A flow battery planned shutdown recovery system and method
The flow battery planned shutdown recovery system, with its modular design and intelligent control, solves the problems of self-discharge and electrolyte damage during shutdown, achieving efficient electrolyte recovery and improved system stability.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2025-10-30
- Publication Date
- 2026-07-31
AI Technical Summary
When flow batteries are shut down for a planned long period of time, there are problems such as energy loss due to self-discharge reaction, hydrogen evolution reaction caused by electrolyte concentration gradient and damage to ion membrane. Existing technologies have not been able to effectively solve the problem of active reflux control of electrolyte and have high energy consumption costs.
The flow battery planned shutdown recovery system, which adopts modular design and intelligent control, includes a branched topology and a BMS battery management system. Through high-precision flow sensors and timing control modules, it achieves accurate electrolyte recovery and reduces system losses.
It achieves efficient electrolyte recovery, reduces system losses and ion membrane damage, improves the stability and lifespan of flow batteries, and reduces energy consumption and the risk of human intervention.
Smart Images
Figure CN121416536B_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of flow battery shutdown disposal technology, specifically to a flow battery planned shutdown recovery system and method. Background Technology
[0002] Flow batteries (such as vanadium redox flow batteries and aqueous organic flow batteries) require frequent planned long-term shutdowns in scenarios such as smart grid peak shaving and renewable energy grid-connected energy storage. During shutdowns, the stack and piping system form a closed loop, and the residual electrolyte continuously undergoes self-discharge reactions, resulting in energy loss (daily self-discharge rate can reach 3%-5%). Static electrolyte generates a concentration gradient within the stack, and when the hydrogen evolution overpotential is below 0.3V, it can easily trigger a local hydrogen evolution reaction. Imbalance in ion concentration across the ion exchange membrane leads to membrane structure damage (the annual growth rate of membrane surface resistance exceeds 15%).
[0003] Currently, patent CN201810569342.X discloses a method for protecting a flow battery during shutdown, but it does not involve active electrolyte reflux control; US patent US20200321842A1 proposes an electrolyte circulation scheme during shutdown, but it has high energy consumption and cost. Summary of the Invention
[0004] To address existing problems, this invention provides a planned shutdown recovery system and method for flow batteries. Through the organic combination of modular design and intelligent control, it achieves precise control over the entire shutdown process of the flow battery. Its branched recovery structure and phased control strategy ensure electrolyte recovery efficiency while minimizing system losses and ion membrane damage, providing key technical support for the long-term stable operation of flow batteries. From an engineering application perspective, the system's design concept meets the comprehensive requirements of large-scale energy storage systems for safety, reliability, and economy. The parameter optimization logic of its control algorithm can provide a reference paradigm for the design of shutdown control systems for similar energy storage devices.
[0005] To achieve the above objectives, the present invention provides the following technical solution.
[0006] This invention provides a planned shutdown and recycling system for a flow battery, comprising a main circulation system, an electrolyte recycling system, and a battery management system (BMS). The main circulation system includes a positive electrode main pump, a negative electrode main pump, a positive electrode main pipeline, a negative electrode main pipeline, and a battery stack, used for charging and discharging the flow battery. The electrolyte recycling system adopts a branched topology, including a first branch pipeline branched onto the positive electrode main pipeline, a second branch pipeline branched onto the negative electrode main pipeline, a positive electrode pump, a negative electrode pump, a first flow meter, a second flow meter, a first independent recycling pipeline, and a second independent recycling pipeline. The system includes a recovery pipeline; the positive electrode main pipeline is connected to the inlet of the positive electrode pump via a first branch pipeline, and the outlet of the positive electrode pump is connected to the positive electrode storage tank via a first independent recovery pipeline, with a first flow meter installed on the first branch pipeline; the negative electrode main pipeline is connected to the inlet of the negative electrode pump via a second branch pipeline, and the outlet of the negative electrode pump is connected to the negative electrode storage tank via a second independent recovery pipeline, with a second flow meter installed on the second branch pipeline; the BMS battery management system is electrically connected to the main circulation system and the electrolyte recovery system respectively, and is used to control the electrolyte recovery during shutdown.
