A detection device for recovering a vanadium redox flow battery stack

Abstract

The application discloses a kind of detection devices for vanadium redox flow battery stack recovery applied to the field of electric pile performance analysis, by adopting a shared positive electrode liquid storage tank and a negative electrode liquid storage tank, provide concentration, valence state, temperature and other state uniform standard electrolyte for all to be measured electric pile, the outlet electrolyte of each to be measured electric pile respectively flows into the corresponding positive electrode, negative electrode independent jar of itself, realizes the physical isolation of electrolyte in flow end, makes the electrolyte that flows into electric pile continuously maintain uniform state, while realizing batch, efficient detection to electric pile, effectively avoid the distortion of detection result caused by electrolyte cross contamination, cause other electric pile secondary damage and other problems;By introducing flow control tube in branch, on the one hand, indirect monitoring electrolyte input flow is realized, on the other hand, after stopping pumping, electrolyte anti-backflow function and abnormal backflow monitoring function are realized.

Description

Technical Field

[0001] This invention relates to the field of fuel cell stack performance analysis, and in particular to a testing device for recycling vanadium redox flow battery stacks. Background Technology

[0002] A vanadium redox flow battery is a redox battery that uses vanadium as the active material in a circulating liquid state. An external pump pumps electrolyte into the battery stack, where it circulates within different storage tanks and half-cells under mechanical force. A proton exchange membrane serves as the separator in the battery pack. The electrolyte solution flows parallel across the electrode surfaces and undergoes an electrochemical reaction. Current is collected and conducted through dual electrode plates, converting the chemical energy stored in the solution into electrical energy.

[0003] Efficient and accurate health status assessment of vanadium redox flow battery stacks entering their retirement period is a key prerequisite for achieving cascade utilization or refined recycling. For example, Chinese patent application CN118294516A discloses a device and method for testing the performance of flow battery electrodes under different charge and discharge states, which can autonomously change the SOC state of the electrolyte in the system and realize in-situ monitoring of the electrochemical performance of battery materials under different SOC states. Another example is the energy-saving mobile vanadium redox flow battery testing and evaluation device disclosed in Chinese patent CN202372629U, which integrates the vanadium redox flow battery storage tank, pipeline system, monitoring system and bidirectional converter into a mobile housing, and is equipped with sensors such as flow rate, liquid level and potentiometer to monitor various battery parameters in real time.

[0004] However, most existing technologies involve testing each vanadium redox flow battery stack individually, which is inefficient and cannot meet the recycling industry's need for rapid grading of large batches of stacks. Summary of the Invention

[0005] The core of this invention lies in providing a common electrolyte supply structure (including a positive electrode reservoir, a negative electrode reservoir, a positive electrode main line, and a negative electrode main line) and different output structures (including an independent positive electrode tank and an independent negative electrode tank) for multiple test stacks through an electrolyte supply module. This solves the problem that existing technologies cannot perform batch testing of stacks under the premise of unified testing standards and avoiding cross-contamination. At the same time, flow control tubes are introduced in different branches (including branch A and branch a) to indirectly monitor the electrolyte input flow rate, while also having electrolyte backflow prevention function and abnormal backflow monitoring function.

[0006] To solve the above problems, the present invention adopts the following technical solution.

[0007] A detection device for recycling vanadium redox flow battery stacks includes an electrolyte supply module and a test parameter acquisition module. The electrolyte supply module comprises a positive electrode storage tank, multiple independent positive electrode tanks, a negative electrode storage tank, and multiple independent negative electrode tanks. The positive electrode storage tank is connected to a main positive electrode circuit via an acid-resistant pump. The main positive electrode circuit is connected to the positive electrode inlets of multiple battery stacks under test via multiple branches A. The positive electrode outlet of the battery stack under test is connected to an independent positive electrode tank via branch B. The negative electrode storage tank is connected to a main negative electrode circuit via another acid-resistant pump. The main negative electrode circuit is connected to the negative electrode inlets of multiple battery stacks under test via multiple branches a. The negative electrode outlet of the battery stack under test is connected to an independent negative electrode tank via branch b. A flow meter and a regulating valve are fixedly connected to branches A and a.

[0008] The test parameter acquisition module includes a voltage acquisition unit, a current acquisition unit, a flow control unit, a standard parameter library, and a status assessment unit. The voltage acquisition unit and the current acquisition unit acquire voltage and current data during the stack testing process, respectively. The flow control unit is used to acquire and control the electrolyte flow rate on branch A and branch a. The standard parameter library stores the normal voltage and current data ranges of healthy stacks under different electrolyte flow rates. The status assessment unit is used to compare the voltage or current data of each stack under test during the testing process with the data ranges in the standard parameter library to batch determine the health status of the stacks under test.

