A filtration system and method for high viscosity lubricating oils

Abstract

A kind of filtering system and filtering method of high viscosity lubricating oil, including secondary waste oil pool and a finished oil barrel, system is powered by oil pump, high viscosity lubricating oil is filtered gradually by intelligent control system control each stage valve body, and cooperate with pressure relief line and backwash line to ensure the service life of filtering equipment and the smooth filtration of high viscosity oil body.The present application solves the problem of filtering and recycling of high viscosity waste oil in the prior art, which can recycle the waste oil at low cost, and can be used again, especially solving the problem that the precision filter element is easily fractured when filtering high viscosity waste oil, or the precision filter element cannot be used to filter high viscosity waste oil;At the same time, with the help of temperature rising means, the problem of difficult pumping of high viscosity waste oil is also solved.The overall cost of the equipment is low, the control is simple, the use is safe, and the machine market popularization value is high.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of lubricating oil filtration, in particular to a high-viscosity lubricating oil filtration system and method. BACKGROUND

[0002] High-viscosity lubricating oil refers to lubricating oil with viscosity exceeding 5000 mPa / s, which is waste oil after use. In practical applications, such high-viscosity waste oil cannot be recycled and reused due to its high viscosity. In the prior art, there are also methods for recycling and filtering such waste oil for reuse, but there are many difficulties in filtering waste oil. The main problems are that the high viscosity of the waste oil causes high pressure in the pipeline, which easily causes the filter core to crack, and the filter core cannot be used or has a short service life; and the high viscosity of the waste oil makes it difficult to pump.

[0003] The prior art also provides solutions to related problems, such as a mobile high-viscosity lubricating oil filtration device disclosed in Chinese patent CN201020149780. The device directly connects a filter, i.e. a filter cartridge, through a gear pump set, thereby achieving direct filtration. However, the implementation of this device is only theoretically feasible. In actual operation, the gear pump cannot pump the waste oil to the filter cartridge when the viscosity of the waste oil is too high, and the subsequent filtration process cannot be implemented. In other words, the viscosity of the waste oil filtered by this device is still relatively low. At present, there is still a lack of corresponding solutions for filtering high-viscosity waste lubricating oil in the market. SUMMARY

[0004] The present application aims to overcome the shortcomings of the prior art and provide a high-viscosity lubricating oil filtration system and method that is simple in structure, safe and reliable, and easy to use.

[0005] The high-viscosity lubricating oil filtration system comprises a waste oil pool and a machine body shell. The machine body shell is provided with a heating and heat preservation unit, a waste oil barrel, an oil pump, a primary filter, and a secondary filter.

[0006] The waste oil pool is arranged in a place where the ambient temperature is not lower than 60 degrees;

[0007] The waste oil pool is connected to the oil pump through valve F1, the oil pump is connected to valve F7 through a pipeline, and valve F7 is connected to the primary filter through a pipeline. The primary filter is connected to a primary oil return pipe and a filtered oil pipe through a three-way valve. The primary oil return pipe is connected to the waste oil barrel through valve F4. The waste oil barrel is arranged in the machine body shell.

[0008] The waste oil barrel is connected to the main oil inlet pipe through valve F3 and a three-way valve. The main oil inlet pipe is the pipeline between the waste oil pool and the oil inlet of the primary filter.

[0009] The filter oil pipe is connected with the valve F11 pipe through a four-way valve and a precision filter; the precision filter is provided with a two-stage oil return pipeline and an oil production pipeline; the two-stage oil return pipeline is connected with a waste oil tank through a valve F5 pipeline; and the oil production pipeline is connected with a finished oil tank through a valve F8 pipeline;

[0010] The filter system of the high-viscosity lubricating oil further comprises an oil path backwashing system and an air path backwashing system; the oil path backwashing system comprises a valve F10; the valve F10 is connected with the finished oil tank and an oil pump through pipelines, that is, the finished oil in the finished oil tank is pumped out through the oil pump and is used for backwashing;

[0011] The pipeline between the oil pump and the valve F7 and the pipeline between the precision filter and the valve F5, that is, the above two pipelines, are cross-connected with a precision filter backwashing oil path through two three-way valves, and the valve F6 is arranged on the precision filter backwashing oil path.

[0012] The valve F11 is connected with a four-way valve, and the valve F14 is further arranged on the sequential connection pipeline of the valve F11, that is, the front part of the four-way valve; the valve F14 is connected with the valve F2 through a pipeline; and the valve F2 is connected with the pipeline between the waste oil tank and the valve F1 through a three-way valve.