[0007] As a further improvement of the present invention, the BMS battery management system includes an MCU, a flow rate monitoring module, a timing control module, and a frequency conversion control module; the flow rate monitoring module adopts a high-precision flow sensor with a sampling frequency of not less than 10Hz, and its signal output is connected to the MCU through analog-to-digital conversion.
[0008] As a further improvement of the present invention, the timing control module includes: a shutdown detection unit, which identifies the moment when the battery voltage drops to a preset lower limit; a delayed start unit, which starts recycling after a delay of 0-30 seconds adjustable after shutdown; and a cutoff timing unit, which automatically terminates the process after the accumulated recycling time reaches the set value of the residual removal time.
[0009] As a further improvement of the present invention, the residual removal time T of the timing control module is calculated by the following formula: T = (total volume of the fuel cell stack × 0.1) / 0.1m 3 / h and below, where the total volume of the fuel cell stack is the maximum capacity of the electrolyte inside the fuel cell stack, and 0.1 is the residual coefficient.
[0010] As a further improvement of the present invention, the electrolyte recovery system further includes: a two-way valve, respectively installed at the outlet of the positive electrode pump and the outlet of the negative electrode pump, for controlling the flow of electrolyte to the stack or the electrolyte recovery tank; and a pressure sensor installed on the first branch pipe, the second branch pipe, the first independent recovery pipe and the second independent recovery pipe to monitor changes in pipeline pressure and prevent leakage.
[0011] As a further improvement of the present invention, the electrolyte recovery system further includes: a nitrogen storage tank, a nitrogen injection pipeline and a nitrogen flow valve disposed on the nitrogen injection pipeline, a nitrogen discharge pipeline and a nitrogen discharge valve disposed on the nitrogen discharge pipeline; the nitrogen injection pipeline and the nitrogen discharge pipeline are both connected to the fuel cell stack.
[0012] As a further improvement of the present invention, the operating frequency range of the positive electrode pump and the negative electrode pump is 0-45Hz.
[0013] This invention also provides a method for planned shutdown and recycling of a flow battery, comprising the following steps: detecting charge / discharge status signals or determining whether a preset shutdown time has been reached; triggering the shutdown of the main circulation system, shutting down the positive and negative main pumps; activating the electrolyte recycling system, starting the positive and negative small pumps; real-time monitoring of the electrolyte flow rate in the first and second independent recycling pipes; and determining when the flow rates in both the first and second branch pipes drop to a preset threshold of 0.1 m. 3 When the speed is / h or less, wait for the preset delay, and then start the residual cleaning based on the fuel cell volume parameters; after the residual cleaning time is over, shut down the electrolyte recovery system; and perform pre-start frequency conversion control before the preset start time.
[0014] As a further improvement of the present invention, the pre-start frequency conversion control performed before the preset start-up time includes the following steps: starting the positive main pump and the negative main pump at a frequency of 20Hz 3 minutes before the preset start-up time; increasing the frequency of the main pump to 45Hz at a frequency increase rate of 0.2Hz / s.
[0015] As a further improvement of the present invention, the activation of the electrolyte recovery system and the starting of the positive electrode pump and the negative electrode pump include the following steps: opening the nitrogen flow valve and introducing nitrogen from the nitrogen tank into the fuel cell stack to balance the negative pressure.
[0016] Compared with the prior art, the present invention has the following beneficial effects: This recycling system achieves efficient electrolyte recovery through a branched topology, with a decoupled design between the main circulation system and the electrolyte recovery system. Integrated control by the BMS enhances system automation and reduces the risk of manual intervention. By designing a flow battery planned shutdown recycling system that includes a main circulation system, a branched topology electrolyte recovery system, and a BMS battery management system, effective electrolyte recovery is achieved during planned shutdowns of the flow battery. The branched topology electrolyte recovery system allows for more precise control of the positive and negative electrode electrolyte recovery process. The BMS battery management system monitors and controls both the main circulation system and the electrolyte recovery system, improving the overall stability and reliability of the system, reducing the impact of electrolyte residue on battery performance, and extending battery life.
