Automatic liquid level balance control device for positive and negative storage tanks of all-vanadium redox flow battery

Abstract

The invention discloses an all-vanadium redox flow battery positive and negative electrode storage tank liquid level automatic balance control device which comprises a positive electrode electrolyte storage tank, a negative electrode electrolyte storage tank and a galvanic pile, a first circulation loop is formed between the positive electrode electrolyte storage tank and the galvanic pile, and a second circulation loop is formed between the negative electrode electrolyte storage tank and the galvanic pile. Venturi tubes are arranged on the positive electrode electrolyte return pipeline and the negative electrode electrolyte return pipeline, liquid pumping holes of the Venturi tubes are communicated with the negative electrode electrolyte storage tank and the positive electrode electrolyte storage tank through an electrolyte pumping pipeline, and a liquid level monitoring device is arranged on the electrolyte pumping pipeline. The venturi tube is communicated with the electrolyte suction pipeline, and redundant electrolyte in one electrolyte storage tank is sucked into the other electrolyte storage tank by means of pressure difference generated by the venturi tube, so that the design of the positive and negative electrolyte storage tanks is not limited by the relative height of the electrolyte level, and the space of the storage tanks can be fully utilized; the integration level of the battery system is improved, and the occupied area is reduced.

Description

Technical Field

[0001] This invention relates to the field of flow battery technology, and in particular to an automatic balancing control device for the positive and negative electrode storage tanks of a vanadium redox flow battery. Background Technology

[0002] In existing vanadium redox flow battery system architectures, a leveling pipe or overflow pipe is typically installed between the positive and negative electrolyte tanks. When these pipes are connected, given the relative height difference between the electrolyte levels in the positive and negative electrolyte tanks, the electrolyte will naturally flow from the tank with the higher level to the tank with the lower level under the influence of gravity, thus achieving a balance in the electrolyte level.

[0003] During the charging and discharging of a vanadium redox flow battery, water molecules in the electrolyte migrate in various forms between the stack membranes, causing continuous changes in the volume of the positive and negative electrolytes. Specifically, during charging and discharging, water molecules generally tend to migrate towards the positive electrolyte, leading to an expansion of the positive electrolyte volume. The liquid level in the positive electrolyte tank gradually rises, reaching a peak level at the end of the discharge process.

[0004] To ensure the stable and reliable operation of the vanadium redox flow battery system, if the volume of electrolyte added to the positive electrode electrolyte tank exceeds a certain limit, the excess positive electrolyte needs to be diverted to the negative electrode electrolyte tank via an overflow pipe connecting the upper parts of the positive and negative electrode tanks. However, in conventional designs, the overflow pipe relies on the liquid level difference between the positive and negative electrode electrolyte tanks, using the electrolyte's own gravity to achieve overflow. This places specific requirements on the relative liquid levels inside the positive and negative electrode electrolyte tanks, inevitably constraining the tank design and their relative positions to a certain extent. Summary of the Invention

[0005] To address the aforementioned problems, this invention provides an automatic liquid level balancing control device for the positive and negative electrode storage tanks of a vanadium redox flow battery, thereby solving the limitation of existing vanadium redox flow battery positive and negative electrode storage tanks that rely on the liquid level difference between storage tanks to achieve liquid level balance.

[0006] This invention is implemented as follows: An automatic balancing control device for the positive and negative electrode tanks of a vanadium redox flow battery includes a positive electrode electrolyte tank, a negative electrode electrolyte tank, and a battery stack. The positive electrode electrolyte tank and the battery stack form a first circulation loop through a positive electrode electrolyte suction pipe and a positive electrode electrolyte return pipe, respectively. The negative electrode electrolyte tank and the battery stack form a second circulation loop through a negative electrode electrolyte suction pipe and a negative electrode electrolyte return pipe, respectively. Both the positive and negative electrode electrolyte return pipes are equipped with Venturi tubes. The suction hole in the middle of the Venturi tube is connected to the negative electrode electrolyte tank and the positive electrode electrolyte tank through a suction electrolyte pipe, respectively. The suction electrolyte pipe is equipped with a liquid level monitoring device for connecting or disconnecting it.

