CN107670373A - Changeable operation and the filter and control method of automatic back-washing - Google Patents

Abstract

The invention relates to a filter device capable of switching operations and automatic backwashing and a control method, which are used for maintaining continuous operation of the filter and performing automatic deep backwashing. The filter device includes a filter unit, a programmable controller, and monitoring equipment. The two filter units have the same structure and are set in parallel. The differential pressure transmitter monitors the pressure values of the filter inlet and outlet of the filter unit. The programmable controller The operation of the two filter units is switched through the pressure value and filtration time monitored by the differential pressure transmitter to ensure that the filtration operation can be carried out continuously. Effect. The invention solves the problems of continuous operation and automatic backwashing of the filtering device, and can still carry out filtering operation while backwashing and discharging sewage, without affecting the normal operation of the filtering device. The invention has the advantages of compact structure, stable and reliable operation, large processing capacity, long service life, etc., and has excellent popularization and use value.

Description

Filtration device and control method with switchable operation and automatic backwashing

technical field

The invention relates to a filtering device capable of switching and maintaining continuous operation and capable of automatic deep backwashing and a control method, and belongs to the technical field of filtering equipment and methods.

Background technique

In the filter devices used by many enterprises, as the filter continues to filter, the solid phase impurities in the liquid are trapped on the surface by the filter element and gradually deposited, resulting in a larger pressure difference between the two ends of the filter element and a further increase in filtration resistance. Large, resulting in a decrease in filtration efficiency, must be shut down for maintenance to restore the filtration function. If the filter element is severely clogged, it is likely to cause the filter element to fail or be damaged, which will cause a production accident or stop the system. Therefore, the clogged filter element must be replaced.

The general filter device needs to interrupt the filter operation during cleaning, so as to replace the filter element or take out the filter element for cleaning, which is time-consuming and troublesome, affects the processing efficiency, and cannot meet the requirements of automatic continuous operation. At present, filters with automatic backwashing function generally use a single medium such as water and gas for backwashing. The ability is poor, which also affects the backwashing effect of the filter.

To sum up, at present, the filter devices of enterprises have the disadvantages of continuous operation during maintenance, unsatisfactory backwashing effect and automatic control. With the advancement of technology and the improvement of automation and intelligence, it is very necessary to upgrade the The filtering device is improved.

Contents of the invention

The technical problem to be solved by the present invention is to provide a filter device and control method that can switch between operations and automatic backwashing. The operation mode of the unit, switching the filter unit and automatically performing deep backwashing can maintain the continuous operation of the filtration system and ensure the backwashing effect.

The technical solution adopted by the present invention to solve the problems of the technologies described above is:

A filter device with switchable operation and automatic backwashing, including a filter unit, a programmable controller, and monitoring equipment. There are two filter units. The two filter units have the same structure and are arranged in parallel. , outlet control valve, backwash water control valve, sewage control valve, and blowback control valve. The inlet of the filter of each filter unit is connected to the inlet control valve and sewage control valve through a tee, and the inlet control valve is connected to the sewage control valve through a pipeline. The pipeline to be filtered is connected, the sewage control valve is connected to the sewage pipeline through the pipeline, the outlet of the filter is connected to the outlet control valve and the backwash water control valve through a tee, and the outlet control valve is connected to the filter medium pipeline through the pipeline , the backwash water control valve is connected to the external water supply pipe through the pipeline, and the tee pipe connected to the backwash water control valve is also connected to the backflush control valve through the pipeline, and the backflush control valve is connected to the external compressor through the pipeline. The air pipelines are connected, and the inlet control valve pipelines, sewage control valve pipelines, outlet control valve pipelines, backwash water control valve pipelines, and backflush control valve pipelines of the two filter units are connected respectively, and the differential pressure transmission The two ends of the filter are respectively connected between the inlet control valve pipeline and the outlet control valve pipeline of the two filter units, the programmable controller is connected with the control valves of the two filter units, and the monitoring equipment is connected with the programmable controller connected.

