A vanadium flow battery system with negative pressure protection device

Abstract

This invention belongs to the technical field of flow battery energy storage systems, specifically relating to a vanadium redox flow battery system with a negative pressure protection device. It includes a capacity unit, a power unit positioned above the capacity unit, an electrolyte piping assembly, and a buffer valve mounted on the electrolyte piping assembly. The capacity unit stores the electrolyte, the power unit performs the electrochemical reaction, and the electrolyte piping assembly connects the capacity unit and the power unit, forming a flow path for the electrolyte and constructing an electrolyte circulation channel. The buffer valve slows down the electrolyte backflow rate when the vanadium redox flow battery system is shut down, reducing the instantaneous negative pressure inside the stack. This invention, by using a buffer valve to slow down the electrolyte backflow rate during shutdown, protects the internal structure of the stack and improves the reliability and service life of the vanadium redox flow battery system.

Description

Technical Field

[0001] This utility model relates to the technical field of flow battery energy storage systems, specifically to a full vanadium redox flow battery system with a negative pressure protection device. Background Technology

[0002] In vanadium redox flow battery systems, to save system space, a non-planar layout is typically used, stacking power units (mainly the battery stack) and capacity units (electrolyte tanks, circulation pumps, etc.) with the power units located above the capacity units. During charging and discharging of the battery stack, the circulation pump pumps the electrolyte from the positive and negative electrode electrolyte tanks to the upper battery stack, where it undergoes an electrochemical reaction before flowing back to the electrolyte tank.

[0003] Since fuel cell stacks are typically assembled from multiple individual cells, as shown in patent CN118763260A, each cell includes components such as bipolar plates, electrode frames, carbon felt, and separators. The bipolar plates are thin and brittle, and the separators are also relatively thin. After system shutdown, due to the height difference, the electrolyte in the stack will automatically flow back to the electrolyte storage tank due to gravity, and the backflow rate is very fast. This process can cause a large negative pressure inside the stack, leading to damage to components such as bipolar plates and separators, affecting the subsequent normal operation of the stack. In existing technology, a breather valve (vacuum breaker valve) is usually installed at the highest point of the system to avoid the formation of a vacuum. However, before the breather valve is activated, the electrolyte falls rapidly, still posing a risk of damage to stack components.

[0004] Therefore, it is necessary to provide a new all-vanadium redox flow battery system with anti-negative pressure protection device. Utility Model Content

[0005] In view of this, the present invention provides a vanadium redox flow battery system with a negative pressure protection device. By setting a buffer valve to slow down the electrolyte backflow rate when the system is shut down, the internal structure of the battery stack is protected, thereby improving the reliability and service life of the vanadium redox flow battery system.

[0006] The technical solution adopted by this utility model to solve its technical problem is as follows: a vanadium redox flow battery system with a negative pressure protection device is provided, including: a capacity unit, a power unit disposed above the capacity unit, an electrolyte pipeline assembly, and a buffer valve disposed on the electrolyte pipeline assembly. The capacity unit is used to store electrolyte, the power unit is used to carry out electrochemical reactions, and the electrolyte pipeline assembly is used to connect the capacity unit and the power unit to form a flow path for electrolyte and construct an electrolyte circulation channel. The buffer valve is used to slow down the backflow rate of electrolyte and reduce the instantaneous negative pressure inside the stack when the vanadium redox flow battery system is shut down.

[0007] Furthermore, the buffer valve is a Tesla valve, and the forward installation direction of the buffer valve is consistent with the forward flow direction of the electrolyte.

[0008] Furthermore, the capacity unit includes a first housing, an electrolyte storage tank disposed within the first housing, and a circulation pump.

[0009] Furthermore, the power unit includes a second housing and an electrode stack disposed within the second housing. The electrode stack is provided with a second liquid inlet and a second liquid outlet, both of which are pipe interfaces located on the side of the electrode stack.

[0010] Furthermore, the electrolyte piping assembly includes an outlet pipe, an inlet pipe, and a return pipe. One end of the outlet pipe is connected to the first outlet on the electrolyte storage tank, and the other end is connected to the circulation pump. One end of the inlet pipe is connected to the circulation pump, and the other end is connected to the second inlet on the fuel cell stack. One end of the return pipe is connected to the second outlet on the fuel cell stack, and the other end is connected to the first inlet on the electrolyte storage tank.

[0011] Furthermore, the battery stack is provided with a second liquid inlet and a second liquid outlet, both of which are pipe interfaces located on the side of the battery stack for inputting and outputting electrolyte.

[0012] Furthermore, the buffer valve is installed on the liquid inlet pipe.

