Device and control method for cleaning the inner wall of PFA pipelines

Abstract

This invention relates to a device and control method for cleaning the inner wall of PFA pipelines, belonging to the technical field of silicon wafer processing equipment. It includes an inlet pipe, a flushing pipe, and a solution tank. The inlet pipe and flushing pipe are connected to the pipe fittings at both ends of the PFA pipeline. The solution tank is equipped with a partition, dividing the tank into a mixing chamber and a recovery chamber. A return pipe is provided between the inlet pipe and the recovery chamber, and a filter element is installed on the return pipe. A suction pipe is provided between the flushing pipe and the mixing chamber, and a diaphragm pump is installed between the suction pipe and the flushing pipe. It has the advantages of simple structure, good operational stability, safety and reliability, and energy saving and cost reduction. It solves the problem of crystallization of PFA pipeline polishing fluid. By cleaning the pipeline, the pipeline can be recycled.

Description

Technical Field

[0001] This invention relates to the field of silicon wafer processing equipment technology, specifically to a device and control method for cleaning the inner wall of PFA pipelines. Background Technology

[0002] In the semiconductor silicon wafer polishing process, silicon and silicon dioxide crystals will form on the pipe walls of the pipelines involved in the recycling and reuse of polishing slurry. These pipelines are often quite long (10-20m).

[0003] If the original grinding fluid is replaced with KOH for circulating flushing without disassembling the pipeline, the originally loose crystals in the pipeline will melt and clump together, resulting in extremely poor cleaning effect.

[0004] When the pipes are disassembled and soaked in HF in a tank-type component cleaning machine, although the crystals near the pipe opening can be cleaned, the cleaning effect on crystals more than 2m away from the pipe opening is extremely poor.

[0005] The current mainstream solution is to replace the pipeline with a new one. However, PFA pipes are not only expensive and have long delivery times, but also represent an unsustainable waste of valuable resources.

[0006] There are no complete sets of products on the market specifically designed for cleaning this type of pipeline. The simple pump cleaning structure is too simplistic and poses a significant safety hazard, making it extremely easy for personal injury accidents to occur. Summary of the Invention

[0007] This invention addresses the shortcomings of existing technologies by providing a device and control method for cleaning the inner wall of PFA pipelines. It features simple structure, good operational stability, safety, reliability, and energy saving. It also solves the problem of crystallization in PFA pipe polishing fluid. By cleaning the pipeline, it enables its recycling.

[0008] The above-mentioned technical problems of the present invention are mainly solved by the following technical solutions:

[0009] A device for cleaning the inner wall of a PFA pipeline includes an inlet pipe, a flushing pipe, and a solution tank. The inlet pipe and the flushing pipe are connected to the pipe joints at both ends of the PFA pipeline, respectively. The solution tank is equipped with a partition that divides the solution tank into a mixing chamber and a recovery chamber. A return pipe is provided between the inlet pipe and the recovery chamber, and a filter element is provided on the return pipe. A suction pipe is provided between the flushing pipe and the mixing chamber, and a diaphragm pump is provided between the suction pipe and the flushing pipe.

[0010] Preferably, the lower part of the liquid tank is provided with a drain pipe that is connected to the inlet pipe and the filter element respectively. A pressure gauge is provided on the flushing pipe. A three-way connector is provided between the drain pipe and the inlet pipe, and between the pressure gauge and the flushing pipe. An AV15 pneumatic valve is provided between the three-way connector and the drain pipe. An AV14 pneumatic valve is provided between the filter element and the drain pipe. An AV12 pneumatic valve, which is connected and fixed to the drain pipe, is provided between the AV14 pneumatic valve and the recovery chamber.

[0011] Preferably, a flow meter is provided between the filter element and the three-way connector, an AV1 pneumatic valve is provided between the flow meter and the three-way connector, a pH meter is provided between the flow meter and the filter element, and an AV13 pneumatic valve connected to the return pipe is provided between the filter element and the recovery chamber.

