A system and method for pyrolysis pretreatment and flue gas safe disposal of retired lithium batteries

Abstract

The application discloses a kind of decommissioned lithium battery pyrolysis pretreatment and flue gas safe disposal system and method, including pyrolysis furnace, smoke collection tank and control and data acquisition unit;Pyrolysis furnace is connected with smoke collection tank by connecting pipeline and forms closed system;Pyrolysis furnace includes furnace body, heating cavity is arranged in furnace body, tray is arranged in heating cavity, lithium battery is placed, high-temperature load bar is fixed in the bottom of tray, electronic balance is connected with the bottom of high-temperature load bar and is penetrated through furnace body, low-temperature insulation area for installing electronic balance is equipped below furnace body;Smoke collection tank includes tank body, safety pressure relief device and ignition device are arranged on the top of tank body, vacuum pipeline is arranged on the bottom of tank body, and vacuum pump is arranged on vacuum pipeline.The application solves the safety and reliability problem of kilogram level lithium battery pyrolysis experiment, realizes the integration of synchronous monitoring and active safety control of "heat-heavy-gas-pressure" whole process data.

Description

Technical Field

[0001] This invention relates to the field of lithium battery recycling and experimental safety technology, specifically to a system and method for the pretreatment of pyrolysis and safe disposal of flue gas from retired lithium batteries. Background Technology

[0002] Pyrolysis technology is a crucial step in the processing and recycling of spent lithium-ion batteries. In the early stages of process development and safety assessment for industrial applications, pyrolysis experiments on complete lithium-ion battery cells or modules are typically required. In existing experimental studies, the pyrolysis furnace and flue gas collection or treatment device are usually set up separately, forming a loosely combined system. This discrete system still has several technical shortcomings when handling large samples and high gas loads: 1. Low system integration and high scale-up risk: Functional modules such as pyrolysis, collection, and safe disposal are scattered and have complex connections. When dealing with a large amount of flue gas generated by the pyrolysis of kilogram-level batteries, the risk of leakage and connection failure increases dramatically, and the stability and safety of the experimental process are difficult to guarantee. 2. Poor data coordination and insufficient basis for process scale-up: Key engineering parameters such as real-time material weight loss, temperature and pressure of gas collection unit in the pyrolysis process are recorded separately, making it difficult to achieve accurate synchronous correlation analysis and failing to provide a reliable data chain for industrial-scale process scale-up.

[0003] 3. Passive safety protection, unable to cope with sudden and violent reactions: The safety design is isolated and lacks the ability to actively intervene from the source of pyrolysis to the end. When a kilogram-level battery undergoes a violent reaction or thermal runaway during pyrolysis, the instantaneous high-pressure and high-speed gas flow can easily lead to system overpressure or even explosion. Traditional passive pressure relief devices have a delayed response and pose an extremely high risk.

[0004] 4. Lack of in-situ monitoring methods: Especially under kilogram-level samples and high-temperature closed conditions, it is extremely difficult to obtain the core process and safety monitoring parameter of real-time material quality changes, making it impossible to achieve continuous and stable online weighing, which restricts process kinetics research and safety early warning. Summary of the Invention

[0005] In view of the above-mentioned shortcomings of the prior art, the present invention provides a system and method for pretreatment of pyrolysis and safe disposal of flue gas of retired lithium batteries, which can safely and stably handle pyrolysis experiments of kilogram-level lithium batteries and realize integrated experiments with synchronous monitoring of data and active safety control throughout the entire process.

[0006] To achieve the above-mentioned objectives, the technical solution adopted by this invention is as follows: A system and method for the pretreatment and safe disposal of flue gas from the pyrolysis of retired lithium batteries includes a pyrolysis furnace, a flue gas collection tank, and a control and data acquisition unit. The flue gas outlet of the pyrolysis furnace and the pyrolysis gas inlet of the flue gas collection tank are connected by connecting pipes to form a closed system. The pyrolysis furnace includes a furnace body with a heating chamber inside. A tray for placing lithium batteries is placed inside the heating chamber. A high-temperature resistant load-bearing rod is fixed to the bottom of the tray. The tray and the high-temperature resistant load-bearing rod can move vertically. An electronic balance is connected to the bottom of the high-temperature resistant load-bearing rod through the furnace body. A low-temperature heat-insulating zone for installing the electronic balance is provided below the furnace body. The electronic balance is used for real-time, in-situ weighing of lithium battery samples during the pyrolysis process. The flue gas collection tank includes a tank body with a safety pressure relief device and an ignition device at the top. A vacuum pipe is provided at the bottom of the tank, and a vacuum pump is installed on the vacuum pipe.

