to the water inlet of the alkali circulation system and the liquid inlet of the gas-liquid separation system, respectively, for purifying seawater to replenish the water in the alkali circulation system and wash the gas separated by the gas-liquid separation system. The alkaline outlet of the gas-liquid separation system is connected to the alkaline inlet of the electrolyzer through the alkaline circulation system. The gas-liquid inlet of the gas-liquid separation system is connected to the outlet of the electrolyzer. This system is used to separate the gas and alkaline from the gas-liquid mixture produced by the electrolysis of hydrogen in the electrolyzer and to recover the alkaline back to the electrolyzer. The alkaline solution circulation system is also connected to the inlet of the salt precipitation system, for inputting a portion of the alkaline solution into the salt precipitation system for desalination. The outlet of the salt precipitation system is connected to the gas-liquid separation system to send the desalted alkaline solution back to the gas-liquid separation system in order to control the salt concentration of the alkaline solution. The gas outlet of the gas-liquid separation system is connected to the gas cooling device for cooling the gas separated by the gas-liquid separation system.

[0008] Preferably, the seawater treatment system includes a dosing tank, a stirring tank, a sedimentation tank, a second filter, a seawater storage tank, a seawater pump, a makeup water pump, and an ion exchange resin tank; The mixing tank is connected to the dosing tank and the sedimentation tank. After the seawater enters the mixing tank, the dosing tank adds a certain amount of sodium carbonate, sodium hydroxide and flocculant to the mixing tank in sequence according to the volume of seawater in the mixing tank and the initial calcium ion concentration and magnesium ion concentration of the seawater, so that the calcium and magnesium ion concentrations of the seawater are reduced to the target concentration. The drugs and seawater are mixed evenly by stirring to form a suspension, and the suspension enters the sedimentation tank for sedimentation. The seawater outlet at the top of the sedimentation tank is connected to the seawater storage tank via a seawater pump, an ion exchange resin tank, and a seawater pump. The seawater pump draws the upper layer of seawater from the sedimentation tank. The filter screen at the top of the sedimentation tank initially filters the sediment remaining in the upper layer of seawater. After passing through a second filter to filter the remaining small amount of sediment in the seawater, it enters the ion exchange resin tank to further remove calcium and magnesium ions before entering the seawater storage tank. The seawater storage tank is connected to the liquid inlet of the gas-liquid separation system and the water supply inlet of the alkali circulation system. Seawater is transported to the gas-liquid separation system and the alkali circulation system through a water supply pump and a switch valve.

[0009] Preferably, the seawater storage tank is also connected to a mixing tank, and the seawater is transported to the mixing tank by gravity through a pipeline to rinse away any residual sediment in the mixing tank.

[0010] Preferably, the alkali circulation system includes an alkali circulation pump, a third filter, and an alkali heat exchanger, used to transport the alkali separated by the gas-liquid separation system through the alkali circulation pump, cool it through the alkali heat exchanger, and then return it to the electrolytic cell through the third filter.

[0011] Preferably, the cooling water for the alkaline heat exchanger is seawater.

[0012] Preferably, the gas-liquid separation system includes a hydrogen-oxygen side gas-liquid separator and a hydrogen-oxygen side scrubber, wherein the hydrogen-oxygen side gas-liquid separator includes a hydrogen side gas-liquid separator and an oxygen side gas-liquid separator; the hydrogen-oxygen side scrubber includes a hydrogen side scrubber and an oxygen side scrubber. The gas-liquid inlet of the hydrogen-side gas-liquid separator is connected to the hydrogen-side outlet of the electrolyzer, the gas outlet is connected to the inlet of the hydrogen-side scrubber, the liquid inlet of the hydrogen-side scrubber is connected to the seawater treatment system, and the seawater is used to scrub the hydrogen; the liquid outlet of the hydrogen-side scrubber is connected to the hydrogen-side gas-liquid separator, and the liquid in the hydrogen-side scrubber is returned to the hydrogen-side gas-liquid separator; the alkaline outlet of the hydrogen-side gas-liquid separator is connected to the alkaline circulation system. The gas-liquid inlet of the oxygen-side gas-liquid separator is connected to the oxygen-side outlet of the electrolyzer, and the gas outlet is connected to the inlet of the oxygen-side scrubber. The liquid inlet of the oxygen-side scrubber is connected to the seawater treatment system, and the seawater is used to scrub the oxygen. The liquid outlet of the oxygen-side scrubber is connected to the oxygen-side gas-liquid separator, and the liquid in the oxygen-side scrubber is returned to the oxygen-side gas-liquid separator. The alkali outlet of the oxygen-side gas-liquid separator is connected to the alkali circulation system.

[0013] Preferably, the salt precipitation system includes a salt precipitation device, a fourth filter, and a alkali return pump; The salt precipitation device is connected to the alkali solution circulation system. After part of the alkali solution enters the salt precipitation device, sodium chloride crystallizes out to obtain desalted alkali solution. The salt precipitation device is equipped with a filter screen at the top. When the alkali return pump draws alkali solution from the salt precipitation device, the alkali solution passes through the filter screen at the top of the salt precipitation device to initially filter out the residual salt crystals in the alkali solution. Then, the remaining salt crystals are filtered out by the fourth filter and finally transported to the gas-liquid separation system.

[0014] Preferably, the gas cooling device includes a hydrogen-side gas cooling device and an oxygen-side gas cooling device; The gas inlet of the hydrogen-side gas cooling device is connected to the gas outlet of the hydrogen-side scrubber, and the gas in the hydrogen-side scrubber enters the hydrogen-side gas cooling device for cooling. The gas inlet of the oxygen-side gas cooling device is connected to the gas outlet of the oxygen-side scrubber, and the gas from the oxygen-side scrubber enters the oxygen-side gas cooling device for cooling.

