A safety control system and method for preventing overpressure explosion of a sludge phosphorus recovery device

Abstract

The present invention discloses a safety control system and method for preventing overpressure explosion of a mud phosphorus recovery device, and belongs to the field of waste recovery and treatment. The device comprises a mud phosphorus rotary kiln, which is provided with a temperature detection system and a pressure detection system. The mud phosphorus rotary kiln is connected to a phosphorus passing pipe, which is provided with an automatic spraying system to prevent the generation of red phosphorus and a pressure difference control system connected to an air supply valve. The phosphorus passing pipe is connected to a condensation tower, and phosphorus vapor enters a phosphorus receiving pool after being condensed in the condensation tower. The device realizes the safe recovery of phosphorus in mud phosphorus, and effectively prevents the blockage of the phosphorus passing pipe in the mud phosphorus recovery system. The present invention makes the mud phosphorus recovery process safe and controllable by automatically connecting the control system.

Description

Technical Field

[0001] The invention relates to a safety control system and method for preventing overpressure explosion of a mud phosphorus recovery device, belonging to the field of waste recovery and treatment. Background Art

[0002] In the production of yellow phosphorus by electric furnace method, the phosphorus furnace gas contains CO, P2 and fine impurities such as phosphate rock powder and coal powder. These impurities enter the condensation system together with the furnace gas, and after water washing and condensation, a large amount of latex-like mixture is formed in the phosphorus receiving tank. This mixture is collectively called mud phosphorus. Part of the mud phosphorus formed is put into the refining tank with the crude phosphorus for refining, and the other part enters the sewage treatment and purification system with the overflow water of the phosphorus receiving tank. The phosphorus content in the mud phosphorus is very high. The phosphorus content of the mud phosphorus produced in the refining tank can be as high as 90%. The phosphorus content of the mud phosphorus entering the sewage treatment is relatively low, generally 35-60%. The phosphorus content of the sandy mud phosphorus entering the ditch and other places is also about 30-35%. Mud phosphorus recovery can not only achieve energy conservation and emission reduction, save resources, but also reduce the pollution of mud phosphorus to the environment, so mud phosphorus recovery is of great significance. The main methods for treating sludge phosphorus in China include phosphorus evaporation, chemical agent method and vacuum filtration method, and there are also electric field treatment method and adsorption separation method in foreign countries. However, the existing sludge phosphorus rotary furnace in China has defects such as unstable sludge phosphorus feed amount, easy blockage of the rotary pot phosphorus pipe, and uncontrollable temperature and pressure during use. Therefore, it is desirable for yellow phosphorus enterprises to invent an automatic interlocking control system with reasonable design, safe and controllable production process, and ability to prevent sludge phosphorus blockage. Summary of the invention

[0003] The purpose of the present invention is to solve the technical problems existing in the existing treatment process, such as easy blockage of phosphorus pipes and unsafe and uncontrollable production processes, and to provide a safety control system for preventing overpressure explosion of a mud phosphorus recovery device.

[0004] The technical solution adopted by the present invention to solve its technical problem is:

[0005] A safety control system for preventing overpressure explosion of a mud phosphorus recovery device, the mud phosphorus recovery device comprising a motor 1, a mud phosphorus rotary furnace 2, a phosphorus passing pipe 3, a condensation tower 4, a phosphorus receiving pool 5, and a high-pressure multistage pump 6; the motor 1 is connected to the mud phosphorus rotary furnace 2 through a rotating shaft to drive the mud phosphorus rotary furnace 2 to rotate; one end of the mud phosphorus rotary furnace 2 is connected to the phosphorus passing pipe 3, the phosphorus passing pipe 3 is connected to the condensation tower 4, and the inlet of the condensation tower 4 is immersed below the liquid level of the phosphorus receiving pool 5; a three-way pipe is arranged in the middle of the phosphorus passing pipe 3, and one outlet of the three-way pipe is connected to a high-pressure water flushing system through a flushing pipe 8.

[0006] An infrared temperature sensor Ⅰ9 is provided at the rear of the mud phosphorus rotary furnace 2, and the infrared temperature sensor Ⅰ9 is connected to the controller, and the controller is connected to the gas supply valve; the infrared temperature sensor Ⅰ9 transmits the detected temperature to the controller, compares it with the temperature set by the controller, and realizes the control of the switch of the gas supply valve.

