Integrated reverse electrodialysis seawater hydrogen production system and method of operation thereof

Abstract

The application discloses an integrated reverse electrodialysis seawater hydrogen production system and a running method thereof. The system comprises: an alkali hydrogen production electrolytic cell, an alkali liquor circulation outlet of which is communicated with a high-concentration chamber of a multi-stage reverse electrodialysis device; the multi-stage reverse electrodialysis device comprises a concentration difference power generation module composed of a stack of at least three electrodialysis cell stack units, and the power output ends of the concentration difference power generation module are respectively connected to a driving component of the alkali hydrogen production electrolytic cell and an online seawater desalination device, so that ion migration is driven by the concentration difference between concentrated alkali liquor and dilute alkali liquor to generate electric energy; the online seawater desalination device is of an alkali regeneration type and is of a permeation structure, and pure water is separated by using a permeation pressure difference to obtain desalination water, and a desalination water outlet of the online seawater desalination device is communicated with a water supplementing opening of the alkali hydrogen production electrolytic cell and a low-concentration chamber of the multi-stage reverse electrodialysis device. The application has the advantages of simple structure, cooperative closed-loop operation of concentration difference power generation, electrolytic waste heat recovery and online seawater desalination, energy cascade utilization and material closed loop, and reduced hydrogen production energy consumption.

Description

Technical Field

[0001] This invention belongs to the field of seawater electrolysis hydrogen production technology in the new energy sector, specifically relating to an integrated reverse electrodialysis seawater hydrogen production system and its operation method. Background Technology

[0002] Seawater hydrogen production is an important direction for green hydrogen production, which can get rid of dependence on freshwater. However, traditional technologies have problems such as complex processes and high energy consumption: First, electrolysis hydrogen production has high energy consumption and does not make full use of the concentration difference in the hydrogen production process to reduce energy consumption; second, seawater desalination mostly adopts energy-consuming methods such as membrane distillation, which does not make full use of the natural driving force of osmotic pressure difference; third, the waste heat of electrolysis is not effectively utilized, resulting in energy waste.

[0003] To address the aforementioned shortcomings, this invention proposes a seawater hydrogen production system with reduced energy consumption. By employing reverse electrodialysis (RED) technology, concentration gradient power generation is achieved, reducing the energy consumption of the seawater hydrogen production system. Online seawater desalination technology is used to achieve pure water replenishment without additional energy consumption. Waste heat from electrolysis is used to supply the RED system, improving efficiency while eliminating the need for heating structures, thus supporting a reduction in the overall cost of green hydrogen production. Summary of the Invention

[0004] The purpose of this invention is to address the shortcomings of existing technologies by providing an integrated reverse electrodialysis seawater hydrogen production system and its operation method.

[0005] The objective of this invention is achieved through the following technical solution: A first aspect of this invention provides an integrated reverse electrodialysis seawater hydrogen production system, comprising:

[0006] Alkali solution hydrogen production electrolysis cell;

[0007] A multi-stage reverse electrodialysis device includes a concentration power generation module composed of at least three stages of electrodialysis cell stacks. The concentration power generation module uses the concentration difference between concentrated alkaline solution and dilute alkaline solution to drive ion migration and generate electrical energy.

[0008] An online seawater desalination device, wherein the online seawater desalination device is an alkaline regeneration permeation structure, which utilizes osmotic pressure difference to achieve pure water separation to obtain desalinated water;

[0009] The power output terminal of the concentration power generation module is connected to the drive components of the alkaline hydrogen electrolyzer and the online seawater desalination device to provide them with power.

[0010] The alkaline solution circulation outlet of the alkaline solution hydrogen production electrolyzer is connected to the high-concentration chamber of the multi-stage reverse electrodialysis device.

[0011] The desalinated water outlet of the online seawater desalination device is connected to the water inlet of the alkaline hydrogen electrolysis cell and the low-concentration chamber of the multi-stage reverse electrodialysis device, respectively.

[0012] The mixed solution outlet of the multi-stage reverse electrodialysis device is connected to the mixed solution inlet of the online seawater desalination device.

[0013] Furthermore, the multi-stage reverse electrodialysis device is equipped with a high-concentration chamber inlet and a low-concentration chamber inlet, which are used to introduce concentrated alkali solution and dilute alkali solution, respectively; the multi-stage reverse electrodialysis device is equipped with a mixed solution outlet, which is used to discharge the mixed alkali solution after ion exchange and return it to the online seawater desalination device.

