Combined mechanical seal and auxiliary liquid sealing system for middle-high pressure reaction polymerization kettle

Abstract

The utility model provides a combined type mechanical seal for a middle-high pressure reaction polymerization kettle, which comprises a stirring shaft, a packaging type double-end-face mechanical seal is arranged on the stirring shaft, the packaging type double-end-face mechanical seal comprises a static ring assembly, a movable ring assembly and a throttling assembly, the movable ring assembly is arranged on the inner side of the static ring assembly, and the throttling assembly is arranged on the inner side of the movable ring assembly. A spacer fluid sealing cavity is formed in the movable ring assembly, a pressing assembly is arranged at the end, facing the interior of the reaction kettle, of the container type double-end-face mechanical seal, the throttling assembly is arranged between the pressing assembly and the shell, a flushing fluid sealing cavity is formed among the shell, the stirring shaft and the pressing assembly, and a flushing fluid channel is formed in the shell. And the flushing fluid channel is communicated with the flushing fluid sealing cavity, the throttling assembly and the interior of the reaction kettle. According to the combined mechanical seal assembly, the mode that the double-end-face mechanical seal and the flushing combined seal are combined is adopted, the mechanical seal is prevented from losing efficacy, meanwhile, materials and the double-end-face mechanical seal are isolated through flushing fluid, the service life of the combined mechanical seal assembly is greatly prolonged, and the safety performance of a system is greatly improved.

Description

Technical Field

[0001] This utility model relates to the field of mechanical seal technology, and in particular to a combined mechanical seal and auxiliary sealing liquid system for medium and high pressure reaction polymerization reactors. Background Technology

[0002] In the petrochemical industry, stirred reactors are crucial equipment in chemical production, and the reliability of the shaft seal assembly is essential for the safe and stable operation of the production unit. For polymerization reactors, the operating pressure is relatively high, and the polymer monomers, due to their unstable structure, are often flammable and explosive media. Furthermore, their tendency to self-polymerize results in a large number of solid particles within the reactor. These reactors place extremely high demands on the design of the stirred shaft seal; therefore, research on high-pressure reactor stirred shaft seals is of great significance.

[0003] Currently, high-pressure reactors in the chemical industry mostly use double-end mechanical seals for their agitator shaft seals. These seals consist of two pairs of sealing end faces perpendicular to the axis, separated from the atmospheric side by a separating fluid. If the seal fails, the separating fluid either enters the material side or flows to the atmospheric side, preventing the leakage of flammable, explosive, or toxic media from the reactor, thus avoiding environmental pollution and safety hazards. However, due to the high solid content during polymerization reactions, many solid particles remain free on the sealing end faces, especially in bottom-entry or side-entry agitators where the material level is generally higher than the mechanical seal end faces. Solid particles generated during polymerization, or liquid and gaseous monomers, can enter the sealing end faces and self-polymerize, damaging them and leading to leakage. This poses a significant safety hazard due to mechanical seal leakage during the reaction process, and the cost of spare parts and maintenance for high-pressure reactor mechanical seals is also high. Therefore, a reliable sealing system is needed for medium- and high-pressure reactors that can handle flammable, explosive, toxic, corrosive, and easily self-polymerizing media, and can be used in both bottom-entry and side-entry applications. Utility Model Content

[0004] This utility model aims to at least partially solve one of the technical problems in the related art.

[0005] To achieve the above objectives, this utility model proposes a combined mechanical seal for a medium- and high-pressure reaction polymerization reactor, comprising a stirring shaft and a housing sleeved outside the stirring shaft. A cartridge-type double-end face mechanical seal is installed on the stirring shaft. The cartridge-type double-end face mechanical seal includes a stationary ring assembly, a rotating ring assembly, and a throttling assembly. The rotating ring assembly is disposed inside the stationary ring assembly, and a sealing cavity for a separating liquid for lubrication and sealing of the double ends is provided within the rotating ring assembly. A clamping assembly is provided at one end of the cartridge-type double-end face mechanical seal facing the inside of the reactor. The throttling assembly is disposed between the clamping assembly and the housing. A flushing liquid sealing cavity is provided between the housing, the stirring shaft, and the clamping assembly. A flushing liquid channel is provided on the housing, and the flushing liquid channel is connected to the flushing liquid sealing cavity, the throttling assembly, and the inside of the reactor.

[0006] This invention employs a combination of double-end mechanical seal and flushing seal. While preventing material leakage from the medium- and high-pressure reactor due to mechanical seal failure, the flushing fluid isolates the material from the double-end mechanical seal, significantly improving the service life of the combined mechanical seal assembly and the safety performance of the system.

