Flow battery and reverse electrodialysis integrated system based on salinity difference energy

Abstract

The utility model provides a flow cell and reverse electrodialysis integrated system based on salinity gradient energy. The flow cell and reverse electrodialysis integrated system comprises a reverse electrodialysis membrane stack, a flow cell membrane stack, a positive electrode electrolyte tank, a negative electrode electrolyte tank, a fresh water tank, a saline water tank, an auxiliary electrode water tank and conventional universal accessories. In the reverse electrodialysis membrane stack, two electrode water chambers are positioned on the outer sides of the two electrode plates, a positive electrode chamber for circulating a positive electrode electrolyte is formed between an anode plate and a membrane stack clamping plate, a negative electrode chamber for circulating a negative electrode electrolyte is formed between a cathode plate and a membrane stack clamping plate, and a plurality of fresh water chambers and concentrated water chambers which are alternately arranged are arranged in the reverse electrodialysis membrane stack. According to the utility model, the salinity difference energy is directly converted into the chemical energy of the electrolyte, the system can meet the working requirements of continuous charging and discharging at the same time, and the reverse electrodialysis membrane stack of the system effectively improves the potential problem of leakage or streaming of the electrolyte in the pole chamber.

Description

Technical Field

[0001] The utility model relates to the technical field of salt difference energy power generation, in particular to a salt difference energy-based liquid flow battery and reverse electrodialysis integrated system. Background Art

[0002] Salinity energy is a green renewable energy source. Theoretically, the chemical potential difference between each cubic meter of fresh water flowing into the sea and seawater (salinity content 35wt%) can generate 0.8kWh of electricity. According to statistics, the salinity energy stored in seawater is the second largest marine energy source after wave energy. The amount that can be extracted and utilized is about 2000TWh / year, accounting for more than 10% of the world's renewable energy. The annual runoff of coastal rivers in my country into the sea is about 1.7×10 12 ~1.8×10 12 m 3 The theoretical reserves of salt difference energy resources are about 3.58×1015kJ, and the theoretical total power is about 114GW, which are mainly distributed at the estuary of the Yangtze River and the estuaries of rivers in South China.

[0003] The salt difference between fresh water and salt water can be converted into electrical energy using reverse electrodialysis technology. Reverse electrodialysis (RED) is a process that uses anion and cation exchange membranes to achieve directional ion diffusion and migration driven by salt water concentration differences, thereby generating potential electrical energy. The electrical energy output by the RED device can be directly output to do work, such as for hydrolysis to produce hydrogen, and for driving other water treatment equipment, such as electrodialysis and capacitor deionization. It can also be connected to a flow battery for charging and storing electrical energy. Literature reports that the energy conversion efficiency of laboratory-level reverse electrodialysis power generation is currently 20-35%, and the energy conversion efficiency of commercial application-level flow batteries is mostly in the range of 60%-85%. The use of flow batteries to generate electricity, collect and store the salt difference energy of reverse electrodialysis has a simple conversion energy efficiency of 12%-30%. In this process, there is a lot of electrical energy loss and the energy conversion effect is poor. At present, the relevant technical methods to improve energy efficiency lie in the research and development of ion exchange membrane materials for reverse electrodialysis devices, the optimization of comprehensive operating conditions and parameters, the development and operation optimization of redox reaction pairs for flow batteries, and the optimized design of device integrated systems to improve power generation and operation effects, but there is a lack of relevant original innovative technologies.

[0004] CN 109351196B discloses "a method and device for recycling electric energy of an electrodialyser based on liquid flow battery technology". Liquid flow battery electrolyte is introduced into the polar chamber of the electrodialysis membrane stack, which belongs to the internal coupling technology of electrodialysis and liquid flow battery, and is used to recycle the electric energy of electrodialysis and reduce process energy consumption. CN 108483573A discloses "a method for desalination using a fluid battery and its application". A salt solution is used as the intermediate fluid electrolyte of the fluid battery, and the purpose of desalination of the solution is achieved by charging and discharging the positive and negative active materials.

