A multi-stage reverse electrodialysis device system for generating electricity using concentrated seawater salinity difference and a method for generating electricity

Abstract

The application provides a multi-stage reverse electrodialysis device system and a power generation method thereof, which utilizes the salt difference energy of concentrated seawater. The device system comprises a concentrated seawater tank, n-stage river water tanks, n-stage electrolyte tanks and n-stage reverse electrodialysis membrane stacks connected in series, and n is greater than or equal to 2. The concentrated seawater tank is connected to the first-stage reverse electrodialysis membrane stack. The i-stage river water tank and the i-stage electrolyte tank are independently connected to the i-stage reverse electrodialysis membrane stack, and 1 is less than or equal to i and is less than or equal to n. The power generation method comprises the following steps: (1) introducing the concentrated seawater, the river water and the electrolyte into the concentrated seawater tank, the n-stage river water tanks and the n-stage electrolyte tanks respectively; (2) setting the flow rates of the concentrated seawater, the river water and the electrolyte, and starting the n-stage reverse electrodialysis membrane stacks to generate power. The device system provided by the application effectively utilizes the salt difference energy and reduces the salinity of the concentrated seawater, realizes the standard discharge of the concentrated seawater, meets the green and environmental protection resource utilization requirements and is conducive to large-scale popularization and application.

Description

Technical Field

[0001] This invention belongs to the field of power generation technology, and relates to a reverse electrodialysis device system, and more particularly to a multi-stage reverse electrodialysis device system and its power generation method that utilizes the salinity gradient energy of concentrated seawater to generate electricity. Background Technology

[0002] With the introduction of the "dual carbon" target, replacing traditional fossil fuels with clean energy has become an important development direction for the future. my country has vast sea areas, and the utilization and development of salinity gradient energy has profound research value. In near-shore estuaries, especially in the Yangtze River region and areas south of it, salinity gradient energy reserves account for approximately 92% of the national total. Meanwhile, regions like Qinghai Province, which contain inland salt lakes, also possess substantial exploitable salinity gradient energy. Furthermore, with the continuous development of my country's seawater desalination technology, the effective treatment of its byproduct, concentrated seawater, has attracted widespread attention from industry professionals. The salinity of concentrated seawater is generally twice that of normal seawater; direct discharge would impact or disrupt the marine ecosystem and result in significant energy waste.

[0003] CN 112648159A discloses an automatic seawater salinity differential water supply and power generation mechanism, including a power generation chamber. A freshwater booster chamber is fixedly connected to the left side of the power generation chamber, and a potential energy chamber is fixedly connected to the right side of the power generation chamber. A pumping frame is fixedly connected to the left side of the freshwater booster chamber. An acceleration component is rotatably connected inside the pumping frame, and a pressurization component is rotatably connected to the left side of the acceleration component. This automatic seawater salinity differential water supply and power generation mechanism uses a booster turbine to drive the acceleration component to rotate, which in turn drives the pressurization component to rotate. Simultaneously, the power generation turbine drives the generator assembly through an acceleration gear set. With the cooperation of structures such as the booster pipe, it achieves power generation assisted by various natural energy sources, resulting in a clean and environmentally friendly effect. An expansion block is displaced outwards, and with the cooperation of mechanisms such as the potential energy chamber, it achieves automatic energy storage. However, the structural design of this power generation mechanism is relatively complex, its operation is cumbersome, and it cannot achieve the desalination of concentrated seawater.

[0004] CN 112636635A discloses an energy-saving and environmentally friendly power generation device that utilizes seawater salinity gradient energy for seawater desalination. Both ends of the screw are movably connected to limiting components, which provide protection. The rotating shaft of the screw gradually moves downwards under pressure and into the power generation chamber. Through the action of a track adapted on the sliding groove and the activation of an inductive switch, the internal coolant changes from a blocky solid state to a liquid state, thus generating seawater salinity gradient energy. This energy is then pumped into the reverse osmosis unit using low pressure. Furthermore, the downward movement of the rotating shaft drives the transmission shaft, which in turn drives the low-pressure component to rotate synchronously, desalinating the seawater simultaneously with the low-pressure component and the seawater inside the reverse osmosis unit. However, this power generation device also suffers from complex structural design and cumbersome operation, and its seawater processing capacity is relatively limited, making large-scale application difficult.