[0017] Preferably, a flow sensor with a sampling frequency of 10Hz combined with analog-to-digital conversion technology ensures the accuracy of electrolyte residue detection and significantly reduces the electrolyte residue rate after shutdown. The high-precision flow sensor ensures the accuracy of the measurement data, and the higher sampling frequency can capture flow rate changes in real time, providing more reliable data support for the BMS battery management system, so as to more accurately control the electrolyte recovery process and improve recovery efficiency and system performance.
[0018] Preferably, the shutdown detection unit can accurately identify the moment when the battery voltage drops to the preset lower limit, providing an accurate timing for subsequent operations; the delayed start unit (adjustable from 0 to 30 seconds) avoids pipeline pressure shocks caused by instantaneous shutdown; the cutoff timing unit automatically terminates the process after the accumulated recycling time reaches the set value of the residual removal time, realizing the automation and precise control of the recycling process, preventing over-recycling or under-recycling, and improving the recycling effect and system safety.
[0019] Preferably, the formula for residual removal time is (T = total volume of fuel cell stack × 0.1 / 0.1m). 3 / h) enables dynamic adaptation to different battery stack specifications, improving residual removal efficiency; this quantitative calculation method makes the setting of residual removal time more scientific and reasonable, avoiding the arbitrariness of manual setting, ensuring that residual electrolyte can be effectively removed under different battery stack volume conditions, improving recycling efficiency and battery performance.
[0020] Preferably, the bidirectional valve is linked with the pressure sensor, which can flexibly control the flow of electrolyte to the fuel cell stack or electrolyte recovery tank to meet the needs of different working conditions; the pressure sensor is installed on each pipeline to monitor pipeline pressure changes in real time, detect and prevent leakage problems in time, ensure the safe and stable operation of the system, and reduce electrolyte loss and potential environmental hazards caused by leakage.
[0021] Preferably, the nitrogen injection pipeline balances the negative pressure, and also avoids problems caused by negative pressure, such as affecting the flow of electrolyte and damaging equipment, thereby further improving the stability and safety of the recovery process and ensuring the normal operation of the system; at the same time, it prevents the electrolyte from oxidizing and deteriorating, and extends the electrolyte life.
[0022] Preferably, the 0-45Hz wideband adjustment extends the flow rate range of the small pump to 0.01-0.5m³ / h. 3 / h, adaptable to electrolytes of different viscosities, reducing energy consumption; under different recovery conditions, by adjusting the operating frequency, the electrolyte suction speed can be precisely controlled, improving recovery efficiency, while avoiding equipment damage or poor recovery effect caused by excessively high or low frequencies.
[0023] The recycling method triggers the main circulation system to shut down by detecting charge / discharge status signals or a preset shutdown time. It then activates the electrolyte recycling system, monitors the flow rate in real time, and controls the recycling process based on flow rate changes and preset parameters. Finally, after the residual removal time is completed, the recycling system is shut down, and pre-start frequency conversion control is executed before the preset start-up time. This method automates and standardizes the recycling process, improves recycling efficiency and battery restart performance, and reduces the risks associated with human intervention and operational errors.
[0024] Preferably, the main circulation system is shut down by detecting the charge / discharge status signal or a preset shutdown time. Then, the electrolyte recovery system is activated, and the flow rate is monitored in real time. The recovery process is controlled based on flow rate changes and preset parameters. Finally, after the residual removal time is completed, the recovery system is shut down, and pre-start frequency conversion control is performed before the preset start-up time. This method automates and standardizes the recovery process, improves recovery efficiency and battery restart performance, and reduces the risks associated with human intervention and operational errors.