[0007] Furthermore, the control and data acquisition unit includes a control cabinet, a PLC controller installed in the control cabinet, a paperless recorder, and an alarm. The alarm and the paperless recorder are both electrically connected to the PLC controller.

[0008] Furthermore, a first temperature sensor for measuring the temperature inside the furnace and a second temperature sensor for measuring the surface temperature of the lithium battery sample are installed inside the heating chamber, and a pressure sensor is installed inside the tank. The first temperature sensor, the second temperature sensor, and the pressure sensor are all electrically connected to the PLC controller.

[0009] Furthermore, a first exhaust port is provided on the connecting pipeline, and a first exhaust purification device is provided on the first exhaust port. A second exhaust port is provided on the top of the smoke collection tank, and a second exhaust purification device is provided on the second exhaust port.

[0010] Furthermore, the first exhaust purification device and the second exhaust purification device have the same structure. The first exhaust purification device includes a vertical spiral coil condenser installed at the inlet end of the first exhaust port and a cylindrical filter installed at the outlet end of the first exhaust port. The inlet end of the vertical spiral coil condenser is connected to the outlet end of the first exhaust port, and the outlet end of the vertical spiral coil condenser is connected to the inlet end of the cylindrical filter.

[0011] Furthermore, the furnace body is equipped with an inert gas inlet and a spare purging port.

[0012] Furthermore, the tank is equipped with a high-temperature resistant observation window.

[0013] Furthermore, the furnace body is wrapped with a high-performance insulation layer, and the tank body is wrapped with a tank heating component.

[0014] Furthermore, a check valve is installed on the connecting pipeline.

[0015] An experimental method for a pyrolysis pretreatment and flue gas safety treatment system for retired lithium batteries includes the following steps: Step S1: Perform experimental system preparation and safety self-check. Specifically: The control and data acquisition unit is started to perform a safety self-test, checking whether the first temperature sensor and the second temperature sensor are working properly, whether the balance is zero and stable, and whether the initial state of each valve is correct; if the first temperature sensor, the second temperature sensor, and the balance are all working properly, proceed to the next step; if at least one of the first temperature sensor, the second temperature sensor, and the balance is not working properly, the alarm will sound, the experiment will be terminated, and the first temperature sensor, the second temperature sensor, and the balance will be adjusted until they are working properly before proceeding to the next step. Step S2: Vacuum and inert gas are applied to the sealed system consisting of the pyrolysis furnace and the smoke collection canister. Atmosphere replacement and leak detection are performed. The determination of whether to proceed to the next step S3 is based on the atmosphere replacement and leak detection. If the sealed system is well sealed, proceed to the next step S3. If the sealed system is not well sealed, the alarm will sound and the experiment will be terminated. S3: After completing the atmosphere replacement and leak detection work, set the preset heating temperature of the pyrolysis furnace, preheat the smoke collection canister to the preset heating temperature, start the pyrolysis furnace heating program to carry out the lithium battery pyrolysis experiment, and record the lithium battery pyrolysis experiment data. S4: During the lithium battery pyrolysis experiment, the lithium battery temperature is acquired by a second temperature sensor. The pressure of the smoke collection canister is collected by a pressure sensor. According to the temperature of lithium batteries and smoke collection canister pressure Determine whether the protection mode is triggered during the lithium battery pyrolysis experiment; if the protection mode is not triggered, continue the lithium battery pyrolysis experiment until the lithium battery pyrolysis experiment is completed and proceed to the next step S5; if the protection mode is triggered, continue to execute step S4 to carry out the lithium battery pyrolysis experiment, or stop the lithium battery pyrolysis experiment and proceed to step S6. Step S5: After the lithium battery pyrolysis experiment is completed, determine whether the ignition conditions are met. If the ignition conditions are not met, return to step S4. If the ignition conditions are met, ignite and conduct a combustible gas combustion characteristic experiment. After completing the combustible gas combustion characteristic experiment, proceed to the next step S6. S6: After completing the whole lithium battery pyrolysis experiment and the combustible gas combustion characteristic experiment, the pyrolysis furnace and smoke collection tank are purged and cooled down. After the closed system is cooled to room temperature, the experiment ends.