[0005] Therefore, it is evident that providing a device system for generating electricity using the salinity gradient of concentrated seawater, while effectively utilizing salinity gradient energy and reducing the salinity of concentrated seawater to achieve compliant discharge of concentrated seawater, meeting the requirements of green and environmentally friendly resource utilization, and reducing the complexity of the device structure, simplifying the operation process, and improving the treatment efficiency, has become an urgent problem that needs to be solved by those skilled in the art. Summary of the Invention

[0006] The purpose of this invention is to provide a multi-stage reverse electrodialysis device system and its power generation method that utilizes the salinity gradient energy of concentrated seawater to generate electricity. The device system effectively utilizes the salinity gradient energy while reducing the salinity of concentrated seawater, achieving the standard discharge of concentrated seawater, meeting the requirements of green and environmentally friendly resource utilization, reducing the complexity of the device structure, simplifying the operation process, improving the treatment efficiency, and facilitating large-scale promotion and application.

[0007] To achieve this objective, the present invention adopts the following technical solution:

[0008] In a first aspect, the present invention provides a multi-stage reverse electrodialysis device system that utilizes the salinity gradient energy of concentrated seawater to generate electricity. The multi-stage reverse electrodialysis device system includes a concentrated seawater tank, an n-stage river water tank, an n-stage electrolyte tank, and an n-stage reverse electrodialysis membrane stack connected in series, where n ≥ 2. For example, n can be 2, 3, 4, 5, 6, 7, 8, 9, or 10, but is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0009] The concentrated seawater tank is connected to the first-stage reverse electrodialysis membrane stack;

[0010] The i-th stage river water tank and the i-th stage electrolyte tank are independently connected to the i-th stage reverse electrodialysis membrane stack, and 1≤i≤n.

[0011] The device system provided by this invention is based on reverse electrodialysis technology. It uses the salinity gradient energy between concentrated seawater and river water to generate electricity, and fully recovers the salinity gradient energy through multi-stage reverse electrodialysis. At the same time, it significantly reduces the salinity of concentrated seawater, achieving the standard discharge of concentrated seawater and meeting the requirements of green and environmentally friendly resource utilization.

[0012] Furthermore, the device system provided by this invention has a simple structure, is easy to operate, improves processing efficiency, and is conducive to large-scale promotion and application.

[0013] Preferably, the reverse electrodialysis membrane stack includes an ion exchange membrane stack and a cathode plate and an anode plate respectively disposed on both sides of the ion exchange membrane stack.

[0014] Preferably, the ion exchange membrane stack comprises alternating anion exchange membranes and cation exchange membranes, and a partition is provided between the anion exchange membranes and cation exchange membranes.

[0015] Preferably, a cathode chamber is formed between the cathode plate and the ion exchange membrane stack.

[0016] Preferably, an anode chamber is formed between the anode plate and the ion exchange membrane stack.

[0017] Preferably, alternating concentrate chambers and desalination chambers are formed between the alternating anion exchange membranes and cation exchange membranes.

[0018] Preferably, the cathode chamber and the anode chamber are independently and cyclically connected to the same electrolyte tank.

[0019] Preferably, the inlet of the concentrate chamber is connected to the concentrate tank or the concentrate chamber of the previous stage reverse electrodialysis membrane stack, and the outlet is connected to the concentrate chamber of the next stage reverse electrodialysis membrane stack or discharged directly.

[0020] Specifically, the inlet of the concentrate chamber of the first-stage reverse electrodialysis membrane stack is connected to the concentrate seawater tank, and the inlets of the concentrate chambers of the remaining stages of the reverse electrodialysis membrane stack are connected to the concentrate chamber of the previous stage of the reverse electrodialysis membrane stack; the outlet of the concentrate chamber of the last stage of the reverse electrodialysis membrane stack is directly discharged, and the outlets of the concentrate chambers of the remaining stages of the reverse electrodialysis membrane stack are connected to the concentrate chamber of the next stage of the reverse electrodialysis membrane stack.

