A floating piston type high and low price state electrolyte separate storage shaft device

Abstract

The application discloses a vertical shaft device for high and low valence state electrolyte storage with a floating piston, which comprises two underground vertical shafts serving as positive and negative vertical shafts respectively, a floating piston arranged in the vertical shafts to separate the vertical shafts into upper and lower liquid storage areas, the density of the floating piston being matched with the density of the electrolyte to suspend in the electrolyte and move freely along the axial direction, a power battery communicating with the upper and lower liquid storage areas through a transmission pipeline, and a circulating pump arranged on the transmission pipeline to drive the electrolyte circulation. During charging, the electrolyte flows from the upper liquid storage area to the lower liquid storage area through the power battery reaction, and the piston moves upward; during discharging, the electrolyte flows reversely, and the piston moves downward. The application realizes the effective isolation of different valence state electrolytes in the same vertical shaft through the floating piston, and only two vertical shafts are needed to complete the storage, so that the number of storage tanks is reduced, the construction cost is lowered, and the ground occupation is reduced by utilizing the underground space.

Description

Technical Field

[0001] This invention relates to the field of electrolyte storage and recycling in flow batteries, and specifically to a vertical shaft device for separating and storing high and low valence electrolytes using a floating piston. Background Technology

[0002] A flow battery is an electrochemical energy storage device that converts electrical energy into chemical energy through redox reactions of active materials in an electrolyte. Unlike closed-cell batteries such as lithium-ion batteries, the electrolyte in a flow battery is stored in an external tank and transported to the stack for electrochemical reactions via a circulation pump. Flow batteries have gained widespread attention in large-scale energy storage applications due to their advantages such as capacity and power decoupling, long cycle life, and high safety. Electrolyte storage is crucial in flow battery systems. Taking a vanadium redox flow battery as an example, the valence state of the electrolyte changes during charging and discharging. If electrolytes with different valence states mix, the battery's coulombic efficiency will decrease, and self-discharge may even occur, resulting in a loss of energy storage capacity.

[0003] Traditionally, flow battery electrolytes are stored in surface tanks, with each type of electrolyte requiring one tank for its high-valence state and one for its low-valence state. This means a single flow battery system requires at least four tanks to store electrolytes. Other solutions use fixed separators or flexible diaphragms to isolate electrolytes of different valence states. Additionally, the idea of ​​using underground shafts for electrolyte storage has been considered, but practical solutions for effectively isolating electrolytes of different valence states within the same shaft are lacking.

[0004] However, these existing technologies have significant drawbacks. Ground-based storage tanks require a large area, making them difficult to deploy in regions with limited land resources. Furthermore, multiple tanks increase system complexity and construction costs, and are significantly affected by environmental temperature variations; electrolyte temperature fluctuations can impact battery performance and lifespan. Fixed separators cannot adapt to changes in electrolyte volume during charging and discharging, while flexible separators suffer from poor corrosion resistance and short lifespan. Additionally, in deep shafts, the piston may become stuck due to the irregularities of the shaft's inner wall, affecting the system's normal operation. Therefore, effectively isolating electrolytes of different valence states within the same shaft and preventing the mixing of high-valence and low-valence electrolytes has become a pressing technical challenge. Summary of the Invention

[0005] The purpose of this invention is to overcome the above-mentioned technical deficiencies and propose a floating piston-type vertical well device for separating and storing high and low valence electrolytes.

[0006] To achieve the above-mentioned technical objectives, the present invention adopts the following technical solution: This invention provides a floating piston-type vertical well device for separating and storing high and low valence electrolytes, comprising: Two vertical shafts, located underground, serve as the positive and negative electrode shafts, respectively, for storing the positive and negative electrolytes of the flow battery. A floating piston is disposed inside each of the vertical shafts, dividing the internal space of the vertical shafts into an upper liquid storage area and a lower liquid storage area. The density of the floating piston matches the density of the electrolyte, enabling it to suspend in the electrolyte and move along the axial direction of the vertical shaft to isolate electrolytes in different valence states. The fuel cell stack is connected to the upper and lower liquid storage areas of the positive electrode shaft and the negative electrode shaft, respectively, via transmission pipelines. A circulation pump, installed on the transmission pipeline, is used to drive the electrolyte to circulate between the vertical shaft and the fuel cell stack; During charging, the circulating pump pumps the electrolyte from the upper storage area of ​​the shaft to the fuel cell stack for electrochemical reaction and then delivers it to the lower storage area of ​​the shaft, while the floating piston moves upward; during discharging, the circulating pump pumps the electrolyte from the lower storage area of ​​the shaft to the fuel cell stack for electrochemical reaction and then delivers it to the upper storage area of ​​the shaft, while the floating piston moves downward.

[0007] In some embodiments, during charging, the low-valence electrolyte in the upper storage area of ​​the positive electrode shaft is converted into a high-valence electrolyte by the stack oxidation reaction and then transported to the lower storage area of ​​the positive electrode shaft; the high-valence electrolyte in the upper storage area of ​​the negative electrode shaft is converted into a low-valence electrolyte by the stack reduction reaction and then transported to the lower storage area of ​​the negative electrode shaft. During discharge, the high-valence electrolyte in the lower storage area of ​​the positive electrode shaft is converted into a low-valence electrolyte by the reduction reaction of the fuel cell stack and then transported to the upper storage area of ​​the positive electrode shaft. The low-valence electrolyte in the lower storage area of ​​the negative electrode shaft is converted into a high-valence electrolyte by the oxidation reaction of the fuel cell stack and then transported to the upper storage area of ​​the negative electrode shaft.

[0008] In some embodiments, the inner wall of the shaft is provided with a grouting reinforcement layer, a sprayed protective layer, an anti-corrosion layer and a plastic facing layer from the outside to the inside, so as to isolate the electrolyte from the rock mass surrounding the shaft; The top of the upper liquid storage area of ​​the vertical shaft is filled with inert gas to isolate the electrolyte from air.

[0009] In some embodiments, a plurality of limiting blocks are provided on the inner wall of the shaft to limit the movement range of the floating piston; the floating piston is a spherical floating piston or a cylindrical floating piston.

[0010] In some embodiments, the transmission conduit is made of at least one material selected from polypropylene, polyvinyl chloride, or polytetrafluoroethylene.

[0011] In some embodiments, the floating piston is an active intelligent piston, which includes: The piston housing is cylindrical, and its outer diameter is smaller than the inner diameter of the vertical shaft; The pressure sensing unit includes a first pressure sensor and a second pressure sensor respectively disposed on the upper end face and the lower end face of the piston housing, for detecting the pressure values ​​of the upper liquid storage area and the lower liquid storage area acting on the two end faces of the piston housing respectively; A variable diameter sealing mechanism is provided on the outer peripheral surface of the piston housing, and can contract and expand in the radial direction to adjust the sealing state between the active intelligent piston and the inner wall of the shaft; The control unit is located in the sealed cavity inside the piston housing and is electrically connected to the pressure sensing unit and the variable diameter sealing mechanism respectively. It controls the working state of the variable diameter sealing mechanism according to the pressure difference detected by the pressure sensing unit. When the absolute value of the pressure difference is greater than the first preset threshold, the control unit controls the variable diameter sealing mechanism to contract to reduce the moving resistance of the active intelligent piston, so that the active intelligent piston can move freely under the action of hydraulic pressure difference; when the absolute value of the pressure difference is less than or equal to the first preset threshold, the control unit controls the variable diameter sealing mechanism to expand so that a seal is formed between the active intelligent piston and the inner wall of the shaft.

[0012] In some embodiments, the variable diameter sealing mechanism includes: An annular rubber sleeve is fixedly fitted onto the outer side wall of the piston housing. The upper and lower ends of the annular rubber sleeve are respectively sealed to the piston housing by fixing clamps, and a closed annular air cavity is formed between the annular rubber sleeve and the outer side wall of the piston housing. The inflation / deflation assembly, located inside the piston housing, includes a high-pressure gas cylinder, a micro air pump, and a valve. The high-pressure gas cylinder is connected to the inlet of the micro air pump via an air passage, and the outlet of the micro air pump is connected to the annular air chamber via the valve through an air passage. When the control unit controls the micro air pump to operate in the forward direction and opens the valve, the gas in the high-pressure gas cylinder is filled into the annular gas chamber through the gas passage, and the annular rubber sleeve expands radially outward until it fits against the inner wall of the vertical shaft to form a seal; when the control unit controls the micro air pump to operate in the reverse direction, the gas in the annular gas chamber is drawn back into the high-pressure gas cylinder, and the annular rubber sleeve contracts radially inward under its own elastic restoring force and fits against the outer wall of the piston housing.

