Coating filter element on-line switching, cleaning and standby state maintaining system and working method
The automatic switching system for online and standby filter cartridges solves the problems of slurry quality fluctuations and slurry waste during filter cartridge switching in the lithium-ion battery electrode slurry coating process. It achieves stability in slurry flow and pressure, improves the filtration performance and lifespan of the filter cartridges, and meets the production continuity and environmental protection requirements of high-end lithium-ion battery manufacturing.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- CHANGDE COSPOWERS NEW ENERGY TECH CO LTD
- Filing Date
- 2025-12-29
- Publication Date
- 2026-04-21
AI Technical Summary
In the current lithium-ion battery electrode slurry coating process, there are problems such as slurry quality fluctuations, slurry waste, and uncertainty in the reliability and lifespan of spare filter elements when switching filters, which leads to uneven coating and increased environmental pressure.
An automatic switching system for online and standby filter cartridges is adopted. The PLC controller monitors the pressure sensor data to achieve online cleaning and standby status maintenance of the filter cartridges. This ensures that the filter cartridges are always filled with NMP solvent and kept in a sealed state to prevent air from entering. The backwashing mechanism recovers residual slurry, reducing solvent consumption and waste liquid discharge.
It achieves stable slurry flow and pressure, reduces coating defects, recovers high-value slurry, improves the filtration performance and lifespan of filter elements, and ensures production continuity and environmental friendliness.
Smart Images
Figure CN121891840A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to a system and method for online switching, cleaning, and standby status maintenance of coated filter elements, belonging to the field of lithium-ion battery electrode manufacturing technology. Background Technology
[0002] In the coating production of lithium-ion battery electrode slurry, the slurry must undergo high-precision filtration before being conveyed to the coating head to remove gel clumps, impurities, and large, undispersed particles generated during stirring and conveying, ensuring uniformity, consistency, and defect-free coating. Currently, high-end coating machines generally employ a dual-filter system with one filter in use and one on standby, allowing switching to the other if one filter becomes clogged, thus ensuring continuous production.
[0003] However, existing one-in-one-out filtration systems have the following significant technical drawbacks: 1. Fluctuations in slurry quality during switching: Before being put into use, the spare filter cartridge is filled with air in its internal cavity and filter membrane. When switching occurs, the slurry suddenly enters and comes into contact with the air and the dry filter membrane, which can easily generate air bubbles. Due to the instability of the initial resistance of the filter membrane, the slurry flow and pressure may pulsate at the moment of switching. This fluctuation will be directly transmitted to the coating head, causing temporary uneven coating weight or quality defects such as streaks.
[0004] 2. Slurry waste and environmental pressure: A filter cartridge that has reached the end of its service life will have a large amount of valuable slurry (especially precious metals such as lithium cobalt oxide and lithium iron phosphate) remaining inside its connecting pipes. If it is directly disassembled and replaced, this part of the slurry can only be scrapped, resulting in direct economic losses. At the same time, manual cleaning of clogged filter cartridges requires a large amount of N-methylpyrrolidone (NMP) solvent, generating a large amount of waste liquid, which increases the cost and pressure of subsequent environmental treatment.
[0005] 3. Uncertainty regarding the reliability and lifespan of spare filter cartridges: Traditional spare filter cartridges are kept in a dry state for a long time. The filter membrane may become damp due to ambient humidity or be exposed to dust in the air, affecting its filtration performance and service life. It cannot be guaranteed that it can be put into operation 100% reliably and efficiently when needed. Summary of the Invention
[0006] To address the problems existing in the background art, the present invention provides a system and method for online switching, cleaning, and standby status maintenance of coated filter elements.