[0013] The air path backwashing system comprises a compressed air inlet pipe; the compressed air inlet pipe is used for connecting external compressed air power; and the compressed air inlet pipe is connected with a precision filter backwashing unit and a primary filter backwashing unit through pipelines.

[0014] The precision filter backwashing unit comprises a valve F9; one end of the valve F9 is connected with the compressed air inlet pipe through a pipeline and a three-way valve; and the other end is connected with the pipeline between the precision filter and the valve F8 through a three-way valve.

[0015] The primary filter backwashing unit comprises a valve F12; the valve F12 is arranged on the compressed air inlet pipe; and the pipeline before the valve F12 is connected with the pipeline between the primary filter and the valve F4 through a three-way valve.

[0016] Further, the compressed air inlet pipe is connected with the valve F13 through a three-way pipeline; the valve F13 is connected with a second oil pump through a pipeline; and the compressed air inlet pipe is connected with the second oil pump in power, that is, the second oil pump is driven by air power.

[0017] The second oil pump is connected with the finished oil tank through a pipeline. In this way, the filtered finished oil can be pumped out and is used for real-time oil supply in cooperation with other oil equipment.

[0018] Further, the heating and heat preservation unit comprises a heating device and a temperature detection module.

[0019] The body shell is double-layer lining filled with fireproof material, and the heating device is arranged in the inner chamber of the body shell.

[0020] Further, the waste oil pool, the waste oil barrel and the finished oil barrel are provided with thermometers and liquid level meters.

[0021] The effect achieved is that the liquid level of each unit oil body temperature is monitored in real time.

[0022] Further, the pressure gauge P1 is arranged between the oil pump and the valve F7, the pressure gauge P2 is arranged between the valve F11 and the precision filter, and the pressure gauge P3 is arranged in the precision filter.

[0023] The effect achieved is that the oil pressure of the key position of the oil circuit circulation and the precision filter is monitored in real time.

[0024] Further, the valves F1 to F14 are electrically controlled valves, and the valve F9 is a pulse valve.

[0025] The liquid level meter and the thermometer are electronic liquid level meter and electronic thermometer respectively.

[0026] Further, the body shell is integrally provided with a general controller and a control unit, the control unit is signal connected to the general controller, and the general controller is signal connected to the heating and temperature maintaining unit, the valve body, the liquid level meter and the thermometer.

[0027] In use, the filtered high-viscosity lubricating oil viscosity range refers to 5000-10000 millipascal / second waste lubricating oil, and the implementation steps include the following steps:

[0028] s1. The inner chamber of the body shell is heated to 70-80 degrees Celsius;

[0029] s2. The waste oil is injected into the waste oil pool, and the waste oil is pumped by the oil pump, enters the first filter through the valve F1, the oil pump and the valve F7, and enters the waste oil barrel through the first oil return pipeline and the valve F4; the oil circuit is preliminarily circulated and first filtered;

[0030] s3. After the liquid level in the waste oil barrel reaches the standard height, the valve F1 is closed, and the oil in the waste oil barrel is pumped into the first filter again through the valve F3, the oil pump and the valve F7 for secondary first filtering;

[0031] s4. After the first filtered oil is pumped out, the valve F4 opening degree is controlled by the pressure gauge P2 and the general controller, and the first filtered oil flows to the first oil return pipeline through the valve F4 and returns to the waste oil barrel, and the other way is through the valve F11 and enters the precision filter;

[0032] s5. When the pressure in the precision filter is too high, the oil outside the filter core of the precision filter returns to the waste oil tank through valve F5, and the finished product oil filtered in the filter core enters the finished product oil tank through valve F8;

[0033] s6. When the liquid level in the waste oil tank is too low or the oil level in the finished product oil tank is too high, the backwashing condition is triggered;

[0034] The backwashing sequence is to first execute the gas path backwashing system, and then execute the oil path backwashing system after the gas path backwashing is completed;

[0035] The present application solves the problem of filtering and recycling high-viscosity waste oil in the prior art, can recycle waste oil at low cost, and can be used again, especially solves the problem that the precision filter core is easily fractured when filtering high-viscosity waste oil, or the precision filter core cannot be used to filter high-viscosity waste oil. In addition, the heating means also solves the problem that high-viscosity waste oil is difficult to pump. The present application has low overall cost, simple control, safe use, and high market promotion value. BRIEF DESCRIPTION OF DRAWINGS