[0014] Furthermore, in the concentration power generation module, the power output terminal of the preceding electrodialysis cell stack unit is connected to the power input terminal of the following electrodialysis cell stack unit; the power input terminal of the first-stage electrodialysis cell stack unit serves as the power input terminal of the concentration power generation module and is electrically connected to the alkaline hydrogen electrolyzer and the online seawater desalination device; the power output terminal of the last-stage electrodialysis cell stack unit serves as the power output terminal of the concentration power generation module.

[0015] Furthermore, the electrodialysis cell stack unit comprises several anion exchange membranes and several cation exchange membranes stacked alternately, and both sides of the cation exchange membranes and anion exchange membranes are supported by polyethylene terephthalate mesh to form flow chambers;

[0016] The electrodialysis cell stack unit has an anode and a cathode on both sides inside, and the chambers where the anode and the cathode are located are filled with electrode liquid.

[0017] Furthermore, the cation exchange membrane is a perfluorosulfonic acid type cation exchange membrane, and the anion exchange membrane is a quaternary ammonium type anion exchange membrane, both with a membrane thickness of 20 μm;

[0018] The thickness of the flow chamber is 0.3 mm;

[0019] The flow chamber includes a high-concentration chamber and a low-concentration chamber, which are alternately distributed.

[0020] The anode is adjacent to the anion exchange membrane, and the cathode is adjacent to the cation exchange membrane.

[0021] Furthermore, the online seawater desalination device includes a cylindrical body, a hydrophobic porous membrane module, an outer metal shell, and a level valve; wherein, the hydrophobic porous membrane module is wrapped around the outside of the cylindrical body and fixed by an iron ring; the outer metal shell is movably fitted onto the outside of the hydrophobic porous membrane module, and a rubber gasket is provided between the outer metal shell and the hydrophobic porous membrane module to form a sealed space; the level valve is connected to the outer metal shell and is used to control the movement of the outer metal shell to adjust the effective contact area between the hydrophobic porous membrane module and seawater.

[0022] Furthermore, the hydrophobic porous membrane component is a polytetrafluoroethylene membrane with a pore size of 0.1 μm.

[0023] Furthermore, the level valve is linked to the outer metal shell:

[0024] When the liquid level in the online seawater desalination unit is lower than the preset value, the liquid level valve drives the outer metal shell to move to increase the exchange area between the hydrophobic porous membrane module and the seawater.

[0025] When the liquid level in the online seawater desalination unit is higher than the preset value, the liquid level valve drives the outer metal shell to move to reduce the exchange area between the hydrophobic porous membrane module and the seawater.

[0026] Furthermore, a heat exchange pipe is provided between the alkaline hydrogen production electrolyzer and the multi-stage reverse electrodialysis device. The heat exchange pipe is used to transfer the waste heat generated by the alkaline hydrogen production electrolyzer to the multi-stage reverse electrodialysis device to help maintain the operating temperature of the electrodialysis cell stack unit at 30-40℃.

[0027] The electrical energy output by the concentration power generation module is used to supplement 10% to 20% of the energy consumption of the alkaline hydrogen electrolyzer, and the remaining electrical energy is used to supply the drive components of the online seawater desalination device.

[0028] A second aspect of this invention provides an operation method for the integrated reverse electrodialysis seawater hydrogen production system as described above, comprising the following steps:

[0029] S1. After being pretreated by quartz sand filtration, seawater comes into contact with the hydrophobic porous membrane module of the online seawater desalination unit. The liquid level valve controls the movement of the outer metal shell according to the liquid level in the online seawater desalination unit. Through the osmotic pressure difference, pure water in the seawater is driven to pass through the hydrophobic porous membrane module to form desalinated water, which is then transported to the alkaline hydrogen electrolysis cell for water replenishment and to the low-concentration chamber of the multi-stage reverse electrodialysis unit as dilute alkaline solution.

[0030] S2. The alkaline solution hydrogen production electrolysis cell is energized to electrolyze the alkaline solution to produce hydrogen. The concentrated alkaline solution formed after electrolysis is transported to the high-concentration chamber of the multi-stage reverse electrodialysis device. The waste heat released during the process is indirectly transferred to the electrodialysis cell stack unit of the multi-stage reverse electrodialysis device through heat exchange pipes to help maintain its operating temperature.