[0007] An infrared temperature sensor Ⅱ10 is provided above the phosphorus tube 3. The infrared temperature sensor Ⅱ10 is connected to the controller, and the controller is connected to the switch of the high-pressure multi-stage pump 6. The infrared temperature sensor Ⅱ10 transmits the detected temperature to the controller, and compares it with the temperature set by the controller to control the switch of the high-pressure multi-stage pump 6, thereby controlling the high-pressure water flushing system.

[0008] An infrared temperature sensor III11 is provided above the phosphorus receiving pool 5, and the infrared temperature sensor III11 is connected to the controller, and the controller is connected to the gas supply valve; the infrared temperature sensor III11 transmits the detected temperature to the controller, and compares it with the temperature set by the controller to realize the control of the switch of the gas supply valve;

[0009] A pressure sensor 7 is provided at the steam outlet of the three-way pipe, and the pressure sensor 7 is connected to the controller, and the controller is connected to the air supply valve. The pressure sensor 7 transmits the detected pressure to the controller, and compares it with the pressure set by the pressure controller to control the switch of the air supply valve.

[0010] An infrared signal transmitter 12 is provided below the feed port of the mud phosphorus rotary furnace 2, and an infrared signal receiver 13 is provided on the outer cover of the mud phosphorus rotary furnace 2. The infrared signal receiver 13 is connected to a relay, and the relay is connected to a mud pump power supply to realize control of the mud pump switch; the infrared signal transmitter 12 and the infrared signal receiver 13 both have built-in power supplies.

[0011] Preferably, the controller of the present invention is a computer, a PLC or a single chip microcomputer.

[0012] Preferably, the high-pressure water flushing system of the present invention is connected to a high-level water tank through a pipe, and the high-pressure water flushing system flushing pipe 8 is connected to the tail end of the tee pipe. The centerline angle of the tee pipe main pipe is maintained at 30° to 45°, so that the high-pressure water enters the tee pipe and presents a tangential vortex.

[0013] Preferably, there are two condensation towers 4 in the present invention, which are connected by pipelines and are also immersed below the liquid surface of the phosphorus receiving pool 5 .

[0014] Preferably, the infrared signal transmitter 12 of the present invention is located directly below the feed port, with a vertical distance of 10 to 25 cm below the center axis. When the feed port of the mud phosphorus rotary kiln 2 is located at the lower right side of the boiler and the feed port is tangent to the horizontal center axis of the rotary pot, the infrared signal receiver 13 can just receive the signal sent by the infrared signal transmitter 12.

[0015] Another object of the present invention is to provide a control method for the safety control system for preventing overpressure explosion of the mud phosphorus recovery device, which specifically comprises the following steps:

[0016] (2) An infrared signal transmitter 12 is provided below the feed port of the mud phosphorus rotary kiln 2, and an infrared signal receiver 13 is provided on the outer cover of the mud phosphorus rotary kiln 2. The infrared signal receiver 13 is connected to a relay, and the relay is connected to a mud pump power supply to realize the control of the mud pump switch; when and only when the infrared signal receiver 13 receives a signal, the mud pump power supply is connected to feed; and the highest liquid level of the feed shall not be higher than the horizontal line of the lower edge of the feed port; to prevent the mud phosphorus rotary kiln 2 from being blocked due to excessive feed.

[0017] (3) An infrared temperature sensor I9 is ​​used to constantly monitor the furnace wall temperature of the sludge phosphorus rotary furnace 2. When blocked, the temperature of the sludge phosphorus rotary furnace will continue to rise. When the furnace wall temperature is higher than 600°C, gas supply is stopped to prevent overpressure explosion caused by blockage.

[0018] (4) The infrared temperature sensor Ⅱ10 is used to constantly detect the temperature of the phosphorus tube 3. The infrared temperature sensor Ⅱ10 transmits the detected temperature to the controller and compares it with the temperature set by the controller. When the temperature of the phosphorus tube is lower than 100°C, the controller controls the high-pressure water flushing system to flush the scale from the pipeline.

[0019] (5) An infrared temperature sensor III11 is used to constantly detect the temperature in the phosphorus receiving pool 5. The infrared temperature sensor III11 transmits the detected temperature to the controller and compares it with the temperature set by the controller. The infrared temperature sensor III11 constantly detects the water seal temperature of the phosphorus receiving pool 5. When the water seal temperature is lower than 50°C, the gas supply is stopped to prevent the phosphorus pipe from exploding due to overpressure caused by blockage at the rear end.