[0009] Furthermore, the test parameter acquisition module also includes an electrolyte parameter acquisition unit, which is used to monitor the valence state change of the electrolyte in each branch A and branch a after flowing through the corresponding test stack.

[0010] Furthermore, the flow measuring tube includes a main pipe and a pair of first connector pipes fixedly connected to the main pipe. The ends of the pair of first connector pipes away from the main pipe are fixedly connected to the corresponding branch A or branch a through flanges. A flow meter is fixedly connected inside the main pipe. The flow meter and the regulating valve are both connected to the flow control unit.

[0011] Optionally, a flow control tube can be used instead of a flow measuring tube. The flow control tube includes an inner liquid tube and a pair of second connector tubes that are fixedly connected to the inner liquid tube. The ends of the pair of second connector tubes away from the inner liquid tube are fixedly connected to the corresponding branch A or branch a through flanges. An outer fixed tube and an outer air hood are connected to the inner liquid tube.

[0012] Optionally, the outer fixed tube includes a tube sleeve fixedly sleeved on the outer end of the inner liquid tube. A pair of ring plates and a pair of piston rings are slidably connected between the inner wall of the tube sleeve and the outer end of the inner liquid tube, and the ring plates are located between the pair of piston rings. A connecting rod is fixedly connected between adjacent ring plates and piston rings, and a compression spring is fixedly connected between the piston rings and the inner wall of the tube sleeve.

[0013] Optionally, an arc plate is provided on the inner side of the ring plate. The arc plate is slidably connected to the inside of the inner liquid tube. The central angle corresponding to the arc plate is 210°-270°. The horizontal cross-sections of a pair of arc plates are located on the upper and lower sides of the central axis of the inner liquid tube, respectively. Multiple evenly distributed sliders are fixedly connected between the ring plate and the corresponding arc plate.

[0014] Optionally, a pair of main slides are provided on the cylindrical surface of the inner liquid tube, and the pair of main slides are located directly above and directly below the central axis of the inner liquid tube, respectively. A pair of sliders are slidably connected to the inside of the pair of main slides. Multiple secondary slides are also provided on the cylindrical surface of the inner liquid tube, and the remaining sliders are slidably connected to the inside of the secondary slides at the corresponding positions.

[0015] Optionally, a pressure sensor is fixedly connected to the outer end of the tube. A pair of annular air holes are provided on the tube, and the pair of annular air holes are located on the side of a pair of piston rings away from the connecting rod. Both the annular air holes and the pressure sensor are located inside the outer air cover.

[0016] Optionally, the external air hood includes a pair of semi-circular sleeves fitted on the outside of the tube. A pair of horizontal plates are fixedly connected between the left and right inner walls of the semi-circular sleeves. A semi-circular mesh plate and an elastic membrane layer are fixedly connected between the pair of horizontal plates. In the initial state, the inner surface of the elastic membrane layer is attached to the outer surface of the semi-circular mesh plate. One of the semi-circular sleeves has multiple vent holes that communicate with the outside.

[0017] Optionally, a pair of ring plates are fixedly connected to the outer end of the tube, and a semi-circular sleeve is located between the pair of ring plates, with the ring plates and the semi-circular sleeve connected by multiple bolts.

[0018] Compared with the prior art, the advantages of this invention are:

[0019] (1) This scheme uses a shared positive electrode storage tank and a negative electrode storage tank to provide a standard electrolyte with uniform concentration, valence state, temperature and other states for all the test stacks. The outlet electrolyte of each test stack flows into its corresponding independent positive and negative electrode tanks, which realizes the physical isolation of the electrolyte at the outflow end. This ensures that the electrolyte flowing into the stacks is in a uniform state. While realizing batch and efficient testing of the stacks, it effectively avoids the problems of test result distortion and secondary damage to other stacks caused by cross-contamination of electrolyte.

[0020] (2) A flow control tube is introduced into the branch line. The internal structure is driven to move by the flow pressure to realize the smooth delivery of electrolyte. The movement of the internal structure of the flow control tube will indirectly trigger the data change of the pressure sensor. The flow situation is indirectly reflected by the pressure data, and the flow rate of electrolyte is indirectly measured. At the same time, after the pumping stops, its internal structure can automatically reset and seal the pipeline, effectively reducing the situation of electrolyte flowing back from the stack to the main line due to diffusion, siphon, gravity and other reasons, and protecting the purity of the next batch of stacks to be tested.

[0021] (3) By analyzing the changes in the data of the pressure sensor after the pump stops, it is possible to identify abnormally severe backflow situations, thereby providing early warning of possible faults (such as pump check failure, abnormal gas generation of the fuel cell stack, etc.), further enhancing the reliability of this detection device.