[0031] S3, the multi-stage reverse electrodialysis device uses the concentration difference between concentrated and dilute alkaline solutions to drive ion migration and generate electrical energy, which is supplied to the drive components of the alkaline hydrogen electrolysis cell and the online seawater desalination device.

[0032] S4. The mixed solution after multi-stage reverse electrodialysis ion exchange is sent into the online seawater desalination unit through the mixed solution inlet.

[0033] Compared with existing technologies, the beneficial effects of this invention are as follows: This invention achieves concentration gradient power generation by employing reverse electrodialysis technology. Concentration gradient power generation supplements 10%~20% of the energy consumption of the electrolyzer, and the waste heat from electrolysis helps maintain the temperature of the cell stack. The energy consumption for hydrogen production is reduced from the traditional 4.5 kWh / m³ to below 3.8 kWh / m³, a reduction of over 17%. Online desalination relies on osmotic pressure difference and only requires controlling the energy consumption of the exchange area at 0.1 kWh / m³, which is 90% lower than membrane distillation. The KOH solution is continuously circulated, with no wastewater discharge, which helps reduce environmental pollution. It can solve the problems of high energy consumption for hydrogen production, dependence on external freshwater resources, and lack of comprehensive utilization of waste heat in existing technologies. Attached Figure Description

[0034] Figure 1 This is a schematic diagram of an integrated reverse electrodialysis seawater hydrogen production system;

[0035] Figure 2 This is a schematic diagram of the internal structure of a single electrodialysis cell stack unit.

[0036] In the diagram, there is an alkaline hydrogen production electrolyzer 1, a water inlet 11, and an alkaline circulation outlet 12.

[0037] Electrodialysis cell stack unit 2, high concentration chamber 21, high concentration chamber inlet 211, mixed liquid outlet 212, low concentration chamber 22, low concentration chamber inlet 221, cation exchange membrane 23, anion exchange membrane 24, anode 25, cathode 26, potassium ion 27, hydroxide ion 28, electrode liquid circulation channel 29.

[0038] Online seawater desalination unit 3, desalinated water outlet 31, mixed solution inlet 32, cylindrical body 33, hydrophobic porous membrane module 34, outer metal shell 35, liquid level valve 36;

[0039] Circuit channel 4, seawater tank 5. Detailed Implementation

[0040] Exemplary embodiments will now be described in detail, examples of which are illustrated in the accompanying drawings. When the following description relates to the drawings, unless otherwise indicated, the same numerals in different drawings denote the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with the present invention. Rather, they are merely examples of apparatuses and methods consistent with some aspects of the invention as detailed in the appended claims.

[0041] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The singular forms “a,” “the,” and “the” used in this invention and the appended claims are also intended to include the plural forms unless the context clearly indicates otherwise. It should also be understood that the term “and / or” as used herein refers to and includes any or all possible combinations of one or more of the associated listed items.

[0042] It should be understood that although the terms first, second, third, etc., may be used in this invention to describe various information, this information should not be limited to these terms. These terms are only used to distinguish information of the same type from one another. For example, first information may also be referred to as second information without departing from the scope of this invention, and similarly, second information may also be referred to as first information. Depending on the context, the word "if" as used herein may be interpreted as "when," "when," or "in response to a determination."

[0043] The present invention will now be described in detail with reference to the accompanying drawings. Unless otherwise specified, the features of the following embodiments and implementations can be combined with each other.

[0044] See Figure 1 The integrated reverse electrodialysis (RED) seawater hydrogen production system of the present invention includes an alkaline hydrogen production electrolyzer 1, a multi-stage reverse electrodialysis unit, and an online seawater desalination unit 3. The multi-stage reverse electrodialysis unit includes a concentration power generation module composed of at least three stacked electrodialysis cell units 2. The concentration power generation module utilizes the concentration difference between the concentrated alkaline solution output from the alkaline hydrogen production electrolyzer 1 and the dilute alkaline solution output from the online seawater desalination unit 3 to drive ion migration and generate electricity. The online seawater desalination unit 3 is an alkaline regeneration permeation structure, which utilizes osmotic pressure difference to achieve pure water separation to obtain desalinated water. The power output terminal of the concentration power generation module is connected to the drive components of the alkaline hydrogen electrolyzer 1 and the online seawater desalination device 3 to provide them with power; the alkaline circulation outlet 12 of the alkaline hydrogen electrolyzer 1 is connected to the high concentration chamber 21 of the multi-stage reverse electrodialysis device; the desalinated water outlet 31 of the online seawater desalination device 3 is connected to the water inlet 11 of the alkaline hydrogen electrolyzer 1 and the low concentration chamber 22 of the multi-stage reverse electrodialysis device; the mixed solution outlet 212 of the multi-stage reverse electrodialysis device is connected to the mixed solution inlet 32 ​​of the online seawater desalination device 3.

