A filtering system and a filtering method

Abstract

The present invention relates to the technical field of filtration, and more specifically, to a filtration system. A filtration system includes: a precoat liquid storage tank: the precoat liquid storage tank includes a first precoat liquid storage tank and a second precoat liquid storage tank, and the inlets of the first precoat liquid storage tank and the second precoat liquid storage tank are connected to the stock solution through pipelines; a number of filter particles are added to the stock solution; a filter: the inlets of the filter are respectively connected to the outlets of the first precoat liquid storage tank and the second precoat liquid storage tank through pipelines; the filter is composed of a fixed filter layer and a movable filter layer; a filter particle separator is connected to the filter and a centrifugal filter through pipelines respectively; the filter particle separator is further connected to a diaphragm pump, and the diaphragm pump is connected to the first precoat liquid storage tank and the second precoat liquid storage tank through pipelines; the centrifugal filter is connected to a rotor pump through a pipeline. Through the cooperation between the devices, the present invention can basically achieve automated operation, greatly reducing the equipment investment and operation costs, and can be applied to large-production-capacity working conditions.

Description

Technical Field

[0001] The present invention relates to the technical field of filtration, and more particularly, to a filtration system and a filtration method. Background Art

[0002] In the solid-liquid separation of high viscosity, high density, fine and hard solid particles, the common method is to use a filter medium with a pore size smaller than the size of the solid particles to intercept the solid particles in the original liquid passing through the filter medium and obtain a filtered liquid. During the process, the solid gradually blocks the filter pores of the filter medium to form a filter cake, resulting in a gradual decrease in the filtration capacity of the filter medium. To a certain extent, the filter medium needs to be backwashed to remove the solid filter cake blocking the filter pores of the filter medium and restore the filter pores to be unobstructed to restore the production capacity of the filter medium. The solid-liquid separation of the original liquid is completed in the continuous cycle operation of filtration-backwashing-filtration. Moreover, the backwashing requires the use of backwashing liquid that is much more expensive than the original liquid.

[0003] In actual operation, for the backwashing treatment of the filter medium, it is necessary to use backwashing liquid that is much more expensive than the original liquid. Moreover, due to the fact that the solid particles are too fine and hard, the filter pores will be blocked, and it cannot be guaranteed that each backwashing can completely remove the solid particles blocking the filter pores. After each backwashing, the filtration capacity of the filter medium will decrease to a certain extent. After the cyclic operation for a certain period of time, the filter medium will lose its filtration function. At this time, it is necessary to perform an external regeneration treatment on the filter medium to restore the filter pores to be unobstructed. Usually, there are treatment methods such as incineration, ultrasonic waves, and solution immersion. These methods will cause different degrees of damage to the filter medium, which will greatly increase the production cost and seriously affect the output for some expensive filter media. For special liquids, this problem is particularly serious. In actual applications, in order to reduce the severity of the problem, auxiliary filtration media (such as diatomite, perlite, wood chips, fibers, etc.) are often added to the original liquid, thereby improving the stacking structure of the filter cake, reducing the degree of blockage of the filter pores by solid particles, extending the cycle time of filtration-backwashing, increasing the output, but still need to perform an external regeneration treatment on the filter medium, and the problem still exists. At the same time, the treatment link of the auxiliary filtration medium is increased, which not only increases the cost but also increases the process difficulty. For example, in the patent CN201510159999.9 of the applicant, a filtration device and its filtration method can achieve the effect of solid-liquid separation, but there are problems such as too many dynamic devices (centrifuges) (small production capacity per single device), low automation degree, and large management difficulty, and it is difficult to cope with large production capacity working conditions. Therefore, a filtration system and a filtration method are needed that can reduce the filtration cost and can be applied to large production capacity working conditions. Summary of the Invention

[0004] Based on this, the purpose of the present invention is to provide a filtration system and a filtration method, which can reduce the filtration cost through the cooperation between devices and can be applied to large production capacity working conditions.