[0012] Preferably, the side of the medicine tank is provided with, from top to bottom, an HNO3 replenishment pipe, an HF replenishment pipe, and a water replenishment pipe that communicate with the mixing chamber. The HNO3 replenishment pipe is equipped with an AV11 pneumatic valve, the HF replenishment pipe with an AV9 pneumatic valve, and the water replenishment pipe with an AV10 pneumatic valve. The mixing chamber is equipped with level sensors, which, from top to bottom, are a maximum level sensor, an HNO3 level sensor, an HF level sensor, a water level sensor, and a minimum level sensor.

[0013] Preferably, reducing couplings are provided between the inlet pipe and the PFA pipeline, and between the flushing pipe and the PFA pipeline. These reducing couplings facilitate pipeline cleaning or pre-cleaning of components requiring high crystallinity, reducing downtime caused by maintenance. An AV8 pneumatic valve, connected to the suction pipe, is provided between the diaphragm pump and the suction pipe. Manual valves are provided on the sides of the AV11, AV9, and AV10 pneumatic valves, between the pH meter and the filter element, between the reducing coupling and the tee fitting, between the filter element and the AV13 pneumatic valve, and between the AV8 pneumatic valve and the medicine tank.

[0014] Preferably, the three-way connector is provided with an AV6 pneumatic valve between itself and the diaphragm pump, and an overflow pipe is provided between the AV6 pneumatic valve and the diaphragm pump to connect to the mixing chamber, and an AV7 pneumatic valve is provided on the overflow pipe.

[0015] Preferably, a nitrogen pipe and an ultrapure water pipe are provided on the filter element, between the liquid extraction pipe and the diaphragm pump. The nitrogen pipe and the ultrapure water pipe are connected in parallel. An AV2 pneumatic valve is provided between the nitrogen pipe and the filter element. An AV5 pneumatic valve is provided between the nitrogen pipe and the liquid extraction pipe. An AV3 pneumatic valve is provided between the ultrapure water pipe and the filter element. An AV4 pneumatic valve is provided between the ultrapure water pipe and the liquid extraction pipe.

[0016] The control method for the PFA pipeline inner wall cleaning device includes the following operating steps:

[0017] Step 1: The medicine tank is divided into a mixing chamber and a recovery chamber by a partition, allowing for the selection of whether or not to recover the medicine. In the mixing chamber, a minimum liquid level sensor is used to determine whether the medicine tank is empty. Then, the AV10 pneumatic valve on the water supply pipe is opened. When the water level sensor is reached, the AV10 pneumatic valve closes, and the AV9 pneumatic valve on the HF supply pipe opens. When the HF level sensor is reached, the AV9 pneumatic valve closes, and the AV11 pneumatic valve on the HNO3 supply pipe opens. When the HNO3 level sensor is reached, the AV11 pneumatic valve closes, completing the injection process of medicine in the mixing chamber.

[0018] Step 2: Next, open the AV8 pneumatic valve and the AV7 pneumatic valve, and start the diaphragm pump so that the liquid in the mixing chamber flows from the extraction pipe through the overflow pipe to achieve liquid mixing.

[0019] Step 3: Open the AV4 and AV6 pneumatic valves on the ultrapure water pipeline. After the ultrapure water pipeline is pressurized to 5kg by the diaphragm pump, close the AV4 and AV6 pneumatic valves and monitor the pressure change trend of the pressure gauge to ensure that there is no leakage in the pipeline and flushing pipe.

[0020] Step 4: Connect both ends of the PFA pipeline to the inlet pipe and the flushing pipe respectively. Then start the diaphragm pump, open the AV8, AV6, AV1 and AV13 pneumatic valves, and the liquid extraction pipe sends the drug solution in the mixing chamber into the PFA pipeline through the flushing pipe for flushing. Then, through the inlet pipe and the filter element, the drug solution is recovered to the recovery chamber through the return pipe.

[0021] Step 5: When the pH count value stabilizes after cleaning with the chemical solution, the PFA pipeline cleaning is complete.

[0022] Step 6: Open pneumatic valves AV4, AV6, AV1 and AV14. Ultrapure water will be used to flush the PFA pipeline through the diaphragm pump to clean the chemical solution inside the pipeline.

[0023] Step 7: Clean until the pH count is close to that of pure water. Then open the AV5 and AV15 pneumatic valves. At this time, the AV1 and AV8 pneumatic valves are closed. Dry the PFA pipeline with nitrogen through the inlet pipe and flushing pipe.