[0036] Figure 1 is an embodiment schematic view of the high-viscosity lubricating oil filtering system and filtering method according to the present application;

[0037] Reference signs:

[0038] 1-main oil inlet pipe 2-oil pump 3-precision backwashing oil path 4-first-stage oil return pipe 5-first-stage filter 6-filtered oil pipe 7-precision filter 8-finished product oil tank 9-waste oil tank 10-waste oil pool

[0039] The implementation, functional characteristics and advantages of the present application will be further described with reference to the embodiments and the accompanying drawings. DETAILED DESCRIPTION

[0040] Reference Figure 1 The high-viscosity lubricating oil filtering system according to the present application comprises a waste oil pool 10 and a machine body shell, and the machine body shell is provided with a heating and heat preservation unit, a waste oil tank 9, an oil pump 2, a first-stage filter 5 and a second-stage filter.

[0041] The waste oil pool 10 is arranged at a place where the ambient temperature is not lower than 60 degrees;

[0042] The waste oil pool 10 is connected to the oil pump 2 through valve F1, the oil pump 2 is connected to valve F7, and valve F7 is connected to the first-stage filter 5; the first-stage filter 5 is connected to the first-stage oil return pipe 4 and the filtered oil pipe 6 through a three-way valve; the first-stage oil return pipe 4 is connected to the waste oil tank 9 through valve F4; and the waste oil tank 9 is arranged in the machine body shell.

[0043] The implementation purpose is that, due to the high viscosity of waste oil, the implementation environment needs to be heated in the engine housing, and after the temperature reaches the standard, the waste oil in the waste oil tank 10 is first pumped out by the oil pump 2 into the waste oil tank 9, realizing the preliminary oil circuit circulation while filtering the waste oil once, and the waste oil in the waste oil tank 9 is heated twice; that is, the temperature inside the engine housing is increased to 70-80℃ compared with the external environment of the engine housing, that is, the oil temperature is further increased.

[0044] The waste oil tank 9 is connected to the main oil inlet pipe 1 through the valve F3 and the three-way valve; the main oil inlet pipe 1 is the pipeline between the waste oil tank 10 and the oil inlet of the first filter 5;

[0045] The implementation purpose is that, after the oil temperature in the waste oil tank 9 reaches the standard, the valve F1 is closed, and the oil is pumped to the valve F7 through the valve F3 and the oil pump 2, and is filtered again through the first filter 5;

[0046] The filtered oil pipe 6 is connected to the precision filter 7 through the four-way valve and the valve F11; the precision filter 7 is provided with a secondary oil return pipeline and an oil production pipeline; the secondary oil return pipeline is connected to the waste oil tank 9 through the valve F5; and the oil production pipeline is connected to the finished oil tank 8 through the valve F8;

[0047] The implementation purpose is that, after the preliminary oil circuit circulation is realized, the oil in the waste oil tank 9 is pumped to the first filter 5 again under the control of the valve body, and after being filtered by the first filter 5, when the internal pressure of the communication pipeline of the precision filter 7 is too high, the oil outlet of the first filter 5 is branched, part of which flows back to the waste oil tank 9, and the other part is filtered by the precision filter 7, and also to avoid the internal pressure of the precision filter 7 being too high, the oil is returned to the waste oil tank 9 through the secondary oil return pipeline;

[0048] The high-viscosity lubricating oil filtering system further comprises an oil circuit backwashing system and a gas circuit backwashing system; the oil circuit backwashing system comprises a valve F10, and the valve F10 is connected to the finished oil tank 8 and the oil pump 2 in the pipeline, that is, the finished oil in the finished oil tank 8 is pumped out by the oil pump 2, and is used for backwashing;

[0049] The pipeline between the oil pump 2 and the valve F7 and the pipeline between the precision filter 7 and the valve F5, that is, the above two pipelines, are connected by two three-way valves, and the precision filter backwashing oil circuit is connected across the two pipelines, and the valve F6 is arranged on the precision filter backwashing oil circuit 3;

[0050] The implementation purpose is that, in cooperation with the closing of other control valves, the valve F6 is opened to pump the finished oil into the precision filter 7 in the reverse direction; that is, the oil is discharged from the tail end of the precision filter 7 to the valve F11;

[0051] The valve F11 is connected with a four-way valve, and a valve F14 is arranged on the sequence connecting pipeline of the valve F11, that is, the front part of the four-way valve, and the valve F14 is connected with a valve F2 through a pipeline, and the valve F2 is connected with the pipeline between the waste oil pool 10 and the valve F1 through a three-way valve pipeline;

[0052] The implementation purpose is to sequentially return the backwash oil to the waste oil pool 10.

