Comprehensive energy storage device and method based on underground flow battery and compressed air energy storage

Abstract

The invention discloses a comprehensive energy storage device and method based on an underground flow battery and compressed air energy storage, the device comprises a liquid storage unit, an electric pile unit, a compressed air energy storage unit and two groups of conveying units, the liquid storage unit comprises two groups of liquid storage chambers arranged underground; the electric pile unit comprises a reactor, a proton exchange membrane and two polar plates; the compressed air energy storage unit comprises an underground air storage chamber, a heat exchanger, an air injection assembly and an exhaust assembly. Each conveying unit comprises a first conveying pipe, a conveying pump and a second conveying pipe. According to the invention, the flow battery is combined with the compressed air energy storage unit, and when the compressed air energy storage unit is inflated, the electrolyte of the flow battery absorbs heat; when the compressed air energy storage unit discharges, the electrolyte releases heat to increase the temperature of the compressed air, improve the power generation efficiency and reduce the self temperature, so that the problem of high cost of the flow battery due to temperature control is solved, gradient utilization of energy is realized, and heat waste is reduced.

Description

Technical Field

[0001] This invention relates to the field of energy storage technology, specifically to a comprehensive energy storage device and method based on underground flow batteries and compressed air energy storage. Background Technology

[0002] In today's energy sector, energy storage technology is crucial for improving energy efficiency and ensuring the stability of energy supply. Flow batteries and compressed air energy storage, as two commonly used energy storage technologies, play an important role in their integration with renewable energy sources such as photovoltaic and wind power generation.

[0003] A flow battery is an energy storage device that converts electrical energy into chemical energy through redox reactions of active materials in the positive and negative electrode electrolytes. Many flow batteries, such as the vanadium redox flow battery, exhibit electrochemical reaction efficiency that is extremely sensitive to reaction temperature. In actual operation, excessively high temperatures exacerbate internal side reactions, leading to a significant decrease in energy efficiency; conversely, excessively low temperatures reduce the ionic conductivity of the electrolyte, similarly affecting the battery's charge and discharge performance. Therefore, to ensure stable and efficient operation of flow batteries, a dedicated temperature control system is typically required to cool the battery's operating environment. This process not only increases the complexity of the equipment but also introduces additional energy consumption, significantly increasing the overall cost of the flow battery system.

[0004] Compressed air energy storage technology utilizes electricity to drive a compressor during periods of low electricity demand, compressing and storing air in a specific space (such as an underground chamber). During peak electricity demand, the compressed air is released to drive an expander to generate electricity. However, this technology faces several challenges in practical applications. When compressed air rapidly enters the chamber, the work done by gas compression causes a rapid increase in temperature. According to the ideal gas law, this temperature increase causes gas volume expansion. With a fixed chamber volume, this objectively reduces the amount of gas that can be injected, thus decreasing the energy storage capacity. During the power generation phase, as compressed air exits the chamber, gas expansion does work, causing a sharp drop in temperature and gas volume contraction. This further reduces the amount of gas discharged, affecting the expander's intake and ultimately lowering power generation efficiency. Furthermore, these frequent temperature fluctuations negatively impact the structural stability of the chamber, increasing maintenance costs and safety risks. Existing technologies attempt to cool the chamber by adding heat exchange tubes to absorb heat. However, this merely transfers the heat out of the chamber without effectively utilizing it, resulting in energy waste.

[0005] Currently, in existing energy storage system designs, flow batteries and compressed air energy storage typically operate as independent systems. This prevents them from complementing each other's strengths and makes it difficult to fundamentally solve the technical problems they face. Summary of the Invention

[0006] The purpose of this invention is to overcome the above-mentioned technical deficiencies and propose an integrated energy storage device and method based on underground flow batteries and compressed air energy storage. This invention solves the technical problems in the prior art where flow batteries have increased costs due to temperature control, compressed air energy storage has low power generation efficiency and heat waste, and the two cannot be combined to complement each other to solve their respective technical problems. By organically integrating flow batteries and compressed air energy storage, efficient energy utilization and reduced system costs can be achieved.

[0007] To achieve the above-mentioned technical objectives, the present invention adopts the following technical solution: This invention provides a comprehensive energy storage device and method based on underground flow batteries and compressed air energy storage, comprising: A liquid storage unit, comprising two sets of liquid storage chambers located underground; The fuel cell stack unit includes a reactor, a proton exchange membrane, and two electrode plates. The proton exchange membrane is disposed inside the reactor and divides the inner cavity of the reactor into two reaction chambers. The two electrode plates are in contact with the two reaction chambers respectively and are used for electrical connection to the power supply side or the power consumption side respectively. A compressed air energy storage unit includes an underground air storage chamber, a heat exchanger, an air injection assembly, and an exhaust assembly. The heat exchanger is located in the air storage chamber. The air injection assembly is used to inject compressed air into the air storage chamber using electrical energy from the power supply side. The exhaust assembly is used to exhaust the air in the air storage chamber and transmit the energy generated during the exhaust process to the power consumption side. Two sets of conveying units are provided. Each conveying unit includes a first conveying pipe, a conveying pump, and a second conveying pipe. The first conveying pipe is selectively connected to each liquid storage chamber of the corresponding group. One end of the first conveying pipe is connected to one end of the heat exchanger. The inlet of the conveying pump is connected to the other end of the heat exchanger. The outlet of the conveying pump is connected to one end of the corresponding reaction chamber. The second conveying pipe is selectively connected to each liquid storage chamber of the corresponding group. One end of the second conveying pipe is connected to the other end of the corresponding reaction chamber.