[0007] To achieve the above objectives, the present invention adopts the following technical solution: a system for online switching, cleaning, and standby maintenance of coated filter elements, comprising an online filter element, a standby filter element, a screw pump I, a main three-way valve, an online filter element feed valve, an online filter element discharge valve, a standby filter element feed valve, a standby filter element discharge valve, an NMP storage tank, a screw pump II, an NMP main valve, an online NMP valve, a standby NMP valve, an online automatic exhaust valve, a standby automatic exhaust valve, a PLC controller, a slurry source, and a slurry source valve; The discharge end of the slurry source is equipped with a slurry source valve and is connected to the inlet end of the screw pump. The discharge end of the screw pump is connected to the inlet ends of the parallel online slurry pipeline and the standby slurry pipeline via a main three-way valve. The online slurry pipeline is equipped with an online filter element inlet valve, an online filter element, and an online filter element outlet valve in sequence. The standby slurry pipeline is equipped with a standby filter element inlet valve, a standby filter element, and a standby filter element outlet valve in sequence. The discharge ends of both the online slurry pipeline and the standby slurry pipeline are connected to the coating machine die head. The discharge end of the NMP storage tank is connected to the inlet end of the screw pump II. The discharge end of the screw pump II is connected to the inlet ends of both the parallel online NMP pipeline and the standby NMP pipeline via the NMP main valve. The online NMP pipeline is equipped with an online NMP valve, and its discharge end is connected to the inlet end of the online filter element. The discharge end of the online NMP pipeline is located between the online filter element inlet valve and the online filter element. The standby NMP pipeline is equipped with a standby NMP valve, and its discharge end is connected to the inlet end of the standby filter element. The discharge end of the standby NMP pipeline is located between the standby filter element inlet valve and the standby filter element. The online filter element is equipped with an online automatic vent valve on its top, and the spare filter element is equipped with a spare automatic vent valve on its top; pressure sensors are installed at the feed end and discharge end of both the online filter element and the spare filter element. The screw pump 1, main three-way valve, online filter element feed valve, online filter element discharge valve, standby filter element feed valve, standby filter element discharge valve, screw pump 2, NMP main valve, online NMP valve, standby NMP valve, online automatic air vent valve, standby automatic air vent valve, slurry source valve, and pressure sensors at the feed and discharge ends of the online and standby filter elements are all connected to the PLC controller for signal transmission.
[0008] Furthermore, the system also includes a backwashing and recovery mechanism, which includes a compressed air source, an online recovery valve, a backup recovery valve, an online backwash valve, a backup backwash valve, a recovery tank, and a compressed air source valve; The outlet of the compressed air source is connected to the inlet of the compressed air source valve, and the outlet of the compressed air source valve is connected to the inlet of both the online NMP pipeline and the standby NMP pipeline. The discharge end of the online NMP pipeline is also connected to the inlet end of the online backwash pipeline. The discharge end of the online backwash pipeline is connected to the inlet end of the online backwash valve. The discharge end of the online backwash valve is connected to the discharge end of the online filter element. The discharge end of the online backwash valve is located between the online filter element and the online filter element discharge valve. The inlet end of the online filter element is connected to the inlet end of the online recovery pipeline. The inlet end of the online recovery pipeline is located between the online filter element inlet valve and the online filter element. The discharge end of the online recovery pipeline is connected to the recovery tank. An online recovery valve is provided on the online recovery pipeline. The discharge end of the backup NMP pipeline is also connected to the inlet end of the backup backwash pipeline. The discharge end of the backup backwash pipeline is connected to the inlet end of the backup backwash valve. The discharge end of the backup backwash valve is connected to the discharge end of the backup filter element. The discharge end of the backup backwash valve is located between the backup filter element and the backup filter element discharge valve. The inlet end of the backup filter element is connected to the inlet end of the backup recovery pipeline. The inlet end of the backup recovery pipeline is located between the backup filter element inlet valve and the backup filter element. The discharge end of the backup recovery pipeline is connected to the recovery tank. A backup recovery valve is provided on the backup recovery pipeline.
[0009] The online recovery valve, standby recovery valve, online backflushing valve, standby backflushing valve, and compressed air source valve are all connected to the PLC controller for signal transmission.
[0010] The present invention discloses a method for operating a coated filter cartridge online switching, cleaning, and standby status maintenance system, the method comprising the following steps: S1: The spare filter element is filled with NMP and is in a sealed, static standby state; S2: Real-time monitoring of the differential pressure of the online filter element, and automatic switching to the backup filter element when the threshold is reached; S3: Automatic backwashing of the cut-out, failed online filter cartridges to recover residual slurry; S4: The cleaned online filter element is used as a new backup filter element and re-initialized for standby.