[0025] Preferably, when activating the electrolyte recovery system, the nitrogen flow valve is opened to introduce nitrogen from the nitrogen tank into the fuel cell stack to balance the negative pressure. This step effectively solves the negative pressure problem that may occur in the fuel cell stack during the recovery process, ensuring that the electrolyte can be smoothly extracted from the fuel cell stack, improving the smoothness and efficiency of electrolyte recovery, and avoiding recovery interruptions or equipment damage caused by negative pressure. Attached Figure Description
[0026] The accompanying drawings described herein are for illustrative purposes only and are not intended to limit the scope of the invention in any way. Furthermore, the shapes and proportions of the components in the drawings are merely schematic to aid in understanding the invention and are not intended to specifically limit the shapes and proportions of the components. In the drawings: Figure 1 This is a schematic diagram of a flow battery planned shutdown recovery system in Example 1; Figure 2 This is a schematic diagram of the BMS battery management system in Example 1; Figure 3 This is a schematic diagram of the steps in a planned shutdown and recycling method for a flow battery in Example 1.
[0027] The components include: 1. Positive electrode main pump; 2. Negative electrode main pump; 3. Positive electrode liquid extraction pump; 4. Negative electrode liquid extraction pump; 5. First flow meter; 6. Second flow meter; 7. Fuel cell stack; 8. Battery Management System (BMS); 9. First bidirectional valve; 10. Second bidirectional valve; 11. First pressure sensor; 12. Second pressure sensor; 13. Third pressure sensor; 14. Fourth pressure sensor; 15. Nitrogen flow valve; 16. Nitrogen discharge valve; 17. Nitrogen storage tank; 18. Positive electrode electrolyte storage tank; 19. Negative electrode electrolyte storage tank; 20. Positive electrode electrolyte recovery tank; 21. Negative electrode electrolyte recovery tank; 22. Third flow meter; 23. Fourth flow meter; 24. First storage tank valve; 25. Second storage tank valve. Detailed Implementation
[0028] To enable those skilled in the art to better understand the technical solutions of this invention, the technical solutions of the embodiments of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this invention, and not all embodiments. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of this invention.
[0029] It should be noted that when an element is referred to as being "set on" another element, it can be directly on the other element or there may be an intervening element. When an element is referred to as being "connected to" another element, it can be directly connected to the other element or there may be an intervening element. The terms "vertical," "horizontal," "left," "right," and similar expressions used herein are for illustrative purposes only and do not represent the only embodiments.
[0030] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the description of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.
[0031] Example 1 like Figure 1 As shown, this embodiment provides a flow battery planned shutdown recovery system, a main circulation system, an electrolyte recovery system, and a BMS battery management system 8.
[0032] The main circulation system includes a positive electrode main pump 1, a negative electrode main pump 2, a positive electrode main pipeline, a negative electrode main pipeline, and a fuel cell stack 7; the electrolyte recovery system adopts a branched topology, including a first branch pipeline branched onto the positive electrode main pipeline, a second branch pipeline branched onto the negative electrode main pipeline, a positive electrode pump 3, a negative electrode pump 4, a first flow meter 5, a second flow meter 6, a first independent recovery pipeline, a second independent recovery pipeline, a nitrogen storage tank 17, a nitrogen injection pipeline, a nitrogen flow valve 15 installed on the nitrogen injection pipeline, a nitrogen discharge pipeline, and a nitrogen discharge valve installed on the nitrogen discharge pipeline. The system includes a nitrogen discharge valve 16, a two-way valve, and a pressure sensor; both the nitrogen injection pipe and the nitrogen discharge pipe are connected to the fuel cell stack 7; the positive electrode main pipe is connected to the inlet of the positive electrode pump 3 via a first branch pipe, and a first flow meter 5 is installed on the first branch pipe; the negative electrode main pipe is connected to the inlet of the negative electrode pump 4 via a second branch pipe, and a second flow meter 6 is installed on the second branch pipe; the outlet of the positive electrode pump 3 is connected to the positive electrode storage tank via a first independent recovery pipe, and the outlet of the negative electrode pump 4 is connected to the negative electrode storage tank via a second independent recovery pipe.
[0033] Optionally, a third flow meter 22 and a first storage tank valve 24 are installed on the positive main pipeline, and a fourth flow meter 23 and a second storage tank valve 25 are installed on the negative main pipeline.
[0034] The first pressure sensor 11 and the second pressure sensor 12 are installed in the first branch pipe and the second branch pipe to monitor changes in pipeline pressure and prevent leaks.