[0020] (6) The pressure sensor 7 is used to constantly detect the pressure at the steam outlet of the three-way pipe. The pressure sensor 7 transmits the detected pressure to the controller and compares it with the pressure set by the controller. In the phosphorus vapor stage, when the pressure decreases significantly, the gas supply valve is closed to stop heating the mud phosphorus rotary kiln to prevent the rotary kiln from operating at overpressure.

[0021] Preferably, the rotation speed of the sludge phosphorus rotary furnace in step (1) of the present invention is 0.5 to 3 r / min.

[0022] Preferably, the medium-to-high pressure water flushing system in step (2) of the present invention flushes the pipeline for 5 to 10 minutes, and the flushing water temperature is 50 to 80°C.

[0023] Beneficial effects of the present invention:

[0024] (1) The present invention provides an anti-blocking, safe automatic interlocking control system for recovering sludge phosphorus. The temperature control system and the pressure control system of the system equipment are interlocked with the gas supply equipment to operate in coordination, thereby solving the potential safety hazards in the sludge phosphorus recovery process, reducing the risk of explosion accidents, and achieving timely disconnection of the sludge phosphorus recovery process.

[0025] (2) The present invention solves the problem of clogging of the phosphorus pipe during the recovery of sludge phosphorus, avoids the danger caused by manual slag removal before and during operation, and realizes the automatic removal of scale during the recovery of sludge phosphorus, thus truly realizing safe production by preventing clogging. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 It is the overall flow chart of the system of the present invention.

[0027] Figure 2 This is a schematic diagram of the high-pressure flushing system connection.

[0028] Figure 3 Schematic diagram of the safe feeding system.

[0029] Figure 4 This is a temperature diagram during the operation phase.

[0030] In the figure: 1-motor; 2-mud phosphorus rotary kiln; 3-phosphorus passing tube; 4-condensation tower; 5-phosphorus receiving pool; 6-high-pressure multi-stage pump; 7-pressure sensor; 8-flushing pipe; 9-infrared temperature sensor I; 10-infrared temperature sensor II; 11-infrared temperature sensor III; 12-infrared signal transmitter; 13-infrared signal receiver. DETAILED DESCRIPTION

[0031] The technical solution of the present invention is further described in detail below through specific embodiments in conjunction with the accompanying drawings.

[0032] Example 1

[0033] A safety control system for preventing overpressure explosion of a mud phosphorus recovery device, the mud phosphorus recovery device comprises a motor 1, a mud phosphorus rotary furnace 2, a phosphorus passing pipe 3, a condensation tower 4, a phosphorus receiving pool 5, and a high-pressure multistage pump 6; the mud phosphorus rotary furnace 2 is a main heating device for a distillation method; the mud phosphorus is pumped into the phosphorus rotary furnace 2 by a mud pump, and the highest liquid level of the feed shall not be higher than the horizontal line of the lower edge of the feed port; to prevent the mud phosphorus rotary furnace 2 from being blocked due to excessive feed, the motor 1 is connected to the mud phosphorus rotary furnace 2 through a rotating shaft to drive the mud phosphorus rotary furnace 2 to rotate; one end of the mud phosphorus rotary furnace 2 is connected to the phosphorus passing pipe 3, the phosphorus passing pipe 3 is connected to the condensation tower 4, and the inlet of the condensation tower 4 is immersed below the liquid level of the phosphorus receiving pool 5; a three-way pipe is arranged in the middle of the phosphorus passing pipe 3, and one outlet of the three-way pipe is connected to a high-pressure water flushing system through a flushing pipe 8.

[0034] An infrared temperature sensor Ⅰ9 is provided at the rear of the mud phosphorus rotary furnace 2, and the infrared temperature sensor Ⅰ9 is connected to the controller, and the controller is connected to the gas supply valve; the infrared temperature sensor Ⅰ9 transmits the detected temperature to the controller, compares it with the temperature set by the controller, realizes the control of the switch of the gas supply valve, and gives the gas supply valve an open or closed signal.