[0008] In one embodiment, each of the liquid storage chambers has an inlet and outlet at its lower end, and the inlet and outlet are connected to two connecting pipes. The two connecting pipes are respectively connected to the first conveying pipe and the second conveying pipe, and the connecting pipes are equipped with inlet and outlet valves.

[0009] In one embodiment, each of the liquid storage chambers is equipped with a liquid level sensor.

[0010] In one embodiment, the conveying unit further includes a third conveying pipe and a fourth conveying pipe. One end of the third conveying pipe is connected to the other end of the heat exchanger, and the other end of the third conveying pipe is connected to the inlet of the conveying pump. One end of the fourth conveying pipe is connected to one end of the first conveying pipe, and the other end of the fourth conveying pipe is connected to one end of the third conveying pipe. A first shut-off valve is provided on the fourth conveying pipe, and a second shut-off valve and a third shut-off valve are respectively provided at both ends of the heat exchanger.

[0011] In one embodiment, the conveying unit further includes a fifth conveying pipe, a sixth conveying pipe, and a seventh conveying pipe. One end of the fifth conveying pipe is connected to the outlet of the conveying pump, and the other end of the fifth conveying pipe is connected to one end of the corresponding reaction chamber. One end of the sixth conveying pipe is connected to the other end of the corresponding reaction chamber, and the other end of the sixth conveying pipe is connected to one end of the second conveying pipe. One end of the seventh conveying pipe is connected to the outlet of the conveying pump, and the other end of the seventh conveying pipe is connected to one end of the second conveying pipe. A fourth shut-off valve is provided on the fifth conveying pipe, and a fifth shut-off valve is provided on the seventh conveying pipe.

[0012] In one embodiment, the gas storage chamber has an injection and exhaust pipe communicating with the gas storage chamber. The end of the injection and exhaust pipe is connected to two branch pipes, and a switching valve is provided on each of the two branch pipes. The injection assembly is an air compressor, the outlet of which is connected to one of the branch pipes, and the air compressor is electrically connected to the power supply side. The exhaust assembly includes a turbine and a generator. The inlet of the turbine is connected to the other branch pipe, the turbine is connected to the input end of the generator, and the generator is electrically connected to the power consumption side.

[0013] In one embodiment, the fuel cell unit further includes two turbofans, which are rotatably disposed within the two reaction chambers respectively.

[0014] In one embodiment, the turbofan includes two end plates and a turbofan body. The two end plates are respectively fixed to both ends of the reaction chamber, and the two ends of the turbofan body are respectively rotatably connected to the two end plates.

[0015] In one embodiment, the electrode plate is arc-shaped, and the two turbine fans are disposed at the center of the corresponding electrode plate.

[0016] The present invention also provides a comprehensive energy storage method based on flow batteries, applicable to the aforementioned comprehensive energy storage device based on underground flow batteries and compressed air energy storage, and includes the following steps: S1. When energy storage is required, the flow battery starts working first, selectively connecting one storage chamber to the first delivery pipe, and simultaneously connecting the empty storage chamber to the second delivery pipe. The delivery pump is started, and the electrolyte starts from the storage chamber connected to the first delivery pipe, passes through the first delivery pipe, heat exchanger, and delivery pump, and is delivered to the corresponding reaction chamber. In the reaction chamber, the electrical energy input from the power supply side causes the electrolyte to undergo a redox reaction, changing its valence state and storing chemical energy. Afterward, the electrolyte is discharged into the empty storage chamber through the second delivery pipe. When the originally empty storage chamber is filled and the corresponding storage chamber is exactly empty, the above operation is repeated to continue selecting other storage chambers for connection, continuously storing energy until the electrolyte in all storage chambers has completed the valence state change. S2. The compressed air energy storage unit starts, and the gas storage chamber is filled with air. During this process, the delivery pump continues to run. The electrolyte in the liquid storage chamber flows into the heat exchanger from the first delivery pipe. The compressed air enters the gas storage chamber and releases a large amount of heat. The electrolyte in the heat exchanger absorbs this heat and stores the heat in the electrolyte. S3. During the discharge phase, the compressed air energy storage unit first discharges, and the compressed air is discharged from the gas storage chamber. During this period, the delivery pump is started again, and the electrolyte in the liquid storage chamber enters the heat exchanger from the first delivery pipe. At this time, the electrolyte releases the heat stored in the energy storage phase and transfers it to the compressed air, increasing the temperature of the compressed air. The heated compressed air expands in volume, increasing the discharge volume and thus improving the power generation efficiency. S4. The flow battery discharges by connecting the first delivery pipe to the storage chamber where the valence state has changed and the second delivery pipe to the empty storage chamber.