[0005] The technical solution of the present invention is: a filtration system, which includes:

[0006] Pre - coating liquid storage tanks: The pre - coating liquid storage tanks include a first pre - coating liquid storage tank and a second pre - coating liquid storage tank. The inlets of the first pre - coating liquid storage tank and the second pre - coating liquid storage tank are connected to the stock solution through pipelines; several filter grains are added into the stock solution.

[0007] Filters: The inlets of the filters are respectively connected to the outlets of the first pre - coating liquid storage tank and the second pre - coating liquid storage tank through pipelines; the filters are composed of a fixed filter layer and a movable filter layer.

[0008] It also includes a filter grain separator, a centrifugal filter, a diaphragm pump, and a rotor pump; the filter grain separator is connected to the filter and the centrifugal filter through pipelines respectively.

[0009] The filter grain separator is also connected to the diaphragm pump, and the diaphragm pump is connected to the first pre - coating liquid storage tank and the second pre - coating liquid storage tank through pipelines.

[0010] The centrifugal filter is connected to the rotor pump through a pipeline.

[0011] In the present invention, through the cooperation between devices, automated operation can be basically achieved, greatly reducing equipment investment and operating costs, and it can be applied to large - production - capacity working conditions.

[0012] Further preferably, a first pneumatic main valve is connected to the inlet of the first pre - coating liquid storage tank, and the first pneumatic main valve is connected to the stock solution through a pipeline; a first pneumatic sub - valve is connected to the inlet of the second pre - coating liquid storage tank, and the first pneumatic sub - valve is connected to the stock solution through a pipeline.

[0013] A second pneumatic main valve is connected to the outlet of the first pre - coating liquid storage tank, a second pneumatic sub - valve is connected to the outlet of the second pre - coating liquid storage tank, and both the second pneumatic main valve and the second pneumatic sub - valve are connected to the inlet of the filter through pipelines.

[0014] Specifically, a third pneumatic valve for inputting back - flushing stock solution is connected to one side of the filter through a pipeline; a fourth pneumatic valve for outputting purified liquid is also connected to one side of the filter through a pipeline.

[0015] Furthermore, a fifth pneumatic valve is also connected to the filter, and the filter is connected to the centrifugal filter through a pipeline and the fifth pneumatic valve.

[0016] A sixth pneumatic valve is connected between the filter and the filter grain separator through a pipeline; a seventh pneumatic valve for inputting back - flushing stock solution is connected to one side of the filter grain separator.

[0017] Specifically, an eighth pneumatic valve is connected between the filter grain separator and the centrifugal filter through a pipeline.

[0018] A ninth pneumatic main valve and a ninth pneumatic sub-valve are also connected to the pipelines between the diaphragm pump and the first pre-coating liquid storage tank and the second pre-coating liquid storage tank. The particle separator is connected to the first pre-coating liquid storage tank and the second pre-coating liquid storage tank through the diaphragm pump, the ninth pneumatic main valve and the ninth pneumatic sub-valve.

[0019] Further preferably, a raw liquid input port is provided on one side of the particle separator, a raw liquid flushing spray pipe is provided inside the particle separator, a particle output port is provided on the other side of the particle separator, and a filter plate is also provided inside the particle separator;

[0020] One end of the raw liquid input port is connected to a pipeline for inputting back-flushing raw liquid, and the other end is connected to the raw liquid flushing spray pipe;

[0021] One end of the particle output port communicates with the inside of the particle separator, and the other end is connected to the diaphragm pump through a pipeline.

[0022] Specifically, in the height direction inside the particle separator, from top to bottom, there are a raw liquid flushing spray pipe, a particle output port, and a filter plate in sequence. A plurality of filter holes are provided on the filter plate, the size of the filter holes is larger than the size of solid particles, and the size of the filter holes is smaller than the size of the filter particles.