[0007] Optionally, a flow gap is formed between the clamping assembly and the housing to allow the flushing liquid to flow into the reactor after passing through the throttling assembly.

[0008] Furthermore, the housing is provided with an isolation liquid inlet channel and an isolation liquid return channel that are connected to the isolation liquid sealing cavity, and the included angle between the isolation liquid inlet channel and the isolation liquid return channel is 180 degrees.

[0009] Furthermore, the flushing fluid channel and the isolation fluid return channel are set at a 90-degree angle.

[0010] Furthermore, a flow gap is formed between the stirring shaft and the housing in the section from the flushing liquid channel to the flushing liquid sealing cavity, so that the flushing liquid flows from the flushing liquid channel to the flushing liquid sealing cavity.

[0011] This utility model also provides an auxiliary sealing liquid system for a combined mechanical seal for a medium- and high-pressure reaction polymerization reactor using any of the above-mentioned methods, including a mechanical seal, wherein the mechanical seal is connected to a flushing liquid pipeline and an isolation liquid circulation pipeline.

[0012] The flushing fluid pipeline includes a water tank, which is connected to the flushing fluid inlet of the mechanical seal via a pipe. A flushing water pump is installed on the pipe connecting the water tank and the mechanical seal.

[0013] The isolation fluid circulation pipeline includes a balance tank, which is connected to the isolation fluid inlet of the mechanical seal via a pipeline, and the balance tank is connected to the isolation fluid outlet pipeline of the mechanical seal. An isolation fluid circulation pump is installed on the pipeline connecting the balance tank and the isolation fluid inlet.

[0014] The balance tank is connected to an oil circuit system for controlling the pressure of the balance tank.

[0015] Furthermore, a remote liquid level interlocking system is installed on the flushing fluid pipeline, the remote liquid level interlocking system including a remote liquid level gauge, a shut-off valve and a replenishment pump;

[0016] The pipeline connecting the water tank and the mechanical seal is equipped with a branch pipeline that connects to the balance tank, and a replenishment pump is installed on the branch pipeline.

[0017] A breather valve is installed on the water tank, and a shut-off valve is installed on the pipeline connecting the water tank and the breather valve;

[0018] Both the water tank and the balance tank are equipped with remote level gauges.

[0019] Furthermore, the oil circuit system includes an oil tank, which is connected to an oil supply line and an oil return line;

[0020] The oil supply pipeline is equipped with a third precision filter and an oil pump in sequence from the oil tank to the balance tank, and the oil supply pipeline is connected to an accumulator.

[0021] The return oil pipeline is connected to the oil pump to accumulator section of the oil supply pipeline, and the other end of the return oil pipeline is connected to the oil tank. A hydraulic check valve, a pneumatic regulating valve and a heat exchanger are sequentially arranged along the direction from the oil pump to the oil tank.

[0022] Furthermore, before the oil supply line is connected to the return line, two sets of oil pumping lines are provided, and each oil pumping line is equipped with the third precision filter and the oil pump.

[0023] Additional aspects and advantages of this invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0024] The above and / or additional aspects and advantages of this utility model will become apparent and readily understood from the following description of the embodiments taken in conjunction with the accompanying drawings, in which:

[0025] Figure 1 This is a schematic diagram of a combined mechanical seal for a medium- and high-pressure reaction polymerization reactor according to the present invention.

[0026] Figure 2 This is a schematic diagram of the overall system structure of an auxiliary sealing liquid system according to the present invention.

[0027] Explanation of reference numerals in the attached figures:

[0028] 1. Static ring assembly; 2. Dynamic ring assembly; 3. Isolation fluid return channel; 4. Isolation fluid sealing chamber; 5. Flushing fluid channel; 6. Flushing fluid sealing chamber; 7. Throttling assembly; 8. Pressing assembly; 9. Housing; 10. Isolation fluid inlet channel; 11. Stirring shaft; 12. Oil tank; 13. Breather valve; 14. Heat exchanger; 15. Pneumatic regulating valve; 16. Third precision filter; 17. Hydraulic check valve; 18. Oil pump; 19. Accumulator; 20. Exhaust pipe; 21. Cartridge-type double-end mechanical seal; 22. First precision filter; 23. Second precision filter; 24. First flow meter; 28. Second flow meter; 25. Flushing water pump; 26. Make-up pump; 27. Water tank; 29. ​​Isolation fluid circulation pump; 30. Balance tank. Detailed Implementation

[0029] The embodiments of this utility model are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain this utility model, and should not be construed as limiting this utility model.