[0015] Preferably, the cooling water for the hydrogen-side gas cooling device and the oxygen-side gas cooling device is seawater.

[0016] A second aspect of this invention provides a control method for a seawater electrolysis hydrogen production system, the method comprising: The seawater treatment system is controlled to purify seawater and deliver the seawater to the scrubber in the gas-liquid separation system to wash the gas separated by the gas-liquid separation system; Electrolytic cell for hydrogen production; gas-liquid separation system and alkali circulation system separate the gas and alkali mixture generated by the electrolytic cell for hydrogen production and recover the alkali back to the electrolytic cell. The liquid level of the hydrogen-oxygen side gas-liquid separator in the gas-liquid separation system is monitored in real time, and water is added to the alkaline solution circulation system when the liquid level is lower than the set value. The salt concentration in the alkali solution of the alkali solution circulation system is monitored in real time. When the salt concentration of the alkali solution is close to saturation, the salt precipitation system is activated to input part of the alkali solution into the salt precipitation system for desalination. The desalinated alkali solution is then sent back to the gas-liquid separation system to control the salt concentration of the alkali solution. The gas cooling device is controlled to cool the gas separated by the gas-liquid separation system, and the alkali heat exchanger in the alkali circulation system is controlled to cool the alkali solution.

[0017] A third aspect of the present invention provides a terminal, including a processor and a storage medium; the storage medium is used to store instructions; the processor is used to perform operations according to the instructions to execute the steps of the method.

[0018] A fourth aspect of the present invention provides a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the steps of the method.

[0019] Compared with the prior art, the beneficial effects of the present invention include at least the following: This invention eliminates the need for seawater desalination. By constructing a unique seawater treatment system, it can effectively remove impurities such as plankton, solid particles, and calcium and magnesium ions from seawater. This avoids blockages caused by plankton, solid particles, and calcium and magnesium ions deposited during system operation, which could severely impact the long-term operation of the hydrogen production system. It improves electrolysis efficiency and system lifespan, while also being energy-efficient and easy to maintain.

[0020] This invention designs a salt precipitation system that solves the problem of salt precipitation caused by the continuous increase in salt concentration during hydrogen production. It can ensure that the salt concentration of the seawater electrolysis hydrogen production system is kept within a safe range, and can also recover the alkaline solution, avoiding pollution and waste. This improves the environmental protection and economy of the seawater electrolysis hydrogen production system and is conducive to promoting the large-scale industrial application of the seawater electrolysis hydrogen production system. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of a seawater electrolysis hydrogen production system and its control method according to the present invention; In the diagram: 1. Seawater storage tank; 2. Mixing tank; 3. Sedimentation tank; 4. Chemical dosing tank; 5. First filter; 6. Make-up water pump; 7. Second filter; 8. Seawater pump; 9. Ion exchange resin tank; 10. Electrolyzer; 11. Alkali circulation pump; 12. Third filter; 13. Alkali heat exchanger; 14. Hydrogen-side gas-liquid separator; 15. Oxygen-side gas-liquid separator; 16. Hydrogen-side scrubber; 17. Oxygen-side scrubber; 18. Hydrogen-side gas cooling device; 19. Oxygen-side gas cooling device; 20. First level gauge; 21. Second level gauge; 22. Third level gauge; 23. Fourth level gauge; 24. Flow meter; 25. First manual ball valve; 26. Second manual ball valve; 27. First switching valve; 28. Second switching valve; 29. ​​Third switching valve; 30. Third manual ball valve; 31. Fourth switching valve; 32. Fifth switching valve; 33. Sixth switching valve; 34. Seventh switching valve; 35. First regulating valve; 36. Fourth manual ball valve; 37. Salt precipitation device; 38. Fourth filter; 39. Alkali return pump; 40. Eighth switching valve; 41. Refractometer. Detailed Implementation

[0022] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of this invention. The embodiments described in this application are merely some embodiments of this invention, and not all embodiments. Based on the spirit of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of this invention.

[0023] Embodiment 1 of the present invention provides a seawater electrolysis hydrogen production system, such as... Figure 1 As shown, it includes a seawater treatment system, an electrolytic cell 10, an alkali circulation system, a salt precipitation system, a gas-liquid separation system, and a gas cooling device; The outlet of the seawater treatment system is connected to the water inlet of the alkali circulation system and the liquid inlet of the gas-liquid separation system, respectively, for purifying seawater to replenish the water in the alkali circulation system and wash the gas separated by the gas-liquid separation system. More preferably, the seawater treatment system is connected to an alkali circulation system and a gas-liquid separation system, and the treated seawater is transported to the alkali circulation system or the gas-liquid separation system; the seawater treatment system includes a dosing tank 4, a stirring tank 2, a sedimentation tank 3, a first filter 5, a second filter 7, a seawater storage tank 1, a seawater pump 8, a water replenishment pump 6, an ion exchange resin tank 9, etc., which can remove plankton, solid impurities and calcium and magnesium ions from the seawater, so that the seawater becomes qualified raw water to enter the electrolytic cell and scrubber; The mixing tank 2 is connected to the dosing tank 4. After the seawater enters the mixing tank 2, the dosing tank 4 automatically adds chemicals such as sodium hydroxide, sodium carbonate and flocculant to the mixing tank 2. The chemicals and seawater are mixed evenly by stirring to form a suspension, which causes calcium and magnesium ions to form water-insoluble precipitates. This step can remove most of the calcium and magnesium ions in the seawater. The stirring tank 2 is connected to the sedimentation tank 3, and the suspension enters the sedimentation tank 3 from the stirring tank 2 through the pipeline for sedimentation. The seawater outlet at the top of the sedimentation tank 3 is connected to the seawater storage tank 1 via a seawater pump 8 and an ion exchange resin tank 9. After complete sedimentation, the first switch valve 27 is opened, and the seawater pump 8 draws the upper layer of clear seawater from the sedimentation tank 3. The filter screen installed at the top of the sedimentation tank 3 can initially filter the sediment remaining in the upper layer of seawater. After the second filter 7 filters the remaining small amount of sediment in the seawater, it enters the ion exchange resin tank 9 to further remove calcium and magnesium ions before entering the seawater storage tank 1 or the gas-liquid separation system. The seawater storage tank 1 is also connected to the alkali circulation system, and seawater can be transported to the alkali circulation system by the water replenishment pump 6 to replenish the system.