[0024] Preferably, when the pH meter detects that the PFA pipeline cleaning fluid cannot be reused, the AV1 pneumatic valve is closed and the AV15 pneumatic valve is opened, allowing direct discharge through the drain pipe. When impurities accumulate at the bottom of the recovery chamber, they are discharged through the drain pipe by opening the AV12 pneumatic valve. When the flow meter detects that the flow rate is as low as half of the initial flow rate, the impurities accumulated inside the filter element are flushed by opening the AV2 and AV14 pneumatic valves, allowing the ultrapure water pipe to rinse the filter element. Then, by opening the AV14 pneumatic valve and intermittently switching the AV2 pneumatic valve, nitrogen is supplied through the nitrogen pipe to vibrate the filter element, which is then discharged through the drain pipe, assisting in the separation of impurities inside the filter element. It also features a nitrogen drying function, achieving dry inlet and dry outlet.

[0025] Preferably, the volume ratio of the mixed medicine solution in the cavity is HF:HNO3:H2O=1:3:10.

[0026] Preferably, a pH meter is used to check the effectiveness of the cleaning solution during the cleaning process. If the solution is found to be ineffective, it is re-prepared to ensure rinsing effect and efficiency. Additionally, the pH meter is kept moist throughout the entire control process to extend its lifespan.

[0027] The present invention can achieve the following effects:

[0028] This invention provides a device and control method for cleaning the inner wall of PFA pipelines. Compared with existing technologies, it has the advantages of simple structure, good operational stability, safety and reliability, and energy saving and cost reduction. It solves the problem of crystallization in PFA pipe polishing fluid. By cleaning the pipeline, the pipeline can be recycled.

[0029] This system enables fully automated cleaning of PFA pipes to remove crystallized grinding fluid. Pre-cleaning pressure tests on pipes and interfaces eliminate the possibility of leakage. Mixed-liquid cleaning is fully automated and requires no human intervention. It also features nitrogen drying for dry inlet and dry outlet operation. Attached Figure Description

[0030] Figure 1 This is a schematic diagram of the structure of the present invention.

[0031] In the diagram: 1. Inlet pipe; 2. AV1 pneumatic valve; 3. Flow meter; 4. pH meter; 5. Nitrogen pipe; 6. AV2 pneumatic valve; 7. Ultrapure water pipe; 8. AV3 pneumatic valve; 9. AV4 pneumatic valve; 10. AV5 pneumatic valve; 11. Diaphragm pump; 12. Flushing pipe; 13. Hand valve; 14. AV6 pneumatic valve; 15. Pressure gauge; 16. AV7 pneumatic valve; 17. AV8 pneumatic valve; 18. HNO3 replenishment pipe; 19. HF replenishment pipe; 20. Water replenishment pipe; 21. AV9 pneumatic valve; 22. AV10 pneumatic valve; 23. AV11 pneumatic valve; 24. Overflow pipe; 25. Liquid level sensor; 26. Suction pipe; 27. Medicine tank; 28. AV12 pneumatic valve; 29. ​​Return pipe; 30. AV13 pneumatic valve; 31. AV14 pneumatic valve; 32. Drain pipe; 33. Filter element; 34. AV15 pneumatic valve; 35. T-connector; 36. Reducer. Detailed Implementation

[0032] The technical solution of the invention will be further described in detail below through embodiments and in conjunction with the accompanying drawings.

[0033] Example: Figure 1 As shown, an apparatus and control method for cleaning the inner wall of a PFA pipeline include an inlet pipe 1, a flushing pipe 12, and a solution tank 27. The inlet pipe 1 and the flushing pipe 12 are connected to the pipe fittings at both ends of the PFA pipeline, respectively. A reducing fitting 36 is provided between the inlet pipe 1 and the PFA pipeline, and between the flushing pipe 12 and the PFA pipeline. The solution tank 27 is equipped with a partition, which divides the solution tank 27 into a mixing chamber and a recovery chamber. A return pipe 29 is provided between the inlet pipe 1 and the recovery chamber, and a filter element 33 is provided on the return pipe 29. A suction pipe 26 is provided between the flushing pipe 12 and the mixing chamber. A diaphragm pump 11 is provided between the suction pipe 26 and the flushing pipe 12. An AV8 pneumatic valve 17, connected to the suction pipe 26, is provided between the diaphragm pump 11 and the suction pipe 26.