[0045] Furthermore, the alkaline hydrogen production electrolyzer 1 is internally filled with a 30% potassium hydroxide (KOH) aqueous solution as the alkaline solution. The alkaline hydrogen production electrolyzer 1 is equipped with a water inlet 11 and an alkaline solution circulation outlet 12. The water inlet 11 is used to receive the desalinated water separated by the online seawater desalination unit 3, and the alkaline solution circulation outlet 12 is used to discharge the concentrated alkaline solution, which has increased in concentration after electrolysis, and send it to the high-concentration chamber 21 of the multi-stage reverse electrodialysis unit. Generally, the concentrated alkaline solution is a 20%-40% KOH aqueous solution, and the dilute alkaline solution is a 0%-10% KOH aqueous solution.

[0046] Furthermore, the multi-stage reverse electrodialysis device is equipped with a high-concentration chamber inlet 211 and a low-concentration chamber inlet 221, which are used to introduce concentrated KOH solution and dilute KOH solution, respectively; the multi-stage reverse electrodialysis device is equipped with a mixed solution outlet 212, which is used to discharge the mixed KOH solution after ion exchange and return it to the online seawater desalination device 3.

[0047] Furthermore, the multi-stage reverse electrodialysis unit includes a concentration power generation module, which is composed of eight stacked electrodialysis cell units 2, such as... Figure 1 As shown. The power output terminal of the first-stage electrodialysis cell stack unit 2 is connected to the power input terminal of the next-stage electrodialysis cell stack unit 2; the power input terminal of the first-stage electrodialysis cell stack unit 2 is also the power input terminal of the concentration power generation module, and is electrically connected to the alkaline hydrogen production electrolyzer 1 and the online seawater desalination device 3 through circuit channel 4; the power output terminal of the last-stage electrodialysis cell stack unit 2 is also the power output terminal of the concentration power generation module, and is electrically connected to the drive components of the alkaline hydrogen production electrolyzer 1 and the online seawater desalination device 3 through circuit channel 4, as shown. Figure 1 As shown.

[0048] It should be understood that the number of stages in the electrodialysis cell stack unit 2 can be adjusted according to actual power requirements, for example, set to 6 stages or 10 stages.

[0049] Furthermore, the electrodialysis cell stack unit 2 comprises alternating stacks of several anion exchange membranes (AEMs) 24 and several cation exchange membranes (CEMs) 23. Both sides of the cation exchange membranes 23 and anion exchange membranes 24 are supported by polyethylene terephthalate mesh to form flow chambers, such as... Figure 2 As shown. Specifically, a polyethylene terephthalate mesh is used as a support layer and attached to both sides of the cation exchange membrane 23 and the anion exchange membrane 24 to support the cation exchange membrane 23 and the anion exchange membrane 24 and ensure that the cation exchange membrane 23 and the anion exchange membrane 24 have a certain physical strength. An anode 25 and a cathode 26 are provided on both sides inside the electrodialysis cell stack unit 2, and the chambers containing the anode 25 and the cathode 26 are filled with electrode solution.

[0050] In such Figure 2 In the example shown, the electrodialysis cell stack unit 2 comprises five anion exchange membranes 24 and five cation exchange membranes 23 stacked alternately. It should be understood that the number of cation exchange membranes 23 and anion exchange membranes 24 can be set according to actual needs.

[0051] Preferably, the cation exchange membrane 23 is a perfluorosulfonic acid type cation exchange membrane, and the anion exchange membrane 24 is a quaternary ammonium type anion exchange membrane, both with a membrane thickness of 20 μm.

[0052] Preferably, the thickness of the flow chamber is 0.3 mm.

[0053] Furthermore, the flow chamber includes a high-concentration chamber 21 and a low-concentration chamber 22, which are alternately distributed. The influent to the high-concentration chamber 21 is a concentrated KOH solution after electrolysis in the alkaline hydrogen production electrolyzer 1, while the influent to the low-concentration chamber 22 is desalinated water produced by the online seawater desalination unit 3 as a dilute KOH solution. The final effluent is a mixed KOH solution after multi-stage reverse electrodialysis.