The control method of the filter device with switchable operation and automatic backwashing is carried out according to the following steps:

a. The differential pressure transmitter (15) installed at both ends of the two filter units, 1# filter unit and 2# filter unit, detects the pressure difference between the filter inlet and outlet, and sends the detection signal to the programmable controller (1 ), the programmable controller (1) determines the working state of the filter unit according to the pressure difference value, or the programmable controller (1) switches the filter unit according to the running time of the filter unit;

b. In normal operation, the 1# filter unit is filtering, the 2# filter unit is in standby state, the inlet control valve (4) and the outlet control valve (5) of the 1# filter unit are opened, and the medium to be filtered is discharged from the inlet of the 1# filter unit Inflow through control valve (4), filter through filter (3) of 1# filter unit, then flow out from outlet control valve (5) of 1# filter unit, and enter the filter medium pipeline;

c. As the filtration progresses, the solid-phase impurities in the liquid are trapped on the surface by the filter element of the filter (3) of the 1# filter unit, and are gradually deposited, resulting in an increase in the pressure difference at both ends of the filter element. When the pressure difference reaches the switching After the pressure setting value, or after the 1# filter unit reaches the set running time, the programmable controller (1) opens the inlet control valve (10) of the 2# filter unit and the outlet control valve of the 2# filter unit ( 11), start the 2# filter unit to carry out the filter operation, after starting for 3 seconds, close the inlet control valve (4) of the 1# filter unit and the outlet control valve (5) of the 1# filter unit, and stop the operation of the 1# filter unit ;

d. After the 1# filter unit stops running for 30 seconds, open the backwash water control valve (6) of the 1# filter unit and the sewage control valve (7) of the 1# filter unit, and open the backwash control valve of the 1# filter unit after 10 seconds (8), start the backwash of the 1# filter unit, after the backwash of the set value time, close the backwash water control valve (6), sewage control valve (7) and backflush control valve (8) of the 1# filter unit ), complete the backwash of the 1# filter unit and put it in a standby state;

e. As the filtration of the 2# filter unit continues, when the differential pressure value of the differential pressure transmitter reaches the switching pressure setting value again, or after the 2# filter unit reaches the set running time, the programmable controller (1 ) Open the inlet control valve (4) and outlet control valve (5) of 1# filter unit, start the 1# filter unit, and close the inlet control valve (10) and outlet control valve ( 11), stop the operation of 2# filter unit;

f. After the 2# filter unit stops for 30 seconds, open the backwash water control valve (12) and the sewage control valve (13) of the 2# filter unit, and open the backwash control valve (14) of the 2# filter unit after 10 seconds to start The backwash of the 2# filter unit, after the backwash at the interval of the backwash time setting value, close the backwash water control valve (12), sewage control valve (3) and backflush control valve (14) of the 2# filter unit, Complete the backwash of the 2# filter unit and put it in a standby state.

Adopt the present invention of above-mentioned technical scheme, compared with prior art, its beneficial effect is:

Using two parallel filter units, the differential pressure transmitter monitors the pressure value of the filter inlet and outlet of the filter unit, and the programmable controller monitors the pressure value through the differential pressure transmitter or the set running time The operation of the two filter units is switched to ensure that the filter operation can be carried out continuously, and the filter unit that is stopped is controlled by the programmable controller for backwashing to ensure the effect of backwashing.

The present invention applies the automatic control technology to the filtration system, improves the function of the filtration system, and solves the problems of continuous operation and automatic backwashing of the filtration device. The sewage discharge process is automatically carried out during the operation of the equipment. At the same time, the filtering operation can still be performed without affecting the normal operation of the filtering device. The invention has the advantages of continuous filtration, automatic backwashing and sewage discharge, compact structure, stable and reliable operation, large processing capacity, low operating cost, and long service life.

As preferably, the further technical scheme of the present invention is:

The water pressure of the external water supply pipeline connected to the backwash water control valve is controlled between 0.4-0.5 MPa; the air pressure of the external compressed air pipeline connected to the backwash control valve is controlled between 0.55-0.65 MPa.

The 1# filter unit and the 2# filter unit run repeatedly and alternately. The programmable controller (1) records the backwash times and running time of each filter unit. If the running time of one of the filter units is too short and the backwash When the number of washings increases, the control system sends out an alarm message corresponding to the certain filter unit, prompting the need for maintenance.