[0035] Preferably, a third pressure sensor 13 is installed on the first independent recovery pipeline to monitor the pressure flowing to the positive electrode electrolyte recovery tank 20; a fourth pressure sensor 14 is installed on the second independent recovery pipeline to monitor the pressure flowing to the negative electrode electrolyte recovery tank 21.
[0036] Two-way valves are respectively installed at the outlet of the positive electrode pump 3 and the outlet of the negative electrode pump 4 to control the flow of electrolyte to the fuel cell stack 7 or the electrolyte recovery tank. Specifically, the first two-way valve 9 controls the flow of positive electrode electrolyte to the positive electrode electrolyte recovery tank 20 or the positive electrode electrolyte storage tank 18, and the second two-way valve 10 controls the flow of negative electrode electrolyte to the negative electrode electrolyte recovery tank 21 or the negative electrode electrolyte storage tank 19.
[0037] Taking the positive electrode side as an example, the valve control principle of this embodiment is as follows: When recovering electrolyte, the first storage tank valve 24 is closed and the first bidirectional valve 9 is opened. At this time, the nitrogen flow valve 15 is opened, and nitrogen flows from the nitrogen storage tank 17 to the fuel cell stack 7. The positive electrode electrolyte in the fuel cell stack 7 flows through the positive electrode main pipe to the first branch pipe, and then flows into the positive electrode electrolyte recovery tank 20 until the positive electrode electrolyte in the fuel cell stack 7 is emptied. At this time, both the nitrogen flow valve 15 and the first bidirectional valve 9 are closed. When restarting, both the nitrogen discharge valve 16 and the first bidirectional valve 9 are opened until all the positive electrode electrolyte flows back to the fuel cell stack 7 from the positive electrode electrolyte recovery tank 20. At this time, both the nitrogen discharge valve 16 and the first bidirectional valve 9 are closed, and the first storage tank valve 24 is opened.
[0038] like Figure 2 As shown, the BMS battery management system 8 includes an MCU, a flow rate monitoring module, a timing control module, and a frequency conversion control module; the BMS battery management system 8 is electrically connected to the main circulation system and the electrolyte recovery system, respectively.
[0039] As the control core of the entire system, the BMS (Battery Management System) integrates a flow rate monitoring module, a timing control module, and a frequency conversion control module. It has core functions such as signal acquisition, command parsing and execution, and pump operation status adjustment. Through frequency conversion technology, it achieves precise control of the pump speed, ensuring the timing coordination and parameter accuracy of the actions of each subsystem, and providing central decision support for the intelligent operation of the system.
[0040] The flow rate monitoring module employs a high-precision flow sensor with a sampling frequency of no less than 10Hz. Its signal output is connected to the MCU via an analog-to-digital converter. Specifically, the signal output of the flow rate monitoring module is connected to the analog signal acquisition interface of the MCU, which is connected to the ADC (analog-to-digital converter) via a multiplexer (MUX).
[0041] The timing control module includes: a shutdown detection unit, which identifies the moment when the battery voltage drops to a preset lower limit; a delayed start unit, which starts recycling after a delay of 0-30 seconds adjustable after shutdown; and a cutoff timing unit, which automatically terminates the process after the accumulated recycling time reaches the set value of the residual removal time.
[0042] The residual removal time T of the timing control module is calculated using the following formula: T = (total volume of fuel cell stack 7 × 0.1) / 0.1m 3 / h, where the total volume of the fuel cell stack 7 is the maximum capacity of the electrolyte inside the fuel cell stack 7, and 0.1 is the residual coefficient.
[0043] The operating frequency range of the positive electrode pump 3 and the negative electrode pump 4 is 0-45Hz.
[0044] In actual operation, the system's reliability is also reflected in its redundant design. The BMS employs a cross-validation mechanism for data from various sensors. When a flow meter malfunctions, it can be compared and corrected with historical data models using another parameter, ensuring the accuracy of key parameter monitoring. Simultaneously, the frequency converter control module has a self-diagnostic function, capable of real-time monitoring of pump operating current, temperature, and other parameters. It automatically triggers protection mechanisms when abnormalities occur, further enhancing the system's operational safety.