[0011] Furthermore, step S1 includes the following steps: S101: Close the standby filter element feed valve, standby filter element discharge valve, online NMP valve and standby recovery valve, and open the standby NMP valve and standby automatic exhaust valve; S102: Start screw pump two and open the NMP main valve to inject NMP solvent into the housing of the spare filter element until NMP overflows from the spare automatic vent valve; S103: Close the standby NMP valve and the standby automatic vent valve to put the standby filter element in a sealed static standby state filled with NMP.
[0012] Furthermore, step S2 includes the following steps: S201: Open the inlet valve and outlet valve of the online filter element to enable the online filter element to perform filtration. The PLC controller collects the pressure data at the inlet and outlet of the online filter element in real time and calculates the pressure difference. S202: When the pressure difference reaches the preset threshold, the PLC controller opens the spare filter element feed valve and the spare filter element discharge valve, so that the spare filter element is connected to the slurry flow path; S203: After the standby filter element has been running stably, close the online filter element feed valve and the online filter element discharge valve to complete the switch from the online filter element to the standby filter element.
[0013] Furthermore, step S3 includes the following steps: S301: Open the online backwash valve and online recovery valve corresponding to the online filter element, and open the compressed air source valve to introduce compressed gas into the online filter element for reverse purging; S302: After purging, open the online NMP valve, inject NMP solvent into the online filter element for low-pressure flushing, and discharge the residual slurry from the online recovery valve to the recovery tank; S303: After rinsing is complete, close the online NMP valve, online backwash valve, and online recovery valve.
[0014] Furthermore, step S4 includes the following steps: S401: For online filter cartridges that have completed backwashing, repeat the operations of S101-S103, inject NMP into the housing and seal it; S402: Puts the online filter element into a sealed static standby state, ready to be switched on as a new standby filter element.
[0015] Compared with the prior art, the beneficial effects of the present invention are: The spare filter cartridge of this invention is always filled with NMP solvent and kept in a sealed static standby state. Its physical and chemical environment is highly compatible with the slurry. When switching, the slurry directly wets the pre-filled filter membrane, avoiding air mixing and sudden changes in drying resistance, ensuring stable slurry flow and pressure, and fundamentally eliminating quality defects such as uneven coating weight and streaks. This invention uses a backwashing and recovery mechanism to perform compressed gas reverse purging and low-pressure NMP solvent rinsing on the cut-out filter cartridges, efficiently recovering the high-value slurry remaining in the filter cartridges and pipelines, reducing direct scrap losses, and at the same time reducing solvent consumption and waste liquid discharge during manual cleaning. The spare filter cartridge of this invention maintains a sealed state of continuous NMP impregnation, preventing the filter membrane from getting damp, dusty, or drying out and failing, ensuring immediate availability during switching, and improving the stability of filtration performance and service life. This invention's PLC controller comprehensively monitors pressure sensor data, valve timing, and actuator actions, achieving seamless integration of the entire process from online filtration, automatic switching, backwashing recovery, to standby state reset. This reduces human intervention errors and forms an intelligent, continuous, and low-interference production closed loop, meeting the core requirements of high-end lithium-ion battery manufacturing for production continuity, product consistency, and green manufacturing. Attached Figure Description
[0016] Figure 1 This is a schematic diagram of the system structure of the present invention; Figure 2 This is a schematic diagram of the state of method S1 of the present invention; Figure 3 This is a schematic diagram of the state of method S201 of the present invention; Figure 4 This is a schematic diagram of the state of method S202 of the present invention; Figure 5 This is a schematic diagram of the state of method S3 of the present invention; Figure 6 This is a flowchart of the method of the present invention. Detailed Implementation
[0017] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the invention, not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.