[0035] An infrared temperature sensor Ⅱ10 is provided above the phosphorus tube 3. The infrared temperature sensor Ⅱ10 is connected to the controller, and the controller is connected to the switch of the high-pressure multi-stage pump 6. The infrared temperature sensor Ⅱ10 transmits the detected temperature to the controller, and compares it with the temperature set by the controller to control the switch of the high-pressure multi-stage pump 6, thereby controlling the high-pressure water flushing system.

[0036] An infrared temperature sensor III11 is provided above the phosphorus receiving pool 5, and the infrared temperature sensor III11 is connected to the controller, and the controller is connected to the gas supply valve; the infrared temperature sensor III11 transmits the detected temperature to the controller, and compares it with the temperature set by the controller to realize the control of the switch of the gas supply valve;

[0037] A pressure sensor 7 is provided at the steam outlet of the three-way pipe, and the pressure sensor 7 is connected to the controller, and the controller is connected to the air supply valve. The pressure sensor 7 transmits the detected pressure to the controller, and compares it with the pressure set by the pressure controller to control the switch of the air supply valve.

[0038] An infrared signal transmitter 12 is provided below the feed port of the mud phosphorus rotary kiln 2, and an infrared signal receiver 13 is provided on the outer cover of the mud phosphorus rotary kiln 2. The infrared signal receiver 13 is connected to a relay, and the relay is connected to a mud pump power supply to control the mud pump switch; both the infrared signal transmitter 12 and the infrared signal receiver 13 have built-in power supplies; the infrared signal transmitter 12 is located directly below the feed port, with a vertical distance of 20 cm below the central axis. When the feed port of the mud phosphorus rotary kiln 2 is located at the lower right side of the boiler and the feed port is tangent to the horizontal central axis of the rotary pot, the infrared signal receiver 13 can just receive the signal sent by the infrared signal transmitter 12.

[0039] The controller microcontroller described in this embodiment.

[0040] As a preferred embodiment of the present invention, the high-pressure water flushing system is connected to the high-level water tank through a pipeline, the high-pressure water flushing system flushing pipe 8 is connected to the tail end of the tee pipe, and the center line angle of the tee pipe main pipe is maintained at 30°~45°, so that the high-pressure water enters the tee pipe and presents a tangential vortex. The high-pressure water flushing system automatically sprays water before the rotary pot is operated and after the phosphorus evaporation stage, and the spraying temperature is 60°C hot water.

[0041] As a preferred embodiment of the present invention, there are two condensation towers 4 , which are connected by pipelines and are also immersed 10 cm below the liquid surface of the phosphorus receiving pool 5 .

[0042] Example 2

[0043] A control method for a safety control system for preventing overpressure explosion of a sludge phosphorus recovery device, specifically comprising the following steps:

[0044] (1) An infrared signal transmitter 12 is provided below the feed port of the mud phosphorus rotary kiln 2, and an infrared signal receiver 13 is provided on the outer cover of the mud phosphorus rotary kiln 2. The infrared signal receiver 13 is connected to a relay, and the relay is connected to a mud pump power supply to realize the control of the mud pump switch; when and only when the infrared signal receiver 13 receives a signal, the mud pump power supply is connected to feed; and the highest liquid level of the feed shall not be higher than the horizontal line of the lower edge of the feed port; to prevent the problem of blockage of the mud phosphorus rotary kiln 2 caused by excessive feed.

[0045] (2) Use infrared temperature sensor I9 to monitor the furnace wall temperature of the phosphorus rotary furnace 2 at all times. When blocked, the temperature of the mud phosphorus rotary furnace will continue to rise. When the furnace wall temperature is higher than 600°C, stop the gas supply to prevent the boiler from overpressure explosion due to blockage.

[0046] (3) Use infrared temperature sensor Ⅱ10 to monitor the temperature of phosphorus pipe 3 at all times. Infrared temperature sensor Ⅱ10 transmits the detected temperature to the controller and compares it with the temperature set by the controller. When the temperature of the phosphorus pipe is lower than 100°C, the controller controls the opening of the high-pressure water flushing system to flush the scale in the pipe and continues flushing for 5 minutes.

[0047] (4) An infrared temperature sensor III11 is used to constantly monitor the temperature in the phosphorus receiving pool 5. The infrared temperature sensor III11 transmits the detected temperature to the controller and compares it with the temperature set by the controller. The infrared temperature sensor III11 constantly detects the water seal temperature of the phosphorus receiving pool 5. When the water seal temperature is lower than 50°C, the gas supply is stopped to prevent the phosphorus pipe from exploding due to overpressure caused by blockage at the rear end.