[0045] like Figure 3 As shown, a recycling method for a flow battery planned shutdown recycling system is characterized by comprising the following steps: Detect charging / discharging status signals or determine whether the preset shutdown time has been reached; Trigger the main circulation system to shut down, turning off positive main pump 1 and negative main pump 2; Activate the electrolyte recovery system and start the positive electrode pump 3 and negative electrode pump 4; simultaneously, open the nitrogen flow valve 15 to introduce nitrogen from the nitrogen tank into the fuel cell stack 7 to balance the negative pressure. Real-time monitoring of electrolyte flow rates in the first and second independent recovery pipelines; When the flow velocity in both the first and second branch pipes drops to a preset threshold of 0.1m... 3 When the time is / h or less, wait for the preset delay, and then start the residual cleaning based on the fuel cell stack 7 volume parameters; The electrolyte recovery system will be shut down after the residue removal time has elapsed. Before the preset start-up time, perform pre-start frequency conversion control. Three minutes before the preset start-up time, start the positive main pump 1 and negative main pump 2 at a frequency of 20Hz; increase the frequency of the main pump to 45Hz at a frequency increase rate of 0.2Hz / s.
[0046] In terms of control strategy, the system adopts a phased logic control architecture to achieve a smooth transition from the running state to the shutdown state, as well as the function of quickly resuming operation after shutdown. When the BMS receives the charging / discharging end signal or reaches the preset shutdown time, the shutdown procedure is immediately initiated: first, the power output of the positive and negative main pumps of the main circulation system is cut off, terminating the main circulation path; then, the electrolyte recovery system is activated, and the operating frequency of the small pump is set to 30-40Hz. This frequency range has been verified by fluid dynamics simulation to ensure that the recovery power meets the requirements while avoiding the water hammer effect in the pipeline caused by high flow rate. During the recovery process, the first and second flow meters continuously monitor the flow velocity parameters in the branch pipe. When the flow velocity drops to 0.1 m / s², the flow meter will detect the velocity drop. 3 When the flow rate is 1 h or less, it indicates that the main electrolyte in the main pipeline and fuel cell stack has been completely recovered. At this time, the BMS automatically starts the timing control module, based on the preset formula T = (total fuel cell stack volume × 0.1) / 0.1 m³. 3The residual removal time is calculated using a formula that precisely quantifies the residual electrolyte removal time by multiplying the stack volume by the residual coefficient and combining it with the minimum flow rate parameter. After the timing is completed, the BMS issues a shutdown command to shut down the pump, completing the electrolyte recovery process during the shutdown phase and effectively avoiding performance degradation and corrosion problems caused by long-term electrolyte retention in the stack. To achieve rapid restart after shutdown, a scientific pre-start control strategy was designed for the system. Three minutes before the end of the shutdown period, the pre-start procedure is automatically triggered: first, the positive and negative main pumps of the main circulation system are started at a low frequency of 20Hz, allowing the electrolyte to circulate at a low flow rate and gradually remove dissolved gases from the pipelines; then, the frequency is linearly increased at a rate of 0.2Hz / s until the main pump frequency reaches 45Hz. This gradual frequency increase mode, verified by coupled thermodynamic and fluid dynamic analysis, can effectively avoid electrolyte impact, while promoting the uniformity and stability of the internal temperature and pressure fields of the fuel cell stack, creating optimal initial conditions for subsequent charging and discharging operations, significantly shortening the transition period from shutdown to normal operation, and improving overall operating efficiency.
[0047] This planned shutdown handling system for flow batteries, through deep integration of structural optimization and intelligent control, constructs a complete shutdown handling solution. The system solves the problems of self-discharge and local voltage imbalance during flow battery shutdown, fundamentally cutting off the battery's self-discharge circuit, reducing energy loss, and improving system efficiency. Simultaneously, it reduces electrolyte residue inside the stack, minimizes redox reactions between the positive and negative electrolytes, reduces electrolyte damage to the ion-exchange membrane during shutdown, and extends the equipment's service life. Its technical features not only meet the current operational requirements of flow batteries but also lay the foundation for the development of shutdown control technology for future higher-capacity and higher-power energy storage systems.