[0016] Furthermore, in step S2, the atmosphere replacement and leak detection operation specifically includes the following steps: S21: Vacuuming: Start the vacuum pump on the vacuum pipeline to perform vacuuming operation on the pyrolysis furnace and smoke collection tank; specifically, the control and data acquisition unit monitors the data of the pressure sensor in real time until the pressure of the sealed system drops to the preset vacuum threshold of -0.095MPa; S22: Inert gas filling: After the vacuuming operation is completed, close the vacuum pump and valve, and introduce nitrogen through the inert gas inlet to fill the pyrolysis furnace and smoke collection tank with nitrogen to carry out the inert gas filling operation; specifically, until the pressure value detected by the pressure sensor returns to a slight positive pressure of 0.02MPa; S23: Cycling and Leak Detection: Repeat the vacuuming and inert gas charging processes of steps S21 and S22 at least twice, and charge the inert gas to the set pressure on the last charge. Afterwards, close all intake valves, and the sealed system enters a pressure holding and static state to complete the circulation and leak detection operations; S24. The control and data acquisition unit continuously monitors the pressure collected by the pressure sensor and sets the time interval for pressure collection. For 5 minutes, by pressure change rate Determine the airtightness of the system; when the pressure change rate of the closed system... If the pressure change rate is less than 0.001 MPa / min, the system is considered to have no leakage, and the next step can be performed; when the pressure change rate of the closed system is less than 0.001 MPa / min, the system is considered to have no leakage, and the next step can be performed. If the pressure is greater than or equal to 0.001 MPa / min, the system is determined to have a leak, the alarm will sound, and the experiment will be terminated.

[0017] The beneficial effects of this invention are as follows: 1. This invention enables seamless integration at the engineering scale. Specifically designed for the pyrolysis of kilogram-level retired lithium batteries, it integrates high-precision weighing, large-volume flue gas treatment, and safety protection modules, filling the gap between laboratory micro-scale research and industrial-grade engineering applications, and providing a direct and reliable simulation experimental platform for process scale-up.

[0018] 2. This invention can construct a high-precision, multi-dimensional, synchronous data stream. Through deep coupling of in-situ weighing and a multi-parameter acquisition system, it achieves, for the first time, second-level synchronous monitoring of "mass-temperature-pressure" data in kilogram-level experiments. This high-precision data stream provides core support for accurately calculating pyrolysis rates, material balance, and energy balance, significantly improving the scientific rigor of process development.

[0019] 3. This invention can improve both proactive and intrinsic safety. Addressing the instantaneous high-pressure risks of kilogram-level pyrolysis, the system integrates multi-dimensional information such as mass loss rate, pressure fluctuations, and flue gas component anomalies to construct an intelligent early warning model. By executing heat source cutoff, gas path isolation, and controllable pressure relief at the millisecond level, it achieves a leap from "passive pressure relief" to "proactive intervention," significantly improving the level of intrinsic safety.

[0020] 4. This invention possesses multi-functional integrated verification capabilities. The system is not limited to pyrolysis experiments; it can also conduct in-situ verification of pyrolysis gas combustion characteristics, explosion limit tests, and exhaust gas purification. This "one-stop" platform effectively solves the safety and environmental assessment challenges in process development, significantly shortening the R&D cycle of refined pyrolysis processes for retired lithium batteries. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the structure of the retired lithium battery pyrolysis pretreatment and flue gas safety treatment system of the present invention; Figure 2 This is a flowchart of the experimental process of the present invention; The symbols for each component are as follows: 100. Pyrolysis furnace; 101. Furnace body; 102. Inert gas inlet; 103. Exhaust gas outlet; 104. Heating chamber; 105. Low-temperature insulation zone; 106. Electronic balance; 107. High-temperature resistant load-bearing rod; 108. First temperature sensor; 109. Second temperature sensor; 110. Furnace body insulation layer; 200. Smoke collection container; 201. Container body; 202. Support; 203. Pyrolysis gas inlet; 204. One-way valve; 205. First flue gas purification device; 207. Second flue gas purification device; 208. Vacuum pipeline; 209. Observation window; 210. Safety pressure relief device; 211. Pressure sensor; 212. Ignition device; 213. Container heating assembly; 300. Control and data acquisition unit; 400. Connecting pipeline. Detailed Implementation

[0022] The specific embodiments of the present invention are described below to enable those skilled in the art to understand the present invention. However, it should be understood that the present invention is not limited to the scope of the specific embodiments. For those skilled in the art, various changes are obvious as long as they are within the spirit and scope of the present invention as defined and determined by the appended claims. All inventions utilizing the concept of the present invention are protected.

[0023] Example: like Figure 1 As shown, the retired lithium battery pyrolysis pretreatment and flue gas safety treatment system includes a pyrolysis furnace 100, a smoke collection tank 200, and a control cabinet. The pyrolysis furnace 100 is equipped with a smoke exhaust outlet 103, and the smoke collection tank 200 is equipped with a pyrolysis gas inlet 203. The smoke exhaust outlet 103 and the pyrolysis gas inlet 203 are connected by a connecting pipe 400 to form a closed system. A one-way valve 204 is installed on the connecting pipe 400, and a first exhaust port is installed on the connecting pipe 400. A first exhaust purification device 205 is installed on the first exhaust port. A second exhaust port is installed on the top of the smoke collection tank 200, and a second exhaust purification device 207 is installed on the second exhaust port.