[0024] In specific implementation, the control scheme for the automatic addition of chemicals such as sodium hydroxide, sodium carbonate, and flocculant from the dosing tank 4 to the mixing tank 2 is as follows: A level gauge is used to monitor the liquid level, and the liquid level in the mixing tank 2 is fed back to the control system to obtain the volume of seawater in the sedimentation tank 3. The concentration of calcium and magnesium ions in seawater varies in different sea areas. According to the sea area where the equipment is used, the initial calcium ion concentration of seawater is input to the control system. mol / L, magnesium ion concentration b mol / L; Based on the seawater volume in sedimentation tank 3, the control system controls the dosing tank 4 to sequentially add a certain amount of sodium carbonate, sodium hydroxide, and flocculants to the mixing tank 2, thereby reducing the target concentration of calcium ions in the seawater to [a certain level]. Below mol / L, the target concentration of magnesium ions drops to mol / L.

[0025] (1) The amount of sodium hydroxide added is calculated as follows: When the hydrogen production system is started up for the first time and alkali is prepared, sodium hydroxide (NaOH) is in excess, forming a 5 wt% sodium hydroxide (NaOH) seawater solution. Then:

[0026] Where v is the volume of fresh seawater treated in a single cycle, in liters (L). To ensure that the magnesium ion concentration is ≤d, the minimum OH- required - Concentration; 40 is the molar mass of sodium hydroxide, in g / mol; The engineering value for the additional alkali required to prepare a 5wt% alkali solution is 52.8, which represents the mass concentration of the 5wt% alkali solution in g / L. In actual initial alkali preparation operations, multiple batches of seawater with a volume of v can be treated in batches, each batch processed according to the formula... Add sodium hydroxide to remove magnesium ions; according to Add the additional amount of alkali required to prepare a 5wt% alkali solution.

[0027] In practical applications, the calculation result of the above formula can be multiplied by an engineering correction factor η (usually taken as 1.01 to 1.05) to compensate for factors such as incomplete reaction.

[0028] When the hydrogen production system is operating normally, the seawater treatment system replenishes with new seawater. The amount of sodium hydroxide (NaOH) added at this time is calculated as follows:

[0029] in, η is the solubility product constant of magnesium hydroxide, which is temperature-dependent and can be taken as a typical value under standard operating conditions; v is the volume of fresh seawater treated in a single treatment; the coefficient η represents the excess value of alkali relative to the stoichiometric value.

[0030] (2) The amount of sodium carbonate added is calculated as follows:

[0031] in, is the solubility product constant of calcium carbonate, which is temperature-dependent and can be taken as a typical value under standard operating conditions; 10⁶ is the molar mass of sodium carbonate, in g / mol; (ac) represents the amount of carbonate ions consumed by the precipitate. represents the minimum carbonate concentration required to maintain the calcium ion concentration in the solution at c; v is the volume of seawater to be treated.

[0032] In practical applications, the calculation result of the above formula can be multiplied by an engineering correction factor η (usually taken as 1.01 to 1.05) to compensate for factors such as incomplete reaction.

[0033] To further improve control accuracy, the control system can calculate the solubility product constant under standard conditions and compensate for deviations between actual operating conditions and standard conditions through engineering correction coefficients. It can also dynamically correct the solubility product constant. This correction is based on real-time monitoring of the sedimentation tank temperature T and the estimated ionic strength I of the solution based on the conductivity of the alkali solution.

[0034] (3) The flocculant concentration is e mg / L, and the flocculant addition amount is calculated as follows:

[0035] In practical applications, the calculation result of the above formula can be multiplied by an engineering correction factor η (usually taken as 1.01 to 1.05) to compensate for factors such as incomplete reaction.

[0036] The seawater storage tank 1 is connected to the liquid inlet of the gas-liquid separation system and the water supply inlet of the alkali circulation system. Seawater is transported to the gas-liquid separation system and the alkali circulation system through the water supply pump 6 and the switch valve.

[0037] Specifically, the seawater storage tank 1 is connected to the hydrogen-oxygen side scrubber. When the hydrogen production system is working, the first manual ball valve 25, the fourth switch valve 31, and the fifth switch valve 32 are kept open. The seawater in the seawater storage tank 1 is transported to the hydrogen-oxygen side scrubber by the water replenishment pump 6 for washing the gas. The seawater storage tank 1 is connected to the alkali circulation system. The third level gauge 22 and the fourth level gauge 23 monitor the liquid level of the hydrogen-oxygen side gas-liquid separator. When the liquid level of the hydrogen-oxygen side gas-liquid separator is lower than the set value, the third switch valve 29 is opened, and the seawater in the seawater storage tank 1 is transported to the alkali circulation system through the water replenishment pump 6. After the water replenishment is completed, the third switch valve 29 is closed.