[0005] The above two inventions have the following technical features and problems: 1. Liquid flow batteries need to work in cycles after charging and then discharging, and the system cannot continuously output electrical energy. 2. Liquid flow battery electrolyte is introduced into the electrode chamber of the membrane stack. There is a phenomenon of cross-flow of electrolyte or ion migration through the membrane into other compartments. This causes the membrane stack effluent to be contaminated, the membrane stack to work unstably, and the operating cost of electrolyte consumption and replenishment to increase. Utility Model Content

[0006] In view of this, the problem to be solved by the utility model is to provide an integrated system of liquid flow battery and reverse electrodialysis based on salt difference energy, which directly converts the salt difference energy into the chemical energy of the electrolyte through the solid-liquid interface of the electrode. The system can meet the working requirements of continuous charging and discharging at the same time, and there is no potential problem of leakage or cross-flow of electrolyte in the electrode chamber in the reverse electrodialysis membrane stack.

[0007] In order to solve the existing technical problems and realize the above-mentioned optimization function, the technical solution adopted by the utility model is:

[0008] A salt difference energy-based liquid flow battery and reverse electrodialysis integrated system, including inlet and outlet pipelines of a fresh water tank, a salt water tank, a liquid flow battery positive electrode electrolyte tank, a liquid flow battery negative electrode electrolyte tank, and an auxiliary electrode water tank are respectively connected to the reverse electrodialysis membrane stack, and necessary conventional supporting components and water pumps, meters, valves, etc. are configured to form a working unit for collecting salt difference energy. The liquid flow battery membrane stack is respectively connected to the inlet and outlet pipelines of the liquid flow battery positive electrode electrolyte tank and the liquid flow battery negative electrode electrolyte tank, and necessary conventional supporting components and water pumps, meters, valves, etc. are configured to form a working unit for energy storage and electrical energy output.

[0009] The reverse electrodialysis membrane stack described above comprises a plurality of alternating anion membranes and a plurality of cationic membranes, a plurality of alternating fresh water chambers and concentrated water chambers, and an electrode water chamber is arranged outside the two electrode plates of the reverse electrodialysis membrane stack, wherein membrane stack clamps are arranged at both ends of the reverse electrodialysis membrane stack, and a positive electrode chamber for circulating positive electrode electrolyte is formed between the anode plate of the reverse electrodialysis membrane stack and the membrane stack clamp, and a negative electrode chamber for circulating negative electrode electrolyte is formed between the cathode plate and the other membrane stack clamp.

[0010] Furthermore, the reverse electrodialysis membrane stack is connected to a fresh water tank for providing fresh water, a concentrated water tank for providing salt water, a positive electrode electrolyte tank for providing positive electrode electrolyte, and a negative electrode electrolyte tank for providing negative electrode electrolyte through pipelines to form a salt difference energy collection unit;

[0011] The flow rates of the positive electrode electrolyte and the negative electrode electrolyte are the same and greater than the flow rates of salt water and fresh water.

[0012] Furthermore, the salinity difference energy collection unit includes an auxiliary anode water tank for removing the reaction products of the anode plate and the cathode plate.

[0013] Further, the positive electrode electrolyte tank and the negative electrode electrolyte tank are connected to the flow battery membrane stack through a discharge pipeline, the positive electrode electrolyte tank includes a first positive electrode electrolyte tank, and the negative electrode electrolyte tank includes a first negative electrode electrolyte tank;

[0014] The water inlet of the first positive electrolyte tank is connected to the flow battery membrane stack and the reverse electrodialysis membrane stack respectively through the first three-way valve, and the water outlet of the first positive electrolyte tank is connected to the flow battery membrane stack and the reverse electrodialysis membrane stack respectively through the second three-way valve;

[0015] The connection structure of the first negative electrode electrolyte tank is exactly the same as that of the first positive electrode electrolyte tank.

[0016] Further, the positive electrode electrolyte tank includes a second positive electrode electrolyte tank, and the negative electrode electrolyte tank includes a second negative electrode electrolyte tank;

[0017] The connection structure between the second positive electrode electrolyte tank and the second negative electrode electrolyte tank is exactly the same as that of the first positive electrode electrolyte tank.

[0018] The advantages and positive effects of the utility model are:

[0019] 1. By setting up a charging membrane stack that only contains a fresh water chamber and a concentrated water chamber, the positive electrode chamber and the negative electrode chamber are located at the two ends of the outside of the charging membrane stack, which can reduce the probability of electrolyte components flowing or migrating to other chambers of the membrane stack, thereby solving a series of adverse effects caused by this phenomenon.

[0020] 2. By directly connecting the positive electrode electrolyte tank and the negative electrode electrolyte tank to the flow battery membrane stack, charging and discharging actions can be performed simultaneously to perform continuous and uninterrupted charging and discharging operations.