[0013] Furthermore, the buffer valve is installed on the liquid outlet pipeline.

[0014] Furthermore, the anti-negative pressure protection device also includes a breather valve, which is located at the highest point of the electrolyte pipeline assembly.

[0015] Furthermore, the buffer valve is a solenoid valve.

[0016] Furthermore, the buffer valve is a one-way valve with an opening on the valve plate.

[0017] The beneficial effects of this invention are as follows: The vanadium redox flow battery system with anti-negative pressure protection device includes a capacity unit, a power unit positioned above the capacity unit, an electrolyte piping assembly, and a buffer valve positioned on the electrolyte piping assembly. The capacity unit stores the electrolyte, the power unit performs the electrochemical reaction, and the electrolyte piping assembly connects the capacity unit and the power unit, forming a flow path for the electrolyte and constructing an electrolyte circulation channel. The buffer valve slows down the backflow rate of the electrolyte when the vanadium redox flow battery system is shut down, reducing the instantaneous negative pressure inside the stack. This vanadium redox flow battery system with anti-negative pressure protection device significantly reduces the instantaneous negative pressure inside the stack by slowing down the backflow rate of the electrolyte during shutdown, preventing damage to components such as bipolar plates and separators due to negative pressure impact, effectively extending the lifespan of the stack, reducing system maintenance costs and frequency, and improving the reliability and economy of the vanadium redox flow battery system. Attached Figure Description

[0018] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0019] Figure 1 This is a structural schematic diagram of a vanadium redox flow battery system with a negative pressure protection device (containing only a single electrolyte storage tank) according to an embodiment of this utility model; Figure 2 This is a schematic diagram of the structure of the buffer valve in an embodiment of the present invention.

[0020] The component names and their numbers in the diagram are as follows: 100 vanadium redox flow battery system with anti-negative pressure protection device; Capacity unit 1, first housing 11, electrolyte storage tank 12, first outlet 121, first inlet 122, circulation pump 13; Power unit 2, second housing 21, fuel cell stack 22, second liquid inlet 221, second liquid outlet 222; Electrolyte piping assembly 3, outlet piping 31, inlet piping 32, return piping 33; Buffer valve 4, valve body 41, valve core 42, forward inlet 43, forward outlet 44; Breathing valve 5. Detailed Implementation

[0021] To make the technical problem to be solved, the technical solution, and the beneficial effects of this utility model clearer, the present utility model will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the present utility model and are not intended to limit the present utility model.

[0022] It should be noted that when a component is referred to as "connected to" or "set on" another component, it can be directly on or indirectly on that other component. When a component is referred to as "connected to" another component, it can be directly connected to or indirectly connected to that other component.

[0023] In the description of this utility model, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "joining" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this utility model according to the specific circumstances.

[0024] It should be understood that the terms "length", "width", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", and "outer" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this utility model.

[0025] Throughout this specification, reference to "an embodiment" or "an embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment is included in at least one embodiment of this application. Therefore, the phrases "in one embodiment," "in some embodiments," or "in some of these embodiments" appear in various places throughout the specification, and not all refer to the same embodiment. Furthermore, in one or more embodiments, a particular feature, structure, or characteristic may be combined in any suitable manner.

[0026] like Figure 1 As shown, this embodiment provides a vanadium redox flow battery system 100 with a negative pressure protection device, including a capacity unit 1, a power unit 2 disposed above the capacity unit 1, an electrolyte pipeline assembly 3, and a buffer valve 4 disposed on the electrolyte pipeline assembly 3. The capacity unit 1 stores electrolyte, providing a reserve of reaction medium for the vanadium redox flow battery system. The power unit 2 performs electrochemical reactions, enabling charge and discharge functions. The electrolyte pipeline assembly 3 connects the capacity unit 1 and the power unit 2, forming a flow path for the electrolyte and constructing an electrolyte circulation channel. The buffer valve 4 slows down the electrolyte backflow rate when the vanadium redox flow battery system is shut down, reducing the instantaneous negative pressure inside the stack and preventing damage to components such as bipolar plates and separators due to negative pressure.