[0017] Compared with the prior art, the technical effects of the technical solution provided by the present invention include: (1) By combining a flow battery with a compressed air energy storage unit, heat transfer and utilization are achieved through a heat exchanger. When the compressed air energy storage unit is being charged, the electrolyte in the flow battery absorbs heat, avoiding the problem of reduced energy storage capacity caused by heat accumulation in the compressed air energy storage chamber. When the compressed air energy storage unit is discharging, the electrolyte releases heat to raise the temperature of the compressed air, thereby improving power generation efficiency and lowering its own temperature. This solves the problem of high temperature control costs for flow batteries, realizes the cascade utilization of energy, and reduces heat waste.

[0018] (2) For compressed air energy storage units, it effectively alleviates the problem of reduced energy storage capacity and power generation efficiency caused by temperature changes, and reduces the impact of alternating hot and cold on the stability of the chamber structure; for flow batteries, it ensures that they work at a suitable temperature, improves electrochemical reaction efficiency, avoids the decline in energy efficiency caused by temperature problems, and improves the stability and reliability of the entire integrated energy storage device.

[0019] (3) There is no need to equip the flow battery with a complex temperature control system, and there is no waste of heat in the compressed air energy storage chamber. This reduces equipment investment and energy consumption, lowers the overall system cost, and improves the economic efficiency and market competitiveness of the energy storage system. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the structure of an integrated energy storage device based on underground flow batteries and compressed air energy storage according to an embodiment of the present invention; Figure 2 yes Figure 1 A schematic diagram of the liquid storage unit, fuel cell stack unit, and compressed air energy storage unit in the diagram; Figure 3 yes Figure 1 A schematic diagram of the gas storage chamber in the middle; Figure 4 yes Figure 1 A schematic diagram of the structure of the fuel cell stack unit; Figure 5 yes Figure 1 A schematic diagram of the structure of a liquid storage chamber; Explanation of reference numerals in the attached drawings: 1-Liquid storage unit, 11-Liquid storage chamber, 111-Inlet / outlet, 112-Connecting pipe, 113-Inlet / outlet valve, 114-Level sensor, 2-Stack unit, 21-Reactor, 22-Proton exchange membrane, 23-Electrode plate, 24-Turbine fan, 241-End plate, 242-Turbine fan body, 3-Compressed air energy storage unit, 31-Gas storage chamber, 311-Inlet / outlet pipe, 312-Branch pipe, 313-Switching valve, 32-Heat exchanger, 321-Second 322-Third shut-off valve, 33-Injection assembly, 34-Exhaust assembly, 341-Turbine, 342-Generator, 4-Transmission unit, 41-First transmission pipe, 42-Transmission pump, 43-Second transmission pipe, 44-Third transmission pipe, 45-Fourth transmission pipe, 451-First shut-off valve, 46-Fifth transmission pipe, 461-Fourth shut-off valve, 47-Sixth transmission pipe, 48-Seventh transmission pipe, 481-Fifth shut-off valve, 5-Power supply side, 6-Power consumption side. Detailed Implementation

[0021] To make the objectives, technical solutions, and advantages of this invention clearer, the invention 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 and not intended to limit the invention.

[0022] To address the technical challenges of increased costs due to temperature control in existing technologies for flow batteries and low power generation efficiency and heat waste in compressed air energy storage, and the inability to combine the two technologies to leverage their respective strengths and solve their problems, this paper proposes to organically integrate flow batteries and compressed air energy storage to achieve efficient energy utilization and reduced system costs.

[0023] Please see Figures 1-5 , Figure 1 This is a schematic diagram of the structure of an integrated energy storage device based on underground flow batteries and compressed air energy storage in one embodiment of the present invention. The integrated energy storage device based on underground flow batteries and compressed air energy storage includes a liquid storage unit 1, a stack unit 2, a compressed air energy storage unit 3, and two sets of delivery units 4.

[0024] The liquid storage unit 1 includes two sets of liquid storage chambers 11 located underground. The two sets of liquid storage chambers 11 are used to store positive electrode electrolyte and negative electrode electrolyte (collectively referred to as electrolytes herein), respectively. The walls of both sets of liquid storage chambers 11 are made of thermal insulation material. During operation, at least one liquid storage chamber 11 in each set is in an emptied state, and all liquid storage chambers 11 have equal volumes.