[0023] A filtering method, applying the filtering system, wherein, it includes the following steps:

[0024] S1. Before the process starts, all valves are in the closed state, and the centrifugal filter and the rotor pump are in the normally open state;

[0025] S2. The raw liquid enters the first pre-coating liquid storage tank and the second pre-coating liquid storage tank through the first pneumatic main valve and the first pneumatic sub-valve, and is formulated into a suitable pre-coating liquid with the measured filter particles. Open the second pneumatic main valve and the fifth pneumatic valve, and the filter enters the pre-coating operation for forming a movable filter layer. After reaching the pre-coating operation time, open the fourth pneumatic valve and close the fifth pneumatic valve to produce clean liquid;

[0026] S3. After reaching the clean liquid production time, close the fourth pneumatic valve and the second pneumatic main valve, open the diaphragm pump, open the third pneumatic valve, the sixth pneumatic valve, the seventh pneumatic valve, and the eighth pneumatic valve to perform a back-flushing operation. The back-flushed concentrated liquid enters the particle separator through the sixth pneumatic valve for particle separation operation. After the back-flushing operation time reaches 10 seconds, two operations are performed simultaneously, namely step S31 and step S32;

[0027] S31. Close the third pneumatic valve, the sixth pneumatic valve, the first pneumatic main valve, and the second pneumatic main valve; open the first pneumatic sub-valve, the second pneumatic sub-valve, and the fifth pneumatic valve to start the next pre-coating - filtering - production operation cycle of the filter;

[0028] S32. Start the diaphragm pump and open the ninth pneumatic main valve. Use the stock solution passing through the seventh pneumatic valve to transport the separated filter particles back to the first pre - coating liquid storage tank through the diaphragm pump for pre - coating liquid preparation as a standby.

[0029] S4. The back - flush concentrated liquid separated by the filter particle separator enters the centrifugal filter through the eighth pneumatic valve. After being processed by the centrifugal filter, the purified liquid is output by the rotor pump, and the solids are discharged manually. Thus, a complete process cycle is completed.

[0030] Further, in step S2, the pre - coating operation time is determined through debugging, based on the liquid passing through the rotor pump meeting the quality index requirements of the purified liquid.

[0031] In step S3, the purified liquid production time is determined through debugging, based on the production volume decreasing to 50% of that at the start of purified liquid production.

[0032] Compared with the prior art, the beneficial effects are as follows: Through the cooperation between devices, the present invention can basically achieve automated operation, greatly reducing equipment investment and operating costs, and can be applied to large - production - capacity working conditions.

[0033] The overall process method of the present invention has simple operation, high automation degree, and good filtering effect.

[0034] For better understanding and implementation, the present invention will be described in detail below with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 is the overall schematic diagram of the system of the present invention.

[0036] Figure 2 is the schematic diagram of the internal filtration principle of the filter of the present invention.

[0037] Figure 3 is the structural and connection schematic diagram of the filter particle separator of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0038] To make the objectives, features, and advantages of the present invention more obvious and understandable, the following detailed description of the specific embodiments of the present invention will be given with reference to the accompanying drawings. Several embodiments of the present invention are shown in the drawings. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein.

[0039] In the present invention, unless otherwise clearly specified or limited, the terms "installed", "connected", "coupled", "fixed", etc. shall be construed in a broad sense. For example, it may be a fixed connection, a detachable connection, or an integral connection; it may be a mechanical connection or an electrical connection; it may be directly connected or indirectly connected through an intermediate medium, and it may be the communication inside two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances. The terms "first" and "second" are only used for descriptive purposes and cannot be construed as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include one or more of such features.