[0048] Example 2 The system is highly targeted in its equipment selection. The positive electrode pump 3 and negative electrode pump 4 are acid- and alkali-resistant magnetic pumps with a flow rate range of 5-15 L / min and a head of 10-15 m. The first flow meter 5 and the second flow meter 6 are electromagnetic flow meters with an accuracy controllable within ±0.5%. The BMS battery management system 8 is equipped with a 32-bit ARM Cortex-M4F processor, ensuring the accuracy and stability of the system operation. When this system is applied to a 100kW vanadium redox flow battery energy storage system, the total volume of the stack 7 is 0.8 m³. 3 The actual operating results are significant: the self-discharge rate during shutdown has decreased from 4.2% to 0.7%, the service life of the ion exchange membrane has been extended from 3 years to 5 years, and the energy consumption per recovery has been reduced to 0.35 kWh.
[0049] Example 3 The system prioritizes adaptability in its equipment configuration. The positive electrode main pump 1 and negative electrode main pump 2 are corrosion-resistant centrifugal pumps with a flow rate range of 20-30 L / min and a head of 15-20 m. High-precision diffused silicon pressure sensors are used, with measurement accuracy controlled within ±0.2%. The BMS battery management system 8 is equipped with a 64-bit ARM Cortex-A53 processor, ensuring efficient and stable system operation. In the application of a 200kW vanadium redox flow battery energy storage system, the total volume of the stack 7 is 1.2 m³. 3 The application has yielded significant results: the self-discharge rate during shutdown has decreased from 5.3% to 0.9%, the service life of the ion exchange membrane has been extended from 3.5 years to 6 years, and the energy consumption per recovery has been reduced to 0.42 kWh.
[0050] Example 4 This system emphasizes professional equipment selection. The positive electrode main pump 1 and negative electrode main pump 2 are corrosion-resistant and wear-resistant gear pumps with a flow rate range of 15-25 L / min and a head of 12-18 m. The battery stack 7 is equipped with a level gauge to measure residual electrolyte during recovery; an ultrasonic level gauge is used with a measurement accuracy of ±0.3%. The control module is equipped with a 32-bit ARM Cortex-M7 processor, ensuring the reliability and accuracy of system operation. In a 150kW all-vanadium redox flow battery energy storage system, the total volume of battery stack 7 is 1.0 m³. 3 The practical application results are outstanding: the self-discharge rate during shutdown has been reduced from 4.8% to 0.8%, the service life of the ion exchange membrane has been extended from 3 years to 5.5 years, and the energy consumption per recovery has been reduced to 0.38 kWh.
[0051] The above embodiments are merely one of the implementation methods for achieving the technical solution of the present invention. The scope of protection claimed by the present invention is not limited to this embodiment, but also includes any variations, substitutions and other implementation methods that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention.