[0022] (4) The flow control tube is detachable both as a whole and in parts. When there is a break in the elastic membrane, sensor failure or corrosion of internal parts, it is convenient to replace the parts, which reduces maintenance costs and improves the long-term availability of the device. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of the electrolyte supply module in the first embodiment of the present invention;

[0024] Figure 2 This is a system block diagram of a first embodiment of the present invention;

[0025] Figure 3 This is a perspective view of the flow measuring tube in the first embodiment of the present invention;

[0026] Figure 4 This is a schematic diagram of the electrolyte supply module in the second embodiment of the present invention;

[0027] Figure 5 This is a perspective view of the flow control tube in the second embodiment of the present invention;

[0028] Figure 6 This is a perspective view of the outer air cover being disassembled from the outer fixed tube in the second embodiment of the present invention;

[0029] Figure 7 This is a schematic diagram of the front structure of the external air cover after installation in the second embodiment of the present invention;

[0030] Figure 8 This is a partial cross-sectional view of the outer fixed pipe in the second embodiment of the present invention;

[0031] Figure 9 This is a schematic diagram of a partial side view of the flow control tube in the second embodiment of the present invention;

[0032] Figure 10 This is a partial perspective view of the outer fixed pipe in the second embodiment of the present invention;

[0033] Figure 11 This is a partial cross-sectional view of the flow control tube in use according to the second embodiment of the present invention;

[0034] Figure 12 This is a partial side view of the flow control tube in use according to the second embodiment of the present invention;

[0035] Figure 13 This is a schematic diagram of a local side structure when electrolyte reflux is severe in the second embodiment of the present invention.

[0036] Explanation of the labels in the diagram:

[0037] 1. Main pipe, 2. First connector pipe, 3. Inner liquid pipe, 301. Main slide, 302. Secondary slide, 4. Second connector pipe, 5. Outer fixed pipe, 51. Tube, 5101. Annular vent area, 52. Ring plate, 53. Connecting rod, 54. Piston ring, 55. Compression spring, 56. Arc plate, 57. Slider, 58. Pressure sensor, 6. Outer hood, 61. Semicircular sleeve, 6101. Vent hole, 62. Horizontal plate, 63. Semicircular mesh plate, 64. Elastic membrane layer. Detailed Implementation

[0038] The technical solutions will now be clearly and completely described with reference to the accompanying drawings in the embodiments of the present invention.

[0039] First implementation method:

[0040] Please see Figure 1 A testing device for recycling vanadium redox flow battery stacks includes an electrolyte supply module and a test parameter acquisition module. The electrolyte supply module includes a positive electrode storage tank, multiple independent positive electrode tanks, a negative electrode storage tank, and multiple independent negative electrode tanks. The positive electrode storage tank is connected to a main positive electrode circuit via an acid-resistant pump. The main positive electrode circuit is connected to the positive electrode inlet of multiple battery stacks under test via multiple branch circuits A. The positive electrode outlet of each battery stack under test is connected to an independent positive electrode tank via a branch circuit B. The negative electrode storage tank is connected to the main negative electrode circuit via another acid-resistant pump. The acid-resistant pump is used to transport the electrolyte. The circuit is connected to the negative electrode inlet of multiple test stacks via multiple branches a. The negative electrode outlet of the test stack is connected to an independent negative electrode tank via branch b. A flow measuring tube and a regulating valve (not shown in the figure) are fixedly connected to both branch A and branch a. The regulating valve is located upstream of the flow measuring tube to facilitate the control of the electrolyte flow rate in the flow measuring tube and its downstream branch A (or branch a). During testing, by controlling the regulating valve, the electrolyte flow rate in branch A and branch a corresponding to the same test stack is made to be close to the same, which helps to maintain the stable redox reaction inside the test stack.

[0041] During testing, the standard positive electrolyte in the positive electrode storage tank is input into multiple test stacks via the main positive electrode circuit and multiple branch circuits A, and the standard negative electrolyte in the negative electrode storage tank is input into multiple test stacks via the main negative electrode circuit and multiple branch circuits a. The electrolyte undergoes a redox reaction in the stack, and the test stack undergoes discharge detection (or charge detection). At the same time, the test parameter acquisition module collects the current or voltage data of the test stack and performs a health assessment. The reacted positive electrolyte flows out to a separate positive electrode tank for storage, and the reacted negative electrolyte flows out to a separate negative electrode tank for storage.