[0040] In the present invention, unless otherwise clearly specified or limited, the first feature being "on" or "under" the second feature may include the direct contact between the first and second features, or may include the situation where the first and second features are not in direct contact but in contact through additional features therebetween. Moreover, the first feature being "above", "over" and "on top of" the second feature includes that the first feature is directly above and obliquely above the second feature, or merely means that the horizontal height of the first feature is higher than that of the second feature. The first feature being "under", "beneath" and "underneath" the second feature includes that the first feature is directly below and obliquely below the second feature, or merely means that the horizontal height of the first feature is lower than that of the second feature. The terms "vertical", "horizontal", "left", "right", "up", "down" and similar expressions are only for the purpose of illustration, rather than indicating or implying that the indicated device or element must have a specific orientation, be constructed and operated in a specific orientation, and thus cannot be construed as a limitation to the present invention.

[0041] The present invention will be described in detail below with reference to the accompanying drawings and embodiments.

[0042] As Figure 1 shown, arrow a represents the stock solution, arrow b represents the backwash stock solution, arrow c represents the purified liquid, arrow d represents the purified liquid, and arrow e represents the solid.

[0043] A filtration system, which includes:

[0044] Precoating liquid storage tank: The precoating liquid storage tank includes a first precoating liquid storage tank 1-1 and a second precoating liquid storage tank 1-2. The inlets of the first precoating liquid storage tank 1-1 and the second precoating liquid storage tank 1-2 are connected to the stock solution through pipelines; a certain number of filter particles are added to the stock solution;

[0045] Filter 2: The inlet of the filter 2 is respectively connected to the outlets of the first precoating liquid storage tank 1-1 and the second precoating liquid storage tank 1-2 through pipelines; the filter 2 is composed of a fixed filter layer and a movable filter layer;

[0046] It also includes a filter particle separator 3, a centrifugal filter 4, a diaphragm pump 5, and a rotor pump 6; the filter particle separator 3 is respectively connected to the filter 2 and the centrifugal filter 4 through pipelines;

[0047] The filter particle separator 3 is also connected to the diaphragm pump 5, and the diaphragm pump 5 is connected to the first pre - coating liquid storage tank 1 - 1 and the second pre - coating liquid storage tank 1 - 2 through pipelines;

[0048] The centrifugal filter 4 is connected to the rotor pump 6 through a pipeline.

[0049] In this embodiment, the number of pre - coating liquid storage tanks is 2, and the two are backup to each other. The pre - coating liquid storage tanks are used to prepare the pre - coating liquid, which is prepared by adding a certain number of filter particles to the stock solution. The number of filter particles is considered according to 2 - 3 times the effective filtration area of covering the fixed filter layer, and is determined by tests in actual applications; the proportion of filter particles in the pre - coating liquid is preferably 3 - 5%, and is determined by tests in actual applications. The number of devices can be configured in parallel according to the output requirements.

[0050] As Figure 2 shown, it is the internal filtration structure and principle of the filter. Arrow a represents the stock solution, and arrow c represents the purified liquid; the filter is composed of a fixed filter layer and a movable filter layer, which plays a filtering role. The movable filter layer is composed of several filter particles 10, and the fixed filter layer is the filter medium 20. The filter medium 20 includes a filter medium pipe wall 22 and several filter holes 21 provided in the filter medium pipe wall 22; several filter particles 10 are closely attached to the side of the filter medium pipe wall 22; the stock solution contains solid particles 40; the sizes of several filter particles 10 are all larger than the sizes of several filter holes 21; the sizes of several filter holes 21 are all larger than 2 times the maximum outer dimension of the solid particles 40, and the solid particles 40 are the impurity particles in the stock solution.

[0051] The above settings ensure that the solid particles 40 will not block the filter holes 21. The filter medium 20 does not intercept the solid particles 40, and the filter medium 20 only intercepts the filter particles 10, so that the filter medium 20 will not be blocked, and backwashing can be carried out with the stock solution, without the need for high - cost backwashing liquid.