[0038] The first level gauge 20 is used to monitor the liquid level of the seawater storage tank 1. When the liquid level of the seawater storage tank 1 is lower than the set value, the raw seawater is started to be pumped out for processing. The second level gauge 21 is used to monitor the liquid level of the mixing tank 2. After the seawater enters the mixing tank 2 and reaches the target liquid level, the water intake stops.

[0039] The seawater storage tank 1 is also connected to the mixing tank 2. Seawater is transported to the mixing tank 2 by gravity through the pipeline to rinse the residual sediment in the mixing tank 2. Specifically, after the upper clear liquid is extracted, the first switch valve 27 is closed and the second switch valve 28 is opened to remove the lower sediment. Then, the second manual ball valve 26 and the third manual ball valve 30 are opened to rinse the tank with a small amount of seawater from the seawater storage tank 1. After that, the second manual ball valve 26, the second switch valve 28, and the third manual ball valve 30 are closed.

[0040] The alkaline outlet of the gas-liquid separation system is connected to the alkaline inlet of the electrolytic cell 10 through the alkaline circulation system. The gas-liquid inlet of the gas-liquid separation system is connected to the outlet of the electrolytic cell 10. This system is used to separate the gas and alkaline from the gas-liquid mixture generated by the electrolysis of hydrogen in the electrolytic cell 10 and to recover the alkaline back to the electrolytic cell 10. More preferably, the alkali circulation system includes an alkali circulation pump 11, a third filter 12, and an alkali heat exchanger 13, which is used to transport the alkali separated by the gas-liquid separation system through the alkali circulation pump 11 and the third filter 12 to the alkali heat exchanger 13 for cooling before returning it to the electrolytic cell 10.

[0041] The cooling water for the alkaline heat exchanger 13 is seawater.

[0042] The gas-liquid separation system includes a hydrogen-oxygen side gas-liquid separator and a hydrogen-oxygen side scrubber, wherein the hydrogen-oxygen side gas-liquid separator includes a hydrogen side gas-liquid separator 14 and an oxygen side gas-liquid separator 15; the hydrogen-oxygen side scrubber includes a hydrogen side scrubber 16 and an oxygen side scrubber 17. The gas-liquid inlet of the hydrogen-side gas-liquid separator 14 is connected to the hydrogen-side outlet of the electrolyzer 10, and the gas outlet is connected to the inlet of the hydrogen-side scrubber 16. After separation in the hydrogen-side gas-liquid separator 14, the hydrogen enters the hydrogen-side scrubber 16 from the gas outlet. After being washed with seawater, the temperature of the hydrogen is reduced, and the alkaline content in the hydrogen is also reduced. The liquid inlet of the hydrogen-side scrubber 16 is connected to the seawater treatment system, and the seawater is used to wash the hydrogen. The liquid outlet of the hydrogen-side scrubber 16 is connected to the hydrogen-side gas-liquid separator 14, and the liquid in the hydrogen-side scrubber 16 flows back to the hydrogen-side gas-liquid separator 14. The alkaline outlet of the hydrogen-side gas-liquid separator 14 is connected to the alkaline circulation system. The gas-liquid inlet of the oxygen-side gas-liquid separator 15 is connected to the oxygen-side outlet of the electrolyzer 10, and the gas outlet is connected to the inlet of the oxygen-side scrubber 17. The liquid inlet of the oxygen-side scrubber 17 is connected to the seawater treatment system. The seawater is used to wash the oxygen. After being separated in the oxygen-side gas-liquid separator 15, the oxygen enters the oxygen-side scrubber 17 from the gas outlet. After being washed by seawater, the temperature of the oxygen is reduced, and the alkalinity content in the oxygen is also reduced. The liquid outlet of the oxygen-side scrubber 17 is connected to the oxygen-side gas-liquid separator 15, and the liquid in the oxygen-side scrubber 17 flows back to the oxygen-side gas-liquid separator 15. The alkaline outlet of the oxygen-side gas-liquid separator 15 is connected to the alkaline circulation system.