[0054] Furthermore, the anode 25 is adjacent to the anion exchange membrane 24, and the cathode 26 is adjacent to the cation exchange membrane 23. Potassium ions 27 and hydroxide ions 28 in the concentrated KOH solution, under the influence of the concentration difference, pass through the cation exchange membrane 23 and the anion exchange membrane 24 respectively into the low-concentration chamber 22, thus forming an internal current. The direction of the internal current is from the anode 25 to the cathode 26. Simultaneously, the electrode solution continuously circulates between the anode 25 and the cathode 26 through the electrode solution circulation channel 29. An oxidation reaction occurs in the anode chamber, releasing electrons, which are then transferred to the cathode 26 via the external circuit, forming an external current. Figure 2 As shown in the diagram, potassium ions 27 and hydroxide ions 28 enter the electrode solution through cation exchange membrane 23 and anion exchange membrane 24, respectively.

[0055] Furthermore, the online seawater desalination device 3 is placed in the seawater tank 5, such as... Figure 1 As shown, the online seawater desalination device 3 includes a cylindrical body 33, a hydrophobic porous membrane module 34, an outer metal shell 35, and a level valve 36. The hydrophobic porous membrane module 34 is wrapped around the outside of the cylindrical body 33 and fixed by an iron ring, selectively allowing water vapor to pass through while blocking liquid water and salt ions. The outer metal shell 35 is movably fitted onto the outside of the hydrophobic porous membrane module 34, with a rubber gasket between the outer metal shell 35 and the hydrophobic porous membrane module 34 to form a sealed space. The level valve 36 is connected to the outer metal shell 35 and is used to control the movement of the outer metal shell 35 to adjust the effective contact area between the hydrophobic porous membrane module 34 and seawater, thereby changing the permeation flux.

[0056] Furthermore, the hydrophobic porous membrane module 34 is a polytetrafluoroethylene membrane with a pore size of 0.1 μm, which allows only water vapor molecules to permeate while blocking liquid water and salt ions from passing through, so that the desalinated water production is matched with the pure water consumption of the alkaline hydrogen electrolyzer 1.

[0057] Furthermore, the level valve 36 is linked with the outer metal shell 35: when the liquid level in the online seawater desalination unit 3 is lower than the preset value (corresponding to a shortage of pure water in the alkaline hydrogen electrolysis cell 1), the level valve 36 drives the outer metal shell 35 to move to increase the exchange area between the hydrophobic porous membrane module 34 and seawater, which helps to increase the permeation rate of pure water and improve the desalination water production rate; when the liquid level in the online seawater desalination unit 3 is higher than the preset value, the level valve 36 drives the outer metal shell 35 to move to reduce the exchange area between the hydrophobic porous membrane module 34 and seawater, reduce the desalination water production rate, thereby maintaining a dynamic balance between desalination water supply and electrolysis consumption.

[0058] Furthermore, a heat exchange pipe is provided between the alkaline hydrogen production electrolyzer 1 and the multi-stage reverse electrodialysis device. This heat exchange pipe is used to transfer the waste heat generated by the operation of the alkaline hydrogen production electrolyzer 1 to the multi-stage reverse electrodialysis device to help maintain the operating temperature of the electrodialysis cell stack unit 2 at 30-40°C. Specifically, the operating temperature of the electrodialysis cell stack unit 2 can be indirectly maintained at 30-40°C through natural air convection, without the need for additional heating components, which can effectively improve the net power density of the electrodialysis cell stack unit 2.

[0059] Furthermore, the electrical energy output by the concentration power generation module is used to supplement 10% to 20% of the energy consumption of the alkaline hydrogen electrolyzer 1, and the remaining electrical energy is supplied to the drive components of the online seawater desalination unit 3.

[0060] It is worth mentioning that this invention also provides an operating method for the integrated reverse electrodialysis seawater hydrogen production system described in the above embodiments. This operating method specifically includes the following steps:

[0061] Step S1: After pretreatment by quartz sand filtration, seawater comes into contact with the hydrophobic porous membrane module 34 of the online seawater desalination device 3. The level valve 36 controls the movement of the outer metal shell 35 according to the liquid level in the online seawater desalination device 3. The pure water in the seawater is driven to pass through the hydrophobic porous membrane module 34 to form desalinated water through the osmotic pressure difference. The desalinated water is then transported to the alkaline hydrogen electrolysis cell 1 for water replenishment and to the low-concentration chamber 22 of the multi-stage reverse electrodialysis device as dilute alkaline solution.