[0052] In addition, it should be noted that when the solid particle cake accumulates to a certain extent and backwashing is required, the entry of the stock solution into the filter is stopped, and the filter is backwashed with the stock solution. As Figure 1 shown by arrow b in, the backwashing stock solution, filter particles and cake form a backwashing concentrated liquid, and the backwashing concentrated liquid enters the filter particle separator 3. The number of filters can be configured in parallel according to the output requirements.

[0053] As Figure 3 shown, one side of the filter particle separator 3 is provided with a stock solution input port 30, the filter particle separator 3 is provided with a stock solution flushing spray pipe 31 inside, the other side of the filter particle separator 3 is provided with a filter particle output port 34, and the filter particle separator 3 is also provided with a filter plate 32;

[0054] One end of the stock solution input port 30 is connected to the pipeline for inputting the backwashing stock solution, and the other end is connected to the stock solution flushing nozzle 31.

[0055] One end of the filter particle output port 34 communicates with the inside of the filter particle separator 3, and the other end is connected to the diaphragm pump 5 through a pipeline.

[0056] In the filter particle separator 3, from top to bottom in the height direction are the stock solution flushing nozzle 31, the filter particle output port 34, and the filter plate 32. A number of filter holes 33 are formed on the filter plate 32. The size of the filter holes 33 is larger than the size of the solid particles 40 and smaller than the size of the filter particles 10.

[0057] In this embodiment, the stock solution is input into the stock solution flushing nozzle 31 as shown by the arrow a. The boiling state is created on the surface of the filter plate 32 by using the stock solution pressure, causing the filter particles 10 to be continuously disturbed and the filtering function not to be generated. Since the size of the filter holes 33 is larger than the size of the solid particles 40 and smaller than the size of the filter particles 10, the filter particles 10 are intercepted above the filter plate 32, while the solid particles 40 can pass through the filter holes 33. The backwashing concentrated liquid is diluted by the stock solution and discharged to the centrifugal filter 4 after passing through the filter plate 32. The separation of the filter particles 10 from the backwashing concentrated liquid is completed. The filter particles 10 are discharged from the filter particle output port 34 by the stock solution, discharged to the precoating liquid storage tank through the diaphragm pump 5, and then the next operation cycle is carried out.

[0058] The diaphragm pump 5 is to avoid damaging the filter particles 10 during transportation. The number of diaphragm pumps 5 can be configured in parallel according to the production requirements.

[0059] As Figure 1 shown, in the centrifugal filter 4, complete solid-liquid separation can be achieved. The solids are discharged as shown by the arrow e, and the clarified liquid after centrifugal filtration of the centrifugal filter 4 is discharged as shown by the arrow d through the rotor pump 6. The number of centrifugal filters 4 can be configured in parallel according to the production requirements. In addition, it should be noted that the structure and principle of the centrifugal filter 4 can refer to the patent CN201510159999.9 A Filtering Device and Its Filtering Method authorized by the applicant.

[0060] As Figure 1 shown, regarding the setting of the pipeline and valve connections, the following is specific. The inlet of the first precoating liquid storage tank 1-1 is connected with the first pneumatic main valve F1-1, and the first pneumatic main valve F1-1 is connected to the stock solution through a pipeline; the inlet of the second precoating liquid storage tank 1-2 is connected with the first pneumatic sub-valve F1-2, and the first pneumatic sub-valve F1-2 is connected to the stock solution through a pipeline.

[0061] The outlet of the first precoating liquid storage tank 1-1 is connected with the second pneumatic main valve F2-1, the outlet of the second precoating liquid storage tank 1-2 is connected with the second pneumatic sub-valve F2-2, and both the second pneumatic main valve F2-1 and the second pneumatic sub-valve F2-2 are connected to the inlet of the filter 2 through pipelines.

