An instant response iron-chromium liquid flow battery quantitative rebalancing system and rebalancing method

Abstract

The present invention relates to the technical field of iron-chromium liquid flow battery, and specifically discloses a quantitative rebalancing system and rebalancing method of an iron-chromium liquid flow battery with instant response, wherein the system comprises an iron-chromium liquid flow battery stack, a positive electrode storage tank, a negative electrode storage tank, a control system, a sieve plate tower, an acid storage tank, a gas generator, a booster pump, an absorption tank, a cyclone separator, a filter, a rebalancing electrolyte storage tank, a solid recovery tank and an air compressor. The sieve plate tower is the place where the rebalancing reaction occurs, and the gas generator is used to generate the rebalancing reactant, which is passed into the sieve plate tower through the booster pump; the electrolyte after the rebalancing is completed is separated by the cyclone separator and the filter, the absorption tank can remove the excess gas in the reaction process, and the absorption liquid can be passed into the air by the air compressor for regeneration and recycling. The system of the present invention can achieve instant response after feeding, start the rebalancing reaction at any time, and can achieve quantitative rebalancing of the excess trivalent iron ions in the positive electrode electrolyte, and the process flow is simple and safe.

Description

Technical Field

[0001] The present invention relates to the technical field of iron-chromium liquid flow batteries, and in particular to an instant-response iron-chromium liquid flow battery quantitative rebalancing system and a rebalancing method. Background Art

[0002] As a new energy storage technology, iron-chromium flow battery is known as one of the longest and safest electrochemical energy storage technologies. Its electrolyte solution is an aqueous solution with high stability and no explosion. The electrolyte has low toxicity and poses less threat to the ecological environment. In addition, iron-chromium flow battery has strong environmental adaptability and can be used in a wide temperature range. The battery is low in cost and is suitable for new power systems with large-scale and long-term energy storage needs.

[0003] The electrolyte performance of the iron-chromium flow battery determines the life, stability and cost of the energy storage system. The active substances of the positive and negative electrode reactions of the electrolyte are Fe 2+ / Fe 3+ and Cr 2+ / Cr 3+ Electrolyte, usually with hydrochloric acid as the supporting electrolyte. In recent years, iron-chromium flow battery technology has made significant progress in both research and development and commercialization, but there are still some technical bottlenecks. 2+ / Cr 3+ The redox reversibility of the electrode pair is poor, and hydrogen evolution reaction is prone to occur at the negative electrode during battery operation, which also causes Fe 3+ Accumulation, as the battery runs for a long time, the positive electrode Fe 3+ The content is getting higher and higher, resulting in battery capacity decay. In order to restore the capacity of the flow battery, a special electrolyte rebalancing system is required. The existing rebalancing technology process is complex and inefficient, so it is of great significance to develop an efficient and low-cost rebalancing system and rebalancing device. Summary of the invention

[0004] In order to solve the problems existing in the prior art, the present invention provides an instant-response iron-chromium liquid flow battery quantitative rebalancing system and rebalancing method, which can realize the rebalancing of the positive electrode electrolyte by feeding at any time without affecting the normal operation of the iron-chromium liquid flow battery, restore the positive electrode electrolyte composition to the original state in the sieve plate tower, reduce the accumulated trivalent iron concentration, replenish the hydrogen ions lost in the negative electrode hydrogen evolution reaction, restore the battery capacity, and absorb the tail gas of the reaction remaining toxic gas to reduce the harm, thereby solving the problems mentioned in the above-mentioned background technology.

[0005] To achieve the above-mentioned object, the present invention provides the following technical solutions: an instant-response iron-chromium liquid flow battery quantitative rebalancing system, the rebalancing system comprising an iron-chromium liquid flow battery stack, a positive electrode storage tank, a negative electrode storage tank, a control system, a sieve plate tower, an acid storage tank, a gas generator, a booster pump, an absorption tank, a cyclone separator, a filter, a rebalancing electrolyte storage tank, a solid recovery tank and an air compressor;

[0006] The control system is a control system with a computer or workstation, which is electrically connected to the pipeline valve and is used to control the closure of the pipeline valve, monitor the state of the rebalancing system, and manage the charge and discharge of the iron-chromium flow battery;

[0007] The positive electrode storage tank and the negative electrode storage tank are used to store positive electrode and negative electrode electrolytes respectively, and are connected to the iron-chromium liquid flow battery stack through pipelines.

[0008] Preferably, the sieve plate tower is a gas-liquid reactor, which is used as the place where the re-equilibrium reaction occurs. A liquid spraying device is arranged on the top of the sieve plate tower, and the electrolyte is sprayed down from the top. Several layers of sieve plates are arranged in the middle of the sieve plate tower, and there are several small holes on each layer of sieve plates. A reducing gas inlet is arranged at the bottom of the sieve plate tower;

[0009] The sieve plate tower is connected to the positive electrode storage tank through a first pipeline, and a liquid pump and a valve are arranged on the first pipeline.

[0010] Preferably, the acid storage tank is used as a storage device for the acid solution, and the acid storage tank is connected to the gas generator through a pipeline, and a valve and a liquid pump are provided on the pipeline, and the acid solution introduced is controlled by the valve and the liquid pump to control the amount of H2S gas generated;

[0011] The acid solution is one of hydrochloric acid and sulfuric acid.

[0012] Preferably, the gas generator is used as a generating device for rebalancing reactants, and a feed port is provided at the upper end of the gas generator. Before the rebalancing reaction, metal sulfide is added to the gas generator from the feed port; a stirring paddle is provided inside the gas generator, and the stirring paddle is used to stir the metal sulfide and the acid solution to react and generate H2S gas;

[0013] The metal sulfide is one of CaS, FeS, ZnS, Na2S or K2S.

[0014] Preferably, the gas generator is connected to the sieve plate tower via a second pipeline, and a valve and a booster pump are provided on the second pipeline;

[0015] The booster pump is used to pressurize the rebalance reactant H2S gas generated by the gas generator and pass it into the sieve plate tower;

[0016] The upper end of the sieve plate tower is also provided with a gas outlet, which is connected to the front end of the booster pump through a third pipeline. The H2S gas returns to the front end of the booster pump through the third pipeline and then is pressurized into the sieve plate tower to circulate and react in the sieve plate tower.

[0017] The gas outlet at the upper end of the sieve plate tower is also connected to the bottom end of the absorption tank through the sixth pipeline, and a valve is arranged on the sixth pipeline. The absorption tank stores absorption liquid to absorb the excess rebalance reaction H2S gas in the sieve plate tower, and a stirring paddle is arranged inside; the absorption liquid is any one of FeCl3, Fe2(SO4)3, Fe 3+ Absorb H2S to generate Fe 2+ and sulfur particles until the reaction is complete and no H2S gas is detected.

[0018] Preferably, the bottom of the sieve plate tower is connected to the cyclone separator through a fourth pipeline, and a valve is provided on the fourth pipeline; the cyclone separator is used to separate the electrolyte and solid precipitate after the rebalancing reaction; the electrolyte after rebalancing in the sieve plate tower passes through the cyclone separator, and under the action of centrifugal force, the solid particles rotate to the bottom and are discharged, and are stored in a solid recovery tank connected to the cyclone separator, and the separated electrolyte flows out from the upper overflow pipe to the filter connected to the cyclone separator, and the filter filters the electrolyte and stores it in the rebalanced electrolyte storage tank.

[0019] Preferably, the rebalancing electrolyte storage tank is connected to the positive electrode storage tank through a fifth pipeline, and a liquid pump and a valve are provided on the fifth pipeline; the electrolyte in the rebalancing electrolyte storage tank is pumped back to the positive electrode storage tank by the liquid pump, and is fully mixed with the electrolyte in the positive electrode storage tank to restore the electrolyte capacity in the positive electrode storage tank.

[0020] Preferably, the absorption tank is connected to the inlet of the cyclone separator through a seventh pipeline, and a valve is provided on the seventh pipeline. After the gas absorption reaction in the absorption tank is completed, the solution containing sulfur particles is passed into the cyclone separator through the seventh pipeline, and the separated solid sulfur particles are stored in a solid recovery tank. The separated solution is filtered through a filter and then returned to the absorption tank through the eighth pipeline.

[0021] Preferably, the absorption tank is connected to an air compressor, and air is introduced into the absorption tank through the air compressor to 2+ Reoxidized to Fe 3+ , so that the absorption liquid can be regenerated and recycled.

[0022] On the other hand, to achieve the above-mentioned purpose, the present invention also provides the following technical solution: a quantitative rebalancing method of an iron-chromium liquid flow battery with instant response, comprising the following steps:

[0023] S1. When the control system detects that the battery capacity has decayed, it determines whether rebalancing is required. The judgment condition is set to any value within the decay rate range of 10% to 20%.

[0024] S2. When it is determined that rebalancing is required, the valve on the first pipeline is opened, and the electrolyte that needs to be rebalanced in the positive electrode storage tank is pumped into the liquid spraying device at the top of the sieve plate tower by a liquid pump, and the electrolyte is sprayed down from the top;

[0025] S3, adding an excess of metal sulfide to the gas generator and sealing the container, then pumping an acid solution into the gas generator through an acid storage tank, and stirring the metal sulfide and the acid solution with a stirring paddle to react and generate H2S gas;

[0026] S4, introducing the generated H2S gas from the bottom of the sieve plate tower through the second pipeline and the booster pump, and increasing the gas-liquid reaction contact time through the small holes on the sieve plate;

[0027] S5. After rebalancing begins, keep the valve of the third pipeline connected to the gas outlet at the upper end of the sieve plate tower open, and the excess H2S returns to the front end of the booster pump through the third pipeline to achieve a cyclic reaction;

[0028] During the reaction, the amount of H2S gas generated is controlled by adding the amount of acid solution, thereby controlling the re-equilibrium reaction rate; during the reaction, the pressure in the gas generator and the sieve plate tower is controlled to be kept below 0.5Mpa, and the overpressure gas enters the absorption tank through the sixth pipeline for reaction removal;

[0029] Detection of Fe in sieve plate tower 3+ Concentration, Fe 3+ All are reduced to Fe 2+ And H + After the concentration increases, reequilibrium is completed;

[0030] S6. The rebalanced electrolyte is passed from the bottom of the sieve plate tower through the fourth pipeline into the cyclone separator, and the solid sulfur particles are discharged from the lower end of the separator to the solid recovery tank for storage, and then recovered after washing and drying;

[0031] The separated electrolyte is filtered through a filter and stored in a rebalanced electrolyte storage tank, and then returned to the positive electrode storage tank through the fifth pipeline and the liquid pump. After being fully mixed with the electrolyte in the positive electrode storage tank, the electrolyte capacity is restored to the original state;

[0032] S7. After the rebalancing is completed, close the valves of the second pipeline and the third pipeline, open the valve of the sixth pipeline connected to the gas outlet at the upper end of the sieve plate tower, and pass the remaining H2S gas into the absorption tank for tail gas treatment until no H2S gas is detected;

[0033] Detection of Fe in the absorption tank 3+ Concentration, if Fe in the absorption tank3+ If the content is too low, turn on the air compressor to introduce air into the absorption tank to remove Fe 2+ Oxidized to Fe 3+ , so that the absorption liquid can be reused;

[0034] After the tail gas treatment is completed, the solution containing sulfur particles in the absorption tank is passed into the cyclone separator through the seventh pipeline, and the separated sulfur particles are stored in the solid recovery tank. The separated solution is filtered through the filter and then returned to the absorption tank through the eighth pipeline.

[0035] The beneficial effects of the present invention are:

[0036] 1) The present invention can start the rebalancing reaction by pumping acid into the gas generator to which metal sulfide is added, and the amount of gas generated is controlled by controlling the addition of acid, thereby controlling the rebalancing reaction rate. The system has high controllability, good reduction effect, and simple process flow. It can also achieve quantitative rebalancing of excess trivalent iron ions in the positive electrode electrolyte, while replenishing hydrogen ions lost in the negative electrode hydrogen evolution reaction to restore the battery capacity, and absorb the tail gas of the remaining toxic gas in the reaction, thereby reducing harm and improving the working efficiency of the iron-chromium liquid flow battery system.

[0037] 2) The present invention rebalances a fixed amount of electrolyte through detection and calculation, and the rebalancing process does not affect the normal operation of the battery, thereby improving system efficiency and saving costs; during the rebalancing process of the present invention, excess hydrogen sulfide gas can be removed by an absorption tank to reduce risks; after the rebalancing is completed, the absorption tank can be used for tail gas absorption to reduce hazards and pollution, and the absorption liquid after the reaction can be regenerated and recycled by passing air through an air compressor. The absorption liquid is low in price and can be recycled, reducing waste. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 This is a schematic diagram of the structure of a quantitative rebalancing system for an iron-chromium liquid flow battery with instant response in an embodiment of the present invention;

[0039] In the figure, 11-the first pipeline, 12-the second pipeline, 13-the third pipeline, 14-the fourth pipeline, 15-the fifth pipeline, 16-the sixth pipeline, 17-the seventh pipeline, 18-the eighth pipeline, 101-the iron-chromium liquid flow battery stack, 102-the positive electrode storage tank, 103-the negative electrode storage tank, 104-the control system, 201-the sieve plate tower, 202-the acid storage tank, 203-the gas generator, 204-the boost pump, 205-the absorption tank, 206-the cyclone separator, 207-the filter, 208-the rebalancing electrolyte storage tank, 209-the solid recovery tank, 210-the air compressor. DETAILED DESCRIPTION

[0040] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0041] It should be noted that the embodiments and features of the embodiments of the present invention can be combined with each other without conflict. It should be noted that similar reference numerals and letters represent similar items in the following drawings, so once an item is defined in one drawing, it does not need to be further defined and explained in the subsequent drawings.

[0042] In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inside", "outside", etc. indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, or the positions or positional relationships in which the product of the invention is usually placed when in use, or the positions or positional relationships commonly understood by those skilled in the art, which are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", etc. are only used to distinguish the description, and cannot be understood as indicating or implying relative importance.

[0043] In the description of the present invention, it is also necessary to explain that, unless otherwise clearly specified and limited, the terms "set", "install", "connect", and "connect" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0044] See also Figure 1 The present invention provides a technical solution: an instant response iron-chromium liquid flow battery quantitative rebalancing system, specifically comprising:

[0045] Iron-chromium liquid flow battery stack 101, positive electrode storage tank 102, negative electrode storage tank 103, control system 104 with computer or workstation, sieve plate tower 210, acid storage tank 202, gas generator 203, booster pump 204, absorption tank 205, cyclone separator 206, filter 207, rebalance electrolyte storage tank 208, solid recovery tank 209, air compressor 210, liquid pump, valves and connecting pipelines.

[0046] The positive electrode storage tank 102 and the negative electrode storage tank 103 are used to store positive and negative electrode electrolytes respectively, and are connected to the positive and negative electrodes of the iron-chromium liquid flow battery stack 101 through pipelines and valves; the control system with a computer or workstation is electrically connected to the pipeline valves, and is used to control the closing of the pipeline valves, monitor the rebalancing system status, and manage the charging and discharging of the iron-chromium liquid flow battery.

[0047] Furthermore, the sieve plate tower 201 is a gas-liquid reactor, which is used as a place for the rebalancing reaction to occur. A liquid spraying device is arranged on the top, and the electrolyte is sprayed down from the top. Several layers of sieve plates are arranged in the middle, and there are several small holes on each layer of sieve plates; a reducing gas inlet is arranged at the bottom; a liquid pump and a valve are arranged between the sieve plate tower 201 and the positive electrode storage tank 102, and they are connected through the first pipeline 11.

[0048] Furthermore, the acid storage tank 202 is used as a storage device for the acid solution.

[0049] The gas generator 203 is used as a generating device for rebalancing reactants, and has a stirring paddle inside; there is a feed port at the upper end, and metal sulfide is added from the feed port before the rebalancing reaction.

[0050] Furthermore, the booster pump 204 is used to pressurize the re-equilibrium reactant gas generated by the gas generator and pass it into the sieve plate tower to perform a re-equilibrium reaction.

[0051] The absorption tank 205 is used as a device for storing absorption liquid and absorbing excess rebalancing reaction gas, and has a stirring paddle inside.

[0052] The cyclone separator 206 is used to separate the electrolyte and the solid precipitate after the re-balance reaction.

[0053] The filter 207 is used as a device for further filtering the electrolyte separated by the cyclone separator.

[0054] The rebalancing electrolyte storage tank 208 is used as a device for temporarily storing the electrolyte after the rebalancing is completed.

[0055] The solid recovery tank 209 is used as a device for recovering and storing the solid precipitates separated by the cyclone separator.

[0056] The air compressor 210 is used as a device for providing gas for regenerating the absorption liquid.

[0057] When the control system 104 with a computer or workstation detects that the battery capacity is declining, the system initiates rebalancing.

[0058] Furthermore, the sieve plate tower 201 is connected to the cathode storage tank 102 through the first pipeline 11, and a liquid pump and a valve are provided on the first pipeline 11. When the rebalancing system is working, the cathode electrolyte that needs to be rebalanced is pumped into the sieve plate tower 201, and the battery can work normally after the pumping is completed. Furthermore, there is a liquid spraying device on the top of the sieve plate tower 201, and the electrolyte is sprayed from the top. There are small holes on each layer of the tower plate in the sieve plate tower. When the gas is introduced from the bottom, it contacts and reacts with the electrolyte through the small holes, prolonging the reaction time and enhancing the reaction effect.

[0059] Furthermore, the electrolyte that needs to be rebalanced can be detected by detecting the positive electrode Fe 3+ concentration, calculate the Fe that needs to be rebalanced 3+ amount to achieve quantitative balance of the electrolyte in the positive electrode tank.

[0060] Further, the reactants in the gas generator 203 may be metal sulfide and acid. The metal sulfide is one of CaS, FeS, ZnS, Na2S or K2S. The metal sulfide is added to the gas generator from the feed port and the container is sealed. The acid is one of hydrochloric acid and sulfuric acid, which is stored in the acid storage tank 202. The acid storage tank 202 is connected to the gas generator 203 through a pipeline, and a valve and a liquid pump are provided on the pipeline. When the rebalancing system is working, the acid is pumped into the gas generator containing the metal sulfide. A stirring paddle is provided inside the gas generator 203. The stirring paddle is used to stir the metal sulfide and the acid solution to react and generate H2S gas. The acid introduced is controlled by the valve and the liquid pump to control the amount of gas generated.

[0061] Furthermore, the gas generator 203 is connected to the sieve plate tower 201 through a second pipeline 12, and a booster pump 204 and a valve are arranged on the second pipeline. The H2S gas generated in the gas generator passes through the booster pump 204 and enters the sieve plate tower to reduce Fe 3+ The rebalance reaction of Fe in the positive electrolyte 3+ Reduced to Fe 2+ , and hydrogen ions and sulfur are produced at the same time; the reaction pressure in the gas generator and the sieve plate tower is lower than 0.5MPa, and the overpressure reaction gas in the sieve plate tower can be removed by the absorption liquid reaction in the absorption tank.

[0062] Furthermore, the gas outlet at the upper end of the sieve plate tower 201 is connected to the front end of the booster pump 204 through a third pipeline 13, and a valve is provided on the third pipeline 13. The H2S gas returns to the front end of the booster pump through the third pipeline and circulates in the sieve plate tower until Fe 3+ All ions are reduced to Fe 2+ , and H + The concentration increases and the reequilibrium reaction is complete.

[0063] The bottom of the sieve plate tower is connected to the cyclone separator 206 through the fourth pipeline 14, and a valve is provided on the fourth pipeline 14; the cyclone separator 206 is used to separate the electrolyte and solid precipitate after the rebalancing reaction; the electrolyte after rebalancing in the sieve plate tower passes through the cyclone separator, and under the action of centrifugal force, the solid particles rotate to the bottom and are discharged, and are stored in the solid recovery tank 209 connected to the cyclone separator, and the separated electrolyte flows out from the overflow pipe at the upper end to the filter 207 connected to the cyclone separator; if there are still fine particles in the electrolyte, the electrolyte is filtered by the filter 207 and stored in the rebalancing electrolyte storage tank 208.

[0064] The rebalancing electrolyte storage tank 208 is connected to the positive electrode storage tank 102 through the fifth pipeline 15, and the fifth pipeline 15 is provided with a liquid pump and a valve; the electrolyte in the rebalancing electrolyte storage tank 208 is pumped back to the positive electrode storage tank 102 by the liquid pump, and is fully mixed with the electrolyte in the positive electrode storage tank to restore the electrolyte capacity in the positive electrode storage tank.

[0065] Furthermore, the rebalanced electrolyte is separated by a cyclone separator, which has a simple process and high working efficiency. Even if the separated electrolyte still needs to be filtered, the workload of the filter can be reduced and the life of the filter element can be extended.

[0066] The gas outlet at the upper end of the sieve plate tower 201 is connected to the bottom end of the absorption tank 205 through a sixth pipeline 16 , and a valve is provided on the sixth pipeline 16 .

[0067] Furthermore, the absorption tank is used as a tail gas absorption device to pass the remaining H2S gas in the sieve plate tower. The reaction mechanism between the absorption liquid and H2S is the same as the re-equilibrium reaction. 3+ The solution absorbs H2S and reacts to generate Fe 2+ and sulfur until the reaction is complete and no H2S gas is detected.

[0068] The absorption liquid in the absorption tank can be any one of FeCl3 and Fe2(SO4)3.

[0069] Furthermore, the absorption tank 205 is connected to the inlet of the cyclone separator 206 through the seventh pipeline 17, and a valve is provided on the seventh pipeline 17. After the gas absorption reaction in the absorption tank 205 is completed, the solution containing sulfur particles is passed into the cyclone separator 206 through the seventh pipeline 17, and the separated solid sulfur particles are stored in the solid recovery tank 209. The separated solution is filtered through the filter 207 and returned to the absorption tank 205 through the eighth pipeline 18.

[0070] Furthermore, the sulfur in the solid recovery tank can be recycled after washing and drying, thus reducing waste.

[0071] Furthermore, the absorption liquid can be recycled, and the Fe 3+ After reacting with hydrogen sulfide gas, air is introduced into the absorption tank through the air compressor to 2+ Reoxidized to Fe 3+ The reaction is enhanced by stirring, and the absorption liquid can be regenerated and recycled.

[0072] Based on the same inventive concept as the above embodiment, when the above rebalancing system is used, the embodiment of the present application also provides a quantitative rebalancing method for an iron-chromium liquid flow battery with instant response, which comprises the following steps:

[0073] After the control system 104 with a computer or workstation detects battery capacity decay, it determines whether rebalancing is required, and the determination condition can be set as the decay rate being greater than any value in the range of 10% to 20%.

[0074] The positive electrode storage tank 102 is connected to the sieve plate tower 201 through a pipeline 11. There is a liquid pump between the pipelines for extracting the electrolyte that needs to be rebalanced at the positive electrode and adjusting the control system 104 to the battery discharge state so that the battery can operate normally.

[0075] The volume of electrolyte that needs to be rebalanced can be calculated as follows:

[0076] Before rebalancing begins, the battery completes the current charge and discharge cycle and detects the accumulated Fe 3+ The concentration of Fe 3+ The amount of substance, that is, the Fe that needs to be rebalanced 3+ , and then charge the iron-chromium flow battery to the cut-off state, the positive electrode electrolyte Fe 3+ The concentration increases, and the Fe in the positive electrode tank is detected again. 3+ concentration, calculate the positive electrolyte contains Fe that needs to be rebalanced 3+ The volume of the substance is calculated to obtain the volume of the positive electrolyte that needs to be rebalanced.

[0077] When the system starts to rebalance, the valve on the first pipeline 11 is opened, and the electrolyte that needs to be rebalanced enters the liquid spray device at the top of the sieve plate tower 201; excess metal sulfide is added to the gas generator 203 and the container is sealed, and the acid storage tank 202 pumps acid into the gas generator 203, the metal sulfide can be one of CaS, FeS, ZnS, Na2S or K2S, and the acid is one of hydrochloric acid and sulfuric acid.

[0078] Taking CaS and hydrochloric acid as an example, the reaction equation in the gas generator is:

[0079] CaS + 2HCl → CaCl2 + H2S↑

[0080] The generated hydrogen sulfide gas is introduced from the bottom of the sieve plate tower 201 through the second pipeline 12 and the booster pump 204, and the small holes on the sieve plate increase the gas-liquid reaction contact time.

[0081] The re-equilibrium reaction equation in the sieve plate tower is:

[0082] H2S + 2Fe 3+ → 2Fe 2+ + 2H + + S↓

[0083] After the rebalancing begins, the valve of the third pipeline 13 connected to the gas outlet at the upper end of the sieve plate tower is kept open, and the excess H2S returns to the front end of the booster pump through the third pipeline 13 to achieve a cyclic reaction; the Fe 3+ Concentration, Fe 3+ All are reduced to Fe 2+ And H + After the concentration increases, reequilibration is completed.

[0084] During the reaction, the amount of H2S gas produced is controlled by adding an amount of acid, thereby controlling the rebalance reaction rate; during the reaction, the pressure in the gas generator and the sieve plate tower is controlled to remain below 0.5Mpa, and the overpressure gas can enter the absorption tank 205 through the sixth pipeline 16 for reaction and removal.

[0085] The absorption liquid in the absorption tank 205 contains Fe 3+ The solution can be any one of FeCl3 and Fe2(SO4)3.

[0086] Reaction equation in the absorption tank:

[0087] H2S + 2Fe 3+ → 2Fe 2+ + 2H + + S↓

[0088] The rebalanced electrolyte is passed from the bottom of the sieve plate tower 201 through the fourth pipeline 14 into the cyclone separator 206, and the solid S element is discharged from the lower end of the separator to the solid recovery tank 209 for storage, and can be recovered after washing and drying; the separated electrolyte is filtered by the filter 207 and temporarily stored in the rebalanced electrolyte storage tank 208, and then returned to the positive electrode storage tank 102 through the pipeline 15 and the liquid pump.

[0089] After the electrolyte in the positive electrode storage tank 102 is fully mixed, the capacity of the positive electrode electrolyte is restored to its original state, and the iron-chromium liquid flow battery can continue to work normally.

[0090] After rebalancing is completed, the valves of the second pipeline 12 and the third pipeline 13 are closed, and the valve of the sixth pipeline 16 connected to the gas outlet at the upper end of the sieve plate tower is opened to pass the remaining hydrogen sulfide gas into the absorption tank 205 for tail gas treatment until no hydrogen sulfide gas is detected.

[0091] Detection of Fe in absorption tank 205 3+ Concentration, if Fe in absorption tank 205 3+ If the content is too low, turn on the air compressor 210 to introduce air into the absorption tank 205 to remove Fe 2+ Oxidized to Fe 3+ , the absorption liquid can be reused, the reaction equation is:

[0092] 4Fe 2+ + O2 + 4H + → 4Fe 3+ + 2H2O

[0093] After the exhaust gas treatment is completed, the solution containing sulfur particles in the absorption tank 205 is passed into the cyclone separator 206 through the seventh pipeline 17, and the separated S element is also stored in the solid recovery tank 209; the separated solution is filtered through the filter 207 and then returned to the absorption tank 205 through the eighth pipeline 18.

[0094] Although the present invention has been described in detail with reference to the aforementioned embodiments, it is still possible for those skilled in the art to modify the technical solutions described in the aforementioned embodiments, or to make equivalent substitutions for some of the technical features therein. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A quantitative rebalancing method for an iron-chromium liquid flow battery with instant response, characterized in that: The steps include: S1. When the control system (104) detects that the battery capacity has decayed, it determines whether rebalancing is required, and the determination condition is set to any value within the decay rate range of 10% to 20%; S2. When it is determined that rebalancing is required, the valve on the first pipeline (11) is opened, and the electrolyte that needs to be rebalanced in the positive electrode storage tank (102) is pumped into the liquid spraying device at the top of the sieve plate tower (201) by a liquid pump, and the electrolyte is sprayed downward from the top; The volume of electrolyte that needs to be rebalanced is calculated in the following manner: before rebalancing begins, the battery completes the current charge and discharge cycle, and the accumulated Fe 3+ The concentration of Fe 3+ The amount of substance, that is, the Fe that needs to be rebalanced 3+ , and then charge the iron-chromium flow battery to the cut-off state, the positive electrode electrolyte Fe 3+ The concentration increases, and the Fe in the positive electrode tank is detected again. 3+ concentration, calculate the positive electrolyte contains Fe that needs to be rebalanced 3+ The volume of the amount of substance is obtained to obtain the volume of the positive electrolyte that needs to be rebalanced; S3, adding an excess amount of metal sulfide to the gas generator (203) and sealing the container, then pumping an acid solution into the gas generator (203) through the acid storage tank (202), and stirring the metal sulfide and the acid solution with a stirring paddle to react and generate H2S gas; S4, introducing the generated H2S gas from the bottom of the sieve plate tower (201) through the second pipeline (12) and the booster pump (204), and increasing the gas-liquid reaction contact time through the small holes on the sieve plate; S5. After rebalancing begins, the valve of the third pipeline (13) connected to the gas outlet at the upper end of the sieve plate tower is kept open, and the excess H2S is returned to the front end of the booster pump through the third pipeline (13) to achieve a cyclic reaction; During the reaction, the amount of H2S gas generated is controlled by adding an acid solution, thereby controlling the re-equilibrium reaction rate; during the reaction, the pressure in the gas generator (203) and the sieve plate tower (201) is controlled to be maintained below 0.5 MPa, and the overpressure gas enters the absorption tank (205) through the sixth pipeline (16) for reaction and removal; Detection of Fe in sieve plate tower 3+ Concentration, Fe 3+ All are reduced to Fe 2+ And H + After the concentration increases, re-equilibrium is completed; The instant response iron-chromium liquid flow battery quantitative rebalancing method is implemented by using a rebalancing system; the rebalancing system comprises an iron-chromium liquid flow battery stack (101), a positive electrode storage tank (102), a negative electrode storage tank (103), a control system (104), a sieve plate tower (201), an acid storage tank (202), a gas generator (203), a booster pump (204), an absorption tank (205), a cyclone separator (206), a filter (207), a rebalancing electrolyte storage tank (208), a solid recovery tank (209) and an air compressor (210).

2. The instant response quantitative rebalancing method of the iron-chromium liquid flow battery according to claim 1, characterized in that: The instant response iron-chromium liquid flow battery quantitative rebalancing method also includes the following steps: The rebalanced electrolyte is passed from the bottom of the sieve plate tower (201) through the fourth pipeline (14) into the cyclone separator (206), and the solid sulfur particles are discharged from the lower end of the separator to the solid recovery tank (209) for storage, and then recovered after washing and drying; The separated electrolyte is filtered through a filter (207) and stored in a rebalanced electrolyte storage tank (208), and then returned to the positive electrode storage tank (102) through a fifth pipeline (15) and a liquid pump, and after being fully mixed with the electrolyte in the positive electrode storage tank, the electrolyte capacity is restored to its original state; S7. After the rebalancing is completed, the valves of the second pipeline (12) and the third pipeline (13) are closed, and the valve of the sixth pipeline (16) connected to the gas outlet at the upper end of the sieve plate tower is opened to pass the remaining H2S gas into the absorption tank (205) for tail gas treatment until no H2S gas is detected; Detection of Fe in the absorption tank (205) 3+ Concentration, if the Fe in the absorption tank (205) 3+ If the content is too low, turn on the air compressor (210) to introduce air into the absorption tank to remove Fe 2+ Oxidized to Fe 3+ , so that the absorption liquid can be reused; After the tail gas treatment is completed, the solution containing sulfur particles in the absorption tank (205) is passed through the seventh pipeline (17) into the cyclone separator (206), and the separated sulfur particles are stored in the solid recovery tank (209). The separated solution is filtered through the filter (207) and then returned to the absorption tank (205) through the eighth pipeline (18).

3. The instant response quantitative rebalancing method of the iron-chromium liquid flow battery according to claim 1, characterized in that: The control system (104) is a control system with a computer or a workstation, which is electrically connected to the pipeline valve and is used to control the closing of the pipeline valve, monitor the state of the rebalancing system, and manage the charging and discharging of the iron-chromium liquid flow battery; The positive electrode storage tank (102) and the negative electrode storage tank (103) are used to store positive electrode and negative electrode electrolytes respectively, and are connected to the iron-chromium liquid flow battery stack (101) through pipelines; The sieve plate tower (201) is a gas-liquid reactor, serving as a place where the rebalancing reaction occurs. A liquid spraying device is arranged at the top of the sieve plate tower, and the electrolyte is sprayed downward from the top. A plurality of sieve plates are arranged in the middle of the sieve plate tower, and a plurality of small holes are provided on each sieve plate. A reducing gas inlet is arranged at the bottom of the sieve plate tower. The sieve plate tower (201) is connected to the positive electrode storage tank (102) via a first pipeline (11), and a liquid pump and a valve are provided on the first pipeline (11).

4. The instant response quantitative rebalancing method of the iron-chromium liquid flow battery according to claim 1, characterized in that: The acid storage tank (202) is used as a storage device for the acid solution. The acid storage tank (202) is connected to the gas generator (203) via a pipeline. A valve and a liquid pump are provided on the pipeline. The valve and the liquid pump control the amount of the acid solution introduced to control the amount of H2S gas generated. The acid solution is one of hydrochloric acid and sulfuric acid.

5. The instant response quantitative rebalancing method of the iron-chromium liquid flow battery according to claim 1, characterized in that: The gas generator (203) is used as a generating device for rebalancing reactants. A feed inlet is provided at the upper end of the gas generator. Before the rebalancing reaction, metal sulfide is added to the gas generator (203) from the feed inlet. A stirring paddle is provided inside the gas generator. The stirring paddle is used to stir the metal sulfide and the acid solution to react and generate H2S gas. The metal sulfide is one of CaS, FeS, ZnS, Na2S or K2S.

6. The instant response quantitative rebalancing method of the iron-chromium liquid flow battery according to claim 1, characterized in that: The gas generator (203) is connected to the sieve plate tower (201) via a second pipeline (12), and a valve and a booster pump (204) are provided on the second pipeline; The booster pump (204) is used to pressurize the re-equilibrium reactant H2S gas generated by the gas generator (203) and pass it into the sieve plate tower (201); The upper end of the sieve plate tower (201) is also provided with a gas outlet, which is connected to the front end of the booster pump (204) through a third pipeline (13). The H2S gas returns to the front end of the booster pump through the third pipeline and is then pressurized to enter the sieve plate tower (201) for a circulated reaction in the sieve plate tower. The gas outlet at the upper end of the sieve plate tower (201) is also connected to the bottom end of the absorption tank (205) through a sixth pipeline (16). A valve is provided on the sixth pipeline (16). The absorption tank (205) stores an absorption liquid for absorbing excess rebalance reaction H2S gas in the sieve plate tower. A stirring paddle is provided inside the absorption tank. The absorption liquid is any one of FeCl3 and Fe2(SO4)3. 3+ Absorb H2S to generate Fe 2+ and sulfur particles until the reaction is complete and no H2S gas is detected.

7. The instant response quantitative rebalancing method of iron-chromium liquid flow battery according to claim 1, characterized in that: The bottom of the sieve plate tower is connected to the cyclone separator (206) via a fourth pipeline (14), and a valve is provided on the fourth pipeline (14); the cyclone separator (206) is used to separate the electrolyte and solid precipitate after the rebalancing reaction; the electrolyte after rebalancing in the sieve plate tower passes through the cyclone separator, and under the action of centrifugal force, the solid particles rotate to the bottom and are discharged, and are stored in a solid recovery tank (209) connected to the cyclone separator; the separated electrolyte flows out from the upper overflow pipe to the filter (207) connected to the cyclone separator, and the filter filters the electrolyte and then stores it in the rebalancing electrolyte storage tank (208).

8. The instant response quantitative rebalancing method of the iron-chromium liquid flow battery according to claim 1, characterized in that: The rebalancing electrolyte storage tank (208) is connected to the positive electrode storage tank (102) via a fifth pipeline (15), and a liquid pump and a valve are provided on the fifth pipeline (15); the electrolyte in the rebalancing electrolyte storage tank (208) is pumped back to the positive electrode storage tank (102) by the liquid pump, and is fully and evenly mixed with the electrolyte in the positive electrode storage tank, so that the electrolyte capacity in the positive electrode storage tank is restored.

9. The instant response quantitative rebalancing method of the iron-chromium liquid flow battery according to claim 1, characterized in that: The absorption tank (205) is connected to the inlet of the cyclone separator (206) via a seventh pipeline (17). The seventh pipeline (17) is provided with a valve. After the gas absorption reaction in the absorption tank (205) is completed, the solution containing sulfur particles is passed into the cyclone separator (206) via the seventh pipeline (17). The separated solid sulfur particles are stored in the solid recovery tank (209). The separated solution is filtered through the filter (207) and then returned to the absorption tank (205) via the eighth pipeline (18); The absorption tank (205) is connected to an air compressor (210), and air is introduced into the absorption tank (205) through the air compressor (210) to absorb Fe 2+ Reoxidized to Fe 3+ , so that the absorption liquid can be regenerated and recycled.

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