During the operation of the filter unit, if the pressure difference across the filter element of the filter suddenly changes from a large value to a small value, it can be considered that the filter of the filter unit is clogged, and the backwash function of the filter unit is triggered immediately, and the control system An alarm message of the filter unit is issued, prompting that maintenance and treatment are required.

The programmable controller (1) switches the operation of the two filter units according to the pressure difference between the inlet and outlet of the filter detected by the differential pressure transmitter (15), and the default value of the pressure is 0.7 kPa, When the pressure difference between the two ends of the filter unit in operation reaches the set switching pressure value, the standby filter unit is put into operation, and the filter unit in operation stops running and switches to a backwashing state, waiting for backwashing.

The programmable controller (1) switches the operation of the two filter units according to the set running time of the filter unit. The default time is 2 hours. When the running time of the filter unit in operation has reached the set switching time , the standby filter unit is put into operation, and the filter unit in operation is stopped, switched to a backwashing state, and waits for backwashing.

The programmable controller (1) controls the backwashing running time of the filter unit according to the set backwashing time, the default backwashing running time is 60 seconds, and the set value must be greater than or equal to the default value.

Description of drawings

Fig. 1 is a schematic structural view of a filter device according to an embodiment of the present invention;

Fig. 2 is a flow chart of filtering process control;

The marks in the figure are as follows: programmable controller 1; monitoring equipment 2; 1# filter 3; 1# inlet control valve 4; 1# outlet control valve 5; 1# backwash water control valve 6; 1# sewage control valve 7; 1# blowback control valve 8; 2# filter 9; 2# inlet control valve 10; 2# outlet control valve 11; 2# backwash water control valve 12; 2# sewage control valve 13; 2# blowback Control valve 14; differential pressure transmitter 15; medium to be filtered 16; filter medium 17; industrial water 18; compressed air 19; sewage 20.

detailed description

The present invention will be described in detail below in conjunction with the accompanying drawings and embodiments.

The filter device with switchable operation and automatic backwashing provided in this embodiment adopts two filter units with the same structure arranged in parallel, and the differential pressure transmitter monitors the pressure values of the filter inlet and outlet of the filter unit, and can be programmed The program controller switches the operation of the two filter units through the pressure value monitored by the differential pressure transmitter or the set running time to ensure the continuity of the filter operation. The filter unit that stops running is controlled by the programmable controller. Backwashing to ensure the effect of backwashing.

Figure 1 shows that the 1# filter unit is controlled by 1# filter 3, 1# inlet control valve 4, 1# outlet control valve 5, 1# backwash water control valve 6, 1# sewage control valve 7, and 1# backblowing control Valve 8 is composed. 2# filter unit is composed of 2# filter 9, 2# inlet control valve 10, 2# outlet control valve 11, 2# backwash water control valve 12, 2# sewage control valve 13, and 2# blowback control valve 14.

1# filter 3 and 2# filter 9 are two vertical long cylindrical filters with built-in filter nets, arranged vertically and parallelly in parallel, the lower port is the inlet of the filter, and the upper port is the outlet of the filter.

The following is the structure of 1# filter unit, and the structure of 2# filter unit is the same as that of 1# filter unit.

Figure 1 shows that the inlet of 1# filter 3 is connected to 1# inlet control valve 4 and 1# sewage control valve 7 respectively through a tee, and 1# inlet control valve 4 is connected with the medium pipeline to be filtered through pipelines, and 1# sewage The control valve 7 is connected with the sewage pipeline through a pipeline. It is used to control the positive flow of the liquid to be filtered into 1# filter 3, and discharge the sewage from 1# filter 3.

Figure 1 shows that the outlet of 1# filter 3 is connected to 1# outlet control valve 5 through a tee, and 1# outlet control valve 5 is connected to the filter medium pipeline through a pipeline to control the outflow of filtered liquid. At the same time, the 1# filter 3 is connected to the 1# backwash water control valve 6 through another outlet of the tee, and the 1# backwash water control valve 6 is connected to the external water supply pipe through the pipeline to control the backwash water backwash It flows into 1# filter 3 and backwashes 1# filter 3. The tee pipe connected to the 1# backwash water control valve 6 is also connected to the 1# backflush control valve 8 through the pipeline, and the 1# backflush control valve 8 is connected to the external compressed air pipeline through the pipeline for Input backwash compressed air to 1# filter 3.