[0007] Furthermore, a first Venturi tube is provided on the positive electrode electrolyte return pipeline. The inlet end of the first Venturi tube is located near the outlet end of the fuel cell stack, and the outlet end of the first Venturi tube is located near the return port of the positive electrode electrolyte storage tank. The suction port of the first Venturi tube is connected to the negative electrode electrolyte storage tank through a first suction electrolyte pipeline.

[0008] Furthermore, a second Venturi tube is provided on the negative electrode electrolyte return pipeline. The inlet end of the second Venturi tube is located near the outlet end of the fuel cell stack, and the outlet end of the second Venturi tube is located near the return port of the negative electrode electrolyte storage tank. The suction port of the second Venturi tube is connected to the positive electrode electrolyte storage tank through a second suction electrolyte pipeline.

[0009] Furthermore, there are two liquid level monitoring devices, which are respectively installed inside the positive electrode electrolyte storage tank and the negative electrode electrolyte storage tank.

[0010] Furthermore, the liquid level monitoring device includes a rotating arm rotatably disposed within the positive electrode electrolyte storage tank or the negative electrode electrolyte storage tank. One end of the rotating arm is fixedly provided with a float ball, and the other end of the rotating arm is connected to a plug pipe. The plug pipe is slidably disposed within the electrolyte suction pipeline to connect or disconnect the electrolyte suction pipeline.

[0011] Furthermore, a hanging rod is fixedly connected to the top wall of the positive electrode electrolyte storage tank and the negative electrode electrolyte storage tank. The middle part of the rotating arm is rotatably connected to the hanging rod through a first rotating shaft, and the other end of the rotating arm is fixedly connected to a second rotating shaft.

[0012] Furthermore, the plug is a cylindrical structure with an open top, and two lugs are fixedly connected to the bottom plate of the plug. Long strip-shaped grooves are opened on the two lugs, and the two ends of the second rotating shaft are respectively inserted into the grooves and slide and rotate within the grooves.

[0013] Furthermore, a first liquid inlet is provided on the bottom plate of the plug, which is located between the two supports, and a second liquid inlet is provided on the side wall of the plug, which is circumferentially oriented.

[0014] Furthermore, the diameter of the suction orifice of the venturi tube is the same as the diameter of its throat.

[0015] Furthermore, the included angle of the conical contraction section of the venturi tube is 20-22°, the included angle of the conical diffusion section is 8-12°, and the ratio of the throat diameter to the inlet diameter is 0.3-0.6.

[0016] The beneficial effects of this invention are: The automatic electrolyte level balancing control device for the positive and negative electrode storage tanks of the vanadium redox flow battery of this invention features a venturi tube connected to an electrolyte suction line. Utilizing the pressure difference generated by the venturi tube, excess electrolyte in one storage tank is suctioned to another, eliminating the limitations imposed by the relative electrolyte levels in the positive and negative electrode electrolyte storage tanks. This allows for full utilization of tank space, improves the integration of the battery system, and reduces the floor space required. The included level monitoring device can connect and disconnect the electrolyte suction line in real time based on the electrolyte levels in the positive and negative electrode electrolyte storage tanks. When the electrolyte level rises, the suction line is connected and excess electrolyte is removed through the venturi tube; when the electrolyte level falls, the suction line is disconnected to maintain balance. As the electrolyte level continues to rise, excess electrolyte can also be suctioned simultaneously through the first and second inlets, improving suction efficiency. The design of the first and second inlets allows for control of the inlet opening based on changes in the electrolyte level, thereby enabling automatic adjustment of the Venturi tube's suction volume according to the electrolyte quantity. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the structure of the present invention; Figure 2 This is a cross-sectional view of the venturi tube of the present invention; Figure 3 This is a three-dimensional structural schematic diagram of the liquid level monitoring device of the present invention; Figure 4 This is an exploded view of the liquid level monitoring device of the present invention; Figure 5 This is a schematic diagram of the liquid level monitoring device of the present invention in its first operating state; Figure 6 This is a schematic diagram of the second operating state of the liquid level monitoring device of the present invention.