[0034] The lower part of the liquid tank 27 is equipped with a drain pipe 32 that is connected to the inlet pipe 1 and the filter element 33 respectively. A pressure gauge 15 is installed on the flushing pipe 12. A three-way connector 35 is installed between the drain pipe 32 and the inlet pipe 1, and between the pressure gauge 15 and the flushing pipe 12. An AV6 pneumatic valve 14 is installed between the three-way connector 35 and the diaphragm pump 11. An overflow pipe 24 connected to the mixing chamber is installed between the AV6 pneumatic valve 14 and the diaphragm pump 11. An AV7 pneumatic valve 16 is installed on the overflow pipe 24. A flow meter 3 is installed between the filter element 33 and the three-way connector 35. An AV1 pneumatic valve 2 is installed between the flow meter 3 and the three-way connector 35. A pH meter 4 is installed between the flow meter 3 and the filter element 33. An AV13 pneumatic valve 30 connected to the return pipe 29 is installed between the filter element 33 and the recovery chamber. An AV15 pneumatic valve 34 is provided between the three-way connector 35 and the drain pipe 32, an AV14 pneumatic valve 31 is provided between the filter element 33 and the drain pipe 32, and an AV12 pneumatic valve 28, which is connected to and fixed to the drain pipe 32, is provided between the AV14 pneumatic valve 31 and the recovery chamber.

[0035] The side of the medicine tank 27, from top to bottom, is provided with an HNO3 replenishment pipe 18, an HF replenishment pipe 19, and a water replenishment pipe 20, which are connected to the mixing chamber. The HNO3 replenishment pipe 18 is equipped with an AV11 pneumatic valve 23, the HF replenishment pipe 19 is equipped with an AV9 pneumatic valve 21, and the water replenishment pipe 20 is equipped with an AV10 pneumatic valve 22. Hand valves 13 are provided on the side of the AV11 pneumatic valve 23, the side of the AV9 pneumatic valve 21, the side of the AV10 pneumatic valve 22, between the pH meter 4 and the filter element 33, between the reducer 36 and the tee 35, between the filter element 33 and the AV13 pneumatic valve 30, and between the AV8 pneumatic valve 17 and the medicine tank 27. If any of the following pneumatic valves—AV11 (23), AV9 (21), AV10 (22), AV1 (2), AV6 (14), AV13 (30), and AV8 (17)—is in an abnormal open state and cannot be closed, maintenance can be performed by closing the manual valve 13. The mixing chamber is equipped with level sensors 25, which, from top to bottom, are: highest level sensor, HNO3 level sensor, HF level sensor, water level sensor, and lowest level sensor.

[0036] A nitrogen pipe 5 and an ultrapure water pipe 7 are provided on the filter element 33, between the liquid extraction pipe 26 and the diaphragm pump 11. The nitrogen pipe 5 and the ultrapure water pipe 7 are connected in parallel. An AV2 pneumatic valve 6 is provided between the nitrogen pipe 5 and the filter element 33. An AV5 pneumatic valve 10 is provided between the nitrogen pipe 5 and the liquid extraction pipe 26. An AV3 pneumatic valve 8 is provided between the ultrapure water pipe 7 and the filter element 33. An AV4 pneumatic valve 9 is provided between the ultrapure water pipe 7 and the liquid extraction pipe 26.

[0037] The control method for the PFA pipeline inner wall cleaning device includes the following operating steps:

[0038] Step 1: The medicine tank 27 is divided into a mixing chamber and a recovery chamber by a partition, allowing for the selection of whether or not the medicine is recovered. The mixing chamber uses a minimum liquid level sensor to determine if the medicine tank 27 is empty. Then, the AV10 pneumatic valve 22 on the water supply pipe 20 opens. When the water level reaches the water level sensor, the AV10 pneumatic valve 22 closes, and the AV9 pneumatic valve 21 on the HF supply pipe 19 opens. When the HF level reaches the HF level sensor, the AV9 pneumatic valve 21 closes, and the AV11 pneumatic valve 23 on the HNO3 supply pipe 18 opens. When the HNO3 level reaches the HNO3 level sensor, the AV11 pneumatic valve 23 closes, completing the injection process of the medicine into the mixing chamber. The volume ratio of the medicine in the mixing chamber is HF:HNO3:H2O = 1:3:10.