The external network water supply pipeline adopts a continuous water supply method, which is industrial water without impurities, and the water pressure is controlled between 0.4 and 0.5 MPa. The compressed air pipeline of the external network adopts a continuous air supply method, which is filtered pure compressed air, and the pressure is controlled between 0.55 and 0.65 MPa.

Figure 1 shows that the inlet control valve pipelines, sewage control valve pipelines, outlet control valve pipelines, backwash water control valve pipelines, and backflush control valve pipelines of the 1# filter unit and the 2# filter unit are respectively connected. The two ends of the differential pressure transmitter 15 are respectively connected between the inlet control valve pipeline and the outlet control valve pipeline of the 1# filter unit and the 2# filter unit, and are used to monitor the gap between the inlet and outlet of the two filters during operation. differential pressure. As an important detection unit of the filter device, the differential pressure transmitter 15 is required to have high detection accuracy and high response speed.

Figure 1 shows that the programmable controller 1 is connected to the control valves of the 1# filter unit and the 2# filter unit respectively, and the monitoring equipment 2 is connected with the programmable controller 1 .

The control functions of the monitoring device 2 include manual/automatic mode, manual switching, and reset of each filter unit; control parameters include switching pressure, switching time, and backwashing time. These parameters can be manually modified according to the operating conditions, or the system default values can be used ; The monitoring function includes the control status of each control valve, the position status of each control valve, the pressure difference value, the backwashing times of each filter unit, the running time of each filter unit, and the system alarm.

The backwashing of the filtering device of the present invention has two operating modes, manual and automatic.

Manual mode: The filter unit can be manually switched and backwashed through the monitoring interface, and the filter unit cannot be switched while backwashing is in progress.

Automatic mode: the switching pressure, switching time and backwashing time can be set through the monitoring device 2. The system default value of switching pressure is 0.7 kPa, the system default value of switching time is 2 hours, and the system default value of backwashing time is 60 seconds , if these setting values are not manually set, the system will adopt the default value.

System startup: The system startup signal comes from the main system where the filter device is located, and the main system sends a startup signal to the filter device after startup.

System stop: The system stop signal comes from the main system where the filter device is located. After the main system stops, it sends a stop signal to the filter device.

A single cycle control process of the present invention in automatic mode is as follows:

Step 1: After the main system where the filter device is located is started, the filter device receives a start signal from the main system, and the filter device is fully started.

Step 2: 1# filter unit is put into operation, 2# filter unit is in standby state, 1# inlet control valve 4 and 1# outlet control valve 5 are opened, and all other control valves are closed.

Step 3: Monitoring device 2 detects whether 1# inlet control valve 4 and 1# outlet control valve 5 are open, and whether the other control valves are closed; if the status of 1# inlet control valve 4 and 1# outlet control valve 5 is abnormal, then Switch the filter unit, execute step 5 and call the police.

Step 4: The filtering process runs continuously, and the differential pressure transmitter 15 detects the pressure difference value at both ends of the 1# filter 3 to judge the filtering status of the 1# filtering unit.

Step 5: When the pressure difference at both ends of 1# filter 3 exceeds the switching pressure setting value, the programmable controller 1 starts the backwashing function of the 1# filter unit, and at this time, put the 2# filter unit into operation first, and open the 2# filter unit. #Inlet control valve 10 and 2#Outlet control valve 11.

Step 6: The monitoring device 2 detects whether the 2# inlet control valve 10 and the 2# outlet control valve 11 are open; if the status of the 2# inlet control valve 10 and the 2# outlet control valve 11 is abnormal, switch the filter unit, perform step 14 and Alarm; if 1# inlet control valve 4 and 1# outlet control valve 5 in step 3 are abnormal, and now 2# inlet control valve 10 and 2# outlet control valve 11 are abnormal again, then stop filtering and report to the police.