[0053] The air path backwash system comprises a compressed air inlet pipe for connecting external compressed air power, and the compressed air inlet pipe is connected with a precision filter 7 backwash unit and a first-stage filter 5 backwash unit through a pipeline.

[0054] The precision filter 7 backwash unit comprises a valve F9, one end of the valve F9 is connected with the compressed air inlet pipe through a pipeline and a three-way valve, and the other end is connected with the pipeline between the precision filter 7 and a valve F8 through a three-way valve.

[0055] The implementation purpose is to cooperate with the closing of other valves, compressed air enters the precision filter 7 through the valve F9 for backwash, and the accumulated oil in the pipeline is backwashed to re-enter the waste oil pool 10 from the tail end of the precision filter 7 through the valves F11, F14 and F2.

[0056] The first-stage filter 5 backwash unit comprises a valve F12 arranged on the compressed air inlet pipe, and the pipeline before the valve F12 is connected with the pipeline between the first-stage filter 5 and a valve F4 through a three-way valve pipeline.

[0057] The implementation purpose is to cooperate with the closing of other valves, compressed air enters the first-stage filter 5 through the valve F12 for backwash, and the accumulated oil in the pipeline is backwashed to re-enter the waste oil pool 10 from the tail end of the first-stage filter 5 through the valves F7 and F1.

[0058] Preferably, the oil path backwash system only backwashes the precision filter 7, and the air path backwash system can control the backwash of the entire filter system through the valve body.

[0059] Further, the compressed air inlet pipe is connected with a valve F13 through a three-way pipeline, and the valve F13 is connected with a second oil pump 2 through a pipeline.

[0060] The second oil pump 2 is connected with a finished oil barrel 8, so that the filtered finished oil can be pumped out and cooperated with other oil equipment to realize real-time oil supply.

[0061] Further, the heating and heat preservation unit comprises a heating device and a temperature detection module.

[0062] The body shell is double-layer lining filled with fireproof material, and the heating device is arranged in the inner chamber of the body shell.

[0063] Further, the waste oil pool 10, the waste oil barrel 9 and the finished oil barrel 8 are all provided with a thermometer and a liquid level gauge.

[0064] The effect achieved thereby is that the liquid level of the temperature of each unit oil body is monitored in real time.

[0065] Further, a pressure gauge P1 is arranged between the oil pump 2 and the valve F7, a pressure gauge P2 is arranged between the valve F11 and the precision filter 7, and a pressure gauge P3 is arranged in the precision filter 7.

[0066] The effect achieved thereby is that the oil pressure at the key position of the oil circuit and on both sides of the precision filter 7 is monitored in real time.

[0067] Further, the valves F1 to F14 are all electrically controlled valves, and the valve F9 is a pulse valve.

[0068] The liquid level gauge and the thermometer are respectively an electronic liquid level gauge and an electronic thermometer.

[0069] Further, the body shell is integrally provided with a general controller and a control unit, the control unit is signal-connected to the general controller, and the general controller is signal-connected to the heating and temperature-keeping unit, the valve bodies, the liquid level gauges and the thermometers.

[0070] Preferably, the general controller can adopt one or more of PLC, MCU and microcomputer intelligent controllers, and the control unit can adopt a touch control panel or a key control unit.

[0071] Preferably, the motor of the oil pump 2 is arranged outside the body shell through an extended transmission shaft, thereby ensuring production safety.

[0072] In use, the filtered high-viscosity lubricating oil has a viscosity range of 5000-10000 millipascal / second, and the implementation steps include the following steps:

[0073] s1. The inner chamber of the body shell is heated to 70-80 degrees Celsius;

[0074] s2. Waste oil is injected into the waste oil pool 10, and the waste oil is pumped by the oil pump 2, enters the first filter 5 through the valve F1, the oil pump 2 and the valve F7, and enters the waste oil barrel 9 through the valve F4 through the first oil return pipe 4, thereby realizing preliminary circulation and first-time filtration of the oil circuit.