[0048] (5) Use the pressure sensor 7 to monitor the pressure at the steam outlet of the three-way pipe at all times. The pressure sensor 7 transmits the detected pressure to the controller and compares it with the pressure set by the controller. In the phosphorus vapor stage, when the pressure decreases significantly (usually the pressure is stable, if the pressure drops sharply, it means there is a blockage, for example, a drop of 200 kPa per minute), close the air supply valve and stop heating the mud phosphorus rotary kiln to prevent the rotary kiln from operating at overpressure.

[0049] Figure 4 This is a temperature diagram for the operation stage. Temperature is an important indicator of the quality of steam produced by the boiler. It is also an important parameter to ensure the normal operation of the boiler. Temperature is also the main factor affecting the heat transfer process and equipment efficiency. Therefore, temperature detection is extremely important to ensure the safety and economic operation of the entire system, improve the output and quality of steam, reduce the labor intensity of workers, and reduce the safety risks of work. It is extremely important to improve working conditions. Figure 3 It can be seen that without changing the gas supply conditions, the temperature of each component of the mud phosphorus rotary furnace fluctuates within a certain range, and the generated phosphorus vapor will take away part of the heat, so that the boiler temperature remains stable. When the boiler is blocked, the phosphorus vapor is continuously heated inside the boiler, which will cause abnormal temperature rise. Blockage can be accurately detected by monitoring the temperature.

[0050] The method solves the problem that the mud phosphorus recovery process is operated in a closed manner, the temperature and pressure are difficult to control, and the blockage of the mud phosphorus process is difficult to sense. The method takes into account all the devices and equipment that are prone to blockage in the process and monitors them, which greatly reduces the safety risk of overpressure explosion in mud phosphorus recovery and realizes a safe and controllable production process.

Claims

1. A safety control system for preventing overpressure explosion of a mud phosphorus recovery device, the mud phosphorus recovery device comprising a motor (1), a mud phosphorus rotary furnace (2), a phosphorus passing pipe (3), a condensation tower (4), a phosphorus receiving pool (5), and a high-pressure multistage pump (6); the motor (1) is connected to the mud phosphorus rotary furnace (2) via a rotating shaft to drive the mud phosphorus rotary furnace (2) to rotate; one end of the mud phosphorus rotary furnace (2) is connected to the phosphorus passing pipe (3), the phosphorus passing pipe (3) is connected to the condensation tower (4), and the inlet of the condensation tower (4) is immersed below the liquid level of the phosphorus receiving pool (5); it is characterized in that: A three-way pipe is provided in the middle of the phosphorus pipe (3), and one outlet of the three-way pipe is connected to a high-pressure water flushing system through a flushing pipe (8); An infrared temperature sensor I (9) is arranged at the rear of the sludge phosphorus rotary furnace (2), and the infrared temperature sensor I (9) is connected to a controller, and the controller is connected to the gas supply valve; the infrared temperature sensor I (9) transmits the detected temperature to the controller, and compares it with the temperature set by the controller, so as to control the opening and closing of the gas supply valve; An infrared temperature sensor II (10) is provided above the phosphorus pipe (3). The infrared temperature sensor II (10) is connected to a controller. The controller is connected to a switch of the high-pressure multistage pump (6). The infrared temperature sensor II (10) transmits the detected temperature to the controller, and compares it with the temperature set by the controller to control the switch of the high-pressure multistage pump (6), thereby controlling the high-pressure water flushing system. An infrared temperature sensor III (11) is provided above the phosphorus receiving pool (5), and the infrared temperature sensor III (11) is connected to a controller, and the controller is connected to the gas supply valve; the infrared temperature sensor III (11) transmits the detected temperature to the controller, and compares it with the temperature set by the controller to realize the control of the opening and closing of the gas supply valve; A pressure sensor (7) is provided at the steam outlet of the three-way pipe, the pressure sensor (7) is connected to the controller, the controller is connected to the air supply valve, the pressure sensor (7) transmits the detected pressure to the controller, and compares it with the pressure set by the pressure controller to realize the control of the opening and closing of the air supply valve; An infrared signal transmitter (12) is provided below the feed port of the mud phosphorus rotary kiln (2), and an infrared signal receiver (13) is provided on the outer cover of the mud phosphorus rotary kiln (2). The infrared signal receiver (13) is connected to a relay, and the relay is connected to a mud pump power supply to realize control of the mud pump switch; the infrared signal transmitter (12) and the infrared signal receiver (13) both have built-in power supplies.