Step 7: After 2# filter unit is put into operation for 3 seconds, cut out 1# filter unit, close 1# inlet control valve 4 and 1# outlet control valve 5. Detect the operation of the 2# filter unit. If the pressure difference between the two ends of the 2# filter 9 exceeds the switching pressure set value within 30 seconds, switch back to the 1# filter unit again, and the 2# filter unit will alarm for maintenance.

Step 8: Check whether the 1# inlet control valve 4 and the 1# outlet control valve 5 are closed, and if the status is abnormal, stop backwashing and give an alarm.

Step 9: After 30 seconds, the 2# filter unit operates normally, and the 1# filter unit starts backwashing. First, open the 1# backwash water control valve 6 and the 1# sewage control valve 7 to perform water backwashing.

Step 10: After 10 seconds, open the 1# backflush control valve 8 to carry out mixed backwashing with water and compressed air.

Step 11: Check whether 1# backwash water control valve 6, 1# sewage control valve 7, and 1# backflush control valve 8 are open, and if the state is abnormal, stop backwashing and give an alarm.

Step 12: When the backwash running time of 1# filter unit reaches the set value of backwash time, close 1# backwash water control valve 6, 1# sewage control valve 7, 1# backflush control valve 8, and 1# filter unit End backwash and enter standby state.

Step 13: Detect whether the other control valves except 2# inlet control valve 10 and 2# outlet control valve 11 are closed, and send an alarm if the status is abnormal.

Step 14: When the pressure difference between the two ends of 2# filter 9 exceeds the switching pressure setting value, the programmable controller 1 starts the backwash function of the 2# filter unit. At this time, the 1# filter unit is first put into operation, and the 1# filter unit is turned on. #Inlet control valve 4 and 1# outlet control valve 5.

Step 15: The monitoring device 2 detects whether the 1# inlet control valve 4 and the 1# outlet control valve 5 are open. If the status of the 1# inlet control valve 4 and the 1# outlet control valve 5 is abnormal, switch the filter unit, perform step 5 and Alarm; if 2# inlet control valve 10 and 2# outlet control valve 11 are abnormal in step 6, and 1# inlet control valve 4 and 1# outlet control valve 5 are abnormal again, stop the filter system and alarm.

Step 16: After 1# filter unit is put into operation for 3 seconds, cut out 2# filter unit, close 2# inlet control valve 10 and 2# outlet control valve 11, check the operation of 1# filter unit, if 1# When the differential pressure value at both ends of the filter 3 exceeds the switching pressure setting value, switch back to the 2# filter unit again, and the 1# filter unit will alarm for maintenance.

Step 17: Check whether the 2# inlet control valve 10 and the 2# outlet control valve 11 are closed, and if the status is abnormal, stop backwashing and give an alarm.

Step 18: After 30 seconds, the 1# filter unit is operating normally, and the 2# filter unit starts backwashing. First, open the 2# backwash water control valve 12 and the 2# sewage control valve 13 to perform water backwashing.

Step 19: After 10 seconds, open the 2# backflushing control valve 14 to carry out mixed backwashing with water and compressed air.

Step 20: The monitoring device 2 detects whether the 2# backwash water control valve 12, the 2# sewage control valve 13, and the 2# backflush control valve 14 are open, and if the state is abnormal, stop the backwash and give an alarm.

Step 21: When the backwash operation time of the 2# filter unit reaches the set value of the backwash time, close the 2# backwash water control valve 12, the 2# sewage control valve 13, the 2# backflush control valve 14, and the 2# filter unit End backwash and enter standby state.

Step 22: Monitoring device 2 detects whether 1# inlet control valve 4 and 1# outlet control valve 5 are open, and whether the rest of the control valves are closed; if the state of 1# inlet control valve 4 and 1# outlet control valve 5 is abnormal, then Switch the filter unit, execute step 5 and call the police.