[0024] The pyrolysis furnace 100 includes a furnace body 101, within which a heating chamber 104 is provided. A tray for holding lithium batteries is placed within the heating chamber 104. A high-temperature resistant load-bearing rod 107 is fixed to the bottom of the tray. The bottom of the high-temperature resistant load-bearing rod 107 passes through the furnace body 101 and is connected to an electronic balance 106. A low-temperature insulation zone 105 for mounting the electronic balance 106 is located below the furnace body 101. A first temperature sensor 108 for measuring the furnace interior temperature and a second temperature sensor 109 for measuring the surface temperature of the lithium battery sample are provided within the heating chamber 104. The furnace body 101 is externally covered with a high-performance insulation layer 110. The low-temperature insulation zone 105 is strictly isolated by insulation material to ensure that the operating environment temperature of the balance is usually below 60°C. The electronic balance 106 is used for real-time, in-situ weighing of lithium battery samples during pyrolysis. The furnace body 101 is equipped with an inert gas inlet 102 and a spare purge port for precise control of the pyrolysis atmosphere. Pyrolysis flue gas is discharged from the top exhaust outlet 103 via a heat-traced connecting pipe 400 to prevent condensation during operation.

[0025] The smoke collection canister 200 includes a canister body 201. The top of the canister body 201 is equipped with a safety pressure relief device 210, a pressure sensor 211, and an ignition device 212. The ignition device 212 adopts a high-voltage electric arc ignition device, an explosion-proof high-energy cold igniter, or a pulse electronic igniter. The safety pressure relief device 210 is preferably an explosion-proof plate. The bottom of the canister body 201 is equipped with a vacuum pipe 208. The canister body 201 is equipped with an observation window 209. The canister body 201 is externally wrapped with a canister heating component 213. The canister heating component 213 is preferably a canister electric heating blanket or an electric heating coil.

[0026] The tank 201 is an inverted tank made of 304 / 316 stainless steel and is fixed to a rigid support 202. Pyrolysis flue gas enters the tank 201 through the pyrolysis gas inlet 203 via the connecting pipe 400. A one-way valve 204 and a first flue gas purification device 205 for sampling are installed on the inlet branch. A second exhaust port and a second flue gas purification device 207 are located at the top of the tank, and a vacuum pipe 208 on the side is used for system vacuuming. A high-pressure resistant quartz glass observation window 209 on the front facilitates optical observation and high-speed imaging. A safety pressure relief device 210, a pressure sensor 211, and an ignition device 212 are integrated on the top of the tank. A tank heating assembly 213 is installed on the outside of the tank 201 to maintain the tank wall temperature above the dew point of the high-boiling-point components in the pyrolysis gas.

[0027] The first exhaust purification device 205 and the second exhaust purification device 207 have the same structure, including a vertical spiral coil condenser installed at the inlet end of the first exhaust port and a cylindrical filter cartridge installed at the outlet end of the first exhaust port. The inlet end of the vertical spiral coil condenser is connected to the outlet end of the first exhaust port, and the outlet end of the vertical spiral coil condenser is connected to the inlet end of the cylindrical filter cartridge. The vertical spiral coil condenser, in conjunction with the cylindrical filter cartridge, is used to treat hydrogen fluoride. The treatment solution inside the cylindrical filter cartridge is a calcium hydroxide alkaline solution. The first exhaust purification device 205 and the second exhaust purification device 207 purify and filter the high-temperature flue gas until it is harmless before discharging it into the environment. Specifically, the high-temperature flue gas enters from the inlet of the vertical spiral coil condenser, flows along the gaps between the spiral coils inside the condenser, exchanges heat with the cooling water inside the coils to cool down, and the water vapor and condensable pollutants in the flue gas condense into liquid and are discharged from the bottom drain port; the cooled flue gas flows out from the outlet of the vertical spiral coil condenser and enters the subsequent filtration device. The condensed flue gas enters from the bottom of the cartridge filter, passes upward through the filter element, and is trapped by the filter element. The clean flue gas flows out from the top of the cartridge filter and enters the heat tracing pipeline to be sent to the flue gas analyzer. Impurities and droplets on the outside of the filter element fall into the bottom of the cartridge filter and are periodically discharged from the drain port.