[0018] Explanation of reference numerals in the attached figures: 1. Positive electrolyte storage tank; 11. Positive electrolyte suction line; 12. Positive electrolyte return line; 13. Positive circulating pump; 14. First Venturi tube; 141. Inlet cylinder; 142. Conical contraction section; 143. Throat; 1431. Suction hole; 144. Conical diffusion section; 145. Outlet cylinder; 15. First electrolyte suction line; 2. Negative electrode electrolyte storage tank; 21. Negative electrode electrolyte suction line; 22. Negative electrode electrolyte return line; 23. Negative electrode circulation pump; 24. Second Venturi tube; 25. Second electrolyte suction line; 3. Fuel cell stack; 4. Liquid level monitoring device; 41. Rotating arm; 42. Float; 43. Plug; 431. Support lug; 432. First liquid inlet; 433. Second liquid inlet; 44. Lifting rod; 45. First rotating shaft; 46. Second rotating shaft; 47. Spring. Detailed Implementation

[0019] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Many specific details are set forth in the following description to provide a thorough understanding of the present invention. However, the present invention may also be implemented in other ways different from those described herein. Those skilled in the art can make similar extensions without departing from the spirit of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0020] like Figures 1-6 The diagram shows the automatic balancing control device for the positive and negative electrode tanks of the vanadium redox flow battery of the present invention. It includes a positive electrode electrolyte tank 1, a negative electrode electrolyte tank 2, and a battery stack 3. The positive electrode electrolyte tank 1 and the battery stack 3 are connected by a positive electrode electrolyte suction pipe 11 and a positive electrode electrolyte return pipe 12, respectively. The negative electrode electrolyte tank 2 and the battery stack 3 are connected by a negative electrode electrolyte suction pipe 21 and a negative electrode electrolyte return pipe 22, respectively. Venturi tubes are provided on both the positive electrode electrolyte return pipe 12 and the negative electrode electrolyte return pipe 22. The suction hole 1431 in the middle of the Venturi tube is connected to the negative electrode electrolyte tank 2 and the positive electrode electrolyte tank 1 through a suction electrolyte pipe. A liquid level monitoring device 4 for connecting or disconnecting the suction electrolyte pipe is provided on the suction electrolyte pipe.

[0021] like Figure 1As shown, the positive electrolyte storage tank 1 and the fuel cell stack 3 form a first circulation loop through a positive electrolyte suction pipe 11 and a positive electrolyte return pipe 12, respectively. One end of the positive electrolyte suction pipe 11 is connected to the suction port of the positive electrolyte storage tank 1, and the other end is connected to the inlet of the fuel cell stack 3. A positive electrolyte circulation pump 13 and a control valve (not shown in the figure) are installed on the positive electrolyte suction pipe 11. The positive electrolyte circulation pump 13 is used to extract the positive electrolyte from the positive electrolyte storage tank 1 and transport it to the positive electrode chamber of the fuel cell stack 3. One end of the positive electrolyte return pipe 12 is connected to the outlet of the fuel cell stack 3, and the other end is connected to the return port of the positive electrolyte storage tank 1.

[0022] A second circulation loop is formed between the negative electrode electrolyte storage tank 2 and the fuel cell stack 3 via a negative electrode electrolyte suction pipe 21 and a negative electrode electrolyte return pipe 22, respectively. One end of the negative electrode electrolyte suction pipe 21 is connected to the suction port of the negative electrode electrolyte storage tank 2, and the other end is connected to the inlet of the fuel cell stack 3. A negative electrode circulation pump 23 and a control valve (not shown in the figure) are installed on the negative electrode electrolyte suction pipe 21. The negative electrode circulation pump 23 is used to extract the negative electrode electrolyte from the negative electrode electrolyte storage tank 2 and transport it to the negative electrode chamber of the fuel cell stack 3. One end of the negative electrode electrolyte return pipe 22 is connected to the outlet of the fuel cell stack 3, and the other end is connected to the return port of the negative electrode electrolyte storage tank 2.

[0023] The positive electrode circulation pump 13 draws the positive electrode electrolyte from the positive electrode electrolyte storage tank 1 and delivers it to the positive electrode chamber of the fuel cell stack 3. The negative electrode circulation pump 23 draws the negative electrode electrolyte from the negative electrode electrolyte storage tank 2 and delivers it to the negative electrode chamber of the fuel cell stack 3. Inside the fuel cell stack 3, the electrolyte undergoes a redox reaction through an ion exchange membrane, realizing the interconversion of electrical energy and chemical energy. The electrolyte in the positive electrode chamber of the fuel cell stack 3 flows back to the positive electrode electrolyte storage tank 1 through the positive electrode electrolyte return pipe 12, and the electrolyte in the negative electrode chamber of the fuel cell stack 3 flows back to the negative electrode electrolyte storage tank 2 through the negative electrode electrolyte return pipe 22, forming a cycle.