[0018] A system for online switching, cleaning, and standby maintenance of coated filter cartridges includes an online filter cartridge 1, a standby filter cartridge 2, a screw pump 1 3, a main three-way valve 4, an online filter cartridge inlet valve 5, an online filter cartridge outlet valve 6, a standby filter cartridge inlet valve 7, a standby filter cartridge outlet valve 8, an NMP storage tank 9, a screw pump 2 10, an NMP main valve 11, an online NMP valve 12, a standby NMP valve 13, an online automatic vent valve 15, a standby automatic vent valve 16, a PLC controller 21, a slurry source 22, and a slurry source valve 25. The discharge end of the slurry source 22 is equipped with a slurry source valve 25 and is connected to the inlet end of the screw pump 3. The discharge end of the screw pump 3 is connected to the inlet ends of the parallel online slurry pipeline and the standby slurry pipeline through the main three-way valve 4. The online slurry pipeline is equipped with an online filter element inlet valve 5, an online filter element 1, and an online filter element outlet valve 6 in sequence. The standby slurry pipeline is equipped with a standby filter element inlet valve 7, a standby filter element 2, and a standby filter element outlet valve 8 in sequence. The discharge ends of both the online slurry pipeline and the standby slurry pipeline are connected to the coating machine die head. The discharge end of the NMP storage tank 9 is connected to the inlet end of the screw pump 10. The discharge end of the screw pump 10 is connected to the inlet ends of both the parallel online NMP pipeline and the standby NMP pipeline via the NMP main valve 11. The online NMP pipeline is equipped with an online NMP valve 12, and its discharge end is connected to the inlet end of the online filter element 1. The discharge end of the online NMP pipeline is located between the online filter element inlet valve 5 and the online filter element 1. The standby NMP pipeline is equipped with a standby NMP valve 13, and its discharge end is connected to the inlet end of the standby filter element 2. The discharge end of the standby NMP pipeline is located between the standby filter element inlet valve 7 and the standby filter element 2. The online filter element 1 is equipped with an online automatic vent valve 15 on its top, and the spare filter element 2 is equipped with a spare automatic vent valve 16 on its top; the automatic vent valve can automatically close when the liquid is full.
[0019] Pressure sensors are installed at both the inlet and outlet ends of the online filter element 1 and the standby filter element 2 to monitor the real-time pressure drop of the filter elements.
[0020] The following components are connected to the PLC controller 21 for signal transmission: screw pump 1 (3), main three-way valve (4), online filter element feed valve (5), online filter element discharge valve (6), standby filter element feed valve (7), standby filter element discharge valve (8), screw pump 2 (10), NMP main valve (11), online NMP valve (12), standby NMP valve (13), online automatic vent valve (15), standby automatic vent valve (16), slurry source valve (25), and pressure sensors at the feed and discharge ends of online filter element 1 and standby filter element 2.
[0021] The PLC controller 21 is configured to execute pre-stored control programs, connect to all sensors and valves, receive real-time data from pressure sensors, temperature sensors and flow meters, determine the degree of filter clogging and trigger switching logic, and automatically control the operation, switching, cleaning and standby status maintenance of the entire system.
[0022] Furthermore, the system also includes a backwashing and recovery mechanism, which includes a compressed air source 14, an online recovery valve 17, a standby recovery valve 18, an online backwash valve 19, a standby backwash valve 20, a recovery tank 23, and a compressed air source valve 24. The outlet of the compressed air source 14 is connected to the inlet of the compressed air source valve 24, and the outlet of the compressed air source valve 24 is connected to the inlet of both the online NMP pipeline and the standby NMP pipeline. The discharge end of the online NMP pipeline is also connected to the inlet end of the online backwash pipeline. The discharge end of the online backwash pipeline is connected to the inlet end of the online backwash valve 19. The discharge end of the online backwash valve 19 is connected to the discharge end of the online filter element 1. The discharge end of the online backwash valve 19 is located between the online filter element 1 and the online filter element discharge valve 6. The inlet end of the online filter element 1 is connected to the inlet end of the online recovery pipeline. The inlet end of the online recovery pipeline is located between the online filter element inlet valve 5 and the online filter element 1. The discharge end of the online recovery pipeline is connected to the recovery tank 23. An online recovery valve 17 is provided on the online recovery pipeline. The discharge end of the backup NMP pipeline is also connected to the inlet end of the backup backwash pipeline. The discharge end of the backup backwash pipeline is connected to the inlet end of the backup backwash valve 20. The discharge end of the backup backwash valve 20 is connected to the discharge end of the backup filter element 2. The discharge end of the backup backwash valve 20 is located between the backup filter element 2 and the backup filter element discharge valve 8. The inlet end of the backup filter element 2 is connected to the inlet end of the backup recovery pipeline. The inlet end of the backup recovery pipeline is located between the backup filter element inlet valve 7 and the backup filter element 2. The discharge end of the backup recovery pipeline is connected to the recovery tank 23. A backup recovery valve 18 is provided on the backup recovery pipeline.