[0013] In some embodiments, the upper end face and the lower end face of the piston housing are respectively provided with an upper liquid inlet hole and a lower liquid inlet hole; The active intelligent piston also includes a self-powered unit, an energy storage capacitor, and a backup lithium battery. The self-powered unit is disposed inside the sealed cavity and includes an upper electrode, a lower electrode, and an ion exchange membrane disposed between the upper electrode and the lower electrode. A closed upper storage cavity is formed within the upper electrode. This upper storage cavity is connected to the upper inlet via a first current-limiting connection channel. Electrolyte in the upper storage area slowly enters the upper storage cavity through the first current-limiting connection channel and contacts the upper electrode. The first current-limiting connection channel is constructed as any one of a capillary channel, a porous current-limiting element, or a slit current-limiting channel to limit the flow rate of electrolyte into the upper storage cavity and suppress macroscopic convection. The upper storage cavity is located above the ion exchange membrane. A closed lower storage cavity is formed within the lower electrode. The lower storage cavity is connected via a second current-limiting connection... The channel is connected to the lower inlet hole. Electrolyte in the lower storage area slowly enters the lower storage cavity through the second flow-limiting connection channel and contacts the lower electrode. The second flow-limiting connection channel is constructed as any one of a capillary channel, a porous flow-limiting element, or a slit flow-limiting channel to limit the flow rate of electrolyte entering the lower storage cavity and suppress macroscopic convection. The lower storage cavity is located below the ion exchange membrane. The upper storage cavity and the lower storage cavity achieve ion conduction through the ion exchange membrane. The ion exchange membrane is a highly selective proton exchange membrane and is not interconnected except for the ion exchange membrane. The self-powered unit generates electricity by utilizing the electrochemical potential difference between electrolytes of different valence states in the upper and lower liquid storage areas, which is used to trickle charge the energy storage capacitor and the backup lithium battery; the variable diameter sealing mechanism is provided with peak power by the energy storage capacitor and / or the backup lithium battery when it is in operation.

[0014] In some embodiments, the active intelligent piston further includes a vibration unlocking unit, which includes an eccentric vibration motor disposed inside the piston housing; When the absolute value of the pressure difference is greater than the second preset threshold, the control unit determines that the active intelligent piston is stuck, controls the variable diameter sealing mechanism to contract to the maximum contraction amount and starts the eccentric vibration motor to vibrate and unblock; wherein, the second preset threshold is greater than the first preset threshold; after the eccentric vibration motor vibrates for a preset time, the control unit rereads the pressure difference value. If the absolute value of the pressure difference drops below the second preset threshold, it determines that the unblocking is successful; if it is still greater than the second preset threshold, it sends a stuck alarm signal to the ground.

[0015] In some embodiments, the active intelligent piston further includes an ultrasonic communication module disposed on the end face of the piston housing, for bidirectional data communication with a ground ultrasonic transceiver disposed at the top of the shaft via the electrolyte as a propagation medium.

[0016] Compared with the prior art, the beneficial effects of the floating piston-type high and low valence electrolyte separation and storage vertical well device provided by the present invention include: (1) By setting up a floating piston in the underground shaft, the same shaft is divided into an upper storage area and a lower storage area to store high-valence and low-valence electrolytes respectively, thus achieving effective isolation of electrolytes of different valences in the same shaft. Compared with the traditional four-tank scheme, only two shafts are needed to complete the separate storage of positive and negative electrode electrolytes, reducing the number of storage tanks and lowering the system complexity and construction cost. At the same time, the use of underground shafts to store electrolytes makes full use of underground space resources, reduces the ground area occupied, and the underground environment temperature is stable, which is conducive to the constant temperature storage of electrolytes.

[0017] (2) When the floating piston adopts an active intelligent piston, the pressure difference between the upper and lower sides is monitored in real time by the pressure sensing unit, and the contraction and expansion states of the variable diameter sealing mechanism are intelligently controlled by the control unit. When movement is required, the annular rubber sleeve is contracted to reduce the movement resistance, and when sealing is required, the annular rubber sleeve is expanded to form an effective seal. This solves the contradiction between sealing reliability and movement flexibility in the traditional fixed sealing structure and achieves a balance between the two.

[0018] (3) The active intelligent piston integrates a self-powered unit and an ultrasonic communication module. The self-powered unit generates electricity by utilizing the electrochemical potential difference between electrolytes of different valence states on both sides of the piston, and can achieve energy self-sufficiency without external power supply cables. The ultrasonic communication module uses electrolyte as a propagation medium to conduct bidirectional data communication with the ground, without the need to lay communication cables. Combined with the automatic card-unlocking function of the vibration card-unlocking unit, the active intelligent piston can operate in underground shafts without external power supply cables and communication cables, and can interact with the ground through ultrasonic communication. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the vertical shaft device structure using a spherical floating piston provided in Embodiment 1 of the present invention; Figure 2 This is a schematic diagram of the vertical shaft device structure using a cylindrical floating piston provided in Embodiment 1 of the present invention; Figure 3 This is a schematic diagram of the active intelligent piston in Embodiment 2 of the present invention; Figure reference numerals: 101—Photovoltaic power generation system; 102—Wind power generation system; 103—Power transmission line; 104—Electric stack; 105—Circulation pump; 106—Transmission pipeline; 107—Limiting block; 108—Positive electrode low-valence electrolyte; 109—Positive electrode high-valence electrolyte; 110—Negative electrode high-valence electrolyte; 111—Negative electrode low-valence electrolyte; 112—Vertical shaft; 113—Inert gas; 114—Spherical floating piston; 115—Cylindrical floating piston; 201—First pressure sensor; 202—Second pressure sensor; 203 — Annular rubber sleeve; 204 — High-pressure gas cylinder; 205 — Miniature air pump; 206 — Valve; 207 — Gas path; 208 — Fixing clamp; 209 — Control unit; 210 — Sealing cavity; 211 — Upper electrode; 2111 — First flow-limiting connection channel; 212 — Lower electrode; 2121 — Second flow-limiting connection channel; 213 — Ion exchange membrane; 214 — Eccentric vibration motor; 215 — Ultrasonic communication module; 216 — Counterweight; 217 — Backup lithium battery; 218 — Piston housing; 2181 — Upper liquid inlet; 2182 — Lower liquid inlet. Detailed Implementation

[0020] 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.

[0021] This application mainly adopts a floating piston in a vertical shaft to store electrolytes of different valence states, which achieves the effects of reducing the number of storage tanks, reducing costs, and effectively isolating electrolytes of different valence states. The following is a further detailed description of this application.

[0022] Example 1 See Figure 1 and Figure 2The floating piston-type vertical shaft device for separating high and low valence electrolytes provided in this application includes two vertical shafts 112, a floating piston, a fuel cell stack 104, and a circulation pump 105. The two vertical shafts 112 are located underground, serving as the positive and negative electrode shafts respectively, for storing the positive and negative electrolytes of the flow battery. The floating piston is positioned inside the vertical shaft 112, dividing it into an upper and lower storage area. The fuel cell stack 104 is connected to the upper and lower storage areas of the vertical shaft 112 via a transmission pipe 106. The circulation pump 105 is mounted on the transmission pipe 106. This device effectively isolates electrolytes of different valence states within the same vertical shaft, reducing the number of storage tanks and lowering system complexity and construction costs. This is because the floating piston isolates electrolytes of different valence states, allowing for separate storage, and the use of underground vertical shafts for electrolyte storage reduces surface land occupation. The vertical shafts 112 can be converted from abandoned mine shafts or specially drilled. The depth of the shaft 112 can be designed according to the energy storage capacity requirements, for example, a depth of 100m to 1000m and a diameter of 1m to 5m. The fuel cell stack 104 can be connected to the photovoltaic power generation system 101 and / or the wind power generation system 102 via the power transmission line 103 to be charged using renewable energy.

[0023] It should be noted that the "isolation" mentioned in this application refers to the floating piston blocking the macroscopic convection mixing of electrolytes with different valence states in the upper and lower storage zones, ensuring that the electrolytes in both zones maintain their respective valence purity within the range required for normal operation of the flow battery system during charge-discharge cycles. This "isolation" does not require an absolute zero-permeability seal between the floating piston and the inner wall of the shaft. In actual operation, there may be a small gap between the floating piston and the inner wall of the shaft. A small amount of electrolyte may slowly migrate between the upper and lower storage zones through this gap via molecular diffusion. However, because the floating piston physically blocks the macroscopic convection channel between the two storage zones, the rate of this diffusion migration is much lower than the rate of charge-discharge cycles of the flow battery system. Therefore, within a single charge-discharge cycle, the proportion of electrolytes with different valence states mixed due to diffusion migration to the total electrolyte volume is negligible and will not have a substantial impact on the coulombic efficiency and energy storage capacity of the flow battery system. For trace amounts of valence state mixing that occur due to cumulative diffusion during long-term operation, recovery can be achieved through the conventional periodic electrolyte mixing and rebalancing process of flow battery systems. Therefore, the term "isolation" in this application encompasses the aforementioned technical meaning of allowing minute amounts of permeation while blocking macroscopic convective mixing.

[0024] Specifically, the inner wall of shaft 112, from the outside to the inside, includes a grouting reinforcement layer, a sprayed protective layer, an anti-corrosion layer, and a plastic veneer layer.