[0021] Preferably, the inlet of the freshwater chamber is connected to the same-stage river water tank, and the outlet is directly discharged.

[0022] Preferably, the multi-stage reverse electrodialysis device system further includes n-stage freshwater tanks, where n≥2. For example, n can be 2, 3, 4, 5, 6, 7, 8, 9 or 10, but is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0023] Preferably, the outlet of the concentrate chamber is connected to the concentrate chamber of the next stage reverse electrodialysis membrane stack via a freshwater tank of the same stage or is discharged directly.

[0024] In this invention, the setting of freshwater tanks facilitates real-time sampling and analysis, and makes it easier to monitor the processing capacity of each level of reverse electrodialysis membrane stack.

[0025] In a second aspect, the present invention provides a method for generating electricity using a multi-stage reverse electrodialysis device system as described in the first aspect, the method comprising the following steps:

[0026] (1) The concentrated seawater, river water and electrolyte are respectively introduced into the concentrated seawater tank, the n-stage river water tank and the n-stage electrolyte tank;

[0027] (2) Set the flow rates of concentrated seawater, river water and electrolyte, and start the n-stage reverse electrodialysis membrane stack to generate electricity.

[0028] Preferably, the salinity of the concentrated seawater in step (1) is 60-80 g / L, for example, it can be 60 g / L, 62 g / L, 64 g / L, 66 g / L, 68 g / L, 70 g / L, 72 g / L, 74 g / L, 76 g / L, 78 g / L or 80 g / L, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0029] Preferably, the salinity of the river water in step (1) is 0.6-0.8 g / L, for example, it can be 0.6 g / L, 0.62 g / L, 0.64 g / L, 0.66 g / L, 0.68 g / L, 0.7 g / L, 0.72 g / L, 0.74 g / L, 0.76 g / L, 0.78 g / L or 0.8 g / L, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0030] Preferably, the electrolyte in the electrolyte in step (1) includes potassium ferrocyanide, potassium ferrocyanide and sodium chloride.

[0031] Preferably, the concentration of potassium ferricyanide is 0.02-0.08 mol / L, for example, it can be 0.02 mol / L, 0.03 mol / L, 0.04 mol / L, 0.05 mol / L, 0.06 mol / L, 0.07 mol / L or 0.08 mol / L, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0032] Preferably, the concentration of potassium ferrocyanide is 0.02-0.08 mol / L, for example, it can be 0.02 mol / L, 0.03 mol / L, 0.04 mol / L, 0.05 mol / L, 0.06 mol / L, 0.07 mol / L or 0.08 mol / L, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0033] Preferably, the concentration of sodium chloride is 30-50 g / L, for example, it can be 30 g / L, 32 g / L, 34 g / L, 36 g / L, 38 g / L, 40 g / L, 42 g / L, 44 g / L, 46 g / L, 48 g / L or 50 g / L, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0034] Preferably, the membrane surface flow velocities of the concentrated seawater and river water in step (2) are independently 0.35-0.40 cm / s, for example, 0.35 cm / s, 0.36 cm / s, 0.37 cm / s, 0.38 cm / s, 0.39 cm / s or 0.40 cm / s, but are not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0035] Preferably, the membrane surface flow rate of the electrolyte in step (2) is 0.42-0.46 cm / s, for example, it can be 0.42 cm / s, 0.43 cm / s, 0.44 cm / s, 0.45 cm / s or 0.46 cm / s, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0036] Preferably, the power density of the electricity generated in step (2) is 0.34-0.44 Wh / m³. 3 For example, it could be 0.34Wh / m 3 0.35Wh / m 3 0.36Wh / m 3 0.37Wh / m 3 0.38Wh / m 3 0.39Wh / m 3 0.40Wh / m 3 0.41Wh / m 3 0.42Wh / m 3 0.43Wh / m 3 Or 0.44Wh / m 3 However, this does not apply to all values ​​listed; other unlisted values ​​within the same range also apply.