[0075] s3. When the oil level in the waste oil bucket 9 reaches the standard height, the valve F1 is closed, and the oil in the waste oil bucket 9 is introduced into the primary filter again through the valve F3, the oil pump 2 and the valve F7 for secondary filtering;

[0076] s4. After the primary filtering, the opening degree of the valve F4 is controlled by the pressure gauge P2 and the total controller, and the oil filtered out by the primary filter flows to the waste oil bucket 9 through the primary return oil pipe 4 controlled by the valve F4, and the other oil flows into the precision filter 7 through the valve F11;

[0077] Here, the opening degree of the valve F4 controlled by the pressure gauge P2 and the total controller means that when the initial pressure of the pressure gauge P2 is too high, the opening degree of the valve F4 is large to reduce the oil pressure in the filtering oil pipe 6, so as to prevent the filter element in the precision filter 7 from being damaged due to excessive pressure. When the pressure of the pressure gauge P2 is stable or low, the opening degree of the valve F4 is gradually reduced.

[0078] s5. When the pressure in the precision filter 7 is too high, the oil outside the filter element in the precision filter 7 flows back to the waste oil bucket 9 through the valve F5, and the finished oil filtered in the filter element flows into the finished oil bucket 8 through the valve F8;

[0079] s6. When the oil level in the waste oil bucket 9 is too low or the oil level in the finished oil bucket 8 is too high, the backwashing condition is triggered;

[0080] The backwashing sequence is to first execute the gas path backwashing system, and then execute the oil path backwashing system after the gas path backwashing is completed;

[0081] When the oil path backwashing system is started, the oil pump 2 needs to be stopped and each valve body needs to be sequentially closed due to the existence of the pipeline pressure, the opening sequence of the oil path backwashing valve is valve F10, valve F6, valve F11, valve F14 and valve F2, and the oil pump 2 is started to make the oil path backwashing flow back to the waste oil pool 10;

[0082] The gas path backwashing system includes the precision filter 7 backwashing unit and the primary filter 5 backwashing unit. When the backwashing is implemented, the oil pump 2 and each valve need to be sequentially closed due to the pipeline pressure problem, and then the valves are sequentially opened according to the backwashing implementation sequence,

[0083] The opening sequence of the precision filter 7 backwashing unit is F9, F11, valve F14 and valve F2, and the pipeline accumulated oil is backwashed to make it re-enter the waste oil pool 10;

[0084] The opening sequence of the primary filter 5 backwashing unit is valve F12, valve F7 and valve F1, and the pipeline accumulated oil is backwashed to make it re-enter the waste oil pool 10.

[0085] Preferably, the backwashing system can also be started by active control.

[0086] Preferably, the pressure in the filter oil pipe 6 and the precision filter 7 is not higher than 0.15-0.2 MPa.

[0087] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered exemplary and non-limiting in all respects. The scope of the invention is defined by the appended claims rather than the foregoing description, and all variations falling within the meaning and scope of equivalents of the claims are intended to be included within the present invention. No reference numerals in the claims should be construed as limiting the scope of the claims.

[0088] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A filtration system for high-viscosity lubricating oil, comprising a waste oil tank and a housing, wherein the housing is equipped with a heating and insulation unit, a waste oil drum, an oil pump, a primary filter, and a secondary filter; the waste oil tank is located at an ambient temperature not lower than 60 degrees Celsius; the waste oil tank is connected to the oil pump via a valve F1 pipe; the oil pump pipe is connected to a valve F7; and the valve F7 pipe is connected to the primary filter, characterized in that: The primary filter is connected with a primary return oil pipeline and a filtered oil pipeline through a three-way valve pipeline; the primary return oil pipeline is connected with a waste oil tank through a valve F4 pipeline; and the waste oil tank is arranged in the machine body shell. The waste oil tank is connected with a main oil inlet pipeline through a valve F3 and a three-way valve; The filtered oil pipeline is connected with a precision filter through a valve F11 pipeline; the precision filter is divided into a secondary return oil pipeline and an oil production pipeline; the secondary return oil pipeline is connected with the waste oil tank through a valve F5 pipeline; and the oil production pipeline is connected with a finished oil tank through a valve F8 pipeline; The high-viscosity lubricating oil filtering system further comprises an oil path backwashing system and an air path backwashing system; the oil path backwashing system comprises a valve F10; and the valve F10 is connected with the finished oil tank and an oil pump through pipelines. A precision filter backwashing oil path is connected between pipelines between the oil pump and the valve F7 and between the precision filter and the valve F5, that is, between the above two pipelines; and a valve F6 is arranged on the precision filter backwashing oil path. The valve F11 is connected with a four-way valve; a valve F14 is further arranged on a pipeline sequentially connected with the valve F11, that is, on a front part of the four-way valve; the valve F14 is connected with the valve F2 through a pipeline; and the valve F2 is connected with a pipeline between a waste oil pool and the valve F1 through a three-way valve pipeline. The air path backwashing system comprises a compressed air inlet pipeline; and the compressed air inlet pipeline is connected with a precision filter backwashing unit and a primary filter backwashing unit through pipelines. The precision filter backwashing unit comprises a valve F9; one end of the valve F9 is connected with the compressed air inlet pipeline through a pipeline and a three-way valve; and the other end is connected with a pipeline between the precision filter and the valve F8 through a three-way valve. The primary filter backwashing unit comprises a valve F12; the valve F12 is arranged on the compressed air inlet pipeline; and a pipeline before the valve F12 is connected with a pipeline between the primary filter and the valve F4 through a three-way valve pipeline. Pressure gauges P1, P2 and P3 are arranged between the oil pump and the valve F7, between the valve F11 and the precision filter, and in the precision filter, respectively. After the primary filtration, the oil is returned to the waste oil tank through the valve F4 and the primary return oil pipeline; and the secondary filtration oil is returned to the waste oil tank through the valve F11 and the precision filter. When the pressure in the precision filter is too high, the oil outside the filter core of the precision filter is returned to the waste oil tank through the valve F5; and the finished oil filtered in the filter core is returned to the finished oil tank through the valve F8.