[0042] Unlike existing technologies, this application utilizes a shared positive electrode storage tank and a shared negative electrode storage tank to provide all tested stacks with a standard electrolyte of uniform state (concentration, valence state, temperature, etc.), ensuring consistency in the testing benchmark. In this case, the difference in discharge performance of each stack reflects its own health status, thus achieving batch and efficient testing of the stacks. Since the internal state of each tested stack differs, the electrolyte flowing out after the internal reaction may be contaminated to varying degrees. Therefore, in this application, the outlet electrolyte of each tested stack flows into its corresponding independent positive and negative electrode tanks, achieving physical isolation of the outlet electrolyte. On the one hand, compared to the existing method of returning to the positive / negative electrode storage tank, this application effectively avoids problems such as cross-contamination of electrolyte affecting the test results of other stacks and causing secondary damage to other stacks. On the other hand, when necessary, sampling and analysis of the electrolyte in the independent positive and negative electrode tanks allows for further analysis and evaluation of the stack's health status.

[0043] After the test stack is completed, the ends of branch A, branch B, branch a and branch b can be removed from the test stack. A new batch of test stacks can then be installed between the above pipelines. Of course, before testing the new batch of test stacks, the residual electrolyte in the positive electrode independent tank and the negative electrode independent tank must be cleaned to prevent cross-contamination.

[0044] Please see Figure 2 The test parameter acquisition module includes a voltage acquisition unit, a current acquisition unit, a flow control unit, a standard parameter library, and a state assessment unit. The voltage acquisition unit and the current acquisition unit acquire voltage and current data during the stack testing process, respectively. Specifically: when the stack under test is discharged, under the same testing conditions (e.g., the same standard electrolyte provided in this application, the same ambient temperature, etc.), the actual discharge current of each stack under test is acquired through the current acquisition unit; when the stack under test is charged, under the same testing conditions (e.g., the same standard electrolyte provided in this application, the same external constant current power supply, etc.), the actual charging voltage of each stack under test is acquired through the voltage acquisition unit.

[0045] The flow control unit is used to collect and control the electrolyte flow rate on branch A and branch a, combined with Figure 3 As shown, the flow measuring tube includes a main pipe 1 and a pair of first connector pipes 2 fixedly connected to the main pipe 1. The ends of the pair of first connector pipes 2 away from the main pipe 1 are fixedly connected to the corresponding branch A or branch a through flanges. A flow meter is fixedly connected inside the main pipe 1. The flow meter and the regulating valve are both connected to the flow control unit. The flow meter is used to measure the electrolyte flow rate on the corresponding branch A or branch a and send the flow data to the flow control unit. The flow control unit controls the opening of the regulating valve according to the flow data. On the one hand, this makes it easier to make the electrolyte flow rate on the branch A and branch a corresponding to the same fuel cell stack under test approach the same, making the test data of the fuel cell stack under test more reliable. On the other hand, it can record the real-time collected flow data and obtain the actual voltage / current data of the fuel cell stack under test under different electrolyte flow conditions, which is convenient for judging the health status of the fuel cell stack. In addition, since the first connector pipe 2 is connected to the corresponding branch A / branch a by a flange, when the flow meter in the main pipe 1 malfunctions (such as decreased sensitivity), the flow measuring tube can be disassembled and replaced, thereby effectively improving the accuracy of the detection results. In the electrolyte supply module, all pipelines in contact with the electrolyte (including main pipe 1, first connector pipe 2, positive main line, negative main line, branch A / B / a / b, etc.) are made of corrosion-resistant materials, such as corrosion-resistant metal pipes such as polytetrafluoroethylene composite steel pipes.

[0046] The standard parameter library stores the normal voltage and current data ranges of healthy fuel cells under different electrolyte flow rates. The status assessment unit is used to compare the voltage or current data of each fuel cell under test during the testing process with the data ranges in the standard parameter library to determine the health status of the fuel cells under test in batches.

[0047] During testing, the test parameter acquisition module collects the electrolyte flow rate on branch A and branch a in real time, as well as the actual current / voltage data of each test stack. The actual current / voltage data corresponds one-to-one with the flow rate data at the same moment. The actual current / voltage data at the time of testing is compared with the normal current data range / normal voltage data range under the current test flow rate. When the actual current / voltage data is within the corresponding normal current data range / normal voltage data range, the test stack is preliminarily determined to be healthy. Otherwise, it indicates that the test stack is faulty and may have health problems such as membrane damage, decreased electrode activity, or flow channel blockage.

[0048] It should be noted that the aforementioned performance health does not refer to the stack being intact, but rather to the stack remaining in an acceptable normal operating state under a given electrolyte flow rate. Stacks judged to be in performance health can be used continuously, while stacks judged to have performance failures can be selectively repaired, disassembled, or recycled based on the absolute value of the difference between the actual current / voltage data and the normal current / voltage data range. For example, when the absolute value of the difference between the actual current / voltage data and the normal current / voltage data range is less than a preset allowable value, the stack under test can be classified as needing repair; when the absolute value of the difference is greater than the preset allowable value, it indicates that the stack under test has suffered severe performance degradation and can be classified as needing disassembly and recycling. This application achieves a health status classification of stacks under test based on the degree of performance degradation, determining whether they are suitable for continuous use, repair, or disassembly and recycling. This provides a rapid and effective reference basis for the utilization value of batch stacks on the recycling production line, greatly improving the batch processing efficiency of recycled stacks.