[0021] 3. No wire circuits are installed on the anode and cathode plates of the membrane stack device, and the salt difference energy is directly converted into the chemical energy of the flow battery. This is significantly different from the conventional RED coupled flow battery technology, in which the salt difference energy is converted into electrical energy and then into chemical energy, which can greatly improve the theoretical energy conversion efficiency of the salt difference energy. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] The accompanying drawings are used to provide a further understanding of the present invention and constitute a part of the specification. Together with the embodiments of the present invention, they are used to explain the present invention and do not constitute a limitation of the present invention. In the accompanying drawings:

[0023] Figure 1 This is an overall system diagram of a flow battery and reverse electrodialysis integrated system based on salt difference energy of the utility model;

[0024] Figure 2 It is a schematic diagram of the core components of a reverse electrodialysis membrane stack in a flow battery and reverse electrodialysis integrated system based on salinity difference energy of the utility model;

[0025] Figure 3 This is a pipeline connection diagram of a first positive electrode electrolyte tank and a second positive electrode electrolyte tank respectively with a reverse electrodialysis membrane stack and a flow battery membrane stack in a liquid flow battery and reverse electrodialysis integrated system based on salt difference energy of the utility model.

[0026] In the figure: 01, reverse electrodialysis membrane stack; 02, positive electrode electrolyte tank; 02-A, first positive electrode electrolyte tank; 02-B, second positive electrode electrolyte tank; 03, negative electrode electrolyte tank; 04, fresh water tank; 05, concentrated water tank; 06, flow battery membrane stack; 07, auxiliary electrode water tank;

[0027] 01-1, anode plate; 01-2, cathode plate; 01-3, membrane group; 01-4, anion membrane; 01-5, cation membrane; 01-6, positive electrode chamber; 01-7, negative electrode chamber; 01-8, fresh water chamber; 01-9, concentrated water chamber; 01-10, membrane stack splint. DETAILED DESCRIPTION

[0028] The following will be combined with the drawings in the embodiments of the utility model to clearly and completely describe the technical solutions in the embodiments of the utility model. Obviously, the described embodiments are only part of the embodiments of the utility model, not all of the embodiments. Based on the embodiments in the utility model, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the utility model.

[0029] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art in the technical field of the present invention. The terms used herein in the specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention. The term "and / or" used herein includes any and all combinations of one or more related listed items.

[0030] The utility model provides a flow battery and reverse electrodialysis integrated system based on salt difference energy, such as Figure 1 As shown, it includes a reverse electrodialysis membrane stack 01, a liquid flow battery membrane stack 06, a positive electrode electrolyte tank 02, a negative electrode electrolyte tank 03, a fresh water tank 04, a salt water tank (corresponding to a water tank 05), an auxiliary electrode water tank 07 and conventional general accessories.

[0031] like Figure 2 As shown, the integrated system includes a reverse electrodialysis membrane stack 01 composed of a plurality of anion membranes and cation membranes arranged alternately, and the reverse electrodialysis membrane stack 01 is divided into a plurality of fresh water chambers 01-8 and concentrated water chambers 01-9 arranged alternately. A membrane stack clamp 01-10 is provided at both ends of the reverse electrodialysis membrane stack 01, and an anode plate 01-1 and a cathode plate 01-2 are respectively provided between the two membrane stack clamps 01-10 and the reverse electrodialysis membrane stack 01, a positive electrode chamber 01-6 is formed between the anode plate 01-1 and the membrane stack clamp 01-10, and a negative electrode chamber 01-7 is formed between the cathode plate 01-2 and the membrane stack clamp 01-10.

[0032] The fresh water chamber 01-8 is connected to the fresh water tank 04 for providing fresh water; the concentrated water chamber 01-9 is connected to the concentrated water tank 05 for providing salt water; the positive electrode chamber 01-6 is connected to the positive electrode electrolyte tank 02 for providing positive electrode electrolyte; the negative electrode chamber 01-7 is connected to the negative electrode electrolyte tank 03 for providing negative electrode electrolyte.

[0033] The reverse electrodialysis membrane stack 01 is connected to the fresh water tank 04, the concentrated water tank 05, the positive electrode electrolyte tank 02, and the negative electrode electrolyte tank 03 through pipelines, and together they constitute a salt difference energy collection unit.

[0034] The salt difference energy collection unit includes an auxiliary pole water tank 07, in which a conventional electrodialysis pole water solution is provided to remove the reaction products of the anode plate 01-1 and the cathode plate 01-2. The pole water solution can be selected from Na2SO4, Na2SO3 and NaNO3.