[0043] Specifically, the hydrogen and oxygen side outlets of the electrolytic cell 10 are connected to the gas-liquid inlets of the hydrogen-oxygen side gas-liquid separator, respectively. The alkaline solution undergoes an electrolysis reaction within the electrolytic cell 10 to generate hydrogen and oxygen. The mixture of hydrogen and alkaline solution enters the hydrogen-side gas-liquid separator 14 from the hydrogen side outlet of the electrolytic cell 10, where hydrogen and alkaline solution are separated. The mixture of oxygen and alkaline solution enters the oxygen-side gas-liquid separator 15 from the oxygen side outlet of the electrolytic cell 10, where oxygen and alkaline solution are separated. The alkaline solution circulation system is connected to both the alkaline solution inlet of the electrolytic cell 10 and the alkaline solution outlet of the gas-liquid separation system. The alkaline solution separated by the gas-liquid separation system is transported by the alkaline solution circulation pump 11. After heat exchange with the alkaline solution heat exchanger 13, impurities are filtered by the third filter 12 before being transported back to the electrolytic cell 10. The alkaline solution circulation system is also connected to the inlet of the salt precipitation system, for inputting a portion of the alkaline solution into the salt precipitation system for desalination. The outlet of the salt precipitation system is connected to the gas-liquid separation system to send the desalted alkaline solution back to the gas-liquid separation system in order to control the salt concentration of the alkaline solution. More preferably, the alkali circulation system is connected to the salt precipitation system. When the alkali salt concentration in the seawater electrolysis hydrogen production system approaches saturation, the alkaline seawater from the alkali circulation system is transported to the salt precipitation system, where sodium chloride is precipitated from the alkali solution, reducing the system's salt content. The salt precipitation system includes a salt precipitation device 37, a fourth filter 38, and a return alkali pump 39. The salt precipitation device 37 is connected to the alkali circulation system. When the alkali salt concentration in the alkali circulation system is close to saturation, it is necessary to reduce the salt content (sodium ions, chloride ions, etc.) in the alkali. At this time, the first regulating valve 35 is opened, and some of the alkali in the alkali circulation system enters the salt precipitation device 37, causing most of the sodium chloride to crystallize and precipitate out, resulting in desalted alkali. The top of the salt precipitation device 37 is equipped with a filter screen. When the alkali return pump 39 draws alkali from the salt precipitation device, the alkali passes through the filter screen at the top of the salt precipitation device 37 to preliminarily filter out the residual salt crystals in the alkali. Then, the fourth filter 38 filters out the remaining salt crystal solids, and finally, the alkali return pump 39 delivers it to the hydrogen-oxygen side gas-liquid separator and scrubber. The flow meter 24 is used to monitor the amount of alkali entering the salt precipitation device 37. When the alkali in the salt precipitation device 37 is full, the first regulating valve 35 is closed. The salt precipitation device 37 can cool the alkali, causing sodium chloride in the alkali to crystallize and precipitate. When the temperature of the alkali drops to the set value, the fourth manual ball valve 36, the sixth switch valve 33, the seventh switch valve 34, and the alkali return pump 39 are opened. The upper layer of alkali is filtered out by the fourth filter 38 to remove a small amount of sodium chloride crystals in the alkali and then transported to the hydrogen-oxygen side gas-liquid separator. Then the fourth manual ball valve 36, the sixth switch valve 33, the seventh switch valve 34, and the alkali return pump 39 are closed.

[0044] The gas outlet of the gas-liquid separation system is connected to the gas cooling device for cooling the gas separated by the gas-liquid separation system.

[0045] More preferably, the gas outlet of the multi-stage gas-liquid separation system is connected to a gas cooling device to cool the gas. The gas cooling device includes a hydrogen-side gas cooling device 18 and an oxygen-side gas cooling device 19. The gas inlet of the hydrogen-side gas cooling device 18 is connected to the gas outlet of the hydrogen-side scrubber 16. The gas (hydrogen) in the hydrogen-side scrubber 16 enters the hydrogen-side gas cooling device 18 for cooling. This step can further reduce the temperature of the hydrogen. The gas inlet of the oxygen-side gas cooling device 19 is connected to the gas outlet of the oxygen-side scrubber 17. The gas (oxygen) from the oxygen-side scrubber 17 enters the oxygen-side gas cooling device 19 for cooling, which can further reduce the oxygen temperature.

[0046] The cooling water for the hydrogen-side gas cooling device 18 and the oxygen-side gas cooling device 19 is seawater.

[0047] Before the first commissioning or first start-up of the seawater electrolysis hydrogen production system, close all ball valves and pumps. After seawater enters the mixing tank 2, the dosing tank 4 automatically adds excess sodium hydroxide, appropriate amount of sodium carbonate, and flocculant, forming alkaline seawater of a specific concentration. The chemicals and seawater are mixed evenly by stirring to form a suspension, which then enters the sedimentation tank 3. After complete sedimentation, open the first switch valve 27 and seawater pump 8 to extract the upper layer of clear seawater. After passing through the second filter 7 and ion exchange resin tank 9, the seawater is transported to the seawater storage tank 1. Repeat the above steps until the seawater storage tank 1 has the amount of alkaline solution required for the seawater electrolysis hydrogen production system. Close the first switch valve 27 and seawater pump 8, and open the first manual ball valve 25, water replenishment pump 6, third switch valve 29, and alkaline solution circulation pump 11 to transport the alkaline seawater in the seawater storage tank 1 to the electrolyzer 10, alkaline solution circulation system, and hydrogen-oxygen side gas-liquid separator. After completion, close the first manual ball valve 25, water replenishment pump 6, and third switch valve 29. This step is used to prepare the alkaline solution for the system.

[0048] When the seawater electrolysis hydrogen production system needs to be shut down for maintenance and alkali needs to be removed, close all ball valves and pumps, and open the first manual ball valve 25, the third switch valve 29, the eighth switch valve 40, and the alkali circulation pump 11. The alkali from the electrolyzer 10, the alkali circulation system, and the hydrogen-oxygen side gas-liquid separator is transported back to the seawater storage tank 1 through the alkali circulation pump 11. This step is used to remove alkali from the system.

[0049] Embodiment 2 of this invention provides a control method for a seawater electrolysis hydrogen production system. Based on a control system, it achieves fully automated control. System start-up and shutdown, regulation control, operating status, and alarm feedback are implemented using hard-wired mode. Other system operation monitoring signals can be communicated to a host computer via RS485. The host computer control software (PLC or DCS) can be used to realize real-time data monitoring, control parameter adjustment, sequential start-up and shutdown, and interlock alarm operations for the seawater electrolysis hydrogen production system. The hydrogen production system achieves automated control through parameter control, interlocking, and full-process testing, without manual intervention. Control parameters include current, voltage, flow rate, pressure, pressure difference, energy consumption, hydrogen in oxygen, hydrogen production, temperature, liquid level, and salt concentration. The control system consists of several parts, including regulation systems (liquid level regulation system, temperature regulation system, flow rate regulation system, salt concentration regulation system, and seawater treatment regulation system), digital logic, and alarm interlocking. By controlling the above systems, this invention can realize functions such as seawater treatment, automatic water replenishment, salt precipitation treatment, and interlock alarms, making control more precise and performance more reliable, stable, and safe.