[0025] The grouting reinforcement layer, formed by injecting reinforcement materials, enhances the stability of the surrounding rock mass and prevents collapse. Materials such as cement grout can be used for this purpose. The sprayed protective layer is typically formed by spraying concrete, resulting in a smoother inner wall surface. The anti-corrosion layer, made of corrosion-resistant materials like coatings, prevents the electrolyte from corroding the shaft wall. The innermost layer, the plastic facing layer, is in direct contact with the electrolyte. It can be made of corrosion-resistant materials such as polypropylene, polyvinyl chloride, or polytetrafluoroethylene, providing a smooth inner wall surface, reducing the resistance of the floating piston, and further isolating the electrolyte from the surrounding rock. These layers, arranged sequentially from the outside in, work together to protect the shaft and provide a favorable environment for electrolyte storage. Their combination logic is as follows: the grouting reinforcement layer provides basic structural stability; the sprayed protective layer provides a smooth adhesion surface for the subsequent anti-corrosion and plastic facing layers; the anti-corrosion layer prevents electrolyte corrosion; and the plastic facing layer, in direct contact with the electrolyte, provides a smooth surface, collectively ensuring the safe storage of the electrolyte within the shaft. Through the above-mentioned multi-layered structure, the electrolyte is completely isolated from the surrounding rock mass of the shaft, which not only ensures the structural safety of the shaft, but also avoids the electrolyte from being contaminated by minerals in the surrounding rock, thereby maintaining the purity and electrochemical activity of the electrolyte.

[0026] Specifically, the floating piston includes a spherical floating piston 114 and a cylindrical floating piston 115.

[0027] Furthermore, to ensure the effective isolation effect of the spherical floating piston 114, in some preferred embodiments, an annular groove is formed at the maximum radial section (i.e., the equator position) of the outer surface of the spherical floating piston 114. A corrosion-resistant elastic sealing ring (such as a fluororubber O-ring or a V-lip seal ring) is embedded in this annular groove. The elastic sealing ring is interference-fitted with the inner wall of the vertical shaft 112 to form a sliding seal. Simultaneously, to prevent the spherical floating piston 114 from rolling during its vertical movement, causing the elastic sealing ring to detach from the horizontal contact surface, a high-density counterweight is embedded in the lower part of the spherical floating piston 114, making its overall center of gravity lower than its geometric center. This ensures that it maintains a stable posture in its suspended state, guaranteeing that the sealing ring is always in a horizontal sealing working state.

[0028] In other embodiments that allow for minute amounts of leakage, the spherical floating piston 114 has no sealing ring on its surface, and a minute fitting gap of 1 mm to 5 mm is maintained between its outer diameter and the inner diameter of the shaft 112. Although not absolutely sealed within this gap, the spherical floating piston 114 blocks macroscopic convection mixing between the upper and lower electrolyte storage zones, and the fluid diffusion channel at the gap is extremely narrow, thereby reducing the diffusion rate of electrolytes in different valence states to a negligible level. This dynamic isolation method allows for extremely small amounts of leakage, and the resulting minimal valence mixing can be recovered through the conventional periodic electrolyte mixing and rebalancing process of flow battery systems. In daily charge-discharge cycles, the drag reduction benefits far outweigh the capacity loss caused by minute leakage.

[0029] The spherical floating piston 114 is spherical, with a diameter slightly smaller than the inner diameter of the shaft 112. This spherical structure makes it less prone to tilting and jamming during movement, allowing for more flexible movement within the shaft. The cylindrical floating piston 115 is cylindrical, with an outer diameter slightly smaller than the inner diameter of the shaft 112. The cylindrical structure provides a larger sealing area, better isolating electrolytes of different valence states. Their densities are matched to the electrolyte density; specifically, the difference between the overall density of the floating piston and the electrolyte density does not exceed ±5% of the electrolyte density, allowing it to float in the electrolyte and move freely along the axial direction of the shaft 112. When the volume of the electrolyte changes during charging and discharging, the floating piston moves with the change in liquid level, always maintaining isolation between electrolytes of different valence states. In practical applications, the appropriate floating piston type can be selected according to the inner diameter of the shaft 112 and the properties of the electrolyte: when the inner diameter of the shaft is small or the inner wall flatness is poor, a spherical floating piston 114 is preferred to reduce the risk of jamming; when the inner diameter of the shaft is large and the inner wall flatness is good, a cylindrical floating piston 115 is preferred to obtain a better sealing and isolation effect.

[0030] The mechanical principles of the floating piston moving within the shaft are analyzed below.

[0031] The overall density of the floating piston is basically the same as that of the electrolyte in the shaft, with the density difference not exceeding ±5% of the electrolyte density. Therefore, the net buoyancy force (the difference between buoyancy and gravity) experienced by the floating piston in the electrolyte is close to zero, and the floating piston is in a near-suspended state. In this state, the axial movement of the floating piston is mainly driven by the difference in hydraulic pressure experienced by its upper and lower end faces.

[0032] Specifically, during the charging process, the circulating pump 105 draws electrolyte from the upper storage area of ​​the shaft 112 and, after reaction in the fuel cell stack 104, transports the electrolyte to the lower storage area of ​​the shaft 112. Because the electrolyte in the upper storage area is continuously drawn out, the height of the liquid column acting on the upper surface of the floating piston in the upper storage area decreases, corresponding to a decrease in the hydraulic pressure value. The pressure decreases; simultaneously, the reacted electrolyte is continuously transported to the lower reservoir, increasing the height of the liquid column acting on the lower end face of the floating piston, and correspondingly increasing the hydraulic pressure value. The pressure rises. Consequently, the hydraulic pressure on the lower end face of the floating piston... Greater than the hydraulic pressure on the upper end face An upward net pressure difference is formed between the upper and lower end faces of the floating piston. The net pressure difference acts on the end face area of ​​the floating piston, generating an upward thrust F = ΔP × A, where A is the effective pressure-bearing area of ​​the floating piston. When this thrust F is greater than the resistance that the floating piston needs to overcome to move, the floating piston moves upward along the axial direction of the shaft 112 under the action of this thrust.

[0033] During the discharge process, the circulating pump 105 draws electrolyte from the lower storage area of ​​the vertical shaft 112 and, after reaction by the fuel cell stack 104, transports the electrolyte to the upper storage area of ​​the vertical shaft 112. At this time, the hydraulic pressure acting on the lower end face of the floating piston in the lower storage area... The hydraulic pressure acting on the upper end face of the floating piston in the upper reservoir area is reduced. The hydraulic pressure on the upper surface of the floating piston increases as it rises. Greater than the hydraulic pressure on the lower end face A downward net pressure difference is formed between the upper and lower end faces of the floating piston. Under the thrust generated by this downward net pressure difference, the floating piston moves downward along the axial direction of the shaft 112.

[0034] The resistance that the floating piston needs to overcome to move mainly includes the following aspects: First, the frictional resistance between the floating piston and the inner wall of the shaft 112, the magnitude of which is related to the contact state between the outer surface of the floating piston and the inner wall of the shaft; Second, the viscous resistance generated by the flow of the electrolyte around the floating piston when it moves; Third, the small difference between the weight of the floating piston itself and the buoyancy (when the density is not perfectly matched).

[0035] In this embodiment, the outer diameter of the spherical floating piston 114 and the cylindrical floating piston 115 is slightly smaller than the inner diameter of the shaft 112, and an annular gap exists between the floating piston and the inner wall of the shaft 112. Without a sealing ring, there is no direct solid contact between the floating piston and the inner wall of the shaft, resulting in near-zero frictional resistance. The movement resistance originates only from the viscous resistance of the electrolyte and a small difference in buoyancy, allowing the floating piston to move freely under a small pressure differential. With an elastic sealing ring, sliding friction exists between the elastic sealing ring and the inner wall of the shaft, increasing the movement resistance. However, the pressure differential generated by the circulating pump 105 provides sufficient thrust to overcome this frictional resistance. The innermost plastic lining layer of the inner wall of the shaft 112 provides a smooth contact surface, reducing the coefficient of friction between the elastic sealing ring and the inner wall of the shaft, thereby reducing the movement resistance. In actual engineering design, the flow rate and head parameters of the circulating pump 105 should be matched according to the depth of the shaft 112, the effective pressure-bearing area of ​​the floating piston, and the moving resistance of the floating piston, so as to ensure that the pressure difference generated by the circulating pump 105 under normal working flow can drive the floating piston to move smoothly.

[0036] Specifically, the fuel cell stack 104 is connected to the upper and lower liquid storage areas of the vertical shaft 112 via the transmission pipe 106.