[0023] Online recovery valve 17, standby recovery valve 18, online backflushing valve 19, standby backflushing valve 20, and compressed air source valve 24 are all connected to the PLC controller 21 for signal transmission.
[0024] The present invention discloses a method for operating a coated filter cartridge online switching, cleaning, and standby status maintenance system, the method comprising the following steps: S1: Spare filter element 2 is filled with NMP and is in a sealed, static standby state; S2: Monitor the pressure difference of online filter element 1 in real time and automatically switch to backup filter element 2 when the threshold is reached; S3: Automatic backwashing of the cut-out, failed online filter element 1 to recover residual slurry; the backwashing process effectively removes the particles accumulated inside the filter element and restores permeability.
[0025] S4: The cleaned online filter element 1 is used as a new backup filter element and re-initialized for standby.
[0026] The system operates in a continuous cycle, enabling automatic switching and cleaning without shutting down the system, significantly improving operating efficiency and extending filter life. The entire backwashing and regeneration process is executed automatically without interrupting the main process feed, ensuring continuous production.
[0027] Furthermore, step S1 includes the following steps: S101: Close the standby filter element feed valve 7, standby filter element discharge valve 8, online NMP valve 12 and standby recovery valve 18, and open the standby NMP valve 13 and standby automatic exhaust valve 16. S102: Start screw pump 2 10 and open NMP main valve 11 to inject NMP solvent into the housing of spare filter element 2 until NMP overflows from spare automatic exhaust valve 16; S103: Close the standby NMP valve 13 and the standby automatic exhaust valve 16 to put the standby filter element 2 in a sealed static standby state filled with NMP. This state effectively prevents the standby filter element 2 from drying out and becoming contaminated, and maintains its activity so that it can be put into operation at any time.
[0028] Furthermore, step S2 includes the following steps: S201: Open the inline filter element feed valve 5 and the inline filter element discharge valve 6 to enable the inline filter element 1 to perform filtration. The PLC controller 21 collects the pressure data at the feed end and discharge end of the inline filter element 1 in real time and calculates the pressure difference. S202: When the pressure difference reaches the preset threshold, the PLC controller 21 opens the backup filter element feed valve 7 and the backup filter element discharge valve 8, so that the backup filter element 2 is connected to the slurry flow path; the system briefly opens the backup filter element feed valve 7, the backup filter element discharge valve 8 and the online valve 1 5 and the online valve 2 6 to realize the parallel conduction of the two paths and ensure the pressure transition is stable.
[0029] The preset filter element pressure differential switching threshold of PLC controller 21 is 0.2~0.4MPa.
[0030] S203: After the standby filter element 2 has been running stably, close the online filter element feed valve 5 and the online filter element discharge valve 6 to complete the switch from online filter element 1 to standby filter element 2.
[0031] Furthermore, step S3 includes the following steps: S301: Open the online backwash valve 19 and the online recovery valve 17 corresponding to the online filter element 1, and open the compressed air source valve 24 to introduce compressed gas into the online filter element 1 for reverse purging; S302: After purging, open the online NMP valve 12 and inject NMP solvent into the online filter element 1 for low-pressure rinsing. The flow direction is opposite to the normal filtration direction. The residual slurry is discharged from the online recovery valve 17 to the recovery tank 23. First, use compressed gas at 0.5~1.0 bar for a short period of purging, then inject an appropriate amount of NMP for low-pressure flushing to save solvent.
[0032] S303: After rinsing is complete, close the online NMP valve 12, the online backwash valve 19, and the online recovery valve 17.