[0049] The test parameter acquisition module also includes an electrolyte parameter acquisition unit. This unit monitors the valence state change of the electrolyte in each branch A and branch a after it flows through the corresponding battery stack under test. After the battery stack under test undergoes a test (charge test or discharge test), the positive and negative electrolytes flowing out of the battery stack under test are collected in the positive and negative independent tanks, respectively. At this time, the operator can selectively take out a small amount of positive and negative electrolytes and test them (the testing methods include ultraviolet-visible spectroscopy analysis, SPR spectroscopy analysis, etc.). Combined with current / voltage data and electrolyte composition data, the battery health status can be further determined.

[0050] In addition, if more accurate test data is needed, reverse testing can be performed on the fuel cell stack (if the first test is a discharge test, then the reverse test is a charge test; if the first test is a charge test, then the reverse test is a discharge test). By combining the voltage / current data from the two tests, a deeper and more accurate judgment can be made on the health status of the fuel cell stack. For example, only when both test results are judged to be in good working order can the fuel cell stack under test be classified as a continuous-use type.

[0051] Second implementation method:

[0052] This embodiment, based on the first embodiment, uses a flow control tube instead of a flow measuring tube, while maintaining the same structure as the first embodiment. The flow control tube in this embodiment, while fulfilling the flow monitoring function of the first embodiment, also provides an electrolyte backflow prevention function. For details, please refer to [link to relevant documentation]. Figure 4 and Figure 5The flow control tube includes an inner liquid tube 3 and a pair of second connector tubes 4 that are fixedly connected to the inner liquid tube 3. The inner liquid tube 3 and the second connector tubes 4 are made of the same material as the flow measuring tube. The ends of the pair of second connector tubes 4 that are away from the inner liquid tube 3 are fixedly connected to the corresponding branch A or branch a through flanges. An outer fixed tube 5 and an outer air cover 6 are connected to the inner liquid tube 3.

[0053] Please see Figure 6 , Figure 8 and Figure 9 The outer fixed tube 5 includes a tube 51 fixedly sleeved on the outer end of the inner liquid tube 3. A pair of ring plates 52 and a pair of piston rings 54 are slidably connected between the inner wall of the tube 51 and the outer end of the inner liquid tube 3, and the ring plates 52 are located between the pair of piston rings 54. A connecting rod 53 is fixedly connected between adjacent ring plates 52 and piston rings 54. A compression spring 55 is fixedly connected between the piston rings 54 and the inner wall of the tube 51. The piston rings 54 and the outer end of the inner liquid tube 3, and the piston rings 54 and the inner wall of the tube 51 are in a sliding sealing state of surface contact, so that the area where the compression spring 55 is located is a closed space.

[0054] Please see Figure 9 and Figure 10 An arc plate 56 is provided on the inner side of the ring plate 52. The arc plate 56 is slidably connected to the inside of the inner liquid tube 3. The central angle corresponding to the arc plate 56 is 210°-270°. The horizontal cross-sections of a pair of arc plates 56 are located on the upper and lower sides of the central axis of the inner liquid tube 3, respectively. Multiple evenly distributed sliders 57 are fixedly connected between the ring plate 52 and the corresponding arc plate 56.

[0055] Please see Figure 8 and Figure 9A pair of main slides 301 are provided on the cylindrical surface of the inner liquid pipe 3, and the pair of main slides 301 are located directly above and directly below the central axis of the inner liquid pipe 3, respectively. A pair of sliders 57 are slidably connected to the inside of the pair of main slides 301. In the initial state, the pair of curved plates 56 are in close contact with each other, forming a surface contact seal. At this time, this area inside the inner liquid pipe 3 is blocked, and the pair of sliders 57 are tightly attached to the inner walls of the pair of main slides 301. Even under the action of external force, the right curved plate 56 cannot move to the left, and the left curved plate 56 cannot move to the right. At the same time, the pressure... The compression spring 55 is in a moderately compressed state, which provides elastic compression to the fixed structure formed by the piston ring 54, connecting rod 53, ring plate 52, slider 57 and arc plate 56, making the fit between the pair of arc plates 56 more stable; when the pair of arc plates 56 separate, they lose their sealing effect on the inside of the inner liquid tube 3; multiple secondary slides 302 are also provided on the cylindrical surface of the inner liquid tube 3, and the remaining sliders 57 are slidably connected to the corresponding positions of the secondary slides 302. Through the connection and sliding of multiple sliders 57, the connection between the arc plate 56 and the ring plate 52 and their synchronous sliding can be made more stable.