[0025] The common types of positive and negative electrode electrolytes are as follows: (1) Vanadium redox flow battery: This is currently the most widely used type of flow battery. Its positive electrode electrolyte is a vanadium-containing electrolyte (V₂O₃). 2+ ) and tetravalent vanadium (VO) 2+ In a sulfuric acid solution, during charging and discharging, VO 2+ and VO 2+ Valence state transitions are achieved through the gain and loss of electrons; the negative electrode electrolyte contains trivalent vanadium (V). 3+ ) and divalent vanadium (V 2+ A sulfuric acid solution, V 3+ and V 2+ Redox reactions occur during charging and discharging. The positive and negative electrolytes of the all-vanadium redox flow battery are both based on vanadium, avoiding cross-contamination between different active materials and resulting in a long cycle life.

[0026] (2) Iron-chromium flow battery: The positive electrode electrolyte contains trivalent iron ions (Fe3+). 3+ ) and ferrous ions (Fe 2+ A sulfuric acid solution, through Fe 3+ and Fe 2+ The redox reaction between the electrodes enables energy storage and release; the negative electrode electrolyte contains trivalent chromium ions (Cr). 3+ ) and divalent chromium ions (Cr 2+ ) sulfuric acid solution, Cr 3+ and Cr 2+Valence state changes during charging and discharging. Iron-chromium redox flow batteries have advantages such as high safety and low cost, but they suffer from relatively low energy density.

[0027] The fuel cell stack unit 2 includes a reactor 21, a proton exchange membrane 22, and two electrode plates 23. The proton exchange membrane 22 is disposed inside the reactor 21 and divides the inner cavity of the reactor 21 into two reaction chambers. The two electrode plates 23 are in contact with the two reaction chambers respectively and are used to electrically connect to the power supply side 5 or the power consumption side 6 respectively.

[0028] The compressed air energy storage unit 3 includes an underground air storage chamber 31, a heat exchanger 32, an air injection assembly 33, and an exhaust assembly 34. The heat exchanger 32 is located inside the air storage chamber 31. The air injection assembly 33 is used to inject compressed air into the air storage chamber 31 using electrical energy from the power supply side 5. The exhaust assembly 34 is used to exhaust the air in the air storage chamber 31 and transmit the energy generated during the exhaust process to the power consumption side 6.

[0029] Each conveying unit 4 includes a first conveying pipe 41, a conveying pump 42, and a second conveying pipe 42. The first conveying pipe 41 is selectively connected to each of the corresponding liquid storage chambers 11. One end of the first conveying pipe 41 is connected to one end of the heat exchanger 32. The inlet of the conveying pump 42 is connected to the other end of the heat exchanger 32, and the outlet of the conveying pump 42 is connected to one end of the corresponding reaction chamber. The second conveying pipe 42 is selectively connected to each of the corresponding liquid storage chambers 11. One end of the second conveying pipe 42 is connected to the other end of the corresponding reaction chamber. In this embodiment, the heat exchanger 32 is a wound copper tube.

[0030] In operation, the flow battery begins working first when energy storage is required. According to the device settings, one storage chamber 11 is selectively connected to the first delivery pipe 41, while the empty storage chamber 11 is connected to the second delivery pipe 42. The delivery pump 42 is started, and the electrolyte flows from the storage chamber 11 connected to the first delivery pipe 41, through the first delivery pipe 41, heat exchanger 32, and delivery pump 42, to the corresponding reaction chamber. Inside the reaction chamber, the electrical energy input from the power supply side 5 causes a redox reaction in the electrolyte, changing its valence state and storing chemical energy. The electrolyte is then discharged back into the empty storage chamber 11 through the second delivery pipe 42. When the originally empty liquid storage chamber 11 is filled and the corresponding liquid storage chamber 11 is just empty, the above operation is repeated to continue to select other liquid storage chambers 11 for connection and continue to store energy until the electrolyte in all liquid storage chambers 11 has completed the valence state change.

[0031] Next, the compressed air energy storage unit 3 is activated. The gas storage chamber 31 is filled with gas, during which the delivery pump 42 continues to operate, and the electrolyte in the liquid storage chamber 11 flows into the heat exchanger 32 from the first delivery pipe 41. Since the compressed air releases a large amount of heat when entering the gas storage chamber 31, the electrolyte in the heat exchanger 32 can effectively absorb this heat and store it in the electrolyte, avoiding heat waste and also creating conditions for cooling during subsequent discharge of the flow battery.

[0032] During the discharge phase, the compressed air energy storage unit 3 discharges first. Compressed air is discharged from the gas storage chamber 31. During this period, the delivery pump 42 starts again, and the electrolyte in the liquid storage chamber 11 enters the heat exchanger 32 from the first delivery pipe 41. At this time, the electrolyte releases the heat stored in the energy storage phase and transfers it to the compressed air, raising the temperature of the compressed air. According to the ideal gas law, the volume of the heated compressed air expands, thereby increasing the discharge volume and improving the power generation efficiency. At the same time, the electrolyte's own temperature decreases during the heat release process, preparing for the subsequent discharge of the flow battery.