[0037] The transmission pipe 106 is made of at least one of polypropylene, polyvinyl chloride, or polytetrafluoroethylene, which have good corrosion resistance and can withstand the corrosion of the electrolyte. A circulation pump 105 is installed on the transmission pipe 106 to drive the electrolyte to circulate between the shaft 112 and the battery stack 104. During charging, the circulation pump 105 pumps the electrolyte from the upper storage area of ​​the shaft 112 to the battery stack 104 for electrochemical reaction and then delivers it to the lower storage area of ​​the shaft 112, causing the floating piston to move upwards. During discharging, the circulation pump 105 pumps the electrolyte from the lower storage area of ​​the shaft 112 to the battery stack 104 for electrochemical reaction and then delivers it to the upper storage area of ​​the shaft 112, causing the floating piston to move downwards. This circulating flow ensures the normal charging and discharging process of the flow battery. The transmission pipelines 106 are connected to the vicinity of the top of the upper liquid storage area and the vicinity of the bottom of the lower liquid storage area of ​​the vertical shaft 112, respectively, to ensure that the electrolyte in each liquid storage area can be fully extracted and transported during the charging and discharging process.

[0038] Specifically, taking a vanadium redox flow battery as an example, during charging, the low-valence electrolyte 108 (including...) in the upper storage area of ​​the positive electrode shaft... The high-valence electrolyte 109 (containing...) is generated by the oxidation reaction of the 104 stack. Afterwards, it is transported to the lower storage area of ​​the positive electrode shaft, and the high-valence electrolyte 110 (containing...) is transported to the upper storage area of ​​the negative electrode shaft. The low-valence electrolyte 111 (containing...) is generated by the reduction reaction of the 104 stack. Afterwards, it is transported to the lower storage area of ​​the negative electrode shaft. During discharge, the high-valence electrolyte 109 (containing...) in the lower storage area of ​​the positive electrode shaft... The low-valence electrolyte 108 (containing...) is generated by the reduction reaction of the 104 stack. Afterwards, it is transported to the upper storage area of ​​the positive electrode shaft, and the negative electrode low-valence electrolyte 111 (containing...) is transported to the lower storage area of ​​the negative electrode shaft. The high-valence electrolyte 110 (containing...) is generated by the oxidation reaction of the 104 stack. The electrolyte is then transported to the upper storage area of ​​the negative electrode shaft. In this way, during charge-discharge cycles, the lower storage area of ​​the positive electrode shaft stores the high-valence electrolyte, and the upper storage area stores the low-valence electrolyte; similarly, the lower storage area of ​​the negative electrode shaft stores the low-valence electrolyte, and the upper storage area stores the high-valence electrolyte. A floating piston acts as a physical separator between the two.

[0039] Specifically, a number of limiting blocks 107 are provided on the inner wall of the shaft 112. The limiting blocks 107 are spaced apart along the axial direction of the shaft 112 to limit the movement range of the floating piston and prevent the floating piston from moving to the top or bottom of the shaft 112 and blocking the interface of the transmission pipe 106. The top of the upper liquid storage area of ​​the shaft 112 is filled with an inert gas 113, such as nitrogen or argon, to isolate the electrolyte from contact with air and prevent the active substances in the electrolyte from being oxidized by oxygen in the air. The inert gas 113 also acts as a buffer. When the floating piston moves upward to near the top of the shaft 112, the pressure generated by the compression of the inert gas 113 can buffer and decelerate the floating piston, preventing the floating piston from having a hard collision with the top of the shaft.

[0040] For details, see Figure 1 The complete working process of the entire device in this embodiment during charging and discharging is described below.

[0041] Charging process: When the electrical energy generated by the photovoltaic power generation system 101 and / or the wind power generation system 102 is transmitted to the fuel cell stack 104 through the power transmission line 103, the system enters the charging mode. At this time, the circulation pump 105 starts, and the circulation pump 105 on the positive electrode side pumps the low-valence electrolyte 108 (containing...) from the liquid storage area above the positive electrode shaft. The electrolyte is pumped to the positive electrode side of the fuel cell stack 104 through the transmission pipeline 106, while the circulation pump 105 on the negative electrode side pumps the high-valence electrolyte 110 (containing...) from the upper storage area of ​​the negative electrode shaft. The fuel cell is pumped to the negative electrode side of the fuel cell stack 104 via transmission pipe 106. In the fuel cell stack 104, an oxidation reaction occurs on the positive electrode side. A reduction reaction occurs on the negative electrode side. After the reaction, the high-valence electrolyte at the positive electrode 109 (containing...) The electrolyte is transported through transmission pipeline 106 to the lower storage area of ​​the positive electrode shaft, and the low-valence electrolyte 111 (containing...) is transported to the lower storage area of ​​the positive electrode shaft. The electrolyte is transported to the lower storage area of ​​the negative electrode shaft via transmission pipe 106. As the charging process continues, the electrolyte in the upper storage area of ​​both the positive and negative electrode shafts gradually decreases, while the electrolyte in the lower storage area gradually increases. The floating pistons in both shafts gradually move upwards due to the changing liquid levels. When charging is complete, the electrolyte in the upper storage area is essentially emptied (the floating piston moves to the upper limit block 107), and the lower storage area is filled with electrolyte after the electrochemical reaction, placing the system in a fully charged state.

[0042] Discharge operation process: When power needs to be supplied to the power grid or electrical load, the system enters discharge mode. At this time, the circulation pump 105 starts, and the circulation pump 105 on the positive electrode side discharges the high-valence electrolyte 109 (containing...) from the liquid storage area at the bottom of the positive electrode shaft. The electrolyte is pumped to the positive electrode side of the fuel cell stack 104 through the transmission pipeline 106, while the circulation pump 105 on the negative electrode side pumps the low-valence electrolyte 111 (containing...) from the lower storage area of ​​the negative electrode shaft. The fuel cell is pumped to the negative side of the fuel cell stack 104 via transmission pipe 106. In the fuel cell stack 104, a reduction reaction occurs on the positive side. An oxidation reaction occurs on the negative electrode side. The fuel cell stack 104 outputs electrical energy. After the reaction, the positive electrode low-valence electrolyte 108 (containing...) The electrolyte is transported through transmission pipeline 106 to the upper storage area of ​​the positive electrode shaft, and the high-valence electrolyte 110 (containing...) is transported to the negative electrode shaft. The electrolyte is transported to the upper storage area of ​​the negative electrode shaft via transmission pipe 106. As the discharge process continues, the electrolyte in the lower storage areas of both the positive and negative electrode shafts gradually decreases, while the electrolyte in the upper storage areas gradually increases. The floating pistons in both shafts gradually move downwards due to the changing liquid levels. When the discharge is complete, the electrolyte in the lower storage area is essentially emptied (the floating piston moves to the lower limit block 107), and the upper storage area is filled with the electrolyte after the electrochemical reaction, placing the system in a fully discharged state.

[0043] Throughout the entire charge-discharge cycle, the floating piston remains suspended in the electrolyte, moving up and down with the changes in the liquid levels on both sides, continuously maintaining physical isolation from electrolytes of different valence states. Because the density of the floating piston matches that of the electrolyte, it can move freely with the liquid surface without additional driving force, ensuring stable and reliable system operation.

[0044] The implementation principle of this embodiment is as follows: By installing a floating piston within an underground shaft, the same shaft is divided into an upper storage area and a lower storage area, storing high-valence and low-valence electrolytes respectively, thus achieving effective isolation of electrolytes of different valence states within the same shaft. Compared to the traditional four-tank scheme, only two shafts are needed to separate the positive and negative electrolytes, reducing the number of tanks and lowering system complexity and construction costs. Simultaneously, utilizing underground shafts for electrolyte storage fully utilizes underground space resources, reducing the surface footprint, making it particularly suitable for areas with limited land resources. The stable underground environment temperature is conducive to the constant-temperature storage of the electrolyte, avoiding changes in electrolyte performance caused by environmental temperature fluctuations in surface storage tanks. The density of the floating piston matches the electrolyte density, allowing it to float in the electrolyte and move freely with changes in the liquid level, requiring no additional drive mechanism, resulting in a simple and reliable structure.

[0045] Example 2 See Figure 3 The difference between this embodiment and the above embodiments is that the floating piston in this embodiment is an active intelligent piston. The active intelligent piston includes a piston housing 218, a pressure sensing unit, a variable diameter sealing mechanism, a control unit 209, a self-powered unit, a backup lithium battery 217, a vibration unlocking unit, and an ultrasonic communication module 215.

[0046] The piston housing 218 is cylindrical and made of corrosion-resistant material, such as polytetrafluoroethylene or titanium alloy. The outer diameter of the piston housing 218 is smaller than the inner diameter of the vertical shaft 112, leaving an annular gap between the piston housing 218 and the inner wall of the vertical shaft 112. The piston housing 218 has a sealed cavity 210 inside, which is completely isolated from the external electrolyte and is used to house internal components such as the control unit 209, the self-powered unit, the backup lithium battery 217, the charging / discharging assembly, and the eccentric vibration motor 214. The upper and lower end faces of the piston housing 218 are respectively provided with an upper liquid inlet 2181 and a lower liquid inlet 2182, which are used to introduce the electrolyte from the upper and lower liquid storage areas into the self-powered unit inside the housing.