[0056] Please see Figure 9 A pressure sensor 58 is fixedly connected to the outer end of the tube 51. The pressure sensor 58 is used to collect the air pressure in the space where it is located and send the air pressure data to the flow control unit. A pair of annular air hole areas 5101 are opened on the tube 51 (that is, multiple air holes are distributed in an annular pattern on the tube 51). The pair of annular air hole areas 5101 are located on the side of a pair of piston rings 54 away from the connecting rod 53. The annular air hole areas 5101 and the pressure sensor 58 are both located inside the outer air cover 6. The annular air hole area 5101 is used to connect the area where the compression spring 55 is located with the inner area of ​​the elastic diaphragm layer 64.

[0057] Please see Figure 6 and Figure 7 The outer air cover 6 includes a pair of semi-circular sleeves 61 sleeved on the outside of the tube 51. A pair of horizontal plates 62 are fixedly connected between the left and right inner walls of the semi-circular sleeves 61. A semi-circular mesh plate 63 and an elastic membrane layer 64 are fixedly connected between the pair of horizontal plates 62. In the initial state, the inner surface of the elastic membrane layer 64 is attached to the outer surface of the semi-circular mesh plate 63. When the pair of semi-circular sleeves 61 form a cylindrical structure, the horizontal plates 62 inside are attached to each other to form a surface contact seal. The left and right edges of the elastic membrane layer 64 are fixedly connected to the left and right inner walls of the semi-circular sleeves 61, thereby forming a closed area between the semi-circular sleeves 61, the horizontal plates 62, the elastic membrane layer 64 and the outer wall of the tube 51 (without considering the annular vent area 5101). Through the setting of the annular vent area 5101, the closed area is connected to the closed area where the compression spring 55 is located.

[0058] One of the semicircular sleeves 61 has multiple vent holes 6101 on its inner wall that communicate with the outside. The vent holes 6101 are used to maintain the air pressure balance between the outer space of the elastic membrane layer 64 and the outside, so as to facilitate the expansion of the elastic membrane layer 64. A pair of ring plates are fixedly connected to the outer end of the tube 51. The semicircular sleeve 61 is located between the pair of ring plates, and the ring plates and the semicircular sleeve 61 are connected by multiple bolts. The structures in the outer fixed tube 5 and the outer air cover 6 that come into contact with the electrolyte (including but not limited to the tube 51, ring plate 52, connecting rod 53, piston ring 54, arc plate 56, slider 57, etc.) are all made of corrosion-resistant materials, such as corrosion-resistant alloys.

[0059] In the first embodiment, the positive and negative electrode storage tanks simultaneously provide electrolyte in a uniform state to multiple test stacks. These test stacks share the main positive and negative electrode circuits. When pumping stops, due to factors such as diffusion, siphoning, and gravity backflow, the electrolyte in the stack may flow back into branch A / branch a, thus contaminating the main positive or negative electrode circuit. This can easily affect the test results of the next batch of test stacks and damage their health status. Therefore, based on the above practical problems, this embodiment uses a flow control tube instead of a flow measuring tube. This achieves indirect monitoring of the flow rate in the branch and simultaneously prevents electrolyte backflow. The specific principle is as follows:

[0060] Indirect flow monitoring process: Please refer to Figure 11 and Figure 12 During the fuel cell stack testing process, when the electrolyte enters branches A and a, due to the pumping pressure, the electrolyte enters the inner liquid pipe 3 and impacts the arc plate 56. This causes the second arc plate 56, located in the electrolyte flow direction, to flow with the electrolyte and separate from the first arc plate 56 (the first arc plate 56 is limited by the main slide 301 and cannot flow with the electrolyte). The electrolyte passes between the pair of arc plates 56 and smoothly enters the fuel cell stack under test, thus realizing the fuel cell stack testing process. At the same time, the movement of the arc plate 56 will drive the connected slider 57, ring plate 52, and connecting rod. 53 and piston ring 54 move synchronously, further compressing the adjacent compression spring 55. The space where the compression spring 55 is located decreases, and excess gas in this space enters the inner side of the elastic membrane layer 64 through the corresponding annular vent area 5101, causing the elastic membrane layer 64 to expand outward. The gas pressure data monitored by the pressure sensor 58 increases. The longer the moving distance of the arc plate 56, the larger the opening between the pair of arc plates 56, and the greater the flow rate of the electrolyte. The gas pressure data detected by the pressure sensor 58 also increases. Therefore, the flow rate of the electrolyte can be indirectly determined through the gas pressure data of the pressure sensor 58.