[0028] The control and data acquisition unit 300 is the core of the system's control. It includes a control cabinet, a PLC controller installed within the cabinet, a paperless recorder, and an alarm. The paperless recorder and alarm are electrically connected to the PLC controller. The balance 106, the first temperature sensor 108, the second temperature sensor 109, and the pressure sensor 211 are all electrically connected to the PLC controller, receiving real-time mass signals from the balance 106, temperature signals from the first and second temperature sensors 108 and 109, and pressure signals from the pressure sensor 211. Simultaneously, the PLC controller outputs control commands to the heater of the pyrolysis furnace 100, the ignition device 212 of the smoke collection tank 200, and the tank heating assembly 213. The paperless recorder serves as the human-machine interface, synchronously acquiring, displaying, and permanently storing all key parameters at high frequency. These key parameters include time, furnace temperature Tf, material temperature Ts, sample mass Ms, tank pressure Pt, and control setpoints.

[0029] An experimental method for a pyrolysis pretreatment and flue gas safety treatment system for retired lithium batteries, such as Figure 2 The experimental flowchart and specific steps are as follows: Step S1: Perform experimental system preparation and safety self-check. Specifically: The control and data acquisition unit 300 is activated to perform a safety self-test, checking whether the first temperature sensor 108 and the second temperature sensor 109 are working properly, whether the balance 106 is stable at zero, and whether the initial state of each valve is correct; if the first temperature sensor 108, the second temperature sensor 109, and the balance 106 are all working properly, proceed to the next step; if at least one of the first temperature sensor 108, the second temperature sensor 109, and the balance 106 is not working properly, the alarm will sound, the experiment will be terminated, and the first temperature sensor 108, the second temperature sensor 109, and the balance 106 will be adjusted until they are working properly before proceeding to the next step. Step S2: Vacuum and inert gas are applied to the sealed system consisting of pyrolysis furnace 100 and smoke collection canister 200. Atmosphere replacement and leak detection are performed. The determination of whether to proceed to the next step S3 is based on the atmosphere replacement and leak detection. If the sealing system is well sealed, proceed to the next step S3. If the sealing system is not well sealed, the alarm is triggered and the experiment is terminated. Atmosphere replacement and leak detection operations specifically include the following steps: S21: Vacuuming: Start the vacuum pump on the vacuum pipeline 209 to perform vacuuming operation on the pyrolysis furnace 100 and the smoke collection tank 200; specifically, the control and data acquisition unit 300 monitors the data of the pressure sensor 211 in real time until the pressure of the sealed system drops to the preset vacuum threshold of -0.095MPa. S22: Inert gas filling: After the vacuuming operation is completed, close the vacuum pump and valve, and introduce nitrogen gas through the inert gas inlet 102 to fill the pyrolysis furnace 100 and the smoke collection canister 200 with nitrogen gas to carry out the inert gas filling operation; specifically, until the pressure value detected by the pressure sensor 211 returns to a slight positive pressure of 0.02MPa; S23: Cycling and Leak Detection: Repeat the vacuuming and inert gas charging processes of steps S21 and S22 at least twice, and charge the inert gas to the set pressure on the last charge. Afterwards, close all intake valves, and the sealed system enters a pressure holding and static state to complete the circulation and leak detection operations; S24. The control and data acquisition unit 300 continuously monitors the pressure collected by the pressure sensor 211 and sets the time interval for collecting the pressure. For 5 minutes, by pressure change rate Determine the airtightness of the system; when the pressure change rate of the closed system... If the pressure change rate is less than 0.001 MPa / min, the system is considered to have no leakage, and the next step can be performed; when the pressure change rate of the closed system is less than 0.001 MPa / min, the system is considered to have no leakage, and the next step can be performed. If the pressure is greater than or equal to 0.001 MPa / min, the system is determined to have a leak, the alarm will sound, and the experiment will be terminated. S3: After completing the atmosphere replacement and leak detection operations, set the preset heating temperature of the pyrolysis furnace 100, preheat the smoke collection canister 200 to the preset heating temperature, start the pyrolysis furnace heating program to conduct the lithium battery pyrolysis experiment, and record the lithium battery pyrolysis experiment data; specifically: S31: Turn on the tank heating component 213 of the smoke collection tank 200 to raise the tank temperature of the smoke collection tank 200. Maintain at the preset temperature; the preset temperature is 150℃ to prevent condensation of pyrolysis vapors; S32: Set the heating temperature of the pyrolysis furnace 100 on the control and data acquisition unit 300; S33: Start the heating program of the pyrolysis furnace through the control and data acquisition unit 300 to carry out the lithium battery pyrolysis experiment and record the lithium battery pyrolysis experiment data; S4: During the lithium battery pyrolysis experiment, the lithium battery temperature is collected by the