[0039] Step 2: Next, open the AV8 pneumatic valve 17 and the AV7 pneumatic valve 16, and turn on the diaphragm pump 11 so that the liquid in the mixing chamber flows from the extraction pipe 26 through the overflow pipe 24 to achieve liquid mixing.

[0040] Step 3: Open the AV4 pneumatic valve 9 and AV6 pneumatic valve 14 on the ultrapure water pipe 7. After the ultrapure water pipe 7 is pressurized to 5kg by the diaphragm pump 11, close the AV4 pneumatic valve 9 and AV6 pneumatic valve 14. Monitor the pressure change trend of the pressure gauge 15 to ensure that there is no leakage in the pipeline and flushing pipe 12.

[0041] Step 4: Connect both ends of the PFA pipeline to the inlet pipe 1 and the flushing pipe 12 respectively. Then, start the diaphragm pump 11, open the pneumatic valves AV8 17, AV6 14, AV1 2 and AV13 30, and the liquid extraction pipe 26 sends the drug solution in the mixing chamber into the PFA pipeline through the flushing pipe 12 for flushing. Then, through the inlet pipe 1 and the filter element 33, the drug solution is recovered to the recovery chamber through the return pipe 29.

[0042] Step 5: When the pH meter reading stabilizes at 4, the PFA pipeline cleaning is complete.

[0043] During the cleaning process, a pH meter 4 is used to check if the cleaning solution has become ineffective. If it has, a new solution is prepared to ensure the rinsing effect and efficiency. Additionally, the pH meter 4 is kept moist throughout the entire process to extend its lifespan.

[0044] When pH meter 4 detects that the PFA pipeline cleaning fluid cannot be reused, it closes pneumatic valve 2 of AV1 and opens pneumatic valve 34 of AV15, allowing the fluid to be discharged directly through drain pipe 32. When impurities accumulate at the bottom of the recovery chamber, they are discharged through drain pipe 32 by opening pneumatic valve 22 of AV12. When flow meter 3 detects that the flow rate is as low as 1 / 2 of the initial flow rate, the impurities accumulated in filter element 33 are flushed by opening pneumatic valves 6 of AV2 and 31 of AV14, and ultrapure water pipe 7. Then, by opening pneumatic valve 31 of AV14 and intermittently switching pneumatic valve 6 of AV2, nitrogen pipe 5 is supplied to vibrate filter element 33, which is then discharged through drain pipe 32, assisting in the separation of impurities in filter element 33.

[0045] Step 6: Open pneumatic valves 9 (AV4), 14 (AV6), 2 (AV1), and 31 (AV14). Ultrapure water 7 will flush the PFA pipeline through diaphragm pump 11 to clean the drug solution inside the pipeline.

[0046] Step 7: Clean until the pH meter reading is close to that of pure water. Then open pneumatic valves AV5 10 and AV15 34. At this time, pneumatic valves AV1 2 and AV8 17 are closed. Dry the PFA pipeline with nitrogen through inlet pipe 1 and flushing pipe 12.

[0047] In summary, the device and control method for cleaning the inner wall of PFA pipelines have the advantages of simple structure, good operational stability, safety and reliability, and energy saving and cost reduction. It solves the problem of crystallization in PFA pipe polishing fluid. By cleaning the pipeline, the system enables its recycling.

[0048] The above description is only a specific embodiment of the present invention, but the structural features of the present invention are not limited thereto. Any changes or modifications made by those skilled in the art within the scope of the present invention are covered by the patent scope of the present invention.