2. The safety control system for preventing overpressure explosion of a sludge phosphorus recovery device according to claim 1 is characterized in that: The controller is a computer, a PLC or a single chip microcomputer.

3. The safety control system for preventing overpressure explosion of a sludge phosphorus recovery device according to claim 1 or 2, characterized in that: The high-pressure water flushing system is connected to the high-level water tank through a pipeline. The high-pressure water flushing system flushing pipe (8) is connected to the tail end of the three-way pipe. The central line angle of the three-way pipe main pipe is maintained at 30° to 45°, so that the high-pressure water enters the three-way pipe and presents a tangential vortex.

4. The safety control system for preventing overpressure explosion of a sludge phosphorus recovery device according to claim 3 is characterized in that: There are two condensation towers (4), which are connected by pipelines and are also immersed below the liquid surface of the phosphorus receiving pool (5).

5. The safety control system for preventing overpressure explosion of a sludge phosphorus recovery device according to claim 1 is characterized in that: The infrared signal transmitter (12) is located directly below the feed port, with a vertical distance of 10 to 25 cm from the bottom of the central axis. When the feed port of the sludge phosphorus rotary kiln (2) is located at the bottom right of the boiler and the top of the feed port is tangent to the horizontal central axis of the rotary kiln, the infrared signal receiver (13) can just receive the signal sent by the infrared signal transmitter (12).

6. The control method of the safety control system for preventing overpressure explosion of a sludge phosphorus recovery device according to any one of claims 1 to 5, characterized in that: The specific steps include: (1) An infrared signal transmitter (12) is provided below the feed port of the mud phosphorus rotary kiln (2), and an infrared signal receiver (13) is provided on the outer cover of the mud phosphorus rotary kiln (2). The infrared signal receiver (13) is connected to a relay, and the relay is connected to a mud pump power supply to realize control of the mud pump switch; when and only when the infrared signal receiver (13) receives a signal, the mud pump power supply is connected to feed; and the highest liquid level of the feed shall not be higher than the horizontal line of the lower edge of the feed port, so as to prevent the mud phosphorus rotary kiln (2) from being blocked due to excessive feed; (2) using an infrared temperature sensor I (9) to constantly detect the furnace wall temperature of the sludge phosphorus rotary furnace (2); when blocked, the temperature of the sludge phosphorus rotary furnace will continue to rise, and when the furnace wall temperature is higher than 600° C., gas supply is stopped; (3) Using an infrared temperature sensor II (10) to constantly detect the temperature of the phosphorus pipe (3), the infrared temperature sensor II (10) transmits the detected temperature to a controller, and compares it with the temperature set by the controller. When the temperature of the phosphorus pipe is lower than 100° C., the controller controls the high-pressure water flushing system to flush the scale from the pipe; (4) using an infrared temperature sensor III (11) to constantly detect the temperature in the phosphorus receiving pool (5), the infrared temperature sensor III (11) transmits the detected temperature to the controller, and compares it with the temperature set by the controller. The infrared temperature sensor III (11) constantly detects the water seal temperature of the phosphorus receiving pool (5), and stops supplying gas when the water seal temperature is lower than 50° C., so as to prevent the phosphorus passing pipe from exploding due to overpressure caused by blockage at the rear end; (5) A pressure sensor (7) is used to constantly detect the pressure at the steam outlet of the three-way pipe. The pressure sensor (7) transmits the detected pressure to the controller and compares it with the pressure set by the controller. In the phosphorus vapor stage, when the pressure decreases significantly, the gas supply valve is closed to stop heating the mud phosphorus rotary kiln to prevent the rotary kiln from operating at overpressure.

7. The method according to claim 6, characterized in that: The rotation speed of the slurry phosphorus rotary kiln in step (1) is 0.5-3 r / min.

8. The method according to claim 6, characterized in that: In step (2), the high-pressure water flushing system flushes the pipeline for 5 to 10 minutes, and the flushing water temperature is 50 to 80°C.

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