[0047] The pressure sensing unit includes a first pressure sensor 201 and a second pressure sensor 202, which are respectively disposed on the upper and lower end faces of the piston housing 218. The first pressure sensor 201 is used to detect the pressure value of the electrolyte in the upper reservoir area acting on the upper end face of the piston housing 218. The second pressure sensor 202 is used to detect the pressure value of the electrolyte in the lower reservoir acting on the lower end face of the piston housing 218. Both pressure sensors are electrically connected to control unit 209, transmitting the detected pressure values ​​to control unit 209 in real time. Control unit 209 calculates the pressure difference. The pressure sensing unit controls the operation of the variable diameter sealing mechanism and the vibration release unit based on the pressure difference. The pressure sensing unit works as follows: the first pressure sensor 201 and the second pressure sensor 202 continuously collect the hydraulic pressure values ​​at the upper and lower end faces of the piston housing 218 in real time, convert the collected analog signals into digital signals, and transmit them to the control unit 209. The control unit 209 reads the data from the two pressure sensors at a preset sampling frequency (e.g., once per second), calculates the pressure difference ΔP, and compares this pressure difference with a preset first threshold value. Second preset threshold By comparing the values, the system can determine the current working state of the piston. Through real-time monitoring of the pressure difference, the system can promptly detect changes in the electrolyte level during charging and discharging, providing a data basis for subsequent sealing control and jamming detection.

[0048] See Figure 3A variable-diameter sealing mechanism is disposed on the outer circumferential surface of the piston housing 218, including an annular rubber sleeve 203 and a gas filling / discharging assembly. The annular rubber sleeve 203 is made of corrosion-resistant elastic rubber material, such as fluororubber or ethylene propylene rubber. The annular rubber sleeve 203 is fixedly sleeved on the outer wall of the piston housing 218, and its upper and lower ends are respectively sealed to the outer wall of the piston housing 218 by fixing clamps 208. The fixing clamps 208 are metal ring clamps, which press the ends of the annular rubber sleeve 203 against the outer wall of the piston housing 218 by bolts or snaps to form a reliable seal. A closed annular gas cavity is formed between the annular rubber sleeve 203 and the outer wall of the piston housing 218. The gas filling / discharging assembly is disposed in the sealed cavity 210 inside the piston housing 218, including a high-pressure gas cylinder 204, a micro gas pump 205, and a valve 206. The high-pressure gas cylinder 204 is pre-filled with a high-pressure inert gas, such as nitrogen. The high-pressure gas cylinder 204 is connected to the inlet of the micro air pump 205 via the gas passage 207, and the outlet of the micro air pump 205 is connected to the annular gas chamber via the gas passage 207 and valve 206. The gas passage 207 passes through the side wall of the piston housing 218 and connects to the annular gas chamber. When the control unit 209 controls the micro air pump 205 to operate in the forward direction and opens the valve 206, the gas in the high-pressure gas cylinder 204 is filled into the annular gas chamber through the gas passage 207. Under the action of air pressure, the annular rubber sleeve 203 expands radially outward until the outer surface of the annular rubber sleeve 203 fits against the inner wall of the vertical well 112, forming a reliable seal. At this time, the annular gap between the active intelligent piston and the inner wall of the vertical well 112 is completely filled by the annular rubber sleeve 203, and the upper liquid storage area and the lower liquid storage area are effectively isolated. When the control unit 209 controls the micro air pump 205 to operate in reverse, the gas in the annular gas chamber is drawn back into the high-pressure gas cylinder 204. The annular rubber sleeve 203, under its own elastic restoring force, contracts radially inward, fitting against the outer wall of the piston housing 218. At this time, the annular gap between the active intelligent piston and the inner wall of the vertical shaft 112 is restored, reducing the piston's movement resistance and allowing it to move freely along the axial direction of the vertical shaft 112 under the action of hydraulic differential. The annular rubber sleeve 203 is annularly fitted around the outer periphery of the piston housing 218. The high-pressure gas cylinder 204 and the micro air pump 205 are located symmetrically within the sealing cavity 210. The spare lithium battery 217 and the control unit 209 are also located within the sealing cavity 210. The technical effect of the variable diameter sealing mechanism is that, through the radial expansion and contraction of the annular rubber sleeve 203, flexible switching between the sealing state and the moving state is achieved, resolving the contradiction between sealing performance and movement flexibility in traditional fixed sealing structures. In the sealed state, the annular rubber sleeve 203 can adapt to the slight irregularities of the inner wall of the shaft 112, forming a good sealing effect; in the moving state, the annular rubber sleeve 203 completely contracts and fits against the surface of the piston housing 218, reducing the piston's moving resistance.

[0049] Based on the dynamics principle of the floating piston described in Example 1, the movement of the active intelligent piston within the vertical shaft 112 is also driven by the hydraulic difference formed between the upper and lower end faces of the piston when the circulating pump 105 is working. Unlike the spherical floating piston 114 and the cylindrical floating piston 115 in Example 1, the active intelligent piston achieves active switching between moving and sealed states through a variable-diameter sealing mechanism. In the moving state, the annular rubber sleeve 203 contracts and fits against the outer wall of the piston housing 218, forming an annular gap between the piston housing 218 and the inner wall of the vertical shaft 112. There is no direct solid contact between the piston and the inner wall of the vertical shaft, resulting in near-zero frictional resistance and minimizing movement resistance. The active intelligent piston can move freely under the action of the hydraulic difference. In the sealed state, the annular rubber sleeve 203 expands and fits against the inner wall of the vertical shaft 112, fixing the active intelligent piston in its current position, forming a sealed isolation between the upper and lower liquid storage areas. Therefore, the active intelligent piston eliminates the frictional resistance of the sealing structure when movement is required through the state switching of the variable diameter sealing mechanism, and provides a reliable sealing effect when static isolation is required, so that the same piston has both low-resistance movement and high-reliability sealing capabilities.

[0050] See Figure 3The self-powered unit is located inside the sealed cavity 210 and includes an upper electrode 211, a lower electrode 212, and an ion exchange membrane 213 disposed between the upper electrode 211 and the lower electrode 212. A closed upper storage cavity is formed within the upper electrode 211, which is connected to the upper liquid inlet 2181 on the upper end face of the piston housing 218 via a first current-limiting connection channel 2111. Electrolyte in the upper storage area enters the upper storage cavity through the upper liquid inlet 2181 and the first current-limiting connection channel 2111, and contacts the upper electrode 211. The upper storage cavity is located above the ion exchange membrane 213. A closed lower storage cavity is formed within the lower electrode 212, which is connected to the lower liquid inlet 2182 on the lower end face of the piston housing 218 via a second current-limiting connection channel 2121. The electrolyte in the lower storage area enters the lower storage chamber through the lower inlet hole 2182 and the second current-limiting connection channel 2121, and comes into contact with the lower electrode 212. The lower storage chamber is located below the ion exchange membrane 213. The upper and lower storage chambers achieve ion conduction through the ion exchange membrane 213, and are not interconnected except for the ion exchange membrane 213. In this way, the electrolyte in the upper and lower storage chambers are in contact with the upper electrode 211 and the lower electrode 212, respectively, forming a complete electrochemical battery structure. Since the electrolytes stored in the upper and lower storage areas have different valence states, there is an electrochemical potential difference between them. The self-powered unit uses this potential difference to generate electricity, which, together with the energy storage capacitor and the backup lithium battery 217, provides power to the pressure sensing unit, control unit 209, micro air pump 205, valve 206, and other electrical units. The self-powered unit operates as follows: Taking the positive electrode vertical shaft of a vanadium redox flow battery as an example, the upper storage area stores the low-valence electrolyte 108 (including...) of the positive electrode. The lower storage area stores 109g of high-valence electrolyte at the positive electrode (including...). The standard electrode potential difference between the two is approximately 1.0V. In the upper storage cavity... The electrolyte is in contact with the upper electrode 211, and the electrolyte in the lower storage chamber... The electrolyte is in contact with the lower electrode 212, and the ion exchange membrane 213 allows hydrogen ions to pass through. The charge migrates between the two reservoirs to maintain charge balance, thereby generating a potential difference between the upper electrode 211 and the lower electrode 212, resulting in a continuous current output.

[0051] It should be noted that the self-powered unit in this embodiment is not used to continuously provide high power output, but rather to provide continuous low-average power replenishment to the pressure sensing unit, control unit, and energy storage unit. Therefore, both the upper and lower storage chambers are designed as small-volume liquid storage chambers, with a preferred single-chamber volume of 10 mL to 100 mL, more preferably 20 mL to 50 mL. The first flow-limiting connection channel 2111 and the second flow-limiting connection channel 2121 are constructed as capillary channels, porous flow-limiting elements, or slit flow-limiting channels, with a preferred channel length of 5 mm to 50 mm and an equivalent hydraulic diameter of 0.3 mm to 1.5 mm. Through the above-mentioned physical flow-limiting structure, flow resistance is increased, cutting off the path for macroscopic convection mixing of the electrolyte in the upper and lower storage zones through the piston interior. The electrolyte in the external storage zone can only slowly diffuse and replenish the upper and lower storage chambers under the influence of concentration gradient, ion migration, and weak fluid disturbance caused by piston movement, in order to replenish active ions near the electrode surface and reduce concentration polarization.