second temperature sensor 109. The pressure of the smoke collection can is collected by pressure sensor 211. According to the temperature of lithium batteries and smoke collection canister pressure Determine whether the protection mode is triggered during the lithium battery pyrolysis experiment; if the protection mode is not triggered, continue the lithium battery pyrolysis experiment until the lithium battery pyrolysis experiment is completed and proceed to the next step S5; if the protection mode is triggered, continue to execute step S4 to carry out the lithium battery pyrolysis experiment, or stop the lithium battery pyrolysis experiment and proceed to step S6. Specifically: If the safety protection mode is not triggered, continue the lithium battery pyrolysis experiment and further determine whether the lithium battery pyrolysis experiment reaction has ended; if the lithium battery pyrolysis experiment reaction has not ended, return to step S4; if the pyrolysis reaction has ended, proceed to step S5. If the safety protection mode is triggered, continue the lithium battery pyrolysis experiment. After entering the step of continuing the lithium battery pyrolysis experiment, if the lithium battery pyrolysis experiment continues, return to step S4; if the lithium battery pyrolysis experiment does not continue, proceed to step S6. The trigger protection safety modes include overpressure level one early warning mode, overpressure level two linkage mode, and temperature anomaly protection mode; Overpressure Level 1 Early Warning Mode: When the pressure in the smoke collection tank... Greater than or equal to the safety warning value At that time, the safety warning value When the pressure of the safety relief device 210 is set to 70% of its operating pressure, the control and data acquisition unit 300 controls the alarm to activate, and proceeds to the next step of the lithium battery pyrolysis experiment judgment; when the pressure of the smoke collection tank... Less than the safety warning value When the lithium battery pyrolysis experiment ends, proceed to the determination step. Overpressure two-stage linkage mode: When the smoke collection tank pressure... Greater than or equal to emergency action value Emergency action value When the pressure of the safety relief device 210 is set to 90% of its operating pressure, the control and data acquisition unit 300 will automatically execute the safety plan: immediately cut off the heating power supply to the pyrolysis furnace 100, and may also close the pyrolysis gas inlet pipeline valve, while forcibly opening the purification bypass of the first exhaust port to relieve pressure, and proceeding to the judgment step for continuing the lithium battery pyrolysis experiment; when the pressure of the smoke collection tank... Less than the emergency action value When the lithium battery pyrolysis experiment ends, proceed to the determination step. Temperature anomaly protection mode: When the heating rate measured by the first temperature sensor 108 is greater than... The heating rate at ℃ / s and / or measured by the second temperature sensor 109 At ℃ / s, If the temperature rise is judged to be "abnormally rapid," the experimental system will trigger an alarm or cooling measures; when the heating rate measured by the first temperature sensor 108 is less than... The heating rate measured by the second temperature sensor 109 at ℃ / s ℃ / s less than When the temperature reaches ℃ / s, it is judged as "normal temperature", and the process continues to the lithium battery pyrolysis experiment judgment step. When the battery temperature exceeds 200-250℃, it is judged as "dangerous temperature"; when the temperature difference change rate is >2-5℃ / s, it is judged as "violent internal reaction". Specifically, the method for determining the end of a lithium battery pyrolysis experiment is as follows: when When the noise level is greater than or equal to the preset pyrolysis reaction threshold (e.g., the preset pyrolysis reaction threshold is 0.001 g / s), the pyrolysis reaction is determined to have started; when... When the value is less than the preset pyrolysis reaction threshold, the main pyrolysis reaction stage is considered to have ended. Step S5: After the lithium battery pyrolysis experiment is completed, determine whether the ignition conditions are met. If the ignition conditions are not met, return to step S4; if the ignition conditions are met, ignite and conduct a combustible gas combustion characteristic experiment. After completing the combustible gas combustion characteristic experiment, proceed to the next step S66. Specifically: after the lithium battery pyrolysis experiment, when combustible gas accumulates in the smoke collection canister 200, combustion characteristics can be studied; during remote ignition, the operator can remotely control the ignition device 212 from a safe distance via the control and data acquisition unit 300; during combustion process monitoring, the pressure sensor 211 captures the peak pressure surge. The pressure change curve is recorded, and the flame shape is recorded by a high-speed camera through the observation window 209, thus recording the experimental data of the combustible gas combustion characteristics experiment. The method for determining whether ignition conditions are met is as follows: Specifically, the combustible gas concentration is 5%–30%, the pressure inside the tank is stable at 0.1–0.4 MPa, the oxygen content is less than 1% in an inert atmosphere or close to 21% in an air atmosphere, the tank temperature is higher than 120°C, the pressure change rate is less than 0.001 MPa / s, and the system is in a safe and ready state with no alarms and the valves in the correct state.