[0062] One side of the filter 2 is connected by a pipeline to the third pneumatic valve F3 for inputting the backwashing stock solution; one side of the filter 2 is also connected by a pipeline to the fourth pneumatic valve F4 for outputting the purified liquid. The filter 2 is further connected with a fifth pneumatic valve F5, and the filter 2 is connected to the centrifugal filter 4 through a pipeline and the fifth pneumatic valve F5;

[0063] There is a sixth pneumatic valve F6 connected by a pipeline between the filter 2 and the filter particle separator 3; one side of the filter particle separator 3 is connected to the seventh pneumatic valve F7 for inputting the backwashing stock solution.

[0064] There is an eighth pneumatic valve F8 connected by a pipeline between the filter particle separator 3 and the centrifugal filter 4;

[0065] There are also a ninth pneumatic main valve F9-1 and a ninth pneumatic sub-valve F9-2 connected to the pipelines between the diaphragm pump 5 and the first pre-coating liquid storage tank 1-1 and the second pre-coating liquid storage tank 1-2. The filter particle separator 3 is connected to the first pre-coating liquid storage tank 1-1 and the second pre-coating liquid storage tank 1-2 through the diaphragm pump 5, the ninth pneumatic main valve F9-1, and the ninth pneumatic sub-valve F9-2.

[0066] As Figures 1-3 shown, in the present invention, its overall process flow is as follows:

[0067] A filtering method, applying the filtering system described above, wherein, it includes the following steps:

[0068] S1. Before the process starts, all valves are in the closed state, and the centrifugal filter 4 and the rotor pump 6 are in the normally open state;

[0069] S2. The stock solution enters the first pre-coating liquid storage tank 1-1 and the second pre-coating liquid storage tank 1-2 through the first pneumatic main valve F1-1 and the first pneumatic sub-valve F1-2, and is formulated into a suitable pre-coating liquid with the measured filter particles. Then, the second pneumatic main valve F2-1 and the fifth pneumatic valve F5 are opened, and the filter 2 enters the pre-coating operation to form a movable filter layer. After reaching the pre-coating operation time, the fourth pneumatic valve F4 is opened, the fifth pneumatic valve F5 is closed, and the purified liquid is produced;

[0070] S3. After reaching the purified liquid production time, the fourth pneumatic valve F4 and the second pneumatic main valve F2-1 are closed, the diaphragm pump 5 is opened, the third pneumatic valve F3, the sixth pneumatic valve F6, the seventh pneumatic valve F7, and the eighth pneumatic valve F8 are opened, and the backwashing operation is carried out. The backwashing concentrated liquid enters the filter particle separator 3 through the sixth pneumatic valve F6 for the filter particle separation operation. After the backwashing operation time reaches 10 seconds, two operations are carried out simultaneously, namely step S31 and step S32;

[0071] S31. Close the third pneumatic valve F3, the sixth pneumatic valve F6, the first main pneumatic valve F1-1, and the second main pneumatic valve F2-1; open the first auxiliary pneumatic valve F1-2, the second auxiliary pneumatic valve F2-2, and the fifth pneumatic valve F5 to start the next precoating-filtration-production operation cycle of the filter 2;

[0072] S32. Start the diaphragm pump 5 and open the ninth main pneumatic valve F9-1. Use the stock solution passing through the seventh pneumatic valve F7 to transport the separated filter particles back to the first precoating liquid storage tank 1-1 through the diaphragm pump 5 for precoating liquid preparation as a standby;

[0073] S4. The backwashing concentrated liquid separated by the filter particles in the filter particle separator 3 enters the centrifugal filter 4 through the eighth pneumatic valve F8. After being processed by the centrifugal filter 4, the purified liquid is output by the rotor pump 6, and the solid is discharged manually by processing, thus completing a complete process cycle.

[0074] Specifically, in step S2, the precoating operation time is determined through debugging, based on the liquid passing through the rotor pump 6 reaching the quality index requirements of the purified liquid; the experimental measurement is about 5 seconds, and 15 seconds is selected for the experiment.