[0052] In some preferred embodiments, the pressure sensing unit and control unit 209 employ ultra-low power devices and operate in an intermittent sampling and sleep-wake mode, thereby controlling the average output power of the self-powered unit within the range of 1μW to 500μW, preferably within the range of 10μW to 100μW. For this extremely low power level, the self-powered unit consumes very little active material in the upper and lower storage chambers, and combined with the slow diffusion replenishment effect of the current-limiting connection channel, it can fully meet the needs of long-term operation.

[0053] Furthermore, to address the issue of transient high-power loads, the self-powered unit preferably supplies power externally via an energy storage capacitor (not shown) and / or a backup lithium battery 217. That is, the self-powered unit first performs a long-term trickle charge on the energy storage capacitor and / or the backup lithium battery 217. When a high-energy-consuming operation is required, the energy storage capacitor and / or the backup lithium battery 217 then supply power to the load with the highest instantaneous power consumption. This avoids the self-powered unit directly bearing the peak load when the micro air pump 205, the eccentric vibration motor 214, or the ultrasonic communication module 215 starts up, ensuring the self-consistency of the system's energy logic.

[0054] Furthermore, the ion exchange membrane 213 is preferably a highly selective ion exchange membrane (e.g., a perfluorosulfonic acid resin membrane). This ion exchange membrane has high conductivity for small hydrogen ions, while having extremely low permeability for active metal ions such as vanadium ions. This ensures that while maintaining charge balance and conductivity between the upper and lower storage chambers, long-term cross-permeation contamination of active materials with different valence states is strictly controlled within an extremely low acceptable range, without substantially affecting the overall capacity of the flow battery system.

[0055] It is important to note that, to prevent the introduced electrolyte from corroding or short-circuiting the electronic components inside the piston, the self-powered unit (including the upper electrode 211, lower electrode 212, upper reservoir, lower reservoir, and ion exchange membrane 213) is entirely encapsulated within an insulating and corrosion-resistant isolation box made of polytetrafluoroethylene or epoxy resin. This isolation box is located inside the piston housing 218, achieving complete physical and fluid isolation between its internal fluid area and the other spaces of the sealed cavity 210 (i.e., the area accommodating the control unit 209, backup lithium battery 217, micro air pump 205, and other electrical units). The electrolyte can only enter the upper and lower reservoirs within the isolation box through the upper inlet port 2181 and the lower inlet port 2182. In addition, the conductive leads of the upper electrode 211 and the lower electrode 212 are made of glass sintering or corrosion-resistant resin potting pressure-resistant sealed terminals that pass through the isolation box and are electrically connected to the external control unit 209 and the backup lithium battery 217. This ensures that the core electrical chamber inside the piston is absolutely dry and sealed while realizing the generation of electricity using the in-situ electrolyte.

[0056] A backup lithium battery 217 is housed in a sealed cavity 210 inside the piston housing 218 and connected in parallel with the self-powered unit. Under normal operating conditions, the self-powered unit provides power to each electrical unit of the active intelligent piston and simultaneously charges the backup lithium battery 217. When the output power of the self-powered unit is insufficient, for example, when the difference in the valence state of the electrolyte in the upper and lower reservoirs is small during charge-discharge switching, resulting in insufficient potential difference, the backup lithium battery 217 provides supplementary power to each electrical unit of the active intelligent piston, ensuring that the active intelligent piston can operate normally under various conditions. The technical advantage of the backup lithium battery 217 is that, as a supplementary power source for the self-powered unit, it provides a stable power supply during transitional operating conditions when the output power of the self-powered unit is insufficient, ensuring that key components such as the control unit 209, pressure sensing unit, and variable diameter sealing mechanism do not fail due to power failure, thereby guaranteeing the operational reliability of the active intelligent piston under various operating conditions.

[0057] The control unit 209 is disposed in the sealed cavity 210 and can be implemented using a low-power microcontroller (MCU). The control unit 209 is electrically connected to the first pressure sensor 201, the second pressure sensor 202, the micro air pump 205, the valve 206, the eccentric vibration motor 214, and the ultrasonic communication module 215, respectively, and coordinates the control of each component according to preset control logic. The control unit 209 first reads the pressure values ​​of the first pressure sensor 201 and the second pressure sensor 202, and calculates the pressure difference. Then determine whether the pressure difference ΔP is greater than the second preset threshold. If yes, the active intelligent piston is determined to be stuck, and the stuck process is initiated; otherwise, the pressure difference ΔP is further checked to see if it exceeds the first preset threshold. If yes, the variable diameter sealing mechanism is controlled to contract, causing the active intelligent piston to enter the moving mode; if no, the variable diameter sealing mechanism is controlled to expand, causing the active intelligent piston to enter the sealing mode. In the jamming process, the control unit 209 controls the variable diameter sealing mechanism to contract to its maximum contraction amount, and then starts the eccentric vibration motor 214 to vibrate and unblock. After the eccentric vibration motor 214 vibrates for a preset time, the control unit 209 rereads the pressure difference value. If the pressure difference value drops to the second preset threshold... If the card is still greater than the second preset threshold, then the card unlocking is considered successful; Then, a jamming alarm signal is sent to the ground via the ultrasonic communication module 215. The first preset threshold... Second preset threshold The parameters, such as the depth of shaft 112, the density and viscosity of the electrolyte, and the mass of the piston, are preset, and .For example, It can be set to 0.5 kPa. It can be set to 5 kPa.

[0058] Specifically, the detailed control logic flow of control unit 209 is as follows: Step S1: The control unit 209 reads the pressure value from the first pressure sensor 201. The pressure value of the second pressure sensor 202 Calculate the pressure difference .

[0059] Step S2: Determine whether ΔP is greater than the second preset threshold. If yes, proceed to step S5 (stuck handling process); if no, proceed to step S3.

[0060] Step S3: Determine whether ΔP is greater than the first preset threshold. If yes, proceed to step S4a (moving mode); if no, proceed to step S4b (sealing mode).

[0061] Step S4a (Moving Mode): Control unit 209 controls micro air pump 205 to reverse, drawing gas from the annular air chamber back to high-pressure gas cylinder 204. Annular rubber sleeve 203 contracts, creating a gap between the active intelligent piston and the inner wall of vertical shaft 112. The piston moves freely under the action of hydraulic differential. Return to step S1 to continue monitoring.

[0062] Step S4b (Sealing Mode): Control unit 209 controls micro air pump 205 to operate in the forward direction and opens valve 206 to inflate the annular air chamber. The annular rubber sleeve 203 expands and adheres to the inner wall of vertical shaft 112 to form a seal. Return to step S1 to continue monitoring.

[0063] Step S5 (Stuck Handling Process): The control unit 209 determines that the active intelligent piston is stuck. First, it controls the variable diameter sealing mechanism to contract to the maximum contraction amount, and then starts the eccentric vibration motor 214 to vibrate and unblock it.

[0064] Step S6: The eccentric vibration motor 214 stops vibrating after a preset time (e.g., 30 seconds), and the control unit 209 rereads the pressure difference value ΔP.

[0065] Step S7: Determine whether ΔP is still greater than the second preset threshold. If not, the card unlocking is considered successful, and the process returns to step S1 to continue normal monitoring; if yes, the card unlocking is considered unsuccessful, and a stuck alarm signal is sent to the ground via the ultrasonic communication module 215, awaiting manual intervention.

[0066] The vibration unlocking unit includes an eccentric vibration motor 214 disposed inside the piston housing 218. The eccentric vibration motor 214 is a miniature eccentric rotor motor that generates vibration by rotating an eccentric mass block at high speed. When the active intelligent piston becomes stuck in the vertical shaft 112 due to irregular inner wall structure, scale, or foreign objects, the vibration generated by the eccentric vibration motor 214 changes the contact state between the piston and the inner wall of the vertical shaft, thereby releasing the stuck piston. The working process of the vibration unlocking unit is as follows: when the control unit 209 detects a pressure difference ΔP greater than a second preset threshold... When the piston is determined to be stuck, the control unit 209 first controls the variable diameter sealing mechanism to contract to its maximum contraction, so that the annular rubber sleeve 203 completely fits against the outer wall of the piston housing 218, thereby minimizing the contact area between the piston and the inner wall of the shaft 112. Then, the control unit 209 starts the eccentric vibration motor 214. The vibration generated by the high-speed rotation of the eccentric vibration motor 214 is transmitted through the piston housing 218 to the contact surface between the piston and the inner wall of the shaft, changing the friction state of the contact surface, thereby disengaging the piston from the stuck position. The technical effect of the vibration release unit is that it automatically releases the piston from the stuck state through mechanical vibration, without manual intervention, improving the operational reliability and maintenance convenience of the system in the deep underground well environment.