[0024] Both the positive electrolyte return line 12 and the negative electrolyte return line 22 are equipped with Venturi tubes. A Venturi tube is a fluid measurement device based on Bernoulli's principle, which creates a pressure difference by changing the cross-sectional area of ​​the pipe to generate a change in flow velocity. The positive electrolyte return line 12 is equipped with a first Venturi tube 14. The inlet end of the first Venturi tube 14 is located near the outlet end of the fuel cell stack 3, and the outlet end of the first Venturi tube 14 is located near the return port of the positive electrolyte storage tank 1. The suction port 1431 of the first Venturi tube 14 is connected to the negative electrolyte storage tank 2 through the first suction electrolyte line 15. A second Venturi tube 24 is provided on the negative electrode electrolyte return line 22. The inlet end of the second Venturi tube 24 is located near the outlet end of the fuel cell stack 3, and the outlet end of the second Venturi tube 24 is located near the return port of the negative electrode electrolyte storage tank 2. The suction port of the second Venturi tube 24 is connected to the positive electrode electrolyte storage tank 1 through the second suction electrolyte line 25.

[0025] In this embodiment, the first Venturi tube 14 and the second Venturi tube 24 have the same structure and size. For example... Figure 2 As shown, taking the first Venturi tube 14 as an example, the first Venturi tube 14 includes an inlet cylinder 141, a conical contraction section 142, a throat 143, a conical diffusion section 144, and an outlet cylinder 145. A liquid extraction hole 1431 is provided at the center of the throat 143. The diameter of the liquid extraction hole 1431 of the Venturi tube is the same as the diameter of its throat 143, so as to maximize the liquid extraction capacity of the liquid extraction hole 1431. The included angle of the conical contraction section 142 of the Venturi tube is 20-22°, and the included angle of the conical diffusion section 144 is 8-12°. This design is used to reduce pressure loss, while ensuring uniform acceleration and pressure recovery of the electrolyte in the throat 143, avoiding increased flow resistance when the included angle is too large, and increasing the complexity of design and manufacturing when the included angle is too small. The ratio of the throat 143 diameter to the inlet diameter of the inlet cylinder 141 is 0.3 to 0.6, which can optimize the pressure and pressure difference of the throat 143 and prevent the increase of local resistance when the pressure difference is too large.

[0026] When the positive electrode circulation pump 13 and the negative electrode circulation pump 23 are operating normally, the electrolyte after the oxidation-reduction reaction flows into the positive electrode electrolyte storage tank 1 and the negative electrode electrolyte storage tank 2 through the positive electrode electrolyte return line 12 and the negative electrode electrolyte return line 22, respectively. At this time, electrolyte flows normally through both the first Venturi tube 14 and the second Venturi tube 24. When the positive electrode electrolyte level in the positive electrode electrolyte storage tank 1 rises, the second Venturi tube 24 draws the positive electrode electrolyte into the negative electrode electrolyte storage tank 2 through the second suction electrolyte line 25. Similarly, when the negative electrode electrolyte level in the negative electrode electrolyte storage tank 2 rises, the first Venturi tube 14 draws the negative electrode electrolyte into the positive electrode electrolyte storage tank 1 through the first suction electrolyte line 15. The specific working process will be described in detail later.

[0027] Two liquid level monitoring devices 4 are installed on the electrolyte suction pipeline for connecting or disconnecting it. They are respectively installed inside the positive electrolyte storage tank 1 and the negative electrolyte storage tank 2. The two liquid level monitoring devices 4 control the connection and disconnection of the first electrolyte suction pipeline 15 and the second electrolyte suction pipeline 25.