[0033] Furthermore, step S4 includes the following steps: S401: For the online filter element 1 that has completed backwashing, repeat the operations of S101-S103, inject NMP into its housing and seal it; S402: Put online filter element 1 into a sealed static standby state, serving as a new standby filter element awaiting switching.
[0034] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of the equivalents of the claims are intended to be included within the present invention. No reference numerals in the claims should be construed as limiting the scope of the claims.
[0035] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.
Claims
1. A system for online switching, cleaning, and standby maintenance of coated filter cartridges, characterized in that: Includes online filter element (1), spare filter element (2), screw pump one (3), main three-way valve (4), online filter element feed valve (5), online filter element discharge valve (6), spare filter element feed valve (7), spare filter element discharge valve (8), NMP storage tank (9), screw pump two (10), NMP main valve (11), online NMP valve (12), spare NMP valve (13), online automatic exhaust valve (15), spare automatic exhaust valve (16), PLC controller (21), slurry source (22), and slurry source valve (25); The discharge end of the slurry source (22) is equipped with a slurry source valve (25) and is connected to the inlet end of the screw pump (3). The discharge end of the screw pump (3) is connected to the inlet ends of the parallel online slurry pipeline and the standby slurry pipeline through the main three-way valve (4). The online slurry pipeline is provided with an online filter element inlet valve (5), an online filter element (1) and an online filter element outlet valve (6) in sequence. The standby slurry pipeline is provided with a standby filter element inlet valve (7), a standby filter element (2) and a standby filter element outlet valve (8) in sequence. The discharge ends of the online slurry pipeline and the standby slurry pipeline are connected to the coating machine die head. The discharge end of the NMP storage tank (9) is connected to the inlet end of the screw pump (10). The discharge end of the screw pump (10) is connected to the inlet ends of the parallel online NMP pipeline and the standby NMP pipeline through the NMP main valve (11). The online NMP pipeline is equipped with an online NMP valve (12). The discharge end of the online NMP pipeline is connected to the inlet end of the online filter element (1). The discharge end of the online NMP pipeline is located between the online filter element inlet valve (5) and the online filter element (1). The standby NMP pipeline is equipped with a standby NMP valve (13). The discharge end of the standby NMP pipeline is connected to the inlet end of the standby filter element (2). The discharge end of the standby NMP pipeline is located between the standby filter element inlet valve (7) and the standby filter element (2). The online filter element (1) is equipped with an online automatic exhaust valve (15) on its top, and the spare filter element (2) is equipped with a spare automatic exhaust valve (16) on its top; pressure sensors are installed at the feed end and the discharge end of both the online filter element (1) and the spare filter element (2); The screw pump 1 (3), main three-way valve (4), online filter element feed valve (5), online filter element discharge valve (6), standby filter element feed valve (7), standby filter element discharge valve (8), screw pump 2 (10), NMP main valve (11), online NMP valve (12), standby NMP valve (13), online automatic exhaust valve (15), standby automatic exhaust valve (16), slurry source valve (25), and the pressure sensors at the feed end and discharge end of online filter element (1) and standby filter element (2) are all connected to the PLC controller (21) for signal transmission.