[0037] Compared with the prior art, the present invention has the following beneficial effects:

[0038] (1) The device system provided by the present invention is based on reverse electrodialysis technology, which uses the salinity gradient energy between concentrated seawater and river water to generate electricity, and fully recovers the salinity gradient energy through multi-stage reverse electrodialysis. At the same time, it significantly reduces the salinity of concentrated seawater, achieves the standard discharge of concentrated seawater, and meets the requirements of green and environmentally friendly resource utilization.

[0039] (2) The device system provided by the present invention has a simple structure, is easy to operate, improves processing efficiency, and is conducive to large-scale promotion and application. Attached Figure Description

[0040] Figure 1 This is a schematic diagram of the multi-stage reverse electrodialysis device system provided by the present invention;

[0041] Figure 2This is a schematic diagram of the first-stage reverse electrodialysis membrane stack in the multi-stage reverse electrodialysis device system provided by the present invention;

[0042] Figure 3 This is the open-circuit voltage diagram of the device system provided in Example 1 during the power generation process;

[0043] Figure 4 This is a power density diagram of the device system provided in Example 1 during the power generation process.

[0044] Wherein: 1-Ion exchange membrane stack; 1a-Concentrate chamber; 1b-Desalinate chamber; 2-Cathode plate; 2a-Cathode chamber; 3-Anode plate; 3a-Anode chamber; 10-Concentrate seawater tank; 20-River water tank; 21-First-stage river water tank; 22-Second-stage river water tank; 2n-Nth-Nth-stage river water tank; 30-Electrolyte tank; 31-First-stage electrolyte tank; 32-Second-stage electrolyte tank; 3n-Nth-stage electrolyte tank; 40-Reverse electrodialysis membrane stack; 41-First-stage reverse electrodialysis membrane stack; 42-Second-stage reverse electrodialysis membrane stack; 4n-Nth-stage reverse electrodialysis membrane stack; 50-Desalinate seawater tank; 51-First-stage desalinate seawater tank; 52-Second-stage desalinate seawater tank; 5n-Nth-stage desalinate seawater tank. Detailed Implementation

[0045] The technical solution of the present invention will be further illustrated below through specific embodiments. Those skilled in the art should understand that the embodiments described are merely illustrative of the present invention and should not be construed as limiting the invention.

[0046] This invention provides a multi-stage reverse electrodialysis device system that utilizes the salinity gradient of concentrated seawater to generate electricity, such as... Figure 1 As shown, the multi-stage reverse electrodialysis device system includes a concentrated seawater tank 10, an n-stage river water tank 20, an n-stage electrolyte tank 30, an n-stage reverse electrodialysis membrane stack 40 connected in series, and an n-stage fresh seawater tank 50, where n ≥ 2. The concentrated seawater tank 10 is connected to the first-stage reverse electrodialysis membrane stack 41. The i-th stage river water tank and the i-th stage electrolyte tank are independently connected to the i-th stage reverse electrodialysis membrane stack, where 1 ≤ i ≤ n. For example, the first-stage river water tank 21 and the first-stage electrolyte tank 31 are independently connected to the first-stage reverse electrodialysis membrane stack 41; the second-stage river water tank 22 and the second-stage electrolyte tank 32 are independently connected to the third-stage reverse electrodialysis membrane stack 42; and so on, ..., the n-th stage river water tank 2n and the n-th stage electrolyte tank 3n are independently connected to the n-th stage reverse electrodialysis membrane stack 4n.