[0050] The method includes: The seawater treatment regulation system controls the seawater treatment system to purify the seawater and delivers the seawater to the scrubber in the gas-liquid separation system to wash the gas separated by the gas-liquid separation system; More preferably, before the seawater treatment system starts working, the second manual ball valve 26, the first switch valve 27, the second switch valve 28, the third switch valve 29, and the third manual ball valve 30 are closed, and the first manual ball valve 25, the fourth switch valve 31, and the fifth switch valve 32 are opened; the first level gauge 20 is used to monitor the liquid level of the seawater storage tank 1. When the liquid level of the seawater storage tank 1 is lower than the set value, seawater is started to be pumped for treatment; the second level gauge 21 is used to monitor the liquid level of the mixing tank 2. After the seawater enters the mixing tank 2 and reaches the target liquid level, the water intake stops, and at the same time, the valve is opened. Open the dosing tank 4 and add a certain amount of precipitant and flocculant to the mixing tank 2. After stirring evenly to form a suspension, enter the sedimentation tank 3. After complete sedimentation, open the first switch valve 27 and use the seawater pump 8 to transport all the clear seawater in the upper layer to the seawater storage tank 1. Then close the first switch valve 27, open the second switch valve 28 to remove the lower layer of sediment, and then open the second manual ball valve 26 and the third manual ball valve 30. After rinsing with a small amount of seawater from the seawater storage tank 1, close the second manual ball valve 26, the second switch valve 28, and the third manual ball valve 30.

[0051] When the seawater electrolysis hydrogen production system is working, the first manual ball valve 25, the fourth switch valve 31, and the fifth switch valve 32 are always open, transporting seawater from the seawater storage tank 1 to the hydrogen-oxygen side scrubber.

[0052] Electrolyzer 10 produces hydrogen by electrolysis. The gas-liquid separation system and the alkali circulation system separate the gas and alkali mixture generated by the electrolysis of hydrogen in electrolyzer 10 and recover the alkali to electrolyzer 10. A level gauge is configured in the gas-liquid separation system to monitor the liquid level of the hydrogen-oxygen side gas-liquid separator in real time and feed the liquid level signal back to the liquid level regulation system. When the liquid level is lower than the set value, water is added to the alkali circulation system. More preferably, when the seawater electrolysis hydrogen production system is working, the third level gauge 22 and the fourth level gauge 23 monitor the liquid level of the hydrogen-oxygen side gas-liquid separator. When the liquid level of the hydrogen-oxygen side gas-liquid separator is lower than the set value, the third switch valve 29 is opened to transport the seawater in the seawater storage tank 1 to the alkaline solution circulation system for water replenishment. After the water replenishment is completed, the third switch valve 29 is closed.

[0053] The alkali circulation system is equipped with a refractometer 41 to monitor the salt concentration in the alkali in the alkali circulation system in real time and feed the salt concentration signal back to the salt concentration regulation system. When the salt concentration of the alkali is close to saturation, the salt concentration regulation system controls the operation of the salt precipitation system to input part of the alkali into the salt precipitation system for desalination. The desalinated alkali is sent back to the gas-liquid separation system to control the salt concentration of the alkali. More preferably, when the concentration of alkaline solution in the hydrogen production system is close to saturation, it is necessary to reduce the salt content (sodium ions, chloride ions, etc.) in the alkaline solution. At this time, after opening the first regulating valve 35 and allowing part of the alkaline solution to enter the salt precipitation device 37, the first regulating valve 35 is closed. After sodium chloride crystals are precipitated in the salt precipitation device 37, the fourth manual ball valve 36, the return alkaline pump 39, the sixth switch valve 33, and the seventh switch valve 34 are opened. The remaining alkaline solution is transported to the hydrogen-oxygen side gas-liquid separator through the return alkaline pump 39. The fourth manual ball valve 36, the return alkaline pump 39, the sixth switch valve 33, and the seventh switch valve 34 are then closed.

[0054] The temperature control system controls the gas cooling device to cool the gas separated by the gas-liquid separation system and controls the alkali heat exchanger 13 of the alkali circulation system to cool the alkali solution.

[0055] Embodiment 3 of the present invention provides a terminal, including a processor and a storage medium; the storage medium is used to store instructions; the processor is used to perform operations according to the instructions to execute the steps of the method.

[0056] Embodiment 4 of the present invention provides a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the steps of the method.

[0057] Compared with the prior art, the beneficial effects of the present invention include at least the following: This invention eliminates the need for seawater desalination. By constructing a unique seawater treatment system, it can effectively remove impurities such as plankton, solid particles, and calcium and magnesium ions from seawater. This avoids blockages caused by plankton, solid particles, and calcium and magnesium ions deposited during system operation, which could severely impact the long-term operation of the hydrogen production system. It improves electrolysis efficiency and system lifespan, while also being energy-efficient and easy to maintain.

[0058] This invention designs a salt precipitation system that solves the problem of salt precipitation caused by the continuous increase in salt concentration during hydrogen production. It can ensure that the salt concentration of the seawater electrolysis hydrogen production system is kept within a safe range, and can also recover the alkaline solution, avoiding pollution and waste. This improves the environmental protection and economy of the seawater electrolysis hydrogen production system and is conducive to promoting the large-scale industrial application of the seawater electrolysis hydrogen production system.