2. The online switching, cleaning, and standby status maintenance system for coated filter elements according to claim 1, characterized in that: The system also includes a backwashing and recovery mechanism, which includes a compressed air source (14), an online recovery valve (17), a standby recovery valve (18), an online backwash valve (19), a standby backwash valve (20), a recovery tank (23), and a compressed air source valve (24). The outlet of the compressed air source (14) is connected to the inlet of the compressed air source valve (24), and the outlet of the compressed air source valve (24) is connected to the inlet of both the online NMP pipeline and the standby NMP pipeline. The discharge end of the online NMP pipeline is also connected to the inlet end of the online backwash pipeline. The discharge end of the online backwash pipeline is connected to the inlet end of the online backwash valve (19). The discharge end of the online backwash valve (19) is connected to the discharge end of the online filter element (1). The discharge end of the online backwash valve (19) is located between the online filter element (1) and the online filter element discharge valve (6). The inlet end of the online filter element (1) is connected to the inlet end of the online recovery pipeline. The inlet end of the online recovery pipeline is located between the online filter element inlet valve (5) and the online filter element (1). The discharge end of the online recovery pipeline is connected to the recovery tank (23). An online recovery valve (17) is provided on the online recovery pipeline. The discharge end of the backup NMP pipeline is also connected to the inlet end of the backup backwash pipeline. The discharge end of the backup backwash pipeline is connected to the inlet end of the backup backwash valve (20). The discharge end of the backup backwash valve (20) is connected to the discharge end of the backup filter element (2). The discharge end of the backup backwash valve (20) is located between the backup filter element (2) and the backup filter element discharge valve (8). The inlet end of the backup filter element (2) is connected to the inlet end of the backup recovery pipeline. The inlet end of the backup recovery pipeline is located between the backup filter element inlet valve (7) and the backup filter element (2). The discharge end of the backup recovery pipeline is connected to the recovery tank (23). A backup recovery valve (18) is provided on the backup recovery pipeline. The online recovery valve (17), the standby recovery valve (18), the online backwash valve (19), the standby backwash valve (20), and the compressed air source valve (24) are all connected to the PLC controller (21) for signal transmission.
3. A method for operating the online switching, cleaning, and standby status maintenance system for coated filter cartridges according to claim 1 or 2, characterized in that: The method includes the following steps: S1: The spare filter element (2) is filled with NMP and is in a sealed static standby state; S2: Real-time monitoring of the differential pressure of the online filter element (1), and automatic switching to the backup filter element (2) when the threshold is reached. S3: Automatic backwashing of the cut-out failed online filter cartridge (1) to recover residual slurry; S4: The cleaned online filter element (1) is used as a new spare filter element and re-initialized for standby.
4. The online switching, cleaning, and standby status maintenance system for coated filter elements according to claim 3, characterized in that: S1 includes the following steps: S101: Close the standby filter element feed valve (7), standby filter element discharge valve (8), online NMP valve (12) and standby recovery valve (18), and open the standby NMP valve (13) and standby automatic exhaust valve (16). S102: Start screw pump two (10) and open the NMP main valve (11) to inject NMP solvent into the housing of the spare filter element (2) until NMP overflows from the spare automatic exhaust valve (16); S103: Close the standby NMP valve (13) and the standby automatic exhaust valve (16) to put the standby filter element (2) into a sealed static standby state filled with NMP.
5. The online switching, cleaning, and standby status maintenance system for coated filter elements according to claim 4, characterized in that: S2 includes the following steps: S201: Open the inlet valve (5) and outlet valve (6) of the online filter element to enable the online filter element (1) to perform filtration. The PLC controller (21) collects the pressure data of the inlet and outlet of the online filter element (1) in real time and calculates the pressure difference. S202: When the pressure difference reaches the preset threshold, the PLC controller (21) opens the spare filter element feed valve (7) and the spare filter element discharge valve (8) to connect the spare filter element (2) to the slurry flow path; S203: After the standby filter element (2) is running stably, close the online filter element feed valve (5) and the online filter element discharge valve (6) to complete the switching from the online filter element (1) to the standby filter element (2).
6. The online switching, cleaning, and standby status maintenance system for coated filter elements according to claim 5, characterized in that: S3 includes the following steps: S301: Open the online backwash valve (19) and online recovery valve (17) corresponding to the online filter element (1), and open the compressed air source valve (24) to introduce compressed gas into the online filter element (1) for reverse purging; S302: After purging, open the online NMP valve (12) and inject NMP solvent into the online filter element (1) for low-pressure rinsing. The residual slurry is then discharged from the online recovery valve (17) to the recovery tank (23). S303: After rinsing is complete, close the online NMP valve (12), the online backwash valve (19), and the online recovery valve (17).
7. The online switching, cleaning, and standby status maintenance system for coated filter elements according to claim 6, characterized in that: S4 includes the following steps: S401: For the online filter element (1) that has completed backwashing, repeat the operations of S101-S103, inject NMP into its housing and seal it; S402: Put the online filter element (1) into a sealed static standby state, and wait for switching as a new standby filter element.