[0028] like Figure 1 , Figure 3 and Figure 4 As shown, the liquid level monitoring device 4 includes a rotating arm 41 rotatably disposed within the positive electrolyte storage tank 1 or the negative electrolyte storage tank 2. The rotating arm 41 has a Z-shaped structure. A float 42 is fixedly disposed at one end of the rotating arm 41, and the density of the float 42 is less than the density of the electrolyte. A plug 43 is connected to the other end of the rotating arm 41. The plug 43 is slidably disposed within the electrolyte suction pipeline to connect or disconnect the electrolyte suction pipeline. In this embodiment, the two plugs 43 are slidably disposed at the inlet ends of the first electrolyte suction pipeline 15 and the second electrolyte suction pipeline 25, respectively. The inlet ends of the first electrolyte suction pipeline 15 and the second electrolyte suction pipeline 25 penetrate the top walls of the negative electrolyte storage tank 2 and the positive electrolyte storage tank 1, respectively, and extend into their cavities. A lifting rod 44 is fixedly connected to the top wall of the positive electrode electrolyte storage tank 1 and the negative electrode electrolyte storage tank 2. The middle part of the rotating arm 41 is rotatably connected to the lifting rod 44 through a first rotating shaft 45, and the other end of the rotating arm 41 is fixedly connected to a second rotating shaft 46. The plug 43 is a cylindrical structure with an open top. Two lugs 431 are fixedly connected to the bottom plate of the plug 43. Long strip-shaped sliding grooves are opened on the two lugs 431. The two ends of the second rotating shaft 46 are respectively inserted into the sliding grooves and slide and rotate within the sliding grooves. A first liquid inlet 432 is opened on the bottom plate of the plug 43, located between the two lugs 431. A second liquid inlet 433 is opened on the side wall of the plug 43, and the second liquid inlet 433 is opened circumferentially. The plug 43 slides up and down within the first and second electrolyte suction lines 15 and 25 to block or open the inlet ends of the first and second electrolyte suction lines 15 and 25. A spring 47 is connected between the first and second electrolyte suction lines 15 and the rotating arm 41. One end of the spring 47 is fixedly connected to the outer wall of the first and second electrolyte suction lines 15 and 25, and the other end of the spring 47 is fixedly connected to the upper side of the rotating arm 41.

[0029] like Figure 5 The diagram shows the state of the float 42 when the electrolyte level is low. At this time, the first inlet 432 of the plug 43 is higher than the bottom of the float 42, preventing the electrolyte from flowing into the electrolyte suction line through the first inlet 432 of the plug 43. Figure 6As shown, as the electrolyte level rises, the float 42 rises under the action of buoyancy, and drives the rotating arm 41 to rotate clockwise around the first rotating shaft 45. The spring 47 is compressed, and one end of the rotating arm 41 connected to the float 42 rotates upward, while the other end of the rotating arm 41 rotates downward and drives the second rotating shaft 46 to rotate. The second rotating shaft 46 drives the support lug 431 sleeved on its outer side to move. The movement of the support lug 431 causes the plug tube 43, which is fixedly connected to it, to slide downward in the electrolyte suction pipeline until the height of the first liquid inlet 432 of the plug tube 43 is lower than the height of the bottom of the float 42. The electrolyte flows into the plug tube 43 and the electrolyte suction pipeline through the first liquid inlet 432. If the electrolyte level continues to rise, the float 42, during its ascent, drives the rotating arm 41 to continue rotating, causing the plug 43 to continue sliding downwards. When the second inlet 433 extends into the electrolyte, the electrolyte can simultaneously enter the suction electrolyte pipeline from both the first inlet 432 and the second inlet 433, increasing the electrolyte flow rate. Since the second inlet 433 is circumferentially located along the plug 43, the electrolyte level affects the height through which it flows, thus automatically controlling the amount of electrolyte flowing into the suction electrolyte pipeline based on the electrolyte level. As the electrolyte level rises, more electrolyte flows through the second inlet 433, improving the electrolyte suction efficiency. When the electrolyte level falls, less electrolyte flows through the second inlet 433, effectively reducing the amount of electrolyte drawn. When the electrolyte level drops again and the bottom of the second inlet 433 is higher than the bottom of the float 42, the electrolyte will flow into the electrolyte suction line only from the first inlet 432.