[0035] Among them: the reverse electrodialysis membrane stack 01 does not contain a chamber for circulating electrolyte, the positive electrode chamber 01-6 and the negative electrode chamber 01-7 are located on both sides of the reverse electrodialysis membrane stack 01, and are separated by sealed electrode plates, which can reduce the probability of electrolyte cross-flow or migration to the fresh water chamber 01-8 or the concentrated water chamber 01-9. When the equipment is used at the confluence of the sea and the river, it reduces the potential environmental risks of polluting seawater and river water. The reverse electrodialysis membrane stack is not connected to the liquid flow battery membrane stack 06 through a wire circuit. The liquid flow battery and the reverse electrodialysis are deeply coupled. The integration of the working system is realized through the circulation, reaction and circulation of the electrolyte.

[0036] The charging process of the flow battery is as follows: salt water and fresh water are introduced into the fresh water chamber 01-8 and the concentrated water chamber 01-9 at the same time. At the same time, the positive electrode chamber 01-6 and the negative electrode chamber 01-7 are introduced into the positive electrode electrolyte and the negative electrode electrolyte at the same time. The salt water and the fresh water undergo directional ion concentration difference diffusion and electrical migration on both sides of the ion exchange membrane in the reverse electrodialysis membrane stack 01, and an instantaneous potential difference is generated between the anode and cathode plates 01-1 and the positive and negative electrode electrolytes. The positive electrode electrolyte undergoes an oxidation reaction in the positive electrode chamber 01-6 to lose electrons, and the negative electrode electrolyte undergoes a reduction reaction in the positive electrode chamber 01-6 to gain electrons. The positive electrode electrolyte and the negative electrode electrolyte each undergo a half-reaction of the charging process. The salt difference energy is directly converted into the chemical energy of the flow battery electrolyte in this process, so that the total potential of the positive and negative electrodes of the flow battery is increased.

[0037] During the charging process, the electrode plates on both sides of the reverse electrodialysis membrane stack 01 produce a charging half-reaction. The reverse electrodialysis membrane stack 01 is not connected to the liquid flow battery membrane stack 06 through a wire circuit, but through the circulation and chemical reaction of the electrolyte, an integrated system structure is achieved, the number of energy conversions is reduced to improve power generation efficiency, the equipment installation is facilitated, and the safety of equipment power generation is improved.

[0038] The flow rates of the positive electrolyte and the negative electrolyte are the same and greater than the flow rates of salt water and fresh water. One embodiment of the present application is that the linear velocity of the flow rate of the positive electrolyte and the negative electrolyte of the flow battery is controlled at 5-10 cm / s, and the flow rate of salt water and fresh water is controlled at 2 cm / s-5 cm / s.

[0039] The adjacent anion membrane 01-4 and cation membrane 01-5 are defined as a membrane group 01-3. The reverse electrodialysis membrane stack 01 is composed of a plurality of membrane groups 01-3. The more membrane groups 01-3 there are in the reverse electrodialysis membrane stack 01, the greater the pressure difference across the liquid flow battery. The power supply of the liquid flow battery can be increased by increasing the number of membrane groups 01-3.

[0040] The positive electrode electrolyte tank 02 and the negative electrode electrolyte tank 03 are connected to the liquid flow battery membrane stack 06 through a discharge pipeline. In order to enable continuous discharge, the positive electrode electrolyte tank 02 includes a first positive electrode electrolyte tank 02-A and a second positive electrode electrolyte tank 02-B, and the negative electrode electrolyte tank 03 includes a first negative electrode electrolyte tank and a second negative electrode electrolyte tank.

[0041] The water inlet of the first positive electrolyte tank 02-A is connected to the flow battery membrane stack 06 and the reverse electrodialysis membrane stack 01 through the first three-way valve, and the water outlet of the first positive electrolyte tank 02-A is connected to the flow battery membrane stack 06 and the reverse electrodialysis membrane stack 01 through the second three-way valve. The connection structure of the second positive electrolyte tank 02-B, the first negative electrolyte tank and the second negative electrolyte tank is exactly the same as that of the first positive electrolyte tank 02-A.

[0042] When the liquid flow battery is discharging: the first positive electrode electrolyte tank 02-A and the first negative electrode electrolyte are connected to the liquid flow battery membrane stack 06, providing the liquid flow battery membrane stack 06 with half-reacted positive electrode electrolyte and negative electrode electrolyte; the second positive electrode electrolyte tank 02-B and the second negative electrode electrolyte tank are connected to the reverse electrodialysis membrane stack 01, receiving and storing the half-reacted positive electrode electrolyte and negative electrode electrolyte.