Continuous operation according to the above automatic mode control flow, two sets of filter units, one for operation and one for backup, programmable controller 1 detects the filtration of the two filters according to the pressure difference between the two ends of 1# filter 3 or 2# filter 9 If the situation exceeds the set value, adjust the operating status of the filter unit in time, put the spare filter unit into operation, and automatically backwash the clogged filter unit. After backwashing, it will be in a standby state to ensure the continuous operation of the system.

In the automatic mode, if the programmable controller 1 controls a control valve to open or close, its valve position signal does not transmit the correct position information to the programmable controller 1, or a filter unit is running or backwashing In the process, if a certain control valve in the filter unit does not change according to the control requirements, the programmable controller 1 will generate alarm information according to the logic control requirements and send it to the monitoring device 2.

In the automatic mode, if a filter unit is in operation and the differential pressure value detected by the differential pressure transmitter 15 is within the set value, but the differential pressure value suddenly drops sharply at a certain moment, it can be judged that this When the filter unit is abnormal, the standby filter unit needs to be switched. The programmable controller 1 sends an alarm message to the monitoring device 2, and the abnormal filter unit automatically backwashes. After the backwash is completed, it waits for maintenance and replacement of the inner filter.

In the automatic mode, the two filter units run repeatedly and alternately, and the programmable controller 1 records the backwash times and running time of each filter unit. If the running time of a certain filter unit is too short and the backwash times increase, the control system Send an alarm message corresponding to the filter unit, prompting the need for maintenance.

The above is only a preferred embodiment of the present invention, and is not intended to limit the present invention in any form, any content that does not deviate from the technical solution of the present invention, any simple modification made to the above embodiments according to the technical essence of the present invention , equivalent changes and modifications all belong to the scope of the technical solution of the present invention.

Claims (8)