[0059] This disclosure can be a system, method, and / or computer program product. A computer program product may include a computer-readable storage medium having computer-readable program instructions loaded thereon for causing a processor to implement various aspects of this disclosure.

[0060] Computer-readable storage media can be tangible devices capable of holding and storing instructions for use by an instruction execution device. Computer-readable storage media can be, for example—but not limited to—electrical storage devices, magnetic storage devices, optical storage devices, electromagnetic storage devices, semiconductor storage devices, or any suitable combination of the foregoing. More specific examples (a non-exhaustive list) of computer-readable storage media include: portable computer disks, hard disks, random access memory (RAM), read-only memory (ROM), erasable programmable read-only memory (EPROM or flash memory), static random access memory (SRAM), portable compact disc read-only memory (CD-ROM), digital multifunction disc (DVD), memory sticks, floppy disks, mechanical encoding devices, such as punch cards or recessed protrusions storing instructions thereon, and any suitable combination of the foregoing. The computer-readable storage media used herein are not to be construed as transient signals themselves, such as radio waves or other freely propagating electromagnetic waves, electromagnetic waves propagating through waveguides or other transmission media (e.g., light pulses through fiber optic cables), or electrical signals transmitted through wires.

[0061] The computer-readable program instructions described herein can be downloaded from computer-readable storage media to various computing / processing devices, or downloaded via a network, such as the Internet, local area network, wide area network, and / or wireless network, to an external computer or external storage device. The network may include copper transmission cables, fiber optic transmission, wireless transmission, routers, firewalls, switches, gateway computers, and / or edge servers. A network adapter card or network interface in each computing / processing device receives the computer-readable program instructions from the network and forwards them to the computer-readable storage media in the respective computing / processing device.

[0062] Computer program instructions used to perform the operations of this disclosure may be assembly instructions, instruction set architecture (ISA) instructions, machine instructions, machine-dependent instructions, microcode, firmware instructions, status setting data, or source code or object code written in any combination of one or more programming languages, including object-oriented programming languages ​​such as Smalltalk, C++, etc., and conventional procedural programming languages ​​such as the "C" language or similar programming languages. The computer-readable program instructions may execute entirely on the user's computer, partially on the user's computer, as a standalone software package, partially on the user's computer and partially on a remote computer, or entirely on a remote computer or server. In cases involving a remote computer, the remote computer may be connected to the user's computer via any type of network—including a local area network (LAN) or a wide area network (WAN)—or may be connected to an external computer (e.g., via the Internet using an Internet service provider). In some embodiments, electronic circuitry, such as programmable logic circuitry, field-programmable gate arrays (FPGAs), or programmable logic arrays (PLAs), is personalized by utilizing the status information of the computer-readable program instructions to implement various aspects of this disclosure.

[0063] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the specific implementation of the present invention. Any modifications or equivalent substitutions that do not depart from the spirit and scope of the present invention should be covered within the protection scope of the claims of the present invention.

Claims

1. A seawater electrolysis hydrogen production system, comprising a seawater treatment system, an electrolyzer, an alkali circulation system, a salt precipitation system, a gas-liquid separation system, and a gas cooling device, characterized in that: The outlet of the seawater treatment system is connected to the water inlet of the alkali circulation system and the liquid inlet of the gas-liquid separation system, respectively, for purifying seawater to replenish the water in the alkali circulation system and wash the gas separated by the gas-liquid separation system. The alkaline outlet of the gas-liquid separation system is connected to the alkaline inlet of the electrolyzer through the alkaline circulation system. The gas-liquid inlet of the gas-liquid separation system is connected to the outlet of the electrolyzer. This system is used to separate the gas and alkaline from the gas-liquid mixture produced by the electrolysis of hydrogen in the electrolyzer and to recover the alkaline back to the electrolyzer. The alkaline solution circulation system is also connected to the inlet of the salt precipitation system, for inputting a portion of the alkaline solution into the salt precipitation system for desalination. The outlet of the salt precipitation system is connected to the gas-liquid separation system to send the desalted alkaline solution back to the gas-liquid separation system in order to control the salt concentration of the alkaline solution. The gas outlet of the gas-liquid separation system is connected to the gas cooling device for cooling the gas separated by the gas-liquid separation system.

2. The seawater electrolysis hydrogen production system according to claim 1, characterized in that: The seawater treatment system includes a dosing tank, a mixing tank, a sedimentation tank, a second filter, a seawater storage tank, a seawater pump, a makeup water pump, and an ion exchange resin tank. The mixing tank is connected to the dosing tank and the sedimentation tank. After the seawater enters the mixing tank, the dosing tank adds a certain amount of sodium carbonate, sodium hydroxide and flocculant to the mixing tank in sequence according to the volume of seawater in the mixing tank and the initial calcium ion concentration and magnesium ion concentration of the seawater, so that the calcium and magnesium ion concentrations of the seawater are reduced to the target concentration. The drugs and seawater are mixed evenly by stirring to form a suspension, and the suspension enters the sedimentation tank for sedimentation. The seawater outlet at the top of the sedimentation tank is connected to the seawater storage tank via a seawater pump, an ion exchange resin tank, and a seawater pump. The seawater pump draws the upper layer of seawater from the sedimentation tank. The filter screen at the top of the sedimentation tank initially filters the sediment remaining in the upper layer of seawater. After passing through a second filter to filter the remaining small amount of sediment in the seawater, it enters the ion exchange resin tank to further remove calcium and magnesium ions before entering the seawater storage tank. The seawater storage tank is connected to the liquid inlet of the gas-liquid separation system and the water supply inlet of the alkali circulation system. Seawater is transported to the gas-liquid separation system and the alkali circulation system through a water supply pump and a switch valve.