2. The filtration system for high viscosity lubricating oil of claim 1, wherein, The compressed air inlet pipeline is connected with a valve F13 through a three-way pipeline; the valve F13 is connected with a second oil pump through a pipeline; and the compressed air inlet pipeline is connected with the second oil pump through air power. The second oil pump is connected with the finished oil tank through a pipeline.

3. The filtration system for high viscosity lubricating oil of claim 1, wherein, The heating and temperature maintaining unit comprises a heating device and a temperature detection module. The machine body shell is double-layered and lined with fireproof material; and the heating device is arranged in an inner chamber of the machine body shell.

4. The filtration system for high viscosity lubricating oil of claim 1, wherein, Temperature gauges and liquid level gauges are arranged on the waste oil pool, the waste oil tank and the finished oil tank.

5. The system for filtering high viscosity lubricating oil of claim 4, wherein, The valves F1 to F14 are electrically controlled valves, and the valve F9 is a pulse valve. The liquid level meter and the thermometer are electronic liquid level meter and electronic thermometer respectively.

6. The system for filtering high viscosity lubricating oil of claim 1, wherein, The general controller and the control unit are integrated on the machine body shell, the control unit is signal connected with the general controller, and the general controller is signal connected with the heating and heat preservation unit, each valve body, the liquid level meter and the thermometer.

7. A method of filtering high viscosity lubricating oil, characterized by, The following implementation steps are: s1. The inner cavity of the machine body shell is heated to 70-80 degrees Celsius, and the machine body shell is provided with a heating and heat preservation unit, a waste oil tank, an oil pump, a primary filter and a secondary filter; s2. Waste oil is injected into the waste oil tank, and the waste oil is pumped by the oil pump, and then enters the primary filter through the valve F1, the oil pump and the valve F7, and then enters the waste oil tank through the primary oil return pipeline and the valve F4; The oil circuit is preliminarily circulated and first filtered; s3. When the liquid level in the waste oil tank reaches the standard height, the valve F1 is closed, and the oil in the waste oil tank enters the primary filter again through the valve F3, the oil pump and the valve F7, and is secondarily filtered; s4. After the primary filter oil, the valve F4 opening degree is controlled by the pressure gauge P2 and the general controller, and the first secondary filter oil flows to the primary oil return pipeline through the valve F4 and returns to the waste oil tank, and the other way is through the valve F11 and enters the precision filter; The valve F4 opening degree controlled by the pressure gauge P2 and the general controller means that when the initial pressure of the pressure gauge P2 is too high, in order to prevent the filter core in the precision filter from being damaged due to excessive pressure, the opening degree of the valve F4 is large, so as to reduce the oil pressure in the filter oil pipe, and when the pressure of the pressure gauge P2 is stable or lower, the opening degree of the valve F4 is gradually reduced; s5. When the pressure in the precision filter is too high, the oil outside the filter core of the precision filter returns to the waste oil tank through the valve F5, and the finished oil filtered in the filter core enters the finished oil tank through the valve F8; s6. When the liquid level in the waste oil tank is too low or the oil level in the finished oil tank is too high, the backwashing condition is triggered; The backwashing sequence is to first execute the gas circuit backwashing system, and then execute the oil circuit backwashing system after the gas circuit backwashing is completed.

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