[0027] In some embodiments, the capacity unit 1 includes a first housing 11, an electrolyte storage tank 12 disposed within the first housing 11, and a circulation pump 13. The first housing 11 is a six-sided cuboid structure, serving as the outer shell of the capacity unit 1. The first housing 1 adopts a container body for easy transportation, and the container body adopts a standardized design, a cuboid metal frame structure with fixed dimensions. The electrolyte storage tank 12 is a container installed inside the first housing 11, storing battery electrolyte to provide the reaction medium for the vanadium redox flow battery system. The electrolyte storage tank 12 is provided with a first outlet 121 and a first inlet 122, both of which are pipe interfaces located on the side or top of the electrolyte storage tank 12. The circulation pump 13 is installed inside the first housing 11. The circulation pump 13 is used to provide circulation power. During charging and discharging, it pumps the electrolyte in the electrolyte storage tank 12 and delivers it to the power unit 2 through the electrolyte pipeline assembly 3 to drive the electrolyte circulation, ensuring that the electrolyte passes through the power unit 2 at a set flow rate, maintaining the normal progress of the electrochemical reaction, and ensuring the system's energy conversion efficiency.

[0028] In some embodiments, the power unit 2 includes a second housing 21 and a fuel cell stack 22 disposed within the second housing 21. The second housing 21 is a six-sided cuboid structure, serving as the outer shell of the power unit 2. The second housing 21 adopts a container body for easy transportation, and the container body adopts a standardized design, a cuboid metal frame structure with fixed dimensions. The fuel cell stack 22 is installed inside the second housing 21 and is a modular structure assembled from multiple single cells connected in series or parallel. A single cell (not shown in the figure) includes bipolar plates, electrode frames, carbon felt, and a separator. The bipolar plates are thin and brittle, typically made of conductive materials, and are used to conduct current and separate the electrolyte. The separator is on the micrometer scale and is made of ion exchange membrane or porous membrane, allowing ions to pass through but blocking electrolyte mixing. The carbon felt serves as the electrode material, providing a site for electrochemical reactions. The electrode frame is used to fix the positions of the components and form electrolyte flow channels. The positive and negative electrolytes flow into the fuel cell stack 22 to carry out electrochemical reactions, achieving the charging and discharging function. During the charging and discharging process, vanadium ions in the electrolyte undergo redox reactions on the surface of the carbon felt electrodes, and ion exchange occurs through the diaphragm. The bipolar plates conduct current, thereby completing energy storage and release. The fuel cell stack 22 is provided with a second liquid inlet 221 and a second liquid outlet 222. Both the second liquid inlet 221 and the second liquid outlet 222 are pipe interfaces located on the side of the fuel cell stack 22, used for inputting and outputting electrolyte.

[0029] In some embodiments, the electrolyte piping assembly 3 includes an outlet pipe 31, an inlet pipe 32, and a return pipe 33. One end of the outlet pipe 31 is connected to a first outlet 121 on the electrolyte storage tank 12, and the other end is connected to a circulation pump 13. One end of the inlet pipe 32 is connected to the circulation pump 13, and the other end is connected to a second inlet 221 on the fuel cell stack 22. One end of the return pipe 33 is connected to the second outlet 222 on the fuel cell stack 22, and the other end is connected to the first inlet 122 on the electrolyte storage tank 12. The electrolyte flow process is as follows: When the circulation pump 13 starts, it provides pumping power to draw the electrolyte from the electrolyte storage tank 12. The electrolyte in the electrolyte storage tank 12 flows into the outlet pipe 31 through the first outlet 121. After being pressurized by the circulation pump 13, the electrolyte is transported to the second inlet 221 of the fuel cell stack 22 through the inlet pipe 32. After the electrolyte completes the electrochemical reaction in the fuel cell stack 22, it flows out from the second outlet 222 located on the fuel cell stack 22. The electrolyte flows back to the electrolyte storage tank 12 through the return pipe 33, thus realizing the circulation of the electrolyte.

[0030] In some of these embodiments, such as Figure 2As shown, buffer valve 4 is installed on electrolyte piping assembly 3. Specifically, buffer valve 4 is installed on inlet pipe 32. Buffer valve 4 is a Tesla valve, and its forward installation direction is consistent with the forward flow direction of the electrolyte. Buffer valve 4 includes valve body 41, valve core 42 disposed in valve body 41, forward inlet 43, and forward outlet 44. Valve core 42 has a continuously alternating bend flow channel. Forward inlet 43 and forward outlet 44 are respectively connected to valve core 42. When electrolyte enters from forward inlet 43, it flows along the bend flow channel of valve core 42. At this time, the resistance of electrolyte is small, which does not affect the normal supply of electrolyte from circulation pump 13 to stack 22, ensuring the circulation efficiency of electrolyte. When the system shuts down, the electrolyte flows in reverse, entering from the forward outlet 44. The electrolyte frequently flows over the sidewall of the bend in the valve core 42, requiring a significant change in flow direction to exit from the forward inlet 43. This greatly increases the reverse flow resistance, slowing the electrolyte's descent from the fuel cell stack 22 through the inlet pipe 32 to the electrolyte storage tank 12, thus preventing a rapid formation of negative pressure within the fuel cell stack 22. By installing a buffer valve 4, when the electrolyte flows in the forward direction, the buffer valve 4 acts as an electrolyte delivery channel. Due to the design of the valve core 42's flow channel, the resistance during forward flow is minimal, not affecting the normal supply of electrolyte from the circulation pump 13 to the fuel cell stack 22, ensuring electrolyte circulation efficiency. When the system shuts down, the electrolyte flows back, and the bend in the valve core 42 significantly increases the reverse flow resistance, slowing the electrolyte's descent from the fuel cell stack 22 through the inlet pipe 32 to the electrolyte storage tank, thus preventing a rapid formation of negative pressure within the fuel cell stack 22. This ensures the normal operation of the battery stack 22; the reverse high resistance characteristic of the Tesla valve effectively suppresses the instantaneous negative pressure in the battery stack 22 caused by electrolyte backflow during shutdown, protecting the fragile components of the battery stack 22 such as bipolar plates and separators from damage due to negative pressure, and improving the reliability and service life of the vanadium redox flow battery system.