[0030] The automatic balancing control device for the positive and negative electrode tank levels of the vanadium redox flow battery of the present invention, when the battery system is operating normally, the positive electrode circulation pump 13 draws the positive electrode electrolyte from the positive electrode electrolyte storage tank 1 and delivers it to the positive electrode chamber of the stack 3. The negative electrode circulation pump 23 draws the negative electrode electrolyte from the negative electrode electrolyte storage tank 2 and delivers it to the negative electrode chamber of the stack 3. Inside the stack 3, the electrolyte undergoes a redox reaction through an ion exchange membrane, realizing the mutual conversion of electrical energy and chemical energy. The electrolyte in the positive electrode chamber of the stack 3 flows back to the positive electrode electrolyte storage tank 1 through the positive electrode electrolyte return pipe 12, and the electrolyte in the negative electrode chamber of the stack 3 flows back to the negative electrode electrolyte storage tank 2 through the negative electrode electrolyte return pipe 22. The overall migration pattern of the electrolyte is that during the charge-discharge cycle, it migrates towards the positive electrode for a period of time and towards the negative electrode for a period of time. During the period when the electrolyte migrates towards the positive electrode, the electrolyte level in the positive electrode electrolyte storage tank 1 gradually rises. When the electrolyte level is low, and the float 42 is in position as follows... Figure 5As shown, the first inlet 432 of the plug 43 is higher than the bottom of the float 42, preventing electrolyte from flowing into the plug 43 and the second suction electrolyte line 25. Electrolyte flows normally within the second venturi tube 24. As the electrolyte level in the positive electrode electrolyte storage tank 1 continues to rise, the float 42 rises accordingly. During the rise, the float 42 drives the rotating arm 41 to rotate. The rotation of the rotating arm 41 causes the lug 431 and the plug 43 to slide downwards along the length of the second suction electrolyte line 25 until the first inlet 432 of the plug 43 is lower than the bottom of the float 42. That is, the first inlet 432 extends into the electrolyte, and the electrolyte flows into the plug 43 and the second suction electrolyte line 25 through the first inlet 432. Combined with the negative pressure generated by the suction hole of the second venturi tube 24, the electrolyte flows into the negative electrode electrolyte storage tank 2. Because the second venturi tube 24 generates sufficient negative pressure, it can ensure that electrolyte is continuously drawn from the positive electrolyte storage tank 1 to the negative electrolyte storage tank 2 through the second suction electrolyte pipeline 25 until the electrolyte level in the positive electrolyte storage tank 1 drops to a predetermined height.

[0031] If the electrolyte level continues to rise, the float 42 will continue to rise, causing the rotating arm 41 to continue rotating, which in turn will cause the plug 43 to continue sliding downwards. When the second inlet 433 extends into the electrolyte, as... Figure 6 As shown, electrolyte can simultaneously enter the second suction electrolyte pipeline 25 from both the first inlet 432 and the second inlet 433. Since the second inlet 433 is circumferentially located along the plug 43, the electrolyte level varies, resulting in different flow heights through the second inlet 433. This allows for automatic control of the electrolyte flow rate into the second suction electrolyte pipeline 25 based on the electrolyte level. As the electrolyte level rises, more electrolyte flows through the second inlet 433, increasing the suction efficiency. When the electrolyte level falls, less electrolyte flows through the second inlet 433, effectively reducing the suction volume. When the electrolyte level continues to drop, and the bottom of the second inlet 433 is higher than the bottom of the float 42, electrolyte flows into the second suction electrolyte pipeline 25 only from the first inlet 432. When the electrolyte level continues to drop until the first inlet 432 is higher than the bottom of the float 42, the electrolyte cannot flow from the first inlet 432 into the second suction electrolyte pipeline 25, and the electrolyte levels in the positive electrode electrolyte storage tank 1 and the negative electrode electrolyte storage tank 2 are balanced again, meeting the usage requirements.

[0032] Similarly, during the period when the electrolyte migrates towards the negative electrode, the electrolyte level in the negative electrode electrolyte storage tank 2 gradually rises. Through the first Venturi tube 14, the first suction electrolyte pipeline 15, and the level monitoring device 4, the negative electrode electrolyte is pumped into the positive electrode electrolyte storage tank 1, thereby restoring the electrolyte levels in the positive electrode electrolyte storage tank 1 and the negative electrode electrolyte storage tank 2 to equilibrium, meeting the usage requirements. The specific adjustment process will not be elaborated further.

[0033] While the present invention discloses preferred embodiments to achieve the above objectives, these are not intended to limit the structural features of the invention. Anyone skilled in the art should know that any easily conceived variations or modifications are possible within the technical spirit of the invention and are covered by the claims of the present invention.