[0075] In step S3, the purified liquid production time is determined through debugging, based on the production volume being reduced to 50% of that at the start of purified liquid production; the experimental measurement is 40 minutes.

[0076] The present invention has the following technical effects:

[0077] Through the cooperation between devices, the present invention can basically achieve automated operation, greatly reducing equipment investment and operating costs, and can be applied to large-production-capacity working conditions. In the filter, the combined filter medium composed of a fixed filter layer and a movable filter layer fundamentally solves the problem of filter holes being blocked. The filter holes will not be clogged, and backwashing can be carried out with the stock solution, reducing costs and simplifying the operation difficulty.

[0078] The overall process method flow of the present invention is simple to operate, has a high degree of automation, and has a good filtering effect.

[0079] Obviously, the above-mentioned embodiments of the present invention are merely examples for clearly illustrating the present invention, rather than limitations on the implementation manners of the present invention. For those of ordinary skill in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation manners here. Any modifications, equivalent replacements, and improvements made within the spirit and principle of the present invention shall be included in the protection scope of the claims of the present invention.

Claims

1. A filtering method, applied to a filtering system, comprising: Pre-coated liquid storage tank: The pre-coated liquid storage tank includes a first pre-coated liquid storage tank (1-1) and a second pre-coated liquid storage tank (1-2). The inlets of the first pre-coated liquid storage tank (1-1) and the second pre-coated liquid storage tank (1-2) are connected to the stock solution through pipelines; several filter particles are added to the stock solution. Filter (2): The inlets of the filter (2) are respectively connected to the outlets of the first pre-coated liquid storage tank (1-1) and the second pre-coated liquid storage tank (1-2) through pipelines; the filter (2) is composed of a fixed filter layer and a movable filter layer. It also includes a filter particle separator (3), a centrifugal filter (4), a diaphragm pump (5), and a rotor pump (6); the filter particle separator (3) is connected to the filter (2) and the centrifugal filter (4) respectively through pipelines. The filter particle separator (3) is also connected to the diaphragm pump (5), and the diaphragm pump (5) is connected to the first pre-coated liquid storage tank (1-1) and the second pre-coated liquid storage tank (1-2) through pipelines. The centrifugal filter (4) is connected to the rotor pump (6) through a pipeline. The inlet of the first pre-coated liquid storage tank (1-1) is connected with a first pneumatic main valve (F1-1), and the first pneumatic main valve (F1-1) is connected to the stock solution through a pipeline; the inlet of the second pre-coated liquid storage tank (1-2) is connected with a first pneumatic sub-valve (F1-2), and the first pneumatic sub-valve (F1-2) is connected to the stock solution through a pipeline. The outlet of the first pre-coated liquid storage tank (1-1) is connected with a second pneumatic main valve (F2-1), and the outlet of the second pre-coated liquid storage tank (1-2) is connected with a second pneumatic sub-valve (F2-2). Both the second pneumatic main valve (F2-1) and the second pneumatic sub-valve (F2-2) are connected to the inlet of the filter (2) through pipelines. One side of the filter (2) is connected to a third pneumatic valve (F3) for inputting backwashing stock solution through a pipeline; one side of the filter (2) is also connected to a fourth pneumatic valve (F4) for outputting purified liquid through a pipeline. The filter (2) is also connected with a fifth pneumatic valve (F5), and the filter (2) is connected to the centrifugal filter (4) through a pipeline and the fifth pneumatic valve (F5). A sixth pneumatic valve (F6) is connected between the filter (2) and the filter particle separator (3) through a pipeline; one side of the filter particle separator (3) is connected to a seventh pneumatic valve (F7) for inputting backwashing stock solution. An eighth pneumatic valve (F8) is connected between the filter particle separator (3) and the centrifugal filter (4) through a pipeline. A ninth pneumatic main valve (F9-1) and a ninth pneumatic sub-valve (F9-2) are also connected to the pipelines between the diaphragm pump (5) and the first pre-coated liquid storage tank (1-1) and the second pre-coated liquid storage tank (1-2). The filter particle separator (3) is connected to the first pre-coated liquid storage tank (1-1) and the second pre-coated liquid storage tank (1-2) through the diaphragm pump (5), the ninth pneumatic main valve (F9-1), and the ninth pneumatic sub-valve (F9-2). One side of the described particle filter separator (3) is provided with a raw liquid input port (30). A raw liquid flushing spray pipe (31) is arranged inside the particle filter separator (3). The other side of the particle filter separator (3) is provided with a particle output port (34). A filter plate (32) is also arranged inside the particle filter separator (3); One end of the raw liquid input port (30) is connected to a pipe for inputting backwashing raw liquid, and the other end is connected to the raw liquid flushing spray pipe (31); One end of the particle output port (34) communicates with the inside of the particle filter separator (3), and the other end is connected to a diaphragm pump (5) through a pipe; Inside the particle filter separator (3), in the height direction from top to bottom are successively arranged the raw liquid flushing spray pipe (31), the particle output port (34), and the filter plate (32); A number of filter holes (33) are formed on the filter plate (32). The size of the filter holes (33) is larger than the size of solid particles and smaller than the size of particles; It is characterized by including the following steps: S1. Before the process starts, all valves are in the closed state, and the centrifugal filter (4) and the rotor pump (6) are in the normally open state; S2. The raw liquid enters the first precoat liquid storage tank (1-1) and the second precoat liquid storage tank (1-2) through the first pneumatic main valve (F1-1) and the first pneumatic sub-valve (F1-2), and is formulated with the measured particles into a suitable precoat liquid. The second pneumatic main valve (F2-1) and the fifth pneumatic valve (F5) are opened, and the filter (2) enters the precoat operation for forming a movable filter layer. After reaching the precoat operation time, the fourth pneumatic valve (F4) is opened, and the fifth pneumatic valve (F5) is closed to produce clean liquid; S3. After reaching the clean liquid production time, the fourth pneumatic valve (F4) and the second pneumatic main valve (F2-1) are closed. The diaphragm pump (5) is started, and the third pneumatic valve (F3), the sixth pneumatic valve (F6), the seventh pneumatic valve (F7), and the eighth pneumatic valve (F8) are opened for backwashing operation. The backwashing concentrated liquid enters the particle filter separator (3) through the sixth pneumatic valve (F6) for particle separation operation. After the backwashing operation time reaches 10 seconds, two operations are carried out simultaneously, namely step S31 and step S32; S31. The third pneumatic valve (F3), the sixth pneumatic valve (F6), the first pneumatic main valve (F1-1), and the second pneumatic main valve (F2-1) are closed; the first pneumatic sub-valve (F1-2), the second pneumatic sub-valve (F2-2), and the fifth pneumatic valve (F5) are opened to start the next precoat - filtration - production operation cycle of the filter (2); S32. The diaphragm pump (5) is started, and the ninth pneumatic main valve (F9-1) is opened. The separated particles are conveyed back to the first precoat liquid storage tank (1-1) through the diaphragm pump (5) by using the raw liquid passing through the seventh pneumatic valve (F7) for formulating the precoat liquid as a standby; S4. The backwashing concentrated liquid that has undergone particle separation in the particle filter separator (3) enters the centrifugal filter (4) through the eighth pneumatic valve (F8). After being processed by the centrifugal filter (4), the clean liquid is output by the rotor pump (6), and the solids are discharged manually by workers, thus completing a complete process cycle.

2. The filtering method according to claim 1, wherein: In the said step S2, the pre-coating operation time is determined through debugging, based on the quality index of the liquid passing through the rotor pump (6) meeting the requirements of the pure liquid; In the said step S3, the pure liquid production time is determined through debugging, based on the output being reduced to 50% of that at the start of pure liquid production.

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