[0067] An ultrasonic communication module 215 is disposed on the end face (preferably the upper end face) of the piston housing 218, and includes an ultrasonic transmitter and an ultrasonic receiver. The ultrasonic communication module 215 uses electrolyte as the ultrasonic propagation medium to conduct bidirectional data communication with a ground ultrasonic transceiver located at the top of the shaft 112. Data that the ultrasonic communication module 215 can transmit to the ground includes the piston's current position (depth calculated based on pressure value), pressure values ​​on both the upper and lower sides, the output voltage and current of the self-powered unit, the remaining power of the backup lithium battery 217, and the piston's operating status (moving mode / sealed mode / stuck state). Commands that the ground ultrasonic transceiver can send to the ultrasonic communication module 215 include adjusting the first and second preset thresholds, forcibly switching operating modes, and initiating a self-test program. The technical advantage of the ultrasonic communication module 215 is that by using electrolyte as the ultrasonic propagation medium, bidirectional data transmission between the underground piston and the ground monitoring system can be achieved without laying communication cables in the shaft. This facilitates remote real-time monitoring and management of the piston's operating status by maintenance personnel, enabling timely detection and handling of abnormal situations.

[0068] The piston housing 218 also contains a counterweight 216, used to adjust the overall density of the active intelligent piston to match the density of the electrolyte. The counterweight 216 can be made of materials of different densities. By adjusting the material and number of the counterweights 216, the overall density of the active intelligent piston can be made essentially consistent with the density of the electrolyte, thus achieving a suspension effect. The technical advantage of the counterweight 216 is that, because the active intelligent piston integrates multiple components such as a high-pressure gas cylinder 204, a micro-pump 205, a control unit 209, and a backup lithium battery 217, and these components have different densities, making it difficult for the overall density of the piston to naturally match the electrolyte density. By setting the counterweight 216, the overall density of the piston can be precisely adjusted to match the electrolyte density, thereby achieving a suspended state of the piston in the electrolyte and ensuring that the piston can move freely with changes in the liquid level.

[0069] Specifically, the complete working process of the active intelligent piston in this embodiment during the entire charging and discharging process of the device is described below.

[0070] Initial state: The system is in standby mode. The active intelligent piston is suspended in the middle of the electrolyte in the vertical shaft 112. The variable diameter sealing mechanism is in an expanded sealing state. The annular rubber sleeve 203 is in contact with the inner wall of the vertical shaft 112, effectively isolating the upper and lower liquid storage areas. The control unit 209 continuously reads the pressure values ​​of the first pressure sensor 201 and the second pressure sensor 202 at a preset sampling frequency and calculates the pressure difference ΔP. At this time... The system maintains a sealed mode.

[0071] Charging process: After the system enters charging mode, the circulation pump 105 starts, drawing electrolyte from the upper storage area of ​​the vertical shaft 112 and transporting the reacted electrolyte to the lower storage area. As the electrolyte in the upper storage area decreases and the electrolyte in the lower storage area increases, the pressure on the upper end face of the piston housing 218 increases. The pressure on the lower end face gradually decreases. The pressure difference gradually increases. Gradually increase. When When the piston needs to be moved, the control unit 209 determines that the piston needs to be moved and controls the variable diameter sealing mechanism to retract (the micro air pump 205 reverses operation, and the annular rubber sleeve 203 retracts). The active intelligent piston enters the moving mode and moves upward under the action of hydraulic differential. During the piston movement, the control unit 209 continuously monitors ΔP. ​​When the piston moves to a new equilibrium position, it... At this time, the control unit 209 controls the expansion of the variable diameter sealing mechanism (the micro air pump 205 operates in the forward direction, and the annular rubber sleeve 203 expands), reforming the seal. This cycle continues, with the piston gradually moving upward during the charging process, always maintaining isolation from electrolytes of different valence states.

[0072] Discharge Process: After the system enters discharge mode, the circulating pump 105 starts, drawing electrolyte from the lower storage area of ​​the vertical shaft 112 and transporting the reacted electrolyte to the upper storage area. As the electrolyte in the lower storage area decreases and the electrolyte in the upper storage area increases, the pressure on the upper end face of the piston housing 218 increases. The pressure on the lower end face gradually increases. As the pressure gradually decreases, the pressure difference ΔP gradually increases. At this time, the control unit 209 controls the variable diameter sealing mechanism to contract, and the active intelligent piston enters the moving mode, moving downwards under the action of hydraulic differential. After the piston moves to a new equilibrium position, the control unit 209 controls the variable diameter sealing mechanism to expand, reforming the seal. This cycle repeats, with the piston gradually moving downwards during the discharge process.

[0073] Jamming Handling Process: During charging or discharging, if the active intelligent piston becomes jammed due to irregularities, scale, or foreign objects on the inner wall of shaft 112, the piston cannot move normally, causing the pressure difference between the upper and lower sides to continuously increase. When When the piston is stuck, the control unit 209 first controls the variable diameter sealing mechanism to contract to its maximum contraction amount, and then starts the eccentric vibration motor 214 to vibrate and unblock it. The eccentric vibration motor 214 vibrates for a preset time (e.g., 30 seconds) and then stops. The control unit 209 then rereads ΔP. ​​If ΔP drops to... If the card is successfully released, the piston will resume normal movement; if ΔP is still greater than 1, the piston will resume normal movement. If the card is not unlocked, the control unit 209 will send a stuck alarm signal to the ground ultrasonic transceiver via the ultrasonic communication module 215, and the maintenance personnel will then manually intervene.

[0074] Throughout the operation, the self-powered unit continuously generates electricity using the electrochemical potential difference between the electrolytes of different valence states on both sides of the piston, providing power to the various power-consuming units of the active intelligent piston. When the output power of the self-powered unit is insufficient, the backup lithium battery 217 automatically connects to provide power. The ultrasonic communication module 215 periodically transmits the piston's operating status data to the ground, and the ground monitoring system can send control commands to the piston as needed to achieve remote monitoring and management.

[0075] The implementation principle of this embodiment is as follows: The active intelligent piston of this embodiment integrates multiple functions such as pressure sensing, intelligent control, variable diameter sealing, self-powered operation, vibration unlocking, and ultrasonic communication, achieving autonomous operation and remote monitoring in the deep underground well environment. It requires no external power supply or wired communication, exhibiting high autonomy and reliability. The active intelligent piston monitors the pressure difference between the upper and lower sides in real time through the pressure sensing unit, and intelligently controls the contraction and expansion states of the variable diameter sealing mechanism through the control unit. It reduces resistance when movement is needed and forms an effective seal when sealing is required, achieving a balance between mobility and sealing reliability. The variable diameter sealing mechanism adopts a scheme of annular rubber sleeve combined with a gas filling and releasing assembly. Radial expansion and contraction of the rubber sleeve are achieved by controlling the filling and releasing of the annular gas chamber. This results in a compact structure, fast response speed, and the ability to adapt to the minute irregularities of the vertical well wall, providing excellent sealing performance. The self-powered unit generates electricity using the electrochemical potential difference between the electrolytes of different valence states on both sides of the piston, providing power to the various power-consuming units of the active intelligent piston, eliminating the need for external power cables and achieving energy self-sufficiency. A backup lithium battery is connected in parallel with the self-powered unit to provide supplementary power when the self-powered unit's output power is insufficient, ensuring reliable operation of the active intelligent piston under various working conditions. The vibration release unit generates vibration through an eccentric vibration motor, effectively releasing the piston from jamming and improving the system's operational reliability in deep well environments. The ultrasonic communication module uses electrolyte as a propagation medium for data communication, enabling bidirectional data transmission between the underground piston and the surface monitoring system, facilitating remote monitoring and management of the piston's status.

[0076] The above are all preferred embodiments of this application, and are not intended to limit the scope of protection of this application. Therefore, all equivalent changes made in accordance with the structure, shape and principle of this application should be covered within the scope of protection of this application.

Claims

1. A vertical shaft device for separating and storing high and low valence electrolytes using a floating piston type, characterized in that, include: Two vertical shafts (112) are located underground and serve as the positive electrode shaft and the negative electrode shaft, respectively, for storing the positive electrode electrolyte and the negative electrode electrolyte of the flow battery; A floating piston is disposed inside each of the vertical shafts (112) to divide the internal space of the vertical shaft (112) into an upper liquid storage area and a lower liquid storage area. The density of the floating piston matches the density of the electrolyte, so that it can be suspended in the electrolyte and can move along the axial direction of the vertical shaft (112) to isolate electrolytes of different valence states. The fuel cell stack (104) is connected to the upper and lower liquid storage areas of the positive electrode shaft and the negative electrode shaft respectively through the transmission pipe (106); A circulation pump (105) is installed on the transmission pipeline (106) to drive the electrolyte to circulate between the vertical shaft (112) and the fuel cell stack (104); During charging, the circulating pump (105) pumps the electrolyte from the upper storage area of ​​the vertical shaft (112) to the fuel cell stack (104) for electrochemical reaction and then delivers it to the lower storage area of ​​the vertical shaft (112), and the floating piston moves upward; during discharging, the circulating pump (105) pumps the electrolyte from the lower storage area of ​​the vertical shaft (112) to the fuel cell stack (104) for electrochemical reaction and then delivers it to the upper storage area of ​​the vertical shaft (112), and the floating piston moves downward.