[0030] S6: After completing the whole lithium battery pyrolysis experiment and the combustible gas combustion characteristic experiment, carry out the purging and cooling operation of pyrolysis furnace 100 and smoke collection canister 200. After the system cools down to room temperature, the experiment ends. Specifically: After completing the whole lithium battery pyrolysis experiment and the combustible gas combustion characteristic experiment, nitrogen gas is introduced into the pyrolysis furnace 100 through the inert gas inlet 102. The nitrogen gas is used to continuously purge the pyrolysis furnace 100 and the smoke collection canister 200 until the residual flue gas in the pyrolysis furnace 100 and the smoke collection canister 200 is completely discharged.

Claims

1. A system for pretreatment of pyrolysis and safe disposal of flue gas from retired lithium batteries, characterized in that, It includes a pyrolysis furnace (100), a smoke collection tank (200), and a control and data acquisition unit (300); the exhaust outlet (103) of the pyrolysis furnace (100) and the pyrolysis gas inlet (203) of the smoke collection tank (200) are connected by a connecting pipeline (400) to form a closed system; The pyrolysis furnace (100) includes a furnace body (101), a heating chamber (104) is provided inside the furnace body (101), a tray for placing lithium batteries is provided inside the heating chamber (104), a high-temperature resistant load-bearing rod (107) is fixed at the bottom of the tray, the tray and the high-temperature resistant load-bearing rod (107) can move vertically, the bottom of the high-temperature resistant load-bearing rod (107) passes through the furnace body (101) and is connected to an electronic balance (106), a low-temperature heat insulation area (105) for installing the electronic balance (106) is provided below the furnace body (101), the electronic balance (106) is used for real-time, in-situ weighing of lithium battery samples during the pyrolysis process; The smoke collection tank (200) includes a tank body (201), a safety pressure relief device (210) and an ignition device (212) are provided on the top of the tank body (201), a vacuum pipe (208) is provided at the bottom of the tank body (201), and a vacuum pump is provided on the vacuum pipe (208).

2. The decommissioned lithium battery pyrolysis pretreatment and flue gas safety treatment system according to claim 1, characterized in that, The control and data acquisition unit (300) includes a control cabinet, a PLC controller installed in the control cabinet, a paperless recorder and an alarm, wherein the alarm and the paperless recorder are electrically connected to the PLC controller.

3. The retired lithium battery pyrolysis pretreatment and flue gas safety treatment system and method according to claim 2, wherein the heating chamber (104) is provided with a first temperature sensor (108) for measuring the temperature inside the furnace and a second temperature sensor (109) for measuring the surface temperature of the lithium battery sample, and the tank (201) is provided with a pressure sensor (211), wherein the first temperature sensor (108), the second temperature sensor (109) and the pressure sensor (211) are all electrically connected to the PLC controller.

4. The decommissioned lithium battery pyrolysis pretreatment and flue gas safety treatment system according to claim 1, characterized in that, The connecting pipe (400) is provided with a first exhaust port, and the first exhaust port is provided with a first exhaust purification device (205). The top of the smoke collection tank (200) is provided with a second exhaust port, and the second exhaust port is provided with a second exhaust purification device (207).

5. The decommissioned lithium battery pyrolysis pretreatment and flue gas safety treatment system according to claim 4, characterized in that, The first exhaust purification device (205) and the second exhaust purification device (207) have the same structure. The first exhaust purification device (205) includes a vertical spiral coil condenser installed at the inlet end of the first exhaust port and a cylindrical filter installed at the outlet end of the first exhaust port. The inlet end of the vertical spiral coil condenser is connected to the outlet end of the first exhaust port, and the outlet end of the vertical spiral coil condenser is connected to the inlet end of the cylindrical filter.

6. The decommissioned lithium battery pyrolysis pretreatment and flue gas safety treatment system according to claim 1, characterized in that, The furnace body (101) is provided with an inert gas inlet (102) and a spare purging port, and the connecting pipeline (400) is provided with a one-way valve (204).

7. The decommissioned lithium battery pyrolysis pretreatment and flue gas safety treatment system according to claim 1, characterized in that, The tank (201) is provided with a high-temperature resistant observation window (209).

8. The decommissioned lithium battery pyrolysis pretreatment and flue gas safety treatment system according to claim 1, characterized in that, The furnace body (101) is wrapped with a high-performance insulation layer (110), and the tank body (201) is wrapped with a tank heating component (213).