[0062] Step S2: The alkaline solution electrolyzer 1 is energized to electrolyze the alkaline solution to generate hydrogen. The concentrated alkaline solution formed after electrolysis is transported to the high-concentration chamber 21 of the multi-stage reverse electrodialysis device. The residual heat released during the process is indirectly transferred to the electrodialysis cell stack unit 2 of the multi-stage reverse electrodialysis device through heat exchange pipes to help maintain its operating temperature.

[0063] Step S3: The multi-stage reverse electrodialysis device uses the concentration difference between concentrated and dilute alkaline solutions to drive ion migration and generate electrical energy, which is supplied to the driving components of the alkaline hydrogen electrolysis cell 1 and the online seawater desalination device 3, thereby reducing system energy consumption.

[0064] Step S4: The mixed solution after multi-stage reverse electrodialysis ion exchange is sent into the online seawater desalination unit 3 through the mixed solution inlet 32.

[0065] Furthermore, when the concentration of alkali solution in the alkaline hydrogen production electrolyzer 1 is lower than a certain value, it is necessary to reduce the exchange area between the hydrophobic porous membrane module 34 and the seawater, thereby increasing the concentration of alkali solution. When the concentration of alkali solution in the alkaline hydrogen production electrolyzer 1 is higher than a certain value, it is necessary to increase the exchange area between the hydrophobic porous membrane module 34 and the seawater, thereby reducing the concentration of alkali solution and maintaining the closed-loop stability of the system.

[0066] In this embodiment, combined with Figure 1 and Figure 2 The working process of the system described in this invention is as follows:

[0067] First, seawater undergoes pretreatment via quartz sand filtration to remove suspended solids, and then comes into contact with the hydrophobic porous membrane module 34 of the online seawater desalination unit 3. The KOH solution concentration within the multi-stage reverse electrodialysis unit is much higher than that of the seawater, creating a strong osmotic pressure difference. Driven by this osmotic pressure difference, pure water from the seawater permeates through the hydrophobic porous membrane module 34 as water vapor and enters the online seawater desalination unit 3, where it mixes with the mixed KOH solution to form the desalinated water produced by the online seawater desalination unit 3, which is a dilute KOH solution.

[0068] The liquid level valve 36 monitors the liquid level in the online seawater desalination unit 3 in real time. When the liquid level in the online seawater desalination unit 3 is lower than the preset value (indicating that the alkaline hydrogen electrolyzer 1 consumes a large amount of water and needs to be replenished quickly), the liquid level valve 36 drives the outer metal shell 35 to move, increasing the effective contact area between the hydrophobic porous membrane module 34 and the seawater, thereby increasing the pure water permeation rate. Conversely, when the liquid level in the online seawater desalination unit 3 is higher than the preset value, the liquid level valve 36 drives the outer metal shell 35 to move, reducing the effective contact area between the hydrophobic porous membrane module 34 and the seawater, and reducing the permeation rate. This control mechanism achieves a dynamic balance between desalinated water supply and electrolysis consumption.

[0069] Then, part of the dilute KOH solution generated by the online seawater desalination unit 3 is sent to the alkaline hydrogen electrolysis cell 1 for water replenishment, and the other part is sent to the low concentration chamber 22 of the multi-stage reverse electrodialysis unit.

[0070] Subsequently, the alkaline hydrogen electrolysis cell 1 is energized to electrolyze the KOH solution, producing hydrogen gas at the cathode and oxygen gas at the anode. During electrolysis, water is consumed, the concentration of the alkaline solution increases, and a concentrated KOH solution is formed. The concentrated KOH solution after electrolysis is sent to the high-concentration chamber 21 of the multi-stage reverse electrodialysis unit. At the same time, the waste heat generated during the electrolysis process is indirectly transferred to the electrodialysis cell stack unit 2 of the multi-stage reverse electrodialysis unit through heat exchange pipes to help maintain its operating temperature.

[0071] In a multi-stage reverse electrodialysis apparatus, a concentration difference is formed between the concentrated KOH solution in the high-concentration chamber 21 and the dilute KOH solution in the low-concentration chamber 22. For example... Figure 2 As shown, driven by the concentration gradient, potassium ions 27 in the high-concentration chamber 21 migrate through the cation exchange membrane 23 to the adjacent low-concentration chamber 22, while hydroxide ions 28 migrate through the anion exchange membrane 24 to the other low-concentration chamber 22. This selective ion migration forms an internal current, which converts chemical energy into electrical energy through the redox reaction (electrode solution circulation) occurring between the anode 25 and the cathode 26, and is output through an external circuit. The output electrical energy is preferentially supplied to the alkaline hydrogen electrolyzer 1, supplementing approximately 10% to 20% of its energy consumption. The remaining electrical energy supplies the drive components of the online seawater desalination unit 3, achieving cascaded energy utilization and reducing system energy consumption.