[0047] like Figure 2As shown, taking the first-stage reverse electrodialysis membrane stack 41 as an example, the reverse electrodialysis membrane stack includes an ion exchange membrane stack 1 and a cathode plate 2 and an anode plate 3 respectively disposed on both sides of the ion exchange membrane stack 1; the ion exchange membrane stack 1 includes alternating anion exchange membranes and cation exchange membranes, and a partition (not shown in the figure) is disposed between the anion exchange membranes and cation exchange membranes. The cathode plate 2 and the ion exchange membrane stack 1 form a cathode chamber 2a; the anode plate 3 and the ion exchange membrane stack 1 form an anode chamber 3a; the alternating anion exchange membranes and cation exchange membranes form alternating concentrate chambers 1a and desalination chambers 1b. The cathode chambers 2a and anode chambers 3a are independently and cyclically connected to the first-stage electrolyte tank 31; the inlet of the concentrate chamber 1a is connected to the concentrated seawater tank 10, and the outlet is connected to the concentrate chamber of the second-stage reverse electrodialysis membrane stack 42 through the first-stage desalination seawater tank 51; the inlet of the desalination chamber 1b is connected to the first-stage river water tank 21, and the outlet is directly discharged.

[0048] Similarly, the structure of the second-stage reverse electrodialysis membrane stack 42 is similar to that of the first-stage reverse electrodialysis membrane stack 41, so it will not be described in detail here. The only difference is that the inlet of the concentrate chamber of the second-stage reverse electrodialysis membrane stack 42 is connected to the concentrate chamber 1a of the first-stage reverse electrodialysis membrane stack 41, instead of the concentrated seawater tank 10. The structure of the nth-stage reverse electrodialysis membrane stack 4n is similar to that of the second-stage reverse electrodialysis membrane stack 42, so it will not be described in detail here. The only difference is that the outlet of the concentrate chamber of the nth-stage reverse electrodialysis membrane stack 4n is directly discharged through the nth-stage fresh seawater tank 5n.

[0049] Example 1

[0050] This embodiment provides a multi-stage reverse electrodialysis device system and its power generation method that utilizes the salinity gradient of concentrated seawater to generate electricity. The multi-stage reverse electrodialysis device system has 10 stages. The effective area of ​​the anion and cation exchange membranes in each stage of the reverse electrodialysis membrane stack 40 is 36cm×63cm, and the number of membrane pairs is 150. The other structures have been described previously, so they will not be repeated here.

[0051] In this embodiment, the power generation method includes the following steps:

[0052] (1) Concentrated seawater with a salinity of 66.6 g / L, river water with a salinity of 0.66 g / L, and electrolyte are respectively introduced into concentrated seawater tank 10, river water tank 20, and electrolyte tank 30; the electrolyte in the electrolyte includes potassium ferricyanide with a concentration of 0.05 mol / L, potassium ferrocyanide with a concentration of 0.05 mol / L, and sodium chloride with a concentration of 40 g / L;

[0053] (2) Set the inflow velocity of concentrated seawater and river water to 520 L / h (membrane surface velocity of 0.35 cm / s) and the inflow velocity of electrolyte to 30 L / h (membrane surface velocity of 0.44 cm / s), and start the reverse electrodialysis membrane stack 40 to generate electricity.

[0054] This embodiment uses a vacuum pump to control the solution flow rate and conducts experiments using a series connection of concentrated solutions and a parallel connection of distilled solutions. The open-circuit voltage is as follows: Figure 3 As shown, its value remains relatively stable at around 20.5V; the power density of the generated electricity is as follows: Figure 4 As shown, from a maximum of 0.44Wh / m 3 Gradually decreased to 0.34Wh / m 3 .

[0055] Based on comprehensive estimates, the total power generation in this embodiment can reach 508Wh / m³. 3 Furthermore, after undergoing 10 stages of reverse electrodialysis, the salinity of the concentrated seawater was reduced to 40 g / L, meeting the discharge standards.

[0056] Example 2

[0057] This embodiment provides a multi-stage reverse electrodialysis device system and its power generation method that utilizes the salinity gradient of concentrated seawater to generate electricity. The multi-stage reverse electrodialysis device system has 10 stages. The effective area of ​​the anion and cation exchange membranes in each stage of the reverse electrodialysis membrane stack 40 is 36cm×63cm, and the number of membrane pairs is 150. The other structures have been described previously, so they will not be repeated here.