[0061] It should be noted that the standard parameter library also stores the air pressure data of the air pressure sensor 58 under different flow conditions. This data is obtained in advance by those skilled in the art through experiments. The acquisition method includes: installing the flow control pipe and the flow meter in a pipeline at the same time, with the flow meter located downstream of the flow control pipe, changing the fluid rate in the pipeline, acquiring the flow data collected by the flow meter and the air pressure data collected by the air pressure sensor 58 at the same time, and grouping them into one set of data to obtain multiple sets of data: flow rate Q1 and air pressure P1, flow rate Q2 and air pressure P2, flow rate Q3 and air pressure P3... flow rate Qn and air pressure Pn; using the above data, the flow rate data can be indirectly obtained based on the actual air pressure data of the air pressure sensor 58 during the fuel cell stack detection process of this embodiment.

[0062] Anti-backflow principle: When the pumping of electrolyte stops, due to the loss of pumping pressure, the displaced arc plate 56 will quickly return to its initial position under the elastic recovery of the compression spring 55, and re-fit tightly with the previous arc plate 56, restoring the sealing effect on the inner liquid pipe 3. When electrolyte backflow occurs, the backflow force is small and insufficient to cause further deformation of the compression spring 55. Therefore, the pair of arc plates 56 can remain in contact, achieving the anti-backflow effect of electrolyte. It should be noted that the selection of the compression spring 55 and the initial compression degree can be set according to the backflow degree of electrolyte under normal circumstances, so that under normal circumstances, the backflow force of electrolyte is much less than the elastic potential energy of the compression spring 55, which is insufficient to push the arc plate 56 to move.

[0063] Furthermore, while the flow control tube performs its normal backflow prevention function, it also activates the function of monitoring abnormal backflow. If, after pumping stops, the air pressure data of the air pressure sensor 58 first decreases and then increases, the initial decrease is a normal data change during the retraction process of the arc plate 56 after pumping stops. The subsequent increase indicates the possibility of severe backflow in the inner liquid pipe 3, that is: Figure 13 As shown, the backflowing electrolyte pushes the arc plate 56 to move, causing an increase in air pressure inside the elastic membrane layer 64. This is an abnormal situation, indicating that there may be some unexpected events during the testing process. For example, the electrolyte may generate gas (such as hydrogen) during operation, pushing the electrolyte backflow; or the acid-resistant pump may be faulty, and its check function may fail, leading to electrolyte backflow. Therefore, after stopping the pump, the change in air pressure data by the air pressure sensor 58 can effectively determine the severity of electrolyte backflow, thereby promptly detecting unexpected faults during the testing process. This allows staff to further check and confirm any possible unexpected situations, thus minimizing the impact on subsequent fuel cell stack testing.

[0064] In this embodiment, the outer air cover 6 and the outer fixed pipe 5 are connected by detachable bolts. When the structure of the outer air cover 6 is damaged (such as the elastic membrane layer 64 is broken), a new outer air cover 6 can be replaced. In this embodiment, the second connector pipe 4 and the corresponding branch A / branch a are also detachably connected. However, when the structure of the outer fixed pipe 5 is damaged (such as the air pressure sensor 58 is faulty or its sensitivity is reduced, the elasticity of the compression spring 55 is reduced, or the arc plate 56 is corroded due to long-term immersion in electrolyte), the flange on the second connector pipe 4 can be removed, and a new inner liquid pipe 3, second connector pipe 4, and outer fixed pipe 5 can be replaced, thereby effectively ensuring the accuracy of the test results.

[0065] The above description is merely a preferred embodiment of the present invention; it encompasses all the protection scope of the present invention. Any equivalent substitutions or modifications made by those skilled in the art within the technical scope disclosed in the present invention, based on the technical solutions and improved concepts of the present invention, should be covered within the protection scope of the present invention.

Claims

1. A testing device for recycling a vanadium redox flow battery stack, comprising an electrolyte supply module and a test parameter acquisition module, characterized in that: The electrolyte supply module includes a positive electrode storage tank, multiple independent positive electrode tanks, a negative electrode storage tank, and multiple independent negative electrode tanks. The positive electrode storage tank is connected to a positive electrode main line via an acid-resistant pump. The positive electrode main line is connected to the positive electrode inlet of multiple test stacks via multiple branches A. The positive electrode outlet of each test stack is connected to an independent positive electrode tank via branch B. The negative electrode storage tank is connected to a negative electrode main line via another acid-resistant pump. The negative electrode main line is connected to the negative electrode inlet of multiple test stacks via multiple branches a. The negative electrode outlet of each test stack is connected to an independent negative electrode tank via branch b. Flow measuring tubes and regulating valves are fixedly connected to branches A and a. The test parameter acquisition module includes a voltage acquisition unit, a current acquisition unit, a flow control unit, a standard parameter library, and a status assessment unit. The voltage acquisition unit and the current acquisition unit acquire voltage and current data during the stack testing process, respectively. The flow control unit is used to acquire and control the electrolyte flow rate on branch A and branch a. The standard parameter library stores the normal voltage and current data ranges of healthy stacks under different electrolyte flow rates. The status assessment unit is used to compare the voltage or current data of each stack under test during the testing process with the data ranges in the standard parameter library to batch determine the health status of the stacks under test.