2. The vertical shaft device for separating and storing high and low valence electrolytes using a floating piston type according to claim 1, characterized in that, During charging, the low-valence electrolyte (108) in the upper storage area of ​​the positive electrode shaft is oxidized by the stack (104) to generate a high-valence electrolyte (109) and then transported to the lower storage area of ​​the positive electrode shaft. The high-valence electrolyte (110) in the upper storage area of ​​the negative electrode shaft is reduced by the stack (104) to generate a low-valence electrolyte (111) and then transported to the lower storage area of ​​the negative electrode shaft. During discharge, the high-valence electrolyte (109) in the lower storage area of ​​the positive electrode shaft is reduced by the fuel cell stack (104) to generate a low-valence electrolyte (108) and then transported to the upper storage area of ​​the positive electrode shaft. The low-valence electrolyte (111) in the lower storage area of ​​the negative electrode shaft is oxidized by the fuel cell stack (104) to generate a high-valence electrolyte (110) and then transported to the upper storage area of ​​the negative electrode shaft.

3. The vertical shaft device for separating and storing high and low valence electrolytes using a floating piston type according to claim 1, characterized in that, The inner wall of the vertical shaft (112) is provided with a grouting reinforcement layer, a spray protection layer, an anti-corrosion layer and a plastic facing layer from the outside to the inside, so that the electrolyte is isolated from the rock mass around the vertical shaft; The top of the upper liquid storage area of ​​the vertical shaft (112) is filled with inert gas (113) to isolate the electrolyte from contact with air.

4. The vertical shaft device for separating and storing high and low valence electrolytes using a floating piston type according to claim 1, characterized in that, The inner wall of the vertical shaft (112) is provided with several limiting blocks (107) to limit the movement range of the floating piston; the floating piston is a spherical floating piston (114) or a cylindrical floating piston (115).

5. The vertical shaft device for separating and storing high and low valence electrolytes using a floating piston type according to claim 1, characterized in that, The transmission pipe (106) is made of at least one of polypropylene, polyvinyl chloride or polytetrafluoroethylene.

6. The vertical shaft device for separating and storing high and low valence electrolytes using a floating piston type according to claim 1, characterized in that, The floating piston is an active intelligent piston, and the active intelligent piston includes: The piston housing (218) is cylindrical, and its outer diameter is smaller than the inner diameter of the vertical shaft (112); The pressure sensing unit includes a first pressure sensor (201) and a second pressure sensor (202) respectively disposed on the upper end face and the lower end face of the piston housing (218), for detecting the pressure values ​​of the upper liquid storage area and the lower liquid storage area acting on the two end faces of the piston housing (218); A variable diameter sealing mechanism is provided on the outer peripheral surface of the piston housing (218) and can contract and expand in the radial direction to adjust the sealing state between the active intelligent piston and the inner wall of the vertical shaft (112); The control unit (209) is located in the sealing cavity (210) inside the piston housing (218), and is electrically connected to the pressure sensing unit and the variable diameter sealing mechanism respectively. It controls the working state of the variable diameter sealing mechanism according to the pressure difference detected by the pressure sensing unit. When the absolute value of the pressure difference is greater than the first preset threshold, the control unit (209) controls the variable diameter sealing mechanism to contract to reduce the moving resistance of the active intelligent piston, so that the active intelligent piston can move freely under the action of hydraulic pressure difference; when the absolute value of the pressure difference is less than or equal to the first preset threshold, the control unit (209) controls the variable diameter sealing mechanism to expand so that the active intelligent piston and the inner wall of the vertical shaft (112) form a seal.

7. The vertical shaft device for separating and storing high and low valence electrolytes using a floating piston type according to claim 6, characterized in that, The variable diameter sealing mechanism includes: An annular rubber sleeve (203) is fixedly sleeved on the outer side wall of the piston housing (218). The upper and lower ends of the annular rubber sleeve (203) are respectively sealed to the piston housing (218) by fixing clamps (208). A closed annular air cavity is formed between the annular rubber sleeve (203) and the outer side wall of the piston housing (218). The inflation / deflation assembly is located inside the piston housing (218) and includes a high-pressure gas cylinder (204), a micro air pump (205), and a valve (206). The high-pressure gas cylinder (204) is connected to the inlet end of the micro air pump (205) through an air passage (207), and the outlet end of the micro air pump (205) is connected to the annular air chamber through the air passage (207) and the valve (206). When the control unit (209) controls the micro air pump (205) to operate in the forward direction and opens the valve (206), the gas in the high-pressure gas cylinder (204) is filled into the annular gas chamber through the gas passage (207), and the annular rubber sleeve (203) expands radially outward until it fits against the inner wall of the vertical shaft (112) to form a seal; when the control unit (209) controls the micro air pump (205) to operate in the reverse direction, the gas in the annular gas chamber is drawn back into the high-pressure gas cylinder (204), and the annular rubber sleeve (203) contracts radially inward under its own elastic restoring force and fits against the outer wall of the piston housing (218).

8. The vertical shaft device for separating and storing high and low valence electrolytes using a floating piston type according to claim 6, characterized in that, The piston housing (218) has an upper liquid inlet hole (2181) and a lower liquid inlet hole (2182) on its upper and lower end faces, respectively. The active intelligent piston also includes a self-powered unit, an energy storage capacitor, and a backup lithium battery (217). The self-powered unit is located inside the sealed cavity (210) and includes an upper electrode (211), a lower electrode (212), and an ion exchange membrane (213) disposed between the upper electrode (211) and the lower electrode (212). A closed upper storage cavity is formed within the upper electrode (211). The upper storage cavity is connected to the upper liquid inlet (2181) via a first current-limiting connection channel (2111). The electrolyte in the upper storage area slowly enters the upper storage cavity through the first current-limiting connection channel (2111) and contacts the upper electrode (211). The first current-limiting connection channel (2111) is constructed as any one of a capillary channel, a porous current-limiting element, or a slit current-limiting channel to limit the flow rate of electrolyte entering the upper storage cavity and suppress macroscopic convection. The upper storage cavity is located above the ion exchange membrane (213). A closed lower storage cavity is formed within the lower electrode (212). The lower storage cavity is connected to a second current-limiting connection channel. (2121) is connected to the lower inlet hole (2182). The electrolyte in the lower storage area slowly enters the lower storage cavity through the second flow-limiting connection channel (2121) and contacts the lower end electrode (212). The second flow-limiting connection channel (2121) is constructed as any one of a capillary channel, a porous flow-limiting element, or a slit flow-limiting channel to limit the flow rate of the electrolyte into the lower storage cavity and suppress macroscopic convection. The lower storage cavity is located below the ion exchange membrane (213). The upper storage cavity and the lower storage cavity achieve ion conduction through the ion exchange membrane (213). The ion exchange membrane (213) is a highly selective ion exchange membrane and is not interconnected except for the ion exchange membrane (213). The self-powered unit generates electricity by utilizing the electrochemical potential difference between electrolytes of different valence states in the upper and lower liquid storage areas, which is used to trickle charge the energy storage capacitor and the backup lithium battery (217); the variable diameter sealing mechanism is provided with peak power by the energy storage capacitor and / or the backup lithium battery (217) when it is in operation.

9. The vertical shaft device for separating and storing high and low valence electrolytes using a floating piston type according to claim 6, characterized in that, The active intelligent piston also includes a vibration unlocking unit, which includes an eccentric vibration motor (214) disposed inside the piston housing (218). When the absolute value of the pressure difference is greater than the second preset threshold, the control unit (209) determines that the active intelligent piston is stuck, controls the variable diameter sealing mechanism to contract to the maximum contraction amount and starts the eccentric vibration motor (214) to vibrate and unblock; wherein, the second preset threshold is greater than the first preset threshold; after the eccentric vibration motor (214) vibrates for a preset time, the control unit (209) rereads the pressure difference value. If the absolute value of the pressure difference drops below the second preset threshold, it is determined that the unblocking is successful; if it is still greater than the second preset threshold, a stuck alarm signal is sent to the ground.

10. The floating piston-type vertical shaft device for separating and storing high and low valence electrolytes according to claim 6, characterized in that, The active intelligent piston also includes an ultrasonic communication module (215), which is disposed on the end face of the piston housing (218) and is used to conduct bidirectional data communication with the ground ultrasonic transceiver disposed on the top of the shaft (112) through the electrolyte as the propagation medium.

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