1. A filter device with switchable operation and automatic backwashing, including a filter unit, a programmable controller (1), and a monitoring device (2), characterized in that there are two filter units, and the two filter units have the same structure , set up in parallel, respectively composed of filters, inlet control valves, outlet control valves, backwash water control valves, sewage control valves, and blowback control valves. The inlets of the filters of each filter unit are connected to the inlet control valves respectively through three-way And the sewage control valve, the inlet control valve is connected to the medium pipeline to be filtered through the pipeline, the sewage control valve is connected to the sewage pipeline through the pipeline, and the outlet of the filter is respectively connected to the outlet control valve and the backwash water control valve through a tee. The outlet control valve is connected with the filter medium pipeline through the pipeline, the backwash water control valve is connected with the external water supply pipeline through the pipeline, and the backwash water control valve is connected with the backwash control valve through the pipeline on the tee pipe. Connection, the blowback control valve is connected to the external compressed air pipeline through the pipeline, the inlet control valve pipeline, the sewage control valve pipeline, the outlet control valve pipeline, the backwash water control valve pipeline, and the backflush water control valve pipeline of the two filter units The control valve pipelines are respectively connected, and the two ends of the differential pressure transmitter (15) are respectively connected between the inlet control valve pipeline and the outlet control valve pipeline of the two filter units, and the programmable controller (1) and The control valves of the two filter units are connected, and the monitoring equipment (2) is connected with the programmable controller (1). 2. A control method of a filter device capable of switching operations and automatic backwashing as claimed in claim 1, characterized in that: proceed as follows: a. The differential pressure transmitter (15) installed at both ends of the two filter units, 1# filter unit and 2# filter unit, detects the pressure difference between the filter inlet and outlet, and sends the detection signal to the programmable controller (1 ), the programmable controller (1) determines the working state of the filter unit according to the pressure difference value, or the programmable controller (1) switches the filter unit according to the running time of the filter unit; b. In normal operation, the 1# filter unit is filtering, the 2# filter unit is in standby state, the inlet control valve (4) and the outlet control valve (5) of the 1# filter unit are opened, and the medium to be filtered is discharged from the inlet of the 1# filter unit Inflow through control valve (4), filter through filter (3) of 1# filter unit, then flow out from outlet control valve (5) of 1# filter unit, and enter the filter medium pipeline; c. As the filtration progresses, the solid-phase impurities in the liquid are trapped on the surface by the filter element of the filter (3) of the 1# filter unit, and are gradually deposited, resulting in an increase in the pressure difference at both ends of the filter element. When the pressure difference reaches the switching After the pressure setting value, or after the 1# filter unit reaches the set running time, the programmable controller (1) opens the inlet control valve (10) of the 2# filter unit and the outlet control valve of the 2# filter unit ( 11), start the 2# filter unit to carry out the filter operation, after starting for 3 seconds, close the inlet control valve (4) of the 1# filter unit and the outlet control valve (5) of the 1# filter unit, and stop the operation of the 1# filter unit ; d. After the 1# filter unit stops running for 30 seconds, open the backwash water control valve (6) of the 1# filter unit and the sewage control valve (7) of the 1# filter unit, and open the backwash control valve of the 1# filter unit after 10 seconds (8), start the backwash of the 1# filter unit, after the backwash of the set value time, close the backwash water control valve (6), sewage control valve (7) and backflush control valve (8) of the 1# filter unit ), complete the backwash of the 1# filter unit and put it in a standby state; e. As the filtration of the 2# filter unit continues, when the differential pressure value of the differential pressure transmitter reaches the switching pressure setting value again, or after the 2# filter unit reaches the set running time, the programmable controller (1 ) Open the inlet control valve (4) and outlet control valve (5) of 1# filter unit, start the 1# filter unit, and close the inlet control valve (10) and outlet control valve ( 11), stop the operation of 2# filter unit; f. After the 2# filter unit stops for 30 seconds, open the backwash water control valve (12) and the sewage control valve (13) of the 2# filter unit, and open the backwash control valve (14) of the 2# filter unit after 10 seconds to start The backwash of the 2# filter unit, after the backwash at the interval of the backwash time setting value, close the backwash water control valve (12), sewage control valve (3) and backflush control valve (14) of the 2# filter unit, Complete the backwash of the 2# filter unit and put it in a standby state. 3. According to claim 2, the control method of the filter device that can switch operation and automatic backwashing is characterized in that: the water pressure of the external water supply pipeline connected to the backwashing water control valve (6), (12) is controlled at Between 0.4 and 0.5 MPa; the air pressure of the external compressed air pipeline connected to the blowback control valve (8) and (14) is controlled between 0.55 and 0.65 MPa. 4. According to claim 2, the control method of the filtering device with switchable operation and automatic backwashing is characterized in that: the 1# filtering unit and the 2# filtering unit are repeatedly and alternately operated, and the programmable controller (1) records The number of times of backwashing and running time of each filter unit. If the running time of one of the filter units is too short and the number of backwash times increases, the control system will send an alarm message corresponding to the certain filter unit, prompting the need for maintenance. 5. According to the control method of the filter device with switchable operation and automatic backwashing according to claim 2, it is characterized in that: during the operation of the filter unit, if the pressure difference value at both ends of the filter element of the filter changes suddenly from a larger value to If the value is smaller, it can be considered that the filter of the filter unit is clogged, and the backwash function of the filter unit is triggered immediately, and the control system sends an alarm message of the filter unit, prompting that maintenance and treatment are required. 6. According to claim 2, the control method of the filter device with switchable operation and automatic backwashing is characterized in that: the programmable controller (1) detects the filter inlet according to the differential pressure transmitter (15) The pressure difference between the outlet and the outlet switches the operation of the two filter units. The default value of the pressure is 0.7 kPa. When the pressure difference at both ends of the filter unit in operation reaches the set switching pressure value, the standby filter unit is put into Running, the filter unit in operation stops running, switches to backwashing state, and waits for backwashing. 7. According to claim 2, the control method of the filtering device with switchable operation and automatic backwashing is characterized in that: the programmable controller (1) operates the two filtering units according to the set running time of the filtering units To switch, the default time is 2 hours. When the running time of the filter unit in operation has reached the set switch time, the standby filter unit will be put into operation, and the filter unit in operation will stop running, switch to the backwashing state, and wait for Backwash. 8. According to claim 2, the control method of the filtering device with switchable operation and automatic backwashing is characterized in that: the programmable controller (1) controls the backwashing operation of the filter unit according to the set backwashing time Time, the backwash running time defaults to 60 seconds, and the set value must be greater than or equal to the default value.