[0058] In this embodiment, the power generation method includes the following steps:

[0059] (1) Concentrated seawater with a salinity of 60 g / L, river water with a salinity of 0.6 g / L, and electrolyte are respectively introduced into concentrated seawater tank 10, river water tank 20, and electrolyte tank 30; the electrolyte in the electrolyte includes potassium ferricyanide with a concentration of 0.02 mol / L, potassium ferrocyanide with a concentration of 0.02 mol / L, and sodium chloride with a concentration of 30 g / L;

[0060] (2) Set the inflow velocity of concentrated seawater and river water to 520 L / h (membrane surface velocity of 0.35 cm / s) and the inflow velocity of electrolyte to 30 L / h (membrane surface velocity of 0.44 cm / s), and start the reverse electrodialysis membrane stack 40 to generate electricity.

[0061] In this embodiment, a vacuum pump was used to control the solution flow rate. Experiments were conducted using a series connection of concentrated water and a parallel connection of desalinated water. The open-circuit voltage remained relatively stable at around 18.1V. The power density generated was a maximum of 52.03Wh / m³. 3 Gradually decreased to 40.32Wh / m 3 .

[0062] Based on comprehensive estimates, the total power generation in this embodiment can reach 468.5Wh / m³. 3 Furthermore, after undergoing 10 stages of reverse electrodialysis, the salinity of the concentrated seawater was reduced to 40.86 g / L, meeting the discharge standards.

[0063] Example 3

[0064] This embodiment provides a multi-stage reverse electrodialysis device system and its power generation method that utilizes the salinity gradient of concentrated seawater to generate electricity. The multi-stage reverse electrodialysis device system has 10 stages. The effective area of ​​the anion and cation exchange membranes in each stage of the reverse electrodialysis membrane stack 40 is 36cm×63cm, and the number of membrane pairs is 150. The other structures have been described previously, so they will not be repeated here.

[0065] In this embodiment, the power generation method includes the following steps:

[0066] (1) Concentrated seawater with a salinity of 80 g / L, river water with a salinity of 0.8 g / L, and electrolyte are respectively introduced into concentrated seawater tank 10, river water tank 20, and electrolyte tank 30; the electrolyte in the electrolyte includes potassium ferricyanide with a concentration of 0.08 mol / L, potassium ferrocyanide with a concentration of 0.08 mol / L, and sodium chloride with a concentration of 50 g / L;

[0067] (2) Set the inflow velocity of concentrated seawater and river water to 520 L / h (membrane surface velocity of 0.35 cm / s) and the inflow velocity of electrolyte to 30 L / h (membrane surface velocity of 0.44 cm / s), and start the reverse electrodialysis membrane stack 40 to generate electricity.

[0068] In this embodiment, a vacuum pump was used to control the solution flow rate. Experiments were conducted using a series connection of concentrated water and a parallel connection of desalinated water. The open-circuit voltage remained relatively stable at around 20.0V. The power density generated was a maximum of 70.03Wh / m³. 3 Gradually decreased to 58.77Wh / m 3 .

[0069] Based on comprehensive estimates, the total power generation in this embodiment can reach 635.83Wh / m³. 3 Furthermore, after undergoing a series of reverse electrodialysis operations, the salinity of the concentrated seawater was reduced to 39 g / L, meeting the discharge standards.

[0070] Comparative Example 1

[0071] This comparative example provides a single-stage reverse electrodialysis device system and its power generation method that utilizes the salinity gradient of concentrated seawater to generate electricity. The effective area of ​​the anion and cation exchange membranes in the reverse electrodialysis membrane stack is 36cm×63cm, and the number of membrane pairs is 150. The rest of the structure is the same as in Example 1, except that the multi-stage is changed to a single-stage. The specific power generation method is the same as in Example 1, so it will not be described in detail here.

[0072] Based on comprehensive estimates, the total power generation of this comparative example is 76.8 Wh / m³. 3 Furthermore, after a single-stage reverse electrodialysis process, the salinity of the concentrated seawater only decreased to 59.71 g / L, which does not meet the discharge standards.