Claims

1. An apparatus for cleaning the inner wall of PFA pipelines, characterized in that: It includes an inlet pipe (1), a flushing pipe (12), and a drug tank (27). The inlet pipe (1) and the flushing pipe (12) are connected to the pipe joints at both ends of the PFA pipeline, respectively. The drug tank (27) is equipped with a partition, which divides the drug tank (27) into a mixing chamber and a recovery chamber. A return pipe (29) is provided between the inlet pipe (1) and the recovery chamber. A filter element (33) is provided on the return pipe (29). A suction pipe (26) is provided between the flushing pipe (12) and the mixing chamber. A diaphragm pump (1) is provided between the suction pipe (26) and the flushing pipe (12). 1); Nitrogen pipe (5) and ultrapure water pipe (7) are provided on the filter element (33), between the liquid extraction pipe (26) and the diaphragm pump (11). The nitrogen pipe (5) and ultrapure water pipe (7) are in parallel. An AV2 pneumatic valve (6) is provided between the nitrogen pipe (5) and the filter element (33). An AV5 pneumatic valve (10) is provided between the nitrogen pipe (5) and the liquid extraction pipe (26). An AV3 pneumatic valve (8) is provided between the ultrapure water pipe (7) and the filter element (33). An AV4 pneumatic valve (9) is provided between the ultrapure water pipe (7) and the liquid extraction pipe (26).

2. The apparatus for cleaning the inner wall of PFA pipelines according to claim 1, characterized in that: The lower part of the liquid tank (27) is provided with a drain pipe (32) that is connected to the inlet pipe (1) and the filter element (33). The flushing pipe (12) is provided with a pressure gauge (15). A three-way connector (35) is provided between the drain pipe (32) and the inlet pipe (1) and between the pressure gauge (15) and the flushing pipe (12). An AV15 pneumatic valve (34) is provided between the three-way connector (35) and the drain pipe (32). An AV14 pneumatic valve (31) is provided between the filter element (33) and the drain pipe (32). An AV12 pneumatic valve (28) is provided between the AV14 pneumatic valve (31) and the recovery chamber and is connected and fixed to the drain pipe (32).

3. The apparatus for cleaning the inner wall of PFA pipelines according to claim 2, characterized in that: A flow meter (3) is provided between the filter element (33) and the three-way connector (35), an AV1 pneumatic valve (2) is provided between the flow meter (3) and the three-way connector (35), a pH meter (4) is provided between the flow meter (3) and the filter element (33), and an AV13 pneumatic valve (30) connected to the return pipe (29) is provided between the filter element (33) and the recovery chamber.

4. The apparatus for cleaning the inner wall of PFA pipelines according to claim 3, characterized in that: The side of the liquid tank (27) is provided with an HNO3 replenishment pipe (18), an HF replenishment pipe (19) and a water replenishment pipe (20) connected to the mixing chamber from top to bottom. The HNO3 replenishment pipe (18) is provided with an AV11 pneumatic valve (23), the HF replenishment pipe (19) is provided with an AV9 pneumatic valve (21), and the water replenishment pipe (20) is provided with an AV10 pneumatic valve (22). The mixing chamber is provided with a liquid level sensor (25). The liquid level sensor (25) is provided with the highest liquid level sensor, the HNO3 liquid level sensor, the HF liquid level sensor, the water liquid level sensor and the lowest liquid level sensor from top to bottom.

5. The apparatus for cleaning the inner wall of PFA pipelines according to claim 4, characterized in that: A reducing connector (36) is provided between the liquid inlet pipe (1) and the PFA pipeline, and between the flushing pipe (12) and the PFA pipeline; an AV8 pneumatic valve (17) connected to the liquid extraction pipe (26) is provided between the diaphragm pump (11) and the liquid extraction pipe (26); a hand valve (13) is provided on the side of the AV11 pneumatic valve (23), the side of the AV9 pneumatic valve (21), the side of the AV10 pneumatic valve (22), between the pH meter (4) and the filter element (33), between the reducing connector (36) and the tee connector (35), between the filter element (33) and the AV13 pneumatic valve (30), and between the AV8 pneumatic valve (17) and the medicine tank (27).

6. The apparatus for cleaning the inner wall of PFA pipelines according to claim 5, characterized in that: An AV6 pneumatic valve (14) is provided between the three-way connector (35) and the diaphragm pump (11). An overflow pipe (24) is provided between the AV6 pneumatic valve (14) and the diaphragm pump (11) to connect the mixing chamber. An AV7 pneumatic valve (16) is provided on the overflow pipe (24).