[0043] The above two processes are carried out simultaneously and alternately, which can continuously provide electrolyte to the liquid flow battery membrane stack 06, so that the liquid flow battery can continuously provide stable electrical energy.

[0044] In order to further improve the continuity of power supply of the flow battery, the fresh water and salt water with changed salinity flowing out of the reverse electrodialysis membrane stack 01 are directly discharged, and the fresh water tank 04 and the concentrated water tank 05 are continuously replenished with fresh water and salt water, and the flow battery is continuously charged.

[0045] One embodiment of the present application is that the output power of the reverse electrodialysis membrane stack 01 should be greater than the discharge power of the flow battery membrane stack 06. The open circuit voltage and output power of the reverse electrodialysis membrane stack 01 are affected by parameters such as the number of membrane pairs, the effective working area of ​​the membrane, the inlet water concentration difference, the inlet water flow rate, and the inlet water temperature. The specific specifications and operating parameters of the membrane stack should be designed to match the discharge power of the flow battery membrane stack 06, and a margin should be left to improve the stability of the discharge power.

[0046] The above embodiments of the utility model are described in detail, but the above contents are only preferred embodiments of the utility model and cannot be considered to limit the scope of implementation of the utility model. All equivalent changes and improvements made within the scope of the utility model should still fall within the scope of this patent.

Claims

1. A flow battery and reverse electrodialysis integrated system based on salinity difference energy, characterized in that: The invention comprises a reverse electrodialysis membrane stack (01), which comprises a plurality of anion membranes and a plurality of cation membranes arranged alternately, and a plurality of fresh water chambers (01-8) and concentrated water chambers (01-9) arranged alternately. Both ends of the reverse electrodialysis membrane stack (01) are provided with membrane stack clamps (01-10). A positive electrode chamber (01-6) for circulating positive electrode electrolyte is formed between the anode plate (01-1) of the reverse electrodialysis membrane stack (01) and the membrane stack clamp (01-10), and a negative electrode chamber (01-7) for circulating negative electrode electrolyte is formed between the cathode plate (01-2) and another membrane stack clamp (01-10).

2. The integrated system of flow battery and reverse electrodialysis based on salinity difference energy according to claim 1, characterized in that: The reverse electrodialysis membrane stack (01) is connected to a fresh water tank (04) for providing fresh water, a concentrated water tank (5) for providing salt water, a positive electrode electrolyte tank (02) for providing positive electrode electrolyte, and a negative electrode electrolyte tank (03) for providing negative electrode electrolyte through pipelines, respectively, to form a salt difference energy collection unit; The flow rates of the positive electrode electrolyte and the negative electrode electrolyte are the same and greater than the flow rates of salt water and fresh water.

3. The integrated system of flow battery and reverse electrodialysis based on salinity difference energy according to claim 2, characterized in that: The salt difference energy collection unit comprises an auxiliary anode water tank (07) for removing reaction products of the anode plate (01-1) and the cathode plate (01-2).

4. The integrated system of flow battery and reverse electrodialysis based on salinity difference energy according to claim 2, characterized in that: The positive electrode electrolyte tank (02) and the negative electrode electrolyte tank (03) are connected to the flow battery membrane stack (06) through a discharge pipeline, the positive electrode electrolyte tank (02) includes a first positive electrode electrolyte tank (02-A), and the negative electrode electrolyte tank (03) includes a first negative electrode electrolyte tank (03); The water inlet of the first positive electrolyte tank (02-A) is respectively connected to the flow battery membrane stack (06) and the reverse electrodialysis membrane stack (01) through a first three-way valve, and the water outlet of the first positive electrolyte tank (02-A) is respectively connected to the flow battery membrane stack (06) and the reverse electrodialysis membrane stack (01) through a second three-way valve; The connection structure of the first negative electrode electrolyte tank (03) is completely the same as that of the first positive electrode electrolyte tank (02-A).

5. The integrated system of flow battery and reverse electrodialysis based on salinity difference energy according to claim 4, characterized in that: The positive electrode electrolyte tank (02) includes a second positive electrode electrolyte tank (02-B), and the negative electrode electrolyte tank (03) includes a second negative electrode electrolyte tank; The connection structure between the second positive electrode electrolyte tank (02-B) and the second negative electrode electrolyte tank is exactly the same as that of the first positive electrode electrolyte tank (02-A).

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