9. An experimental method for a pyrolysis pretreatment and flue gas safety treatment system for retired lithium batteries according to any one of claims 1-8, characterized in that, Includes the following steps: Step S1: Perform experimental system preparation and safety self-check. Specifically: Start the control and data acquisition unit (300) to perform a safety self-check, check whether the first temperature sensor (108) and the second temperature sensor (109) are working properly, whether the balance (106) is zero and stable, and whether the initial state of each valve is correct; if the first temperature sensor (108), the second temperature sensor (109) and the balance (106) are all working properly, proceed to the next step; if at least one of the first temperature sensor (108), the second temperature sensor (109) and the balance (106) is not working properly, the alarm will sound, the experiment will be terminated, and the first temperature sensor (108), the second temperature sensor (109) and the balance (106) will be adjusted until they are working properly before proceeding to the next step; Step S2: Vacuum and inert gas are applied to the sealed system consisting of the pyrolysis furnace (100) and the smoke collection tank (200). Atmosphere replacement and leakage detection are performed. The process of atmosphere replacement and leakage detection determines whether to proceed to the next step S3. If the sealing of the sealed system is good, proceed to the next step S3. If the sealing of the sealed system is not good, the alarm will sound and the experiment will be terminated. S3: After completing the atmosphere replacement and leak detection work, set the preset heating temperature of the pyrolysis furnace (100), preheat the smoke collection canister (200) to the preset heating temperature, start the pyrolysis furnace heating program to carry out the lithium battery pyrolysis experiment, and record the lithium battery pyrolysis experiment data. S4: During the lithium battery pyrolysis experiment, the lithium battery temperature is collected by the second temperature sensor (109). The pressure of the smoke collection can is collected by the pressure sensor (211). According to the temperature of lithium batteries and smoke collection canister pressure Determine whether the protection mode is triggered during the lithium battery pyrolysis experiment; if the protection mode is not triggered, continue the lithium battery pyrolysis experiment until the lithium battery pyrolysis experiment is completed and proceed to the next step S5; if the protection mode is triggered, continue to execute step S4 to carry out the lithium battery pyrolysis experiment, or stop the lithium battery pyrolysis experiment and proceed to step S6. Step S5: After the lithium battery pyrolysis experiment is completed, determine whether the ignition conditions are met. If the ignition conditions are not met, return to step S4. If the ignition conditions are met, ignite and conduct a combustible gas combustion characteristic experiment. After completing the combustible gas combustion characteristic experiment, proceed to the next step S6. S6: After completing the whole lithium battery pyrolysis experiment and the combustible gas combustion characteristic experiment, the pyrolysis furnace (100) and the smoke collection tank (200) are purged and cooled. After the closed system is cooled to room temperature, the experiment ends.

10. The experimental method for the pyrolysis pretreatment and flue gas safety treatment system for decommissioned lithium batteries according to claim 9, characterized in that, In step S2, the atmosphere replacement and leak detection operation specifically includes the following steps: S21: Vacuuming: Start the vacuum pump on the vacuum pipeline (209) to perform vacuuming operation on the pyrolysis furnace (100) and the smoke collection tank (200); Specifically, the control and data acquisition unit (300) monitors the data of the pressure sensor (211) in real time until the pressure of the sealed system drops to the preset vacuum threshold of -0.095MPa; S22: Inert gas filling: After the vacuuming operation is completed, close the vacuum pump and valve, and introduce nitrogen through the inert gas inlet (102) to fill the pyrolysis furnace (100) and the smoke collection tank (200) with nitrogen to carry out the inert gas filling operation; specifically, until the pressure value detected by the pressure sensor (211) returns to a slight positive pressure of 0.02MPa; S23: Cycling and Leak Detection: Repeat the vacuuming and inert gas charging processes of steps S21 and S22 at least twice, and charge the inert gas to the set pressure on the last charge. Afterwards, close all intake valves, and the sealed system enters a pressure holding and static state to complete the circulation and leak detection operations; S24. The control and data acquisition unit (300) continuously monitors the pressure collected by the pressure sensor (211) and sets the time interval for collecting the pressure. For 5 minutes, by pressure change rate Determine the airtightness of the system; when the pressure change rate of the closed system... If the pressure change rate is less than 0.001 MPa / min, the system is considered to have no leakage, and the next step can be performed; when the pressure change rate of the closed system is less than 0.001 MPa / min, the system is considered to have no leakage, and the next step can be performed. If the pressure is greater than or equal to 0.001 MPa / min, the system is determined to have a leak, the alarm will sound, and the experiment will be terminated.

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