[0033] Subsequently, the flow battery discharges. Similar to the charging process, the first delivery pipe 41 connects to the storage chamber 11 where the valence state has changed, and the second delivery pipe 42 connects to the emptied storage chamber 11. Since the electrolyte has been pre-cooled during the discharge stage of the compressed air energy storage unit 3, it can effectively prevent the temperature from becoming too high due to electrochemical reactions during the discharge process, ensuring the stable and efficient operation of the flow battery.

[0034] The technical effects of the technical solution provided by this invention include: (1) By combining the flow battery with the compressed air energy storage unit 3, heat transfer and utilization are achieved through the heat exchanger 32. When the compressed air energy storage unit 3 is filled with gas, the electrolyte of the flow battery absorbs heat, avoiding the problem of reduced energy storage capacity caused by heat accumulation in the compressed air energy storage chamber; when the compressed air energy storage unit 3 is discharged, the electrolyte releases heat to increase the temperature of the compressed air, improves the power generation efficiency, and at the same time reduces its own temperature, solving the problem of high temperature control cost of flow batteries, realizing the cascade utilization of energy and reducing heat waste.

[0035] (2) For the compressed air energy storage unit 3, it effectively alleviates the problem of reduced energy storage capacity and power generation efficiency caused by temperature changes, and reduces the impact of alternating hot and cold on the stability of the chamber structure; for the flow battery, it ensures that it works at a suitable temperature, improves the efficiency of electrochemical reaction, avoids the decrease in energy efficiency caused by temperature problems, and improves the stability and reliability of the entire integrated energy storage device.

[0036] (3) There is no need to equip the flow battery with a complex temperature control system, and there is no waste of heat in the compressed air energy storage chamber. This reduces equipment investment and energy consumption, lowers the overall system cost, and improves the economic efficiency and market competitiveness of the energy storage system.

[0037] In one embodiment, please refer to Figure 1 and Figure 2 Each of the aforementioned liquid storage chambers 11 has an inlet / outlet 111 at its lower end. Each inlet / outlet 111 is connected to two connecting pipes 112, which are respectively connected to the first delivery pipe 41 and the second delivery pipe 42. Each connecting pipe 112 is equipped with an inlet / outlet valve 113. In this embodiment, by controlling the opening and closing of the inlet / outlet valve 113, the liquid storage chamber 11 connected to the first delivery pipe 41 and the second delivery pipe 42 can be selected more precisely and flexibly, making the switching of the electrolyte delivery path more convenient and efficient during energy storage and discharge.

[0038] In one embodiment, please refer to Figure 1 and Figure 2 Each of the aforementioned liquid storage chambers 11 is equipped with a liquid level sensor 114, thereby facilitating the acquisition of the liquid level of the electrolyte in each liquid storage chamber.

[0039] In one embodiment, please refer to Figures 1-5 The conveying unit 4 further includes a third conveying pipe 43 and a fourth conveying pipe 44. One end of the third conveying pipe 43 is connected to the other end of the heat exchanger 32, and the other end of the third conveying pipe 43 is connected to the inlet of the conveying pump 42. One end of the fourth conveying pipe 44 is connected to one end of the first conveying pipe 41, and the other end of the fourth conveying pipe 44 is connected to one end of the third conveying pipe 43. A first shut-off valve 451 is provided on the fourth conveying pipe 44, and a second shut-off valve 321 and a third shut-off valve 322 are respectively provided at both ends of the heat exchanger 32.

[0040] In this embodiment, the newly added fourth delivery pipe 44 and the shut-off valve provide an alternative path for electrolyte delivery. For example, when the compressed air energy storage unit 3 starts to charge the gas storage chamber 31, under normal circumstances, the second shut-off valve 321 and the third shut-off valve 322 are open, and the first shut-off valve 451 is closed. At this time, the electrolyte in the liquid storage chamber 11 enters the heat exchanger 32 through the first delivery pipe 41 to absorb the heat generated during the compressed air charging process. After absorbing heat, the electrolyte flows to the inlet of the delivery pump 42 through the third delivery pipe 43, and is then delivered to the reaction chamber by the delivery pump 42. When it is not necessary to absorb heat through the heat exchanger 32 (e.g., during the charging process of the flow battery), the second shut-off valve 321 and the third shut-off valve 322 can be closed, and the first shut-off valve 451 can be opened. In this way, the electrolyte flows directly from the first delivery pipe 41 through the fourth delivery pipe 44 into the third delivery pipe 43, and then to the delivery pump 42, bypassing the heat exchanger 32, thereby shortening the length of the electrolyte flow path and reducing the flow resistance.

[0041] In one embodiment, please refer to Figures 1-5 The conveying unit 4 further includes a fifth conveying pipe 45, a sixth conveying pipe 46, and a seventh conveying pipe 47. One end of the fifth conveying pipe 45 is connected to the outlet of the conveying pump 42, and the other end of the fifth conveying pipe 45 is connected to one end of the corresponding reaction chamber. One end of the sixth conveying pipe 46 is connected to the other end of the corresponding reaction chamber, and the other end of the sixth conveying pipe 46 is connected to one end of the second conveying pipe 42. One end of the seventh conveying pipe 47 is connected to the outlet of the conveying pump 42, and the other end of the seventh conveying pipe 47 is connected to one end of the second conveying pipe 42. A fourth shut-off valve 461 is provided on the fifth conveying pipe 45, and a fifth shut-off valve 481 is provided on the seventh conveying pipe 47.

[0042] In this embodiment, when the flow battery is charging or discharging, the fourth shut-off valve 461 is opened and the fifth shut-off valve 481 is closed. After the delivery pump 42 is started, the electrolyte in the storage chamber 11 enters the delivery pump 42 through the first delivery pipe 41 and the third delivery pipe 43, and then flows into the reaction chamber through the fifth delivery pipe 45. During the charging process, the electrical energy on the power supply side 5 causes the electrolyte to undergo a redox reaction to change its valence state and achieve energy storage; during the discharging process, the electrolyte in the reaction chamber that has stored energy undergoes a reverse reaction to release electrical energy. The electrolyte that has completed the reaction flows into the second delivery pipe 42 through the sixth delivery pipe 46 and finally returns to the storage chamber 11, forming a complete charge-discharge cycle. When the flow battery does not need to be charged or discharged, the fourth shut-off valve 461 is closed and the fifth shut-off valve 481 is opened. At this time, the operation of the delivery pump 42 drives the electrolyte in the storage chamber 11 to enter the delivery pump 42 from the first delivery pipe 41, heat exchanger 32, and third delivery pipe 43, and then directly transmits it through the seventh delivery pipe 47, bypassing the reaction chamber, thereby shortening the length of the liquid flow path and reducing resistance.

[0043] In one embodiment, please refer to Figures 1-5 The gas storage chamber 31 has an injection and exhaust pipe 311 communicating with the gas storage chamber 31. The end of the injection and exhaust pipe 311 is connected to two branch pipes 312, and a switching valve 313 is respectively provided on the two branch pipes 312. The gas injection assembly 33 is an air compressor. The outlet of the air compressor is connected to one of the branch pipes 312. The air compressor is electrically connected to the power supply side 5. The exhaust assembly 34 includes a turbine 341 and a generator 342. The inlet of the turbine 341 is connected to the other branch pipe 312. The turbine 341 is connected to the input end of the generator 342. The generator 342 is electrically connected to the power consumption side 6.

[0044] In this embodiment, when energy storage is needed during periods of low electricity load, the switching valve 313 on the branch pipe 312 connected to the air compressor is opened, while the switching valve 313 on the other branch pipe 312 is closed. The power supply side 5 supplies power to the air compressor, which starts and compresses outside air. The compressed air enters the air storage chamber 31 for storage through the injection and exhaust pipes 311. During this process, the air compressor continues to run, continuously compressing air and injecting it into the air storage chamber 31 until it reaches the predetermined storage capacity, completing the energy storage operation. During peak electricity demand periods, when energy needs to be released, the switching valve 313 on the branch pipe 312 connected to the air compressor is closed, while the switching valve 313 on the branch pipe 312 connected to the turbine inlet 341 is opened. The compressed air in the air storage chamber 31 enters the turbine 341 through the injection and exhaust pipes 311 and the branch pipe 312, driving the turbine 341 to rotate at high speed. The turbine 341 is connected to the input end of the generator 342. The rotation of the turbine 341 drives the generator 342 to generate electricity, which is then transmitted to the power consumption side 6 to supply power to the user. As compressed air is continuously discharged, the pressure inside the air storage chamber 31 gradually decreases until all the compressed air is discharged, completing the energy release process.

[0045] In one embodiment, please refer to Figure 4The stack unit 2 further includes two turbine fans 24, which are rotatably disposed within the two reaction chambers. Each turbine fan 24 includes two end plates 241 and a turbine fan body 242. The two end plates 241 are fixed to both ends of the reaction chamber, and the two ends of the turbine fan body 242 are rotatably connected to the two end plates 241. In this embodiment, the flow of electrolyte within the reaction chamber drives the turbine fans 24 to rotate. The rotation of the turbine fans 24 causes the electrolyte within the reaction chamber to move in a spiral motion, greatly increasing the contact area and contact frequency between the electrolyte and the electrode plates 23. During the charging and discharging process of the flow battery, the electrochemical reaction mainly occurs at the interface between the electrolyte and the electrode plates 23. More thorough contact allows the active materials to participate in the redox reaction more quickly and effectively, accelerating electron transfer and ion migration. During charging, more electrical energy can be converted into chemical energy and stored in the electrolyte; during discharging, chemical energy can be converted into electrical energy more efficiently and released, thereby significantly improving the overall energy conversion efficiency of the flow battery.

[0046] In one embodiment, please refer to Figure 4 The electrode plate 23 is arc-shaped, and the two turbine fans 24 are disposed at the center of the corresponding electrode plate 23. In this embodiment, the arc-shaped electrode plate 23 and the turbine fans 24 disposed at the center cooperate to create a more closely fitting spiral flow space for the electrolyte in the reaction chamber.

[0047] The present invention also provides a comprehensive energy storage method based on flow batteries, applicable to the aforementioned comprehensive energy storage device based on underground flow batteries and compressed air energy storage, and includes the following steps: S1. When energy storage is required, the flow battery starts working first. According to the device settings, one storage chamber 11 is selectively connected to the first delivery pipe 41, while the empty storage chamber 11 is connected to the second delivery pipe 42. The delivery pump 42 is started, and the electrolyte starts from the storage chamber 11 connected to the first delivery pipe 41, passes through the first delivery pipe 41, the heat exchanger 32, and the delivery pump 42, and is delivered to the corresponding reaction chamber. In the reaction chamber, the electrical energy input from the power supply side 5 causes the electrolyte to undergo a redox reaction, changing its valence state and storing chemical energy. Afterward, the electrolyte is discharged into the empty storage chamber 11 through the second delivery pipe 42. When the originally empty liquid storage chamber 11 is filled and the corresponding liquid storage chamber 11 is just empty, the above operation is repeated to continue to select other liquid storage chambers 11 for connection and continue to store energy until the electrolyte in all liquid storage chambers 11 has completed the valence state change.

[0048] S2. Compressed air energy storage unit 3 starts. The gas storage chamber 31 is filled with gas. During this process, the delivery pump 42 continues to run, and the electrolyte in the liquid storage chamber 11 flows into the heat exchanger 32 from the first delivery pipe 41. Since the compressed air releases a large amount of heat when it enters the gas storage chamber 31, the electrolyte in the heat exchanger 32 can effectively absorb this heat and store it in the electrolyte, avoiding heat waste. It also creates conditions for cooling during the subsequent discharge of the flow battery.

[0049] S3. During the discharge phase, the compressed air energy storage unit 3 discharges first. Compressed air is discharged from the gas storage chamber 31. During this period, the delivery pump 42 starts again, and the electrolyte in the liquid storage chamber 11 enters the heat exchanger 32 from the first delivery pipe 41. At this time, the electrolyte releases the heat stored in the energy storage phase and transfers it to the compressed air, raising the temperature of the compressed air. According to the ideal gas law, the volume of the heated compressed air expands, thereby increasing the discharge volume and improving the power generation efficiency. At the same time, the electrolyte's own temperature decreases during the heat release process, preparing for the subsequent discharge of the flow battery.

[0050] S4. The flow battery discharges. Similar to the charging process, the first delivery pipe 41 connects to the storage chamber 11 where the valence state has changed, and the second delivery pipe 42 connects to the emptied storage chamber 11. Since the electrolyte has been pre-cooled during the discharge stage of the compressed air energy storage unit 3, it can effectively prevent the temperature from becoming too high due to electrochemical reactions during the discharge process, ensuring the stable and efficient operation of the flow battery.

[0051] The specific embodiments of the present invention described above do not constitute a limitation on the scope of protection of the present invention. Any other corresponding changes and modifications made in accordance with the technical concept of the present invention should be included within the scope of protection of the claims of the present invention.

Claims

1. A comprehensive energy storage device based on underground flow batteries and compressed air energy storage, characterized in that, include: A liquid storage unit, comprising two sets of liquid storage chambers located underground; The fuel cell stack unit includes a reactor, a proton exchange membrane, and two electrode plates. The proton exchange membrane is disposed inside the reactor and divides the inner cavity of the reactor into two reaction chambers. The two electrode plates are in contact with the two reaction chambers respectively and are used for electrical connection to the power supply side or the power consumption side respectively. A compressed air energy storage unit includes an underground air storage chamber, a heat exchanger, an air injection assembly, and an exhaust assembly. The heat exchanger is located in the air storage chamber. The air injection assembly is used to inject compressed air into the air storage chamber using electrical energy from the power supply side. The exhaust assembly is used to exhaust the air in the air storage chamber and transmit the energy generated during the exhaust process to the power consumption side. Two sets of conveying units are provided. Each conveying unit includes a first conveying pipe, a conveying pump, and a second conveying pipe. The first conveying pipe is selectively connected to each liquid storage chamber of the corresponding group. One end of the first conveying pipe is connected to one end of the heat exchanger. The inlet of the conveying pump is connected to the other end of the heat exchanger. The outlet of the conveying pump is connected to one end of the corresponding reaction chamber. The second conveying pipe is selectively connected to each liquid storage chamber of the corresponding group. One end of the second conveying pipe is connected to the other end of the corresponding reaction chamber.

2. The integrated energy storage device based on underground flow battery and compressed air energy storage according to claim 1, characterized in that, Each of the liquid storage chambers has an inlet and outlet at its lower end. The inlet and outlet are connected to two connecting pipes, which are respectively connected to the first conveying pipe and the second conveying pipe. The connecting pipes are equipped with inlet and outlet valves.

3. The integrated energy storage device based on underground flow battery and compressed air energy storage according to claim 1, characterized in that, Each of the aforementioned liquid storage chambers is equipped with a liquid level sensor.

4. The integrated energy storage device based on underground flow battery and compressed air energy storage according to claim 1, characterized in that, The conveying unit further includes a third conveying pipe and a fourth conveying pipe. One end of the third conveying pipe is connected to the other end of the heat exchanger, and the other end of the third conveying pipe is connected to the inlet of the conveying pump. One end of the fourth conveying pipe is connected to one end of the first conveying pipe, and the other end of the fourth conveying pipe is connected to one end of the third conveying pipe. A first shut-off valve is provided on the fourth conveying pipe, and a second shut-off valve and a third shut-off valve are respectively provided at both ends of the heat exchanger.

5. The integrated energy storage device based on underground flow battery and compressed air energy storage according to claim 4, characterized in that, The conveying unit further includes a fifth conveying pipe, a sixth conveying pipe, and a seventh conveying pipe. One end of the fifth conveying pipe is connected to the outlet of the conveying pump, and the other end of the fifth conveying pipe is connected to one end of the corresponding reaction chamber. One end of the sixth conveying pipe is connected to the other end of the corresponding reaction chamber, and the other end of the sixth conveying pipe is connected to one end of the second conveying pipe. One end of the seventh conveying pipe is connected to the outlet of the conveying pump, and the other end of the seventh conveying pipe is connected to one end of the second conveying pipe. A fourth shut-off valve is provided on the fifth conveying pipe, and a fifth shut-off valve is provided on the seventh conveying pipe.

6. The integrated energy storage device based on underground flow battery and compressed air energy storage according to claim 1, characterized in that, The gas storage chamber has an injection and exhaust pipe that communicates with the gas storage chamber. The end of the injection and exhaust pipe is connected to two branch pipes, and a switching valve is provided on each of the two branch pipes. The air injection assembly is an air compressor, the outlet of which is connected to one of the branch pipes, and the air compressor is electrically connected to the power supply side. The exhaust assembly includes a turbine and a generator. The inlet of the turbine is connected to another branch pipe. The turbine is connected to the input end of the generator. The generator is electrically connected to the power consumption side.

7. The integrated energy storage device based on underground flow battery and compressed air energy storage according to claim 1, characterized in that, The fuel cell unit also includes two turbofans, which are rotatably disposed in the two reaction chambers respectively.

8. The integrated energy storage device based on underground flow battery and compressed air energy storage according to claim 7, characterized in that, The turbofan includes two end plates and a turbofan body. The two end plates are respectively fixed to both ends of the reaction chamber, and the two ends of the turbofan body are rotatably connected to the two end plates respectively.

9. The integrated energy storage device based on underground flow battery and compressed air energy storage according to claim 7, characterized in that, The electrode plate is arc-shaped, and the two turbine fans are located at the center of the corresponding electrode plate.

10. A comprehensive energy storage method based on underground flow batteries and compressed air energy storage, characterized in that, The integrated energy storage device based on underground flow batteries and compressed air energy storage as described in any one of claims 1-9, and includes the following steps: S1. When energy storage is required, the flow battery starts working first, selectively connecting one storage chamber to the first delivery pipe, and simultaneously connecting the empty storage chamber to the second delivery pipe. The delivery pump is started, and the electrolyte starts from the storage chamber connected to the first delivery pipe, passes through the first delivery pipe, heat exchanger, and delivery pump, and is delivered to the corresponding reaction chamber. In the reaction chamber, the electrical energy input from the power supply side causes the electrolyte to undergo a redox reaction, changing its valence state and storing chemical energy. Afterward, the electrolyte is discharged into the empty storage chamber through the second delivery pipe. When the originally empty storage chamber is filled and the corresponding storage chamber is exactly empty, the above operation is repeated to continue selecting other storage chambers for connection, continuously storing energy until the electrolyte in all storage chambers has completed the valence state change. S2. The compressed air energy storage unit starts, and the gas storage chamber is filled with air. During this process, the delivery pump continues to run. The electrolyte in the liquid storage chamber flows into the heat exchanger from the first delivery pipe. The compressed air enters the gas storage chamber and releases a large amount of heat. The electrolyte in the heat exchanger absorbs this heat and stores the heat in the electrolyte. S3. During the discharge phase, the compressed air energy storage unit first discharges, and the compressed air is discharged from the gas storage chamber. During this period, the delivery pump is started again, and the electrolyte in the liquid storage chamber enters the heat exchanger from the first delivery pipe. At this time, the electrolyte releases the heat stored in the energy storage phase and transfers it to the compressed air, increasing the temperature of the compressed air. The heated compressed air expands in volume, increasing the discharge volume and thus improving the power generation efficiency. S4. The flow battery discharges by connecting the first delivery pipe to the storage chamber where the valence state has changed and the second delivery pipe to the empty storage chamber.

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