3. The seawater electrolysis hydrogen production system according to claim 2, characterized in that: The seawater storage tank is also connected to a mixing tank, and seawater is transported to the mixing tank by gravity through pipelines to flush out residual sediment in the mixing tank.

4. The seawater electrolysis hydrogen production system according to claim 1, characterized in that: The alkali circulation system includes an alkali circulation pump, a third filter, and an alkali heat exchanger. It is used to transport the alkali separated by the gas-liquid separation system through the alkali circulation pump, cool it through the alkali heat exchanger, and then return it to the electrolytic cell through the third filter.

5. The seawater electrolysis hydrogen production system according to claim 4, characterized in that: The cooling water for the alkaline heat exchanger is seawater.

6. The seawater electrolysis hydrogen production system according to claim 1, characterized in that: The gas-liquid separation system includes a hydrogen-oxygen side gas-liquid separator and a hydrogen-oxygen side scrubber, wherein the hydrogen-oxygen side gas-liquid separator includes a hydrogen side gas-liquid separator and an oxygen side gas-liquid separator; the hydrogen-oxygen side scrubber includes a hydrogen side scrubber and an oxygen side scrubber. The gas-liquid inlet of the hydrogen-side gas-liquid separator is connected to the hydrogen-side outlet of the electrolyzer, the gas outlet is connected to the inlet of the hydrogen-side scrubber, the liquid inlet of the hydrogen-side scrubber is connected to the seawater treatment system, and the seawater is used to scrub the hydrogen; the liquid outlet of the hydrogen-side scrubber is connected to the hydrogen-side gas-liquid separator, and the liquid in the hydrogen-side scrubber is returned to the hydrogen-side gas-liquid separator; the alkaline outlet of the hydrogen-side gas-liquid separator is connected to the alkaline circulation system. The gas-liquid inlet of the oxygen-side gas-liquid separator is connected to the oxygen-side outlet of the electrolyzer, and the gas outlet is connected to the inlet of the oxygen-side scrubber. The liquid inlet of the oxygen-side scrubber is connected to the seawater treatment system, and the seawater is used to scrub the oxygen. The liquid outlet of the oxygen-side scrubber is connected to the oxygen-side gas-liquid separator, and the liquid in the oxygen-side scrubber is returned to the oxygen-side gas-liquid separator. The alkali outlet of the oxygen-side gas-liquid separator is connected to the alkali circulation system.

7. A seawater electrolysis hydrogen production system according to claim 1 or 6, characterized in that: The salt precipitation system includes a salt precipitation device, a fourth filter, and a alkali return pump; The salt precipitation device is connected to the alkali solution circulation system. After part of the alkali solution enters the salt precipitation device, sodium chloride crystallizes out to obtain desalted alkali solution. The salt precipitation device is equipped with a filter screen at the top. When the alkali return pump draws alkali solution from the salt precipitation device, the alkali solution passes through the filter screen at the top of the salt precipitation device to initially filter out the residual salt crystals in the alkali solution. Then, the remaining salt crystals are filtered out by the fourth filter and finally transported to the gas-liquid separation system.

8. A seawater electrolysis hydrogen production system according to claim 6, characterized in that: The gas cooling device includes a hydrogen-side gas cooling device and an oxygen-side gas cooling device; The gas inlet of the hydrogen-side gas cooling device is connected to the gas outlet of the hydrogen-side scrubber, and the gas in the hydrogen-side scrubber enters the hydrogen-side gas cooling device for cooling. The gas inlet of the oxygen-side gas cooling device is connected to the gas outlet of the oxygen-side scrubber, and the gas from the oxygen-side scrubber enters the oxygen-side gas cooling device for cooling.

9. A seawater electrolysis hydrogen production system according to claim 8, characterized in that: The cooling water for the hydrogen-side gas cooling device and the oxygen-side gas cooling device is seawater.

10. A control method for a seawater electrolysis hydrogen production system according to any one of claims 1-9, characterized in that, The method includes: The seawater treatment system is controlled to purify seawater and deliver the seawater to the scrubber in the gas-liquid separation system to wash the gas separated by the gas-liquid separation system; Electrolytic cell for hydrogen production; gas-liquid separation system and alkali circulation system separate the gas and alkali mixture generated by the electrolytic cell for hydrogen production and recover the alkali back to the electrolytic cell. The liquid level of the hydrogen-oxygen side gas-liquid separator in the gas-liquid separation system is monitored in real time, and water is added to the alkaline solution circulation system when the liquid level is lower than the set value. The salt concentration in the alkali solution of the alkali solution circulation system is monitored in real time. When the salt concentration of the alkali solution is close to saturation, the salt precipitation system is activated to input part of the alkali solution into the salt precipitation system for desalination. The desalinated alkali solution is then sent back to the gas-liquid separation system to control the salt concentration of the alkali solution. The gas cooling device is controlled to cool the gas separated by the gas-liquid separation system, and the alkali heat exchanger in the alkali circulation system is controlled to cool the alkali solution.

11. A terminal, comprising a processor and a storage medium; characterized in that: The storage medium is used to store instructions; The processor is configured to operate according to the instructions to perform the steps of the method according to claim 10.

12. A computer-readable storage medium having a computer program stored thereon, characterized in that, When the program is executed by the processor, it implements the steps of the method of claim 10.

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