[0030] This utility model proposes a combined mechanical seal for medium- and high-pressure reaction polymerization reactors, which is described below. Figure 1 Please provide a detailed explanation.

[0031] A combined mechanical seal for a medium- and high-pressure reaction polymerization reactor includes a stirring shaft 11 and a housing 9 sleeved outside the stirring shaft 11. A cartridge-type double-end mechanical seal 21 is installed on the stirring shaft 11. The cartridge-type double-end mechanical seal 21 includes a stationary ring assembly 1, a rotating ring assembly 2, and a throttling assembly 7. The rotating ring assembly 2 is located inside the stationary ring assembly 1. The rotating ring assembly 2 has a sealing cavity 4 for providing lubrication and sealing for both ends. A clamping assembly 8 is provided at the end of the cartridge-type double-end mechanical seal 21 facing the inside of the reactor. The throttling assembly 7 is located between the clamping assembly 8 and the housing 9. A flushing fluid sealing cavity 6 is provided between the housing 9, the stirring shaft 11, and the clamping assembly 8. A flushing fluid channel 5 is provided on the housing 9. The flushing fluid channel 5 is connected to the flushing fluid sealing cavity 6, the throttling assembly 7, and the inside of the reactor.

[0032] This utility model adopts a combination of a double-end mechanical seal 21 and a flushing combined seal. While preventing material leakage in the medium and high pressure vessel due to the failure of the mechanical seal 21, the flushing fluid isolates the material from the double-end mechanical seal 21, which greatly improves the service life of the combined mechanical seal 21 assembly and the safety performance of the system.

[0033] In some embodiments, a flow gap is formed between the clamping component 8 and the housing 9 so that the flushing liquid flows into the reactor after passing through the throttling component 7.

[0034] In some embodiments, since the throttling component 7 is a consumable part in contact with the reaction medium, it should be detachable, and the throttling component 7 should be cleaned or replaced online by disassembling the clamping device.

[0035] In some embodiments, the housing 9 is provided with an isolation liquid inlet channel 10 and an isolation liquid return channel 3, which are connected to the isolation liquid sealing cavity 4. The included angle between the isolation liquid inlet channel 10 and the isolation liquid return channel 3 is 180 degrees. An isolation liquid inlet is provided on the outside of the housing 9, which is connected to the isolation liquid inlet channel 10. The isolation liquid enters the isolation liquid sealing cavity 4 from the isolation liquid inlet through the isolation liquid inlet channel 10, providing sealing, lubrication, and cooling to the sealing end face in the isolation liquid sealing cavity 4. Then, it flows out from the isolation liquid return channel 3 and returns to the balance tank 30 to continue the circulation.

[0036] In some embodiments, the flushing fluid channel 5 and the isolation fluid return channel 3 are set at a 90-degree angle. This distinguishes the isolation fluid return channel 3, the isolation fluid inlet channel 10, and the flushing fluid channel 5.

[0037] In some embodiments, a flow gap is formed between the stirring shaft 11 and the housing 9 in the section from the flushing fluid channel 5 to the flushing fluid sealing cavity 6, so that the flushing fluid flows from the flushing fluid channel 5 to the flushing fluid sealing cavity 6.

[0038] This utility model also provides an auxiliary sealing liquid system using the combined mechanical seal 21 for high-pressure reaction polymerization reactors described above, which is described below in conjunction with... Figure 2 Please provide a detailed explanation.

[0039] An auxiliary sealing fluid system includes a mechanical seal 21, which is connected to a flushing fluid line and an isolation fluid circulation line.

[0040] The flushing fluid pipeline includes a water tank 27, which is connected to the flushing fluid inlet of the mechanical seal 21 via a pipeline. A flushing water pump 25 is installed on the pipeline connecting the water tank 27 and the mechanical seal 21.

[0041] The isolation fluid circulation pipeline includes a balance tank 30, which is connected to the isolation fluid inlet of the mechanical seal 21 via a pipeline. The balance tank 30 is also connected to the isolation fluid outlet pipeline of the mechanical seal 21. An isolation fluid circulation pump 29 is installed on the pipeline connecting the balance tank 30 and the isolation fluid inlet.

[0042] The balance tank 30 is connected to an oil circuit system for controlling the pressure of the balance tank 30.

[0043] The isolation fluid provided by the auxiliary sealing fluid system enters the isolation fluid sealing chamber 4 to provide the main seal to prevent leakage of the medium inside the reactor and ensure the safