Method and system for conveying electrolyte in flow battery and operation method of flow battery

Abstract

The invention relates to a method and a system for conveying electrolyte in a flow battery and a flow battery operation method. The electrolyte delivery system provided by the invention comprises three electrolyte storage tanks which are sequentially connected in series, the internal pressures of the three electrolyte storage tanks are respectively normal pressure, variable pressure and low pressure, the delivery method realizes self-circulation of the flow battery system through two times of gas phase pressure equalization and gravity flow of the electrolyte, and the self-circulation of the flow battery system is realized under the condition that an electrolyte delivery pump is not used. The problem of electrolyte leakage caused by sealing failure of a galvanic pile in a traditional flow battery is effectively avoided through a suction type electrolyte conveying mode; and meanwhile, an electrolyte circulating pump is not used, so that the problems of maintenance and the like of the pump are avoided, and long-period continuous operation of the flow battery system can be realized under the condition that a standby pump does not need to be added, so that the safety and the stability of the system are effectively improved.

Description

Technical Field

[0001] This disclosure pertains to the field of flow batteries, specifically relating to a method and system for transporting electrolyte in a flow battery, as well as a method for operating a flow battery. Background Technology

[0002] Flow batteries are a new type of high-capacity electrochemical energy storage device that utilizes separate, circulating electrolytes for the positive and negative electrodes. The active material is a flowing electrolyte solution. Unlike conventional solid-state batteries, the electrolyte solutions for the positive and negative electrodes in flow batteries are stored in external tanks and transported to the battery interior via an electrolyte circulation pump and pipelines for reaction. However, because the electrolyte (30% sulfuric acid) in vanadium redox flow batteries is a highly corrosive liquid, and the connections between the pump body, bearings, and motor of the electrolyte circulation pump, being a moving device, are difficult to completely seal, a series of valve assemblies are typically installed before and after the circulation pump. This adds multiple sealing points and flange connection points to the entire electrolyte circulation system, significantly increasing the risk of electrolyte leakage and preventing the flow battery system from operating continuously for extended periods. Summary of the Invention

[0003] The purpose of this disclosure is to provide a method and system for transporting electrolyte in a flow battery, as well as a method for operating the flow battery. The method provided by this invention can effectively reduce the leakage risk of the flow battery system, enable the flow battery system to operate continuously for a long period of time, and effectively improve the safety and stability of the system.

[0004] To achieve the above objectives, a first aspect of the present invention provides a method for transporting electrolyte in a flow battery, the method comprising: S0, puts the electrolyte storage unit into a ready state; The electrolyte storage unit includes a first electrolyte storage tank, a second electrolyte storage tank, and a third electrolyte storage tank arranged sequentially from top to bottom. A first gas phase pipeline and a first liquid phase pipeline that can be opened and closed are provided between the first electrolyte storage tank and the second electrolyte storage tank. A second gas phase pipeline and a second liquid phase pipeline that can be opened and closed are provided between the second electrolyte storage tank and the third electrolyte storage tank. The preparation state includes: placing the first electrolyte storage tank at normal pressure, and filling the second and third electrolyte storage tanks with low-pressure inert gas respectively; the gas phase and liquid phase are not connected between the first, second, and third electrolyte storage tanks. S1. Allow the electrolyte in the battery stack to enter the first electrolyte storage tank under the action of gravity; S2. When the electrolyte level in the first electrolyte storage tank reaches the highest level, the first electrolyte storage tank is connected to the second electrolyte storage tank by air, and the first electrolyte storage tank is connected to the atmosphere in one direction, so that the low-pressure inert gas in the second electrolyte storage tank can enter the first electrolyte storage tank. S3. After the internal pressures of the first electrolyte storage tank and the second electrolyte storage tank are the same, the electrolyte in the first electrolyte storage tank enters the second electrolyte storage tank under the action of gravity. S4. When the liquid level in the second electrolyte storage tank reaches the highest level, the third electrolyte storage tank is connected to the second electrolyte storage tank by gas, so that the inert gas in the third electrolyte storage tank can enter the second electrolyte storage tank. S5. After the internal pressure of the second electrolyte storage tank and the third electrolyte storage tank are the same, the electrolyte in the second electrolyte storage tank enters the third electrolyte storage tank under the action of gravity. S6. Return the electrolyte in the third positive electrolyte storage tank to the battery stack.

[0005] Optionally, the method further includes: before the electrolyte enters the first electrolyte storage tank, the pressure inside the first electrolyte storage tank is lower than the pressure inside the second electrolyte storage tank; the pressure inside the first electrolyte storage tank is lower than the pressure inside the third positive electrode electrolyte storage tank; The pressure inside the first electrolyte storage tank is 98~102 kPag; the pressure inside the second electrolyte storage tank is 0~500 kPag; and the pressure inside the third electrolyte storage tank is 200~500 kPag. Before the electrolyte enters the first electrolyte storage tank, the liquid level in the first electrolyte storage tank is less than 10% of the maximum liquid level; the liquid level in the second electrolyte storage tank is less than 10% of the maximum liquid level; and the liquid level in the third electrolyte storage tank is 20-80% of the maximum liquid level.

[0006] Optionally, in step S2, the inert gas entering the top of the first electrolyte storage tank is discharged into the atmosphere through a single exhalation valve at the top of the first electrolyte storage tank. In step S2, the third electrolyte storage tank and the second electrolyte storage tank are not connected in terms of gas phase and liquid phase.

[0007] Optionally, before step S6, the method further includes repeating steps S0 to S5.

[0008] Optionally, in step S6, a low-pressure inert gas is introduced into the third electrolyte storage tank to return the electrolyte in the third electrolyte storage tank to the battery stack.

[0009] Optionally, the flow rate and velocity of the electrolyte returning to the battery stack are controlled by the nitrogen pressure at the top of the third electrolyte storage tank.

[0010] Optionally, the volume of the second electrolyte storage tank is greater than or equal to the volume of the first electrolyte storage tank; The volume of the third electrolyte storage tank is larger than the volume of the first electrolyte storage tank and the volume of the second electrolyte storage tank.

[0011] A second aspect of the present invention provides a method for operating a flow battery, wherein the positive electrode electrolyte and the negative electrode electrolyte of the battery stack are respectively transported using the transport method described in the first aspect of the present invention.

[0012] A third aspect of the present invention provides an electrolyte delivery system for a flow battery, wherein the system includes: an electrolyte storage unit; The electrolyte storage unit includes a first electrolyte storage tank, a second electrolyte storage tank, and a third electrolyte storage tank arranged sequentially from top to bottom. A first gas phase pipeline and a first liquid phase pipeline that can be opened and closed are provided between the first electrolyte storage tank and the second electrolyte storage tank. A second gas phase pipeline and a second liquid phase pipeline that can be opened and closed are provided between the second electrolyte storage tank and the third electrolyte storage tank. The electrolyte inlet of the first electrolyte storage tank is used to connect with the electrolyte outlet of the battery stack; the electrolyte outlet of the third positive electrode electrolyte storage tank is used to connect with the electrolyte inlet of the battery stack. The system has a ready state, which includes: the first electrolyte storage tank is under normal pressure, and the second and third electrolyte storage tanks are filled with low-pressure inert gas; the gas phase and liquid phase are not connected between the first, second, and third electrolyte storage tanks.

[0013] Optionally, a first electrolyte solenoid valve is provided on the first liquid phase pipeline; a second electrolyte solenoid valve is provided on the second liquid phase pipeline. A first gas phase solenoid valve is installed on the first gas phase pipeline, and a second gas phase solenoid valve is installed on the second gas phase pipeline. An inert gas venting pipeline is installed at the top of the first electrolyte storage tank, and a single-exhale valve is installed on the inert gas venting pipeline. Optionally, the system further includes a flow control element and a pressure control element; wherein the flow control element is disposed on the outlet pipeline of the third electrolyte storage tank; and the pressure control element is disposed on the inert gas inlet pipeline at the top of the third electrolyte storage tank, for controlling the flow rate and velocity of the electrolyte returning to the battery stack.

[0014] Through the above technical solution, the electrolyte delivery method and system provided by the present invention includes three electrolyte storage tanks arranged in series, with the internal pressures of the three electrolyte storage tanks being atmospheric pressure, variable pressure, and low pressure, respectively. Through two gas-phase pressure equalization processes and the gravity flow of the electrolyte, the self-circulation of the flow battery system is achieved. Without using an electrolyte delivery pump, the suction-type delivery of the electrolyte effectively avoids the electrolyte leakage problem caused by stack seal failure in traditional flow batteries. Simultaneously, the absence of an electrolyte circulation pump avoids pump maintenance issues, enabling long-term continuous operation of the flow battery system without the need for a backup pump, thus effectively improving system safety and stability.

[0015] Other features and advantages of the present invention will be described in detail in the following detailed description section. Attached Figure Description

[0016] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used together with the following detailed description to explain the invention, but do not constitute a limitation thereof. In the drawings: Figure 1 This is a schematic diagram of the process flow of Embodiment 1 of the present invention.

[0017] Figure 2 This is a schematic diagram of the process flow for Comparative Example 1 of the present invention.

[0018] Explanation of reference numerals in the attached figures 1. Battery stack; 2. Positive electrolyte storage unit; 3. Negative electrolyte storage unit; 4. First positive electrolyte tank; 5. Second positive electrolyte tank; 6. Third positive electrolyte tank; 7. First negative electrolyte tank; 8. Second negative electrolyte tank; 9. Third negative electrolyte tank; 10. First positive electrolyte solenoid valve; 11. Second positive electrolyte solenoid valve; 12. First positive gas phase solenoid valve; 13. Second positive gas phase solenoid valve; 14. Nitrogen regulating valve; 15. Single-call valve; 16. First negative electrolyte solenoid valve; 17. Second negative electrolyte solenoid valve; 18. First negative gas phase solenoid valve; 19. Second negative gas phase solenoid valve; 20. Nitrogen regulating valve; 21. Single-call valve.

[0019] D1, Battery stack; D2, Positive electrolyte storage tank; D3, Negative electrolyte storage tank; D4, Positive electrolyte circulation pump; D5, Negative electrolyte circulation pump; D6 and D7, Flow control elements; D8 and D9, Nitrogen regulating valves; D10 and D11, Single call valves. Detailed Implementation

[0020] The specific embodiments of this disclosure will be described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are for illustration and explanation only and are not intended to limit this disclosure.

[0021] The first aspect of this disclosure provides a method for delivering electrolyte in a flow battery, the method comprising: S0, puts the electrolyte storage unit into a ready state; The electrolyte storage unit includes a first electrolyte storage tank, a second electrolyte storage tank, and a third electrolyte storage tank arranged sequentially from top to bottom. A first gas phase pipeline and a first liquid phase pipeline that can be opened and closed are provided between the first electrolyte storage tank and the second electrolyte storage tank. A second gas phase pipeline and a second liquid phase pipeline that can be opened and closed are provided between the second electrolyte storage tank and the third electrolyte storage tank. The preparation state includes: placing the first electrolyte storage tank at normal pressure, and filling the second and third electrolyte storage tanks with low-pressure inert gas respectively; the gas phase and liquid phase are not connected between the first, second, and third electrolyte storage tanks. S1. Allow the electrolyte in the battery stack to enter the first electrolyte storage tank under the action of gravity; S2. When the electrolyte level in the first electrolyte storage tank reaches the highest level, the first electrolyte storage tank is connected to the second electrolyte storage tank by air, and the first electrolyte storage tank is connected to the atmosphere in one direction, so that the low-pressure inert gas in the second electrolyte storage tank can enter the first electrolyte storage tank. S3. After the internal pressures of the first electrolyte storage tank and the second electrolyte storage tank are the same, the electrolyte in the first electrolyte storage tank enters the second electrolyte storage tank under the action of gravity. S4. When the liquid level in the second electrolyte storage tank reaches the highest level, the third electrolyte storage tank is connected to the second electrolyte storage tank by gas, so that the inert gas in the third electrolyte storage tank can enter the second electrolyte storage tank. S5. After the internal pressure of the second electrolyte storage tank and the third electrolyte storage tank are the same, the electrolyte in the second electrolyte storage tank enters the third electrolyte storage tank under the action of gravity. S6. Return the electrolyte in the third positive electrolyte storage tank to the battery stack.

[0022] The electrolyte delivery method and system disclosed herein include three electrolyte storage tanks connected in series, with internal pressures of atmospheric pressure, variable pressure, and low pressure, respectively. Self-circulation of the flow battery system is achieved through two gas-phase pressure equalization processes and the gravity flow of the electrolyte. Without using an electrolyte delivery pump, the suction-type delivery of the electrolyte effectively avoids electrolyte leakage caused by stack seal failure in traditional flow batteries. Furthermore, the elimination of the electrolyte circulation pump avoids pump maintenance issues, enabling long-term continuous operation of the flow battery system without the need for a backup pump, thus effectively improving system safety and stability.

[0023] According to one embodiment of the present invention, the method further includes: before the electrolyte enters the first electrolyte storage tank, the pressure inside the first electrolyte storage tank is lower than the pressure inside the second electrolyte storage tank; the pressure inside the first electrolyte storage tank is lower than the pressure inside the third positive electrode electrolyte storage tank.

[0024] In one specific embodiment, the pressure inside the first electrolyte storage tank is 98~102 kPag; the pressure inside the second electrolyte storage tank is 0~500 kPag, preferably 0~400 kPag; and the pressure inside the third electrolyte storage tank is 200~500 kPag, preferably 300~400 kPag. In one specific embodiment, before the electrolyte enters the first electrolyte storage tank, the liquid level in the first electrolyte storage tank is less than 10% of the maximum liquid level, preferably less than 5%; the liquid level in the second electrolyte storage tank is less than 10% of the maximum liquid level, preferably less than 5%; and the liquid level in the third electrolyte storage tank is 20-80% of the maximum liquid level, preferably less than 30-70%.

[0025] In one specific embodiment, in step S2, the inert gas entering the top of the first electrolyte storage tank is discharged into the atmosphere through a single-exhale valve at the top of the first electrolyte storage tank.

[0026] In one specific embodiment, in step S2, the third electrolyte storage tank and the second electrolyte storage tank are not connected in the gas phase and are not connected in the liquid phase.

[0027] In one specific embodiment, before step S6, the method further includes repeating steps S0 to S5.

[0028] In one specific embodiment, in step S6, a low-pressure inert gas is introduced into the third electrolyte storage tank so that the electrolyte in the third electrolyte storage tank is returned to the battery stack.

[0029] In a further embodiment, the flow rate and velocity of the electrolyte returning to the battery stack are controlled by the nitrogen pressure at the top of the third electrolyte storage tank.

[0030] In one specific embodiment, the volume of the second electrolyte storage tank is greater than or equal to the volume of the first electrolyte storage tank; the volume of the third electrolyte storage tank is greater than both the volume of the first electrolyte storage tank and the volume of the second electrolyte storage tank.

[0031] The second aspect of this disclosure provides a method for operating a flow battery, wherein the positive electrode electrolyte and the negative electrode electrolyte of the battery stack are respectively transported using the transport method described in the first aspect of this disclosure.

[0032] The third aspect of this disclosure provides an electrolyte delivery system for a flow battery, wherein the system includes: an electrolyte storage unit; The electrolyte storage unit includes a first electrolyte storage tank, a second electrolyte storage tank, and a third electrolyte storage tank arranged sequentially from top to bottom. A first gas phase pipeline and a first liquid phase pipeline that can be opened and closed are provided between the first electrolyte storage tank and the second electrolyte storage tank. A second gas phase pipeline and a second liquid phase pipeline that can be opened and closed are provided between the second electrolyte storage tank and the third electrolyte storage tank. The electrolyte inlet of the first electrolyte storage tank is connected to the electrolyte outlet of the battery stack; the electrolyte outlet of the third positive electrode electrolyte storage tank is connected to the electrolyte inlet of the battery stack. The system has a ready state, which includes: the first electrolyte storage tank is under normal pressure, and the second and third electrolyte storage tanks are filled with low-pressure inert gas; the gas phase and liquid phase are not connected between the first, second, and third electrolyte storage tanks.

[0033] The system provided in this disclosure can effectively avoid the problem of electrolyte leakage caused by stack seal failure in traditional flow batteries by using a suction-type electrolyte delivery method without the use of an electrolyte delivery pump. At the same time, the absence of an electrolyte circulation pump avoids pump maintenance and other issues, and enables long-term continuous operation of the flow battery system without the need to add a backup pump, thereby effectively improving the system's safety and stability.

[0034] According to one embodiment of this disclosure, a first electrolyte solenoid valve is provided on the first liquid phase pipeline; and a second electrolyte solenoid valve is provided on the second liquid phase pipeline.

[0035] According to one embodiment of this disclosure, a first gas phase solenoid valve is provided on the first gas phase pipeline, and a second gas phase solenoid valve is provided on the second gas phase pipeline.

[0036] According to one embodiment of this disclosure, an inert gas venting pipeline is provided at the top of the first electrolyte storage tank, and a single-exit valve is provided on the inert gas venting pipeline.

[0037] According to one embodiment of the present invention, the system further includes a flow control element and a pressure control element; wherein the flow control element is disposed on the outlet pipeline of the third electrolyte storage tank; and the pressure control element is disposed on the inert gas inlet pipeline at the top of the third electrolyte storage tank, for controlling the flow rate and velocity of the electrolyte returning to the battery stack.

[0038] The present invention will be further illustrated by the following examples, but the present invention is not limited thereto.

[0039] Example 1 This embodiment provides a flow battery system, which includes: a battery stack 1, a positive electrolyte storage unit 2, and a negative electrolyte storage unit 3; wherein, the positive electrolyte storage unit 2 includes a first positive electrolyte storage tank 4, a second positive electrolyte storage tank 5, and a third positive electrolyte storage tank 6 arranged in series; the negative electrolyte storage unit 3 includes a first negative electrolyte storage tank 7, a second negative electrolyte storage tank 8, and a third negative electrolyte storage tank 9 arranged in series; in the initial state of the system, the pressure inside the first electrolyte storage tank is lower than the pressure inside the second electrolyte storage tank, and the pressure inside the first electrolyte storage tank is lower than the pressure inside the third electrolyte storage tank; the first positive electrolyte storage tank and the second positive electrolyte storage tank have the same volume, and the volume of the third positive electrolyte storage tank is larger than the volumes of the first electrolyte storage tank and the second electrolyte storage tank, respectively; A first positive electrolyte storage tank 4 and a second positive electrolyte storage tank 5 are provided with a first positive electrolyte solenoid valve 10; a second positive electrolyte storage tank 5 and a third positive electrolyte storage tank 6 are provided with a second positive electrolyte solenoid valve 11. A first positive electrode gas phase pipeline is provided between the first positive electrode electrolyte storage tank 4 and the second positive electrode electrolyte storage tank 5, and a first positive electrode gas phase solenoid valve 12 is provided on the first positive electrode gas phase pipeline; a second positive electrode gas phase pipeline is provided between the second positive electrode electrolyte storage tank 5 and the third positive electrode electrolyte storage tank 6, and a second positive electrode gas phase solenoid valve 13 is provided on the second positive electrode gas phase pipeline. A first negative electrode liquid phase pipeline is provided between the first negative electrode electrolyte storage tank 7 and the second negative electrode electrolyte storage tank 8, and a first negative electrode electrolyte solenoid valve 16 is provided on the first negative electrode liquid phase pipeline; a second negative electrode liquid phase pipeline is provided between the second negative electrode electrolyte storage tank 8 and the third negative electrode electrolyte storage tank 9, and a second negative electrode electrolyte solenoid valve 17 is provided on the first negative electrode liquid phase pipeline. A first negative electrode gas phase pipeline is provided between the first negative electrode electrolyte storage tank 7 and the second negative electrode electrolyte storage tank 8, and a first negative electrode gas phase solenoid valve 18 is provided on the first negative electrode gas phase pipeline; a second negative electrode gas phase pipeline is provided between the second negative electrode electrolyte storage tank 8 and the third negative electrode electrolyte storage tank 9, and a second negative electrode gas phase solenoid valve 19 is provided on the second negative electrode gas phase pipeline. The system also includes a flow control element FC and a pressure control element PC; wherein, the flow measurement element FC is respectively installed on the outlet pipeline of the third positive electrolyte storage tank 6 and the third negative electrolyte storage tank 9; the pressure control element PC is respectively installed on the inert gas inlet pipeline at the top of the third positive electrolyte storage tank 6 and the third negative electrolyte storage tank 9; the top of the first positive electrolyte storage tank 4 and the first negative electrolyte storage tank 7 are respectively provided with inert gas venting pipelines, and single exhale valves 15 and 21 are installed on the inert gas venting pipelines.

[0040] Process flow diagram as follows Figure 1 As shown.

[0041] This embodiment provides a method for delivering electrolyte in a flow battery system, the specific steps of which are as follows: a. Before the electrolyte in the battery stack enters the first electrolyte storage tank, the internal pressure of the first electrolyte storage tank is atmospheric pressure (±2kPag). The second electrolyte storage tank is filled with low-pressure nitrogen gas (200~500kPag) and the liquid level is below 10%. The third electrolyte storage tank is filled with low-pressure nitrogen gas (200~500kPag) and the liquid level of the third electrolyte storage tank is controlled to be not lower than 20%. The first electrolyte solenoid valve, the second electrolyte solenoid valve, the first gas phase solenoid valve, and the second gas phase solenoid valve are in the closed state. b. Allow the electrolyte in the battery stack to enter the first electrolyte storage tank; c. When the electrolyte level in the first electrolyte tank reaches the maximum level, open the first gas phase solenoid valve 9 to connect the top of the second electrolyte tank with the top of the first electrolyte tank. Low-pressure nitrogen gas from the second electrolyte tank is introduced into the first electrolyte tank and discharged into the atmosphere through the venting pipeline located at the top of the first electrolyte tank, so that the internal pressure of the first electrolyte tank and the second electrolyte tank are the same. After the gas phase pressure is equalized, open the first electrolyte solenoid valve to allow the electrolyte in the first electrolyte tank to enter the second electrolyte tank under the action of gravity. d. After all the electrolyte in the first electrolyte tank in step c has entered the second electrolyte tank, open the second gas phase solenoid valve to connect the top of the third electrolyte tank with the top of the second electrolyte tank. Then, introduce low-pressure nitrogen from the third electrolyte tank into the second electrolyte tank to equalize the internal pressure of the two electrolyte tanks. After the gas phase pressure is equalized, open the second electrolyte solenoid valve 8 to allow the electrolyte in the second electrolyte tank to enter the third electrolyte tank under gravity. e. The pressure of nitrogen entering the third electrolyte storage tank is controlled by a pressure control element installed on a low-pressure inert gas pipeline, so that the electrolyte in the third positive electrode electrolyte storage tank returns to the battery stack through the gas phase pipeline.

[0042] The electrolyte in the third electrolyte storage tank 3 is propelled by the nitrogen pressure at the top of the tank, leaving the tank from the bottom, flowing through the battery stack, and then flowing to the first electrolyte storage tank located at the highest point. A flow measuring instrument 11 is installed on the electrolyte pipeline at the outlet of the third electrolyte storage tank 3, and a regulating valve 5 and a pressure measuring instrument 10 are installed on the low-pressure nitrogen pipeline connected to the top of the third electrolyte storage tank 3. The flow rate of the electrolyte leaving the third electrolyte storage tank 3 is controlled by the pressure of the nitrogen at the top of the tank, which is controlled by the regulating valve 5 located on the low-pressure nitrogen pipeline. In other words, the electrolyte flow measuring instrument 11 and the nitrogen pressure measuring instrument 10 cascade control the opening of the regulating valve 5.

[0043] Comparative Example 1 This comparative example provides a conventional flow battery system, which includes: a battery stack D1, a positive electrolyte storage tank D2, a negative electrolyte storage tank D3, a positive electrolyte circulation pump D4, and a negative electrolyte circulation pump D5. The process flow diagram is shown below. Figure 2 As shown.

[0044] The electrolyte delivery method in this comparative example includes the following steps: a. The positive electrolyte in the battery stack enters the positive electrolyte storage tank, and after being pressurized by the positive electrolyte circulation pump, it returns to the positive electrode of the battery stack. The negative electrolyte in the battery stack enters the negative electrolyte storage tank, and after being pressurized by the negative electrolyte circulation pump, it returns to the negative electrode of the battery stack. The speed of the variable frequency pump is controlled by the flow meter on the outlet pipeline of the positive and negative electrolyte circulation pumps, thereby controlling the flow rate of the electrolyte circulation loop.

[0045] Test case The flow battery systems provided in Example 1 and Comparative Example 1 were operated for 12 months, 36 months, and 60 months, and the sealing performance of the flow battery systems was tested. The test results are shown in Table 1.

[0046] Table 1

[0047] As can be seen from the test results in Table 1, the method and system provided in this application can effectively avoid the problem of electrolyte leakage caused by the failure of the stack seal in traditional flow batteries by using a suction-type electrolyte delivery method without the use of an electrolyte delivery pump. This effectively reduces the leakage risk of the flow battery system, enables the flow battery system to operate continuously for a long period of time, and effectively improves the safety and stability of the system.

[0048] In Comparative Example 1, the flange connections, bearing seals, and housing seals of the positive and negative electrolyte circulation pumps to the inlet and outlet pipelines, as well as the pump-related valve groups, such as shut-off valves, check valves, pressure gauges, and condensate drain valves before and after the pumps, add multiple sealing points and flange connection points to the entire electrolyte circulation system, greatly increasing the risk of electrolyte leakage. After 12 months of battery operation, the equipment developed leaks; after 36 months of operation, the equipment developed numerous leaks; and after 60 months of operation, the equipment developed a large number of leaks. The sealing performance of the flow battery system provided in Comparative Example 1 under long-term operation is significantly worse than that of Example 1 of this application.

[0049] The preferred embodiments of the present invention have been described in detail above with reference to the accompanying drawings. However, the present invention is not limited to the specific details of the above embodiments. Within the scope of the technical concept of the present invention, various simple modifications can be made to the technical solution of the present invention, and these simple modifications all fall within the protection scope of the present invention.

[0050] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, the present invention will not describe the various possible combinations separately.

[0051] Furthermore, various different embodiments of the present invention can be combined in any way, as long as they do not violate the spirit of the present invention, they should also be regarded as the content disclosed by the present invention.

Claims

1. A method for transporting electrolyte in a flow battery, characterized in that, The method includes: S0, puts the electrolyte storage unit into a ready state; The electrolyte storage unit includes a first electrolyte storage tank, a second electrolyte storage tank, and a third electrolyte storage tank arranged sequentially from top to bottom. A first gas phase pipeline and a first liquid phase pipeline that can be opened and closed are provided between the first electrolyte storage tank and the second electrolyte storage tank. A second gas phase pipeline and a second liquid phase pipeline that can be opened and closed are provided between the second electrolyte storage tank and the third electrolyte storage tank. The preparation state includes: placing the first electrolyte storage tank at normal pressure, and filling the second and third electrolyte storage tanks with low-pressure inert gas respectively; the gas phase and liquid phase are not connected between the first, second, and third electrolyte storage tanks. S1. Allow the electrolyte in the battery stack to enter the first electrolyte storage tank under the action of gravity; S2. When the electrolyte level in the first electrolyte storage tank reaches the highest level, the first electrolyte storage tank is connected to the second electrolyte storage tank by air, and the first electrolyte storage tank is connected to the atmosphere in one direction, so that the low-pressure inert gas in the second electrolyte storage tank can enter the first electrolyte storage tank. S3. After the internal pressures of the first electrolyte storage tank and the second electrolyte storage tank are the same, the electrolyte in the first electrolyte storage tank enters the second electrolyte storage tank under the action of gravity. S4. When the liquid level in the second electrolyte storage tank reaches the highest level, the third electrolyte storage tank is connected to the second electrolyte storage tank by gas, so that the inert gas in the third electrolyte storage tank can enter the second electrolyte storage tank. S5. After the internal pressure of the second electrolyte storage tank and the third electrolyte storage tank are the same, the electrolyte in the second electrolyte storage tank enters the third electrolyte storage tank under the action of gravity. S6. Return the electrolyte in the third positive electrolyte storage tank to the battery stack.

2. The method according to claim 1, wherein, The method further includes: before the electrolyte enters the first electrolyte storage tank, the pressure inside the first electrolyte storage tank is lower than the pressure inside the second electrolyte storage tank; the pressure inside the first electrolyte storage tank is lower than the pressure inside the third positive electrode electrolyte storage tank; The pressure inside the first electrolyte storage tank is 98~102 kPag; the pressure inside the second electrolyte storage tank is 0~500 kPag; and the pressure inside the third electrolyte storage tank is 200~500 kPag. Before the electrolyte enters the first electrolyte storage tank, the liquid level in the first electrolyte storage tank is less than 10% of the maximum liquid level; the liquid level in the second electrolyte storage tank is less than 10% of the maximum liquid level; and the liquid level in the third electrolyte storage tank is 20-80% of the maximum liquid level.

3. The method according to claim 1, wherein, In step S2, the inert gas that enters the top of the first electrolyte storage tank is discharged into the atmosphere through the single exhalation valve at the top of the first electrolyte storage tank. In step S2, the third electrolyte storage tank and the second electrolyte storage tank are not connected in terms of gas phase and liquid phase.

4. The method according to claim 1, wherein, Before step S6, the method further includes repeating steps S0 to S5.

5. The method according to claim 1, wherein, In step S6, low-pressure inert gas is introduced into the third electrolyte storage tank to return the electrolyte in the third electrolyte storage tank to the battery stack.

6. The method according to claim 5, wherein, The flow rate and velocity of the electrolyte returning to the battery stack are controlled by the nitrogen pressure at the top of the third electrolyte storage tank.

7. The method according to claim 1, wherein, The volume of the second electrolyte storage tank is greater than or equal to the volume of the first electrolyte storage tank; The volume of the third electrolyte storage tank is larger than the volume of the first electrolyte storage tank and the volume of the second electrolyte storage tank.

8. A method for operating a flow battery, wherein, The positive and negative electrolytes of the battery stack are transported using the transport method described in any one of claims 1 to 7.

9. A flow battery electrolyte delivery system, wherein, The system includes: an electrolyte storage unit; The electrolyte storage unit includes a first electrolyte storage tank, a second electrolyte storage tank, and a third electrolyte storage tank arranged sequentially from top to bottom. A first gas phase pipeline and a first liquid phase pipeline that can be opened and closed are provided between the first electrolyte storage tank and the second electrolyte storage tank. A second gas phase pipeline and a second liquid phase pipeline that can be opened and closed are provided between the second electrolyte storage tank and the third electrolyte storage tank. The electrolyte inlet of the first electrolyte storage tank is connected to the electrolyte outlet of the battery stack; the electrolyte outlet of the third positive electrode electrolyte storage tank is connected to the electrolyte inlet of the battery stack. The system has a ready state, which includes: the first electrolyte storage tank is under normal pressure, and the second and third electrolyte storage tanks are filled with low-pressure inert gas; the gas phase and liquid phase are not connected between the first, second, and third electrolyte storage tanks.

10. The system according to claim 9, wherein, A first electrolyte solenoid valve is installed on the first liquid phase pipeline; a second electrolyte solenoid valve is installed on the second liquid phase pipeline. A first gas phase solenoid valve is installed on the first gas phase pipeline, and a second gas phase solenoid valve is installed on the second gas phase pipeline. An inert gas venting pipeline is installed at the top of the first electrolyte storage tank, and a single-exhale valve is installed on the inert gas venting pipeline. Optionally, the system further includes a flow control element and a pressure control element; wherein the flow control element is disposed on the outlet pipeline of the third electrolyte storage tank; and the pressure control element is disposed on the inert gas inlet pipeline at the top of the third electrolyte storage tank, for controlling the flow rate and velocity of the electrolyte returning to the battery stack.

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