7. A control method for the PFA pipeline inner wall cleaning device according to claim 6, characterized in that... The following steps are included: Step 1: The medicine tank (27) is divided into a mixing chamber and a recovery chamber by a partition to enable the selection of whether or not to recover the medicine. The lowest liquid level sensor in the mixing chamber is used as the basis for judging whether the medicine tank (27) is empty. Then, the AV10 pneumatic valve (22) on the water supply pipe (20) is opened. When the water level sensor is reached, the AV10 pneumatic valve (22) is closed and the AV9 pneumatic valve (21) on the HF supply pipe (19) is opened. When the HF level sensor is reached, the AV9 pneumatic valve (21) is closed and the AV11 pneumatic valve (23) on the HNO3 supply pipe (18) is opened. When the HNO3 level sensor is reached, the AV11 pneumatic valve (23) is closed, thus completing the injection process of the medicine in the mixing chamber. Step 2: Next, open the AV8 pneumatic valve (17) and the AV7 pneumatic valve (16), and turn on the diaphragm pump (11) so that the liquid in the mixing chamber flows from the liquid extraction pipe (26) through the overflow pipe (24) to achieve liquid mixing and fusion. Step 3: Open the AV4 pneumatic valve (9) and AV6 pneumatic valve (14) on the ultrapure water pipe (7). After the ultrapure water pipe (7) is pressurized to 5kg by the diaphragm pump (11), close the AV4 pneumatic valve (9) and AV6 pneumatic valve (14), monitor the pressure change trend of the pressure gauge (15), and ensure that there is no leakage in the pipeline and flushing pipe (12). Step 4: Connect both ends of the PFA pipeline to the inlet pipe (1) and the flushing pipe (12) respectively. Then, start the diaphragm pump (11), open the AV8 pneumatic valve (17), AV6 pneumatic valve (14), AV1 pneumatic valve (2) and AV13 pneumatic valve (30), and send the liquid in the mixing chamber into the PFA pipeline through the flushing pipe (12) for flushing. Then, through the inlet pipe (1) and the filter element (33), the liquid is recovered to the recovery chamber through the return pipe (29). Step 5: When the pH meter (4) value stabilizes after cleaning with the solution, the PFA pipeline cleaning is complete; Step 6: Open the AV4 pneumatic valve (9), AV6 pneumatic valve (14), AV1 pneumatic valve (2) and AV14 pneumatic valve (31). Ultrapure water is started by the diaphragm pump (11) to flush the PFA pipeline and clean the drug solution in the pipeline. Step 7: Clean until the pH meter (4) value is close to pure water, then open the AV5 pneumatic valve (10) and AV15 pneumatic valve (34). At this time, the AV1 pneumatic valve (2) and AV8 pneumatic valve (17) are closed. The PFA pipeline is dried with nitrogen through the inlet pipe (1) and the flushing pipe (12).

8. The control method of the PFA pipeline inner wall cleaning device according to claim 7, characterized in that: When the pH meter (4) detects that the PFA pipeline cleaning fluid cannot be reused, it closes the AV1 pneumatic valve (2) and opens the AV15 pneumatic valve (34), and discharges it directly through the drain pipe (32); when impurities are deposited at the bottom of the recovery chamber, they are discharged through the drain pipe (32) by opening the AV12 pneumatic valve (22); when the flow meter (3) detects that the flow rate is as low as 1 / 2 of the initial flow rate, the impurities accumulated in the filter element (33) are flushed by the ultrapure water pipe (7) through the opening of the AV2 pneumatic valve (6) and the AV14 pneumatic valve (31); then the nitrogen pipe (5) replenishes nitrogen to vibrate the filter element (33) by opening the AV14 pneumatic valve (31) and intermittently switching the AV2 pneumatic valve (6), and discharges it through the drain pipe (32) to help separate the impurities in the filter element (33).

9. The control method of the PFA pipeline inner wall cleaning device according to claim 7, characterized in that: The volume ratio of the drug solution in the mixing chamber is HF:HNO3:H2O=1:3:10; during the cleaning process, the pH meter (4) is used to detect whether the drug solution is ineffective. If it is ineffective, the solution will be remixed to ensure the rinsing effect and efficiency; throughout the entire control process, the pH meter (4) is kept moist to ensure the service life of the pH meter (4).

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