Claims

1. An automatic balancing control device for the liquid level of the positive and negative electrode storage tanks of a vanadium redox flow battery, characterized in that, The device includes a positive electrolyte storage tank, a negative electrolyte storage tank, and a fuel cell stack. The positive electrolyte storage tank and the fuel cell stack form a first circulation loop through a positive electrolyte suction pipe and a positive electrolyte return pipe, respectively. The negative electrolyte storage tank and the fuel cell stack form a second circulation loop through a negative electrolyte suction pipe and a negative electrolyte return pipe, respectively. Both the positive and negative electrolyte return pipes are equipped with Venturi tubes. The suction port in the middle of the Venturi tube is connected to the negative electrolyte storage tank and the positive electrolyte storage tank through a suction electrolyte pipe, respectively. The suction electrolyte pipe is equipped with a liquid level monitoring device for connecting or disconnecting the connection.

2. The automatic balancing control device for the positive and negative electrode storage tanks of a vanadium redox flow battery according to claim 1, characterized in that, A first Venturi tube is provided on the positive electrode electrolyte return pipeline. The inlet end of the first Venturi tube is located near the outlet end of the fuel cell stack, and the outlet end of the first Venturi tube is located near the return port of the positive electrode electrolyte storage tank. The suction port of the first Venturi tube is connected to the negative electrode electrolyte storage tank through a first suction electrolyte pipeline.

3. The automatic balancing control device for the positive and negative electrode storage tanks of a vanadium redox flow battery according to claim 1 or 2, characterized in that, A second Venturi tube is provided on the negative electrode electrolyte return pipeline. The inlet end of the second Venturi tube is located near the outlet end of the fuel cell stack, and the outlet end of the second Venturi tube is located near the return port of the negative electrode electrolyte storage tank. The suction port of the second Venturi tube is connected to the positive electrode electrolyte storage tank through a second suction electrolyte pipeline.

4. The automatic balancing control device for the positive and negative electrode storage tanks of a vanadium redox flow battery according to claim 1, characterized in that, The liquid level monitoring device consists of two devices, which are respectively installed inside the positive electrode electrolyte storage tank and the negative electrode electrolyte storage tank.

5. The automatic balancing control device for the positive and negative electrode storage tanks of a vanadium redox flow battery according to claim 4, characterized in that, The liquid level monitoring device includes a rotating arm rotatably disposed inside the positive electrode electrolyte storage tank or the negative electrode electrolyte storage tank. One end of the rotating arm is fixedly provided with a float ball, and the other end of the rotating arm is connected to a plug pipe. The plug pipe is slidably disposed inside the electrolyte suction pipeline to connect or disconnect the electrolyte suction pipeline.

6. The automatic balancing control device for the positive and negative electrode storage tanks of a vanadium redox flow battery according to claim 5, characterized in that, A suspension rod is fixedly connected to the top wall of the positive electrode electrolyte storage tank and the negative electrode electrolyte storage tank. The middle part of the rotating arm is rotatably connected to the suspension rod through a first rotating shaft, and the other end of the rotating arm is fixedly connected to a second rotating shaft.

7. The automatic balancing control device for the positive and negative electrode storage tanks of a vanadium redox flow battery according to claim 6, characterized in that, The plug is a cylindrical structure with an open top. Two lugs are fixedly connected to the bottom plate of the plug. Long grooves are provided on the two lugs. The two ends of the second rotating shaft pass through the grooves and slide and rotate within the grooves.

8. The automatic balancing control device for the positive and negative electrode storage tanks of a vanadium redox flow battery according to claim 7, characterized in that, The bottom plate of the plug is provided with a first liquid inlet, which is located between the two lugs. The side wall of the plug is provided with a second liquid inlet, which is opened along its circumference.

9. The automatic balancing control device for the positive and negative electrode storage tanks of a vanadium redox flow battery according to claim 1, characterized in that, The diameter of the suction orifice of a Venturi tube is the same as the diameter of its throat.

10. The automatic balancing control device for the positive and negative electrode storage tanks of a vanadium redox flow battery according to claim 1, characterized in that, The included angle of the conical contraction section of the venturi tube is 20-22°, the included angle of the conical diffusion section is 8-12°, and the ratio of the throat diameter to the inlet diameter is 0.3-0.6.

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