[0031] Since the second inlet 221 of the fuel cell stack 22 is lower than the second outlet 222, less electrolyte flows back through the return pipe 33. The electrolyte mainly flows back to the electrolyte storage tank 12 via the inlet pipe 32. Therefore, by installing a Tesla valve in the inlet pipe 32, resistance adjustment can be achieved for bidirectional electrolyte flow, and the failure of the buffer valve 4 due to unexpected shutdown caused by power failure can be avoided. In some other embodiments, the buffer valve 4 can also be installed on the outlet pipe 31.

[0032] In some embodiments, the negative pressure protection device 100 also includes a breather valve 5, which is located at the highest point of the electrolyte pipeline assembly 3. When the vanadium redox flow battery system is shut down, the breather valve 5 opens to introduce air or nitrogen into the system, further reducing the negative pressure in the stack 22.

[0033] In some other embodiments, the buffer valve 4 is a solenoid valve. When the vanadium redox flow battery system is shut down, the opening of the buffer valve 4 is reduced to slow down the return flow rate of the electrolyte. When using a solenoid valve as the buffer valve 4, in addition to installing the buffer valve 4 on the outlet pipeline 31 and / or the inlet pipeline 32, a buffer valve 4 can also be added on the return pipeline 33 to further reduce the return flow rate of the electrolyte in the return pipeline 33.

[0034] In some other embodiments, the buffer valve 4 is a one-way valve with a small hole on the valve plate, which is located on the liquid outlet line 31 and / or the liquid inlet line 32. When the electrolyte flows in the forward direction, the one-way valve opens; when the vanadium redox flow battery system is shut down, the electrolyte can only flow back through the small hole on the one-way valve plate, thereby slowing down the electrolyte backflow rate.

[0035] In normal operation, the vanadium redox flow battery system 100 with anti-negative pressure protection device of this utility model starts the circulation pump 13. The electrolyte in the electrolyte storage tank 12 passes through the first outlet 121, the outlet pipe 31, the circulation pump 13, and the inlet pipe 32 in sequence, and finally enters the stack 22 from the second inlet 221. After the electrochemical reaction is completed in the stack 22, the electrolyte flows out from the second outlet 222 and flows back to the first inlet 122 of the electrolyte storage tank 12 through the return pipe 33, forming a complete electrolyte circulation path. At this time, the buffer valve 4 has very little resistance to the positive flow of the electrolyte and does not affect the normal supply of electrolyte by the circulation pump 13 to the stack 22, ensuring the circulation efficiency of the electrolyte and ensuring that the stack 22 can stably perform charging and discharging functions, maintaining the normal energy conversion and operation of the system. When the vanadium redox flow battery system is shut down, the circulation pump 13 stops working. Most of the electrolyte in the stack 22 flows back to the electrolyte storage tank 12 under the action of gravity through the inlet pipe 32 and the return pipe 33. At this time, the buffer valve 4 greatly increases the resistance when the electrolyte flows back in reverse, thereby slowing down the rate at which the electrolyte falls from the stack 22 to the electrolyte storage tank 12 through the inlet pipe 32. This prevents the rapid formation of negative pressure in the stack 22 and effectively protects the fragile components such as bipolar plates and diaphragms in the stack 22 from damage. At the same time, the breather valve 5 automatically opens to introduce air or nitrogen into the system, further reducing the negative pressure in the stack 22 and providing double protection for the stack 22, ensuring the safety and stability of the system during shutdown.