[0072] After ion exchange, the concentrated KOH solution in the high-concentration chamber 21 mixes with the dilute KOH solution in the low-concentration chamber 22 to form a uniformly concentrated mixed KOH solution. This mixed KOH solution after reverse electrodialysis is returned to the online seawater desalination unit 3 through the mixed solution inlet 32, completing the entire cycle regeneration process of the alkali solution. By adjusting the exchange area (i.e., effective contact area) between the hydrophobic porous membrane module 34 and the seawater, the concentration of the returned alkali solution can be precisely controlled, thereby maintaining the stable closed-loop operation of the entire system.

[0073] In summary, this invention, by deeply coupling the alkaline hydrogen production electrolyzer 1, the multi-stage reverse electrodialysis device, and the online seawater desalination device 3, not only recovers energy by generating electricity from the concentration difference, but also achieves self-balancing of seawater desalination and alkaline concentration using the osmosis principle. At the same time, it also recovers the waste heat of the alkaline hydrogen production electrolyzer 1, significantly reducing the overall energy consumption of the system and possessing extremely high industrial application value.

[0074] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. An integrated reverse electrodialysis seawater hydrogen production system, characterized in that, include: Alkaline hydrogen production electrolyzer (1); A multi-stage reverse electrodialysis device includes a concentration power generation module consisting of at least three stages of electrodialysis cell stack units (2) stacked together. The concentration power generation module uses the concentration difference between concentrated alkali solution and dilute alkali solution to drive ion migration and generate electrical energy. Online seawater desalination device (3), wherein the online seawater desalination device (3) is an alkaline regeneration permeation structure, which uses osmotic pressure difference to achieve pure water separation to obtain desalinated water; The power output terminal of the concentration power generation module is connected to the drive components of the alkaline hydrogen electrolyzer (1) and the online seawater desalination device (3) respectively to provide them with power. The alkaline solution circulation outlet (12) of the alkaline solution hydrogen production electrolyzer (1) is connected to the high concentration chamber (21) of the multi-stage reverse electrodialysis device; The desalinated water outlet (31) of the online seawater desalination device (3) is connected to the water inlet (11) of the alkaline hydrogen electrolysis cell (1) and the low concentration chamber (22) of the multi-stage reverse electrodialysis device, respectively. The mixed solution outlet (212) of the multi-stage reverse electrodialysis device is connected to the mixed solution inlet (32) of the online seawater desalination device (3).

2. The integrated reverse electrodialysis seawater hydrogen production system according to claim 1, characterized in that, The multi-stage reverse electrodialysis device is provided with a high-concentration chamber inlet (211) and a low-concentration chamber inlet (221), which are used to introduce concentrated alkali solution and dilute alkali solution respectively; the multi-stage reverse electrodialysis device is provided with a mixed solution outlet (212), which is used to discharge the mixed alkali solution after ion exchange and return it to the online seawater desalination device (3).

3. The integrated reverse electrodialysis seawater hydrogen production system according to claim 1, characterized in that, In the concentration power generation module, the power output terminal of the first-stage electrodialysis cell stack unit (2) is connected to the power input terminal of the second-stage electrodialysis cell stack unit (2); the power input terminal of the first-stage electrodialysis cell stack unit (2) serves as the power input terminal of the concentration power generation module and is electrically connected to the alkaline hydrogen electrolyzer (1) and the online seawater desalination device (3); the power output terminal of the last-stage electrodialysis cell stack unit (2) serves as the power output terminal of the concentration power generation module.

4. The integrated reverse electrodialysis seawater hydrogen production system according to claim 1, characterized in that, The electrodialysis cell stack unit (2) comprises several anion exchange membranes (24) and several cation exchange membranes (23) stacked alternately, with both sides of the cation exchange membranes (23) and anion exchange membranes (24) supported by polyethylene terephthalate mesh to form flow chambers; The electrodialysis cell stack unit (2) has an anode (25) and a cathode (26) on both sides inside, and the chambers where the anode (25) and the cathode (26) are located are filled with electrode liquid.