2. The detection device for recycling a vanadium redox flow battery stack according to claim 1, characterized in that: The test parameter acquisition module also includes an electrolyte parameter acquisition unit, which is used to monitor the valence state change of the electrolyte in each branch A and branch a after flowing through the corresponding test stack.

3. The detection device for recycling a vanadium redox flow battery stack according to claim 1, characterized in that: The flow measuring tube includes a main pipe (1) and a pair of first connector pipes (2) fixedly connected to the main pipe (1). The ends of the pair of first connector pipes (2) away from the main pipe (1) are fixedly connected to the corresponding branch A or branch a through flanges. A flow meter is fixedly connected inside the main pipe (1). The flow meter and the regulating valve are both connected to the flow control unit.

4. The detection device for recycling a vanadium redox flow battery stack according to claim 1, characterized in that: The flow control tube is used instead of the flow measuring tube. The flow control tube includes an inner liquid tube (3) and a pair of second connector tubes (4) that are fixedly connected to the inner liquid tube (3). The ends of the pair of second connector tubes (4) that are away from the inner liquid tube (3) are fixedly connected to the corresponding branch A or branch a through flanges. An outer fixed tube (5) and an outer air hood (6) are connected to the inner liquid tube (3).

5. The detection device for recycling a vanadium redox flow battery stack according to claim 4, characterized in that: The outer fixed tube (5) includes a tube sleeve (51) fixedly sleeved on the outer end of the inner liquid tube (3). A pair of ring plates (52) and a pair of piston rings (54) are slidably connected between the inner wall of the tube sleeve (51) and the outer end of the inner liquid tube (3). The ring plates (52) are located between the pair of piston rings (54). A connecting rod (53) is fixedly connected between adjacent ring plates (52) and piston rings (54). A compression spring (55) is fixedly connected between the piston rings (54) and the inner wall of the tube sleeve (51).

6. The detection device for recycling a vanadium redox flow battery stack according to claim 5, characterized in that: The inner side of the ring plate (52) is provided with an arc plate (56), which is slidably connected to the inside of the inner liquid tube (3). The central angle corresponding to the arc plate (56) is 210°-270°, and the horizontal cross-sections of a pair of arc plates (56) are located on the upper and lower sides of the central axis of the inner liquid tube (3). Multiple evenly distributed sliders (57) are fixedly connected between the ring plate (52) and the corresponding arc plate (56).

7. The detection device for recycling a vanadium redox flow battery stack according to claim 6, characterized in that: The inner liquid tube (3) has a pair of main slides (301) on its cylindrical surface, and the pair of main slides (301) are located on the upper and lower sides of the central axis of the inner liquid tube (3), respectively. The pair of sliders (57) are slidably connected to the inside of the pair of main slides (301). The inner liquid tube (3) also has a plurality of secondary slides (302) on its cylindrical surface, and the remaining sliders (57) are slidably connected to the inside of the secondary slides (302) at the corresponding positions.

8. The detection device for recycling a vanadium redox flow battery stack according to claim 7, characterized in that: A pressure sensor (58) is fixedly connected to the outer end of the tube (51). A pair of annular air holes (5101) are provided on the tube (51), and the pair of annular air holes (5101) are located on the side of a pair of piston rings (54) away from the connecting rod (53). The annular air holes (5101) and the pressure sensor (58) are both located inside the outer air cover (6).

9. A detection device for recycling a vanadium redox flow battery stack according to claim 8, characterized in that: The external air hood (6) includes a pair of semi-circular sleeves (61) sleeved on the outside of the tube (51). A pair of horizontal plates (62) are fixedly connected between the left and right inner walls of the semi-circular sleeves (61). A semi-circular mesh plate (63) and an elastic membrane layer (64) are fixedly connected between the pair of horizontal plates (62). In the initial state, the inner surface of the elastic membrane layer (64) is attached to the outer surface of the semi-circular mesh plate (63). The inner wall of one of the semi-circular sleeves (61) is provided with a plurality of air release holes (6101) communicating with the outside.

10. A detection device for recycling a vanadium redox flow battery stack according to claim 9, characterized in that: The outer end of the tube (51) is fixedly connected to a pair of ring plates, and the semi-circular sleeve (61) is located between the pair of ring plates. The ring plates and the semi-circular sleeve (61) are connected by multiple bolts.

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