Claims
1. A flow battery planned shutdown recovery system, characterized in that, It includes the main circulation system, the electrolyte recovery system and the BMS battery management system (8); The main circulation system includes a positive electrode main pump (1), a negative electrode main pump (2), a positive electrode main pipe, a negative electrode main pipe and a stack (7), which are used for the charging and discharging of the flow battery; The electrolyte recovery system adopts a branched topology structure, including a first branch pipe branched on the positive electrode main pipe, a second branch pipe branched on the negative electrode main pipe, a positive electrode pump (3), a negative electrode pump (4), a first flow meter (5), a second flow meter (6), a first independent recovery pipe and a second independent recovery pipe, a two-way valve and an electrolyte recovery tank; The positive electrode main pipeline is connected to the inlet of the positive electrode pump (3) through the first branch pipeline, and the outlet of the positive electrode pump (3) is connected to the positive electrode storage tank through the first independent recovery pipeline. The first flow meter (5) is installed on the first branch pipeline. The negative electrode main pipeline is connected to the inlet of the negative electrode pump (4) through the second branch pipeline, and the outlet of the negative electrode pump (4) is connected to the negative electrode storage tank through the second independent recovery pipeline. The second flow meter (6) is installed on the second branch pipeline. Two-way valves are respectively installed at the outlet of the positive electrode pump (3) and the outlet of the negative electrode pump (4) to control the flow of electrolyte to the stack (7) or the electrolyte recovery tank. The BMS battery management system (8) includes an MCU, a flow rate monitoring module, a timing control module and a frequency conversion control module; the flow rate monitoring module uses a high-precision flow sensor with a sampling frequency of not less than 10Hz, and its signal output is connected to the MCU through analog-to-digital conversion; The timing control module includes: a shutdown detection unit to identify the instant when the battery voltage drops to a preset lower limit; a delayed start unit to start recycling after a delay of 0-30 seconds adjustable after shutdown; and a cutoff timing unit to automatically terminate the process after the accumulated recycling time reaches a set value for the residual removal duration. The residual removal duration T of the timing control module is calculated using the following formula: T = (total battery stack volume × 0.1) / 0.1m³ 3 / h, where the total volume of the fuel cell stack (7) is the maximum capacity of the electrolyte inside the fuel cell stack (7), and 0.1 is the residual coefficient; when the flow velocities of the first branch pipe and the second branch pipe both drop to the preset threshold of 0.1m 3 When the time is / h or less, wait for the preset delay, and then start the residual removal based on the volume parameters of the fuel cell stack (7); after the residual removal time is over, shut down the electrolyte recovery system; and perform pre-start frequency conversion control before the preset start time. The BMS battery management system (8) is electrically connected to the main circulation system and the electrolyte recovery system respectively, and is used to control the electrolyte recovery when the machine is stopped.
2. The flow battery planned shutdown and recovery system according to claim 1, characterized in that, The electrolyte recovery system also includes: Pressure sensors are installed on the first branch pipe, the second branch pipe, the first independent recovery pipe, and the second independent recovery pipe to monitor changes in pipeline pressure and prevent leaks.
3. The flow battery planned shutdown and recovery system according to claim 2, characterized in that, The electrolyte recovery system further includes: a nitrogen storage tank (17), a nitrogen injection pipe and a nitrogen flow valve (15) installed on the nitrogen injection pipe, a nitrogen discharge pipe and a nitrogen discharge valve (16) installed on the nitrogen discharge pipe; the nitrogen injection pipe and the nitrogen discharge pipe are both connected to the fuel cell stack (7).
4. The flow battery planned shutdown and recovery system according to claim 1, characterized in that, The operating frequency range of the positive electrode pump (3) and the negative electrode pump (4) is 0-45Hz.
5. A recycling method for a flow battery planned shutdown recycling system according to any one of claims 1 to 4, characterized in that, Includes the following steps: Detect charging / discharging status signals or determine whether the preset shutdown time has been reached; Trigger the shutdown of the main circulation system and shut down the positive main pump (1) and the negative main pump (2); Activate the electrolyte recovery system and start the positive electrode pump (3) and negative electrode pump (4); Real-time monitoring of electrolyte flow rates in the first and second independent recovery pipelines; When the flow velocity in both the first and second branch pipes drops to a preset threshold of 0.1m... 3 When the time is / h or less, wait for the preset delay, and then start the residual removal based on the volume parameters of the fuel cell stack (7); The electrolyte recovery system will be shut down after the residue removal time has elapsed. Perform pre-start inverter control before the preset start-up time.
6. The recycling method of a flow battery planned shutdown recycling system according to claim 5, characterized in that, The step of performing pre-start inverter control before the preset start-up time includes the following steps: Three minutes before the preset start-up time, start the positive main pump (1) and negative main pump (2) at a frequency of 20Hz; increase the frequency of the main pump to 45Hz at a frequency increase rate of 0.2Hz / s.
7. The recycling method of a flow battery planned shutdown recycling system according to claim 5, characterized in that, The activation of the electrolyte recovery system, including starting the positive electrode pump (3) and the negative electrode pump (4), comprises the following steps: Open the nitrogen flow valve (15) and introduce nitrogen from the nitrogen tank into the fuel cell stack (7) to balance the negative pressure.