[0036] The vanadium redox flow battery system 100 with anti-negative pressure protection device of this utility model includes a capacity unit 1, a power unit 2 disposed above the capacity unit 1, an electrolyte pipeline assembly 3, and a buffer valve 4 disposed on the electrolyte pipeline assembly 3. The buffer valve 4 is used to slow down the return flow rate of the electrolyte when the vanadium redox flow battery system is shut down, reduce the instantaneous negative pressure inside the stack, and prevent the bipolar plates, diaphragms and other components inside the stack from being damaged due to negative pressure. The capacity unit 1 includes an electrolyte storage tank 12 and a circulation pump 13, the power unit 2 includes a stack 22, and the electrolyte pipeline assembly 3 includes an outlet pipeline 31, an inlet pipeline 32 and a return pipeline 33. The buffer valve 4 is a Tesla valve. This utility model of a vanadium redox flow battery system 100 with a negative pressure protection device slows down the electrolyte backflow rate during shutdown through a buffer valve 4, significantly reducing the instantaneous negative pressure inside the battery stack. This prevents damage to components such as bipolar plates and separators due to negative pressure impact, effectively extending the service life of the battery stack, reducing system maintenance costs and frequency, and improving the reliability and economy of the vanadium redox flow battery system. The buffer valve 4 adopts a Tesla valve structure, eliminating the need for additional complex electronic control devices, simplifying the system structure, reducing the risk of system failure due to electronic component malfunctions, and improving the overall stability of the system. It is not only suitable for normal shutdown processes, but also effective in sudden abnormal shutdown situations, such as system failures or power outages, slowing down the electrolyte backflow rate, suppressing negative pressure generation, and protecting battery stack components.

[0037] Based on the above-described preferred embodiments of this utility model, and through the foregoing description, those skilled in the art can make various changes and modifications without departing from the scope of this utility model. The technical scope of this utility model is not limited to the contents of the specification, but must be determined according to the scope of the claims.

Claims

1. A vanadium redox flow battery system with negative pressure protection device, characterized in that, include: The system includes a capacity unit, a power unit disposed above the capacity unit, an electrolyte piping assembly, and a buffer valve disposed on the electrolyte piping assembly. The capacity unit is used to store electrolyte, the power unit is used to perform electrochemical reactions, and the electrolyte piping assembly is used to connect the capacity unit and the power unit to form a flow path for the electrolyte and construct an electrolyte circulation channel. The buffer valve is used to slow down the backflow rate of the electrolyte and reduce the instantaneous negative pressure inside the stack when the vanadium redox flow battery system is shut down.

2. The vanadium redox flow battery system with negative pressure protection device according to claim 1, characterized in that, The buffer valve is a Tesla valve, and the forward installation direction of the buffer valve is consistent with the forward flow direction of the electrolyte.

3. The vanadium redox flow battery system with negative pressure protection device of claim 1, wherein, The capacity unit includes a first housing, an electrolyte storage tank disposed within the first housing, and a circulation pump; the electrolyte storage tank is provided with a first outlet and a first inlet, both of which are pipe interfaces located on the side or top of the electrolyte storage tank.

4. The vanadium redox flow battery system with negative pressure protection device of claim 3, wherein, The power unit includes a second housing and an electrode stack disposed within the second housing. The electrode stack is provided with a second liquid inlet and a second liquid outlet, both of which are pipe interfaces located on the side of the electrode stack.

5. The vanadium redox flow battery system with protection against negative pressure of claim 4, wherein, The electrolyte piping assembly includes an outlet pipe, an inlet pipe, and a return pipe. One end of the outlet pipe is connected to the first outlet on the electrolyte storage tank, and the other end is connected to the circulation pump. One end of the inlet pipe is connected to the circulation pump, and the other end is connected to the second inlet on the fuel cell stack. One end of the return pipe is connected to the second outlet on the fuel cell stack, and the other end is connected to the first inlet on the electrolyte storage tank.

6. The vanadium redox flow battery system with negative pressure protection device of claim 5, wherein, The buffer valve is installed on the inlet pipe.

7. The vanadium redox flow battery system with negative pressure protection device of claim 5, wherein, The buffer valve is installed on the liquid outlet pipe.

8. The vanadium redox flow battery system with protection against negative pressure of claim 1, wherein, The negative pressure protection device also includes a breather valve, which is located at the highest point of the electrolyte pipeline assembly.

9. The all-vanadium redox flow battery system with anti-negative pressure protection device according to claim 1, characterized in that, The buffer valve is a solenoid valve.

10. The vanadium redox flow battery system with protection against negative pressure of claim 1, wherein, The buffer valve is a one-way valve with an opening on the valve plate.

Images