5. The integrated reverse electrodialysis seawater hydrogen production system according to claim 4, characterized in that, The cation exchange membrane (23) is a perfluorosulfonic acid type cation exchange membrane, and the anion exchange membrane (24) is a quaternary ammonium type anion exchange membrane. The thickness of both membranes is 20 μm. The thickness of the flow chamber is 0.3 mm; The flow chamber includes a high-concentration chamber (21) and a low-concentration chamber (22), which are interleaved. The anode (25) is adjacent to the anion exchange membrane (24), and the cathode (26) is adjacent to the cation exchange membrane (23).

6. The integrated reverse electrodialysis seawater hydrogen production system according to claim 1, characterized in that, The online seawater desalination device (3) includes a cylindrical body (33), a hydrophobic porous membrane module (34), an outer metal shell (35), and a level valve (36). The hydrophobic porous membrane module (34) is wrapped around the outside of the cylindrical body (33) and fixed by an iron ring. The outer metal shell (35) is movably fitted around the outside of the hydrophobic porous membrane module (34), and a rubber gasket is provided between the outer metal shell (35) and the hydrophobic porous membrane module (34) to form a sealed space. The level valve (36) is connected to the outer metal shell (35) and is used to control the movement of the outer metal shell (35) to adjust the effective contact area between the hydrophobic porous membrane module (34) and seawater.

7. The integrated reverse electrodialysis seawater hydrogen production system according to claim 6, characterized in that, The hydrophobic porous membrane assembly (34) is a polytetrafluoroethylene membrane with a pore size of 0.1 μm.

8. The integrated reverse electrodialysis seawater hydrogen production system according to claim 6, characterized in that, The liquid level valve (36) is linked to the outer metal shell (35): When the liquid level in the online seawater desalination device (3) is lower than the preset value, the liquid level valve (36) drives the outer metal shell (35) to move to increase the exchange area between the hydrophobic porous membrane module (34) and the seawater. When the liquid level in the online seawater desalination device (3) is higher than the preset value, the liquid level valve (36) drives the outer metal shell (35) to move to reduce the exchange area between the hydrophobic porous membrane module (34) and the seawater.

9. The integrated reverse electrodialysis seawater hydrogen production system according to claim 1, characterized in that, A heat exchange pipe is provided between the alkaline hydrogen production electrolysis cell (1) and the multi-stage reverse electrodialysis device. The heat exchange pipe is used to transfer the waste heat generated by the alkaline hydrogen production electrolysis cell (1) to the multi-stage reverse electrodialysis device to help maintain the operating temperature of the electrodialysis cell stack unit (2) at 30-40℃. The electrical energy output by the concentration power generation module is used to supplement 10% to 20% of the energy consumption of the alkaline hydrogen electrolyzer (1), and the remaining electrical energy is supplied to the drive components of the online seawater desalination device (3).

10. A method for operating an integrated reverse electrodialysis seawater hydrogen production system as described in any one of claims 1-9, characterized in that, Includes the following steps: S1. After being pretreated by quartz sand filtration, seawater comes into contact with the hydrophobic porous membrane module (34) of the online seawater desalination device (3). The liquid level valve (36) controls the movement of the outer metal shell (35) according to the liquid level inside the online seawater desalination device (3). Through the osmotic pressure difference, pure water in the seawater is driven to pass through the hydrophobic porous membrane module (34) to form desalinated water, which is then transported to the alkaline hydrogen electrolysis cell (1) for water replenishment and to the low concentration chamber (22) of the multi-stage reverse electrodialysis device as dilute alkaline solution. S2, Alkali Hydrogen Electrolysis Cell (1) Electrolyzes alkaline solution to generate hydrogen. The concentrated alkaline solution formed after electrolysis is transported to the high-concentration chamber (21) of the multi-stage reverse electrodialysis device. The residual heat released during the process is indirectly transferred to the electrodialysis cell stack unit (2) of the multi-stage reverse electrodialysis device through heat exchange pipes to help maintain its operating temperature. S3. The multi-stage reverse electrodialysis device uses the concentration difference between concentrated alkali solution and dilute alkali solution to drive ion migration and generate electrical energy, which is supplied to the driving components of the alkali solution hydrogen electrolysis cell (1) and the online seawater desalination device (3). S4. The mixed solution after multi-stage reverse electrodialysis ion exchange is sent to the online seawater desalination unit (3) through the mixed solution inlet (32).

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