[0073] Therefore, the device system provided by the present invention is based on reverse electrodialysis technology, which uses the salinity gradient energy between concentrated seawater and river water to generate electricity. The salinity gradient energy is fully recovered through multi-stage reverse electrodialysis, while the salinity of the concentrated seawater is significantly reduced, achieving the standard discharge of concentrated seawater and meeting the requirements of green and environmentally friendly resource utilization.

[0074] Furthermore, the device system provided by this invention has a simple structure, is easy to operate, improves processing efficiency, and is conducive to large-scale promotion and application.

[0075] The applicant declares that the above description is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention fall within the protection and disclosure scope of the present invention.

Claims

1. A multi-stage reverse electrodialysis device system that utilizes the salinity gradient of concentrated seawater to generate electricity, characterized in that, The multi-stage reverse electrodialysis device system includes a concentrated seawater tank, an n-stage river water tank, an n-stage electrolyte tank, and an n-stage reverse electrodialysis membrane stack connected in series, where n≥2; The concentrated seawater tank is connected to the first-stage reverse electrodialysis membrane stack; The i-th stage river water tank and the i-th stage electrolyte tank are independently connected to the i-th stage reverse electrodialysis membrane stack, and 1≤i≤n; The reverse electrodialysis membrane stack includes an ion exchange membrane stack and a cathode plate and an anode plate respectively disposed on both sides of the ion exchange membrane stack; the ion exchange membrane stack includes alternating anion exchange membranes and cation exchange membranes, and a partition is disposed between the anion exchange membranes and cation exchange membranes; A cathode chamber is formed between the cathode plate and the ion exchange membrane stack; an anode chamber is formed between the anode plate and the ion exchange membrane stack; alternating concentrate and desalination chambers are formed between the alternating anion exchange membranes and cation exchange membranes; the cathode chamber and anode chamber are independently and cyclically connected to the same electrolyte tank; the inlet of the concentrate chamber is connected to the concentrate tank or the concentrate chamber of the previous stage reverse electrodialysis membrane stack, and the outlet is connected to the concentrate chamber of the next stage reverse electrodialysis membrane stack or directly discharged; the inlet of the desalination chamber is connected to the same stage river water tank, and the outlet is directly discharged. The multi-stage reverse electrodialysis device system also includes n-stage freshwater tanks, where n≥2; the outlet of the concentrate chamber is connected to the concentrate chamber of the next stage reverse electrodialysis membrane stack via the same-stage freshwater tank or is directly discharged.

2. A method for generating electricity using the multi-stage reverse electrodialysis device system as described in claim 1, characterized in that, The method includes the following steps: (1) The concentrated seawater, river water and electrolyte are respectively introduced into the concentrated seawater tank, the nth-stage river water tank and the nth-stage electrolyte tank; (2) Set the flow rates of concentrated seawater, river water and electrolyte, and start the n-stage reverse electrodialysis membrane stack to generate electricity.

3. The method according to claim 2, characterized in that, The salinity of the concentrated seawater in step (1) is 60-80 g / L.

4. The method according to claim 2, characterized in that, The salinity of the river water in step (1) is 0.6-0.8 g / L.

5. The method according to claim 2, characterized in that, The electrolyte in the electrolyte of step (1) includes potassium ferricyanide, potassium ferrocyanide and sodium chloride.

6. The method according to claim 5, characterized in that, The concentration of potassium ferricyanide is 0.02-0.08 mol / L.

7. The method according to claim 5, characterized in that, The concentration of potassium ferrocyanide is 0.02-0.08 mol / L.

8. The method according to claim 5, characterized in that, The concentration of sodium chloride is 30-50 g / L.

9. The method according to claim 2, characterized in that, In step (2), the membrane surface flow velocities of the concentrated seawater and the river water are independently 0.35-0.40 cm / s.

10. The method according to claim 2, characterized in that, The membrane flow rate of the electrolyte in step (2) is 0.42-0.46 cm / s.

11. The method according to claim 2, characterized in that, The power density of the electricity generated in step (2) is 0.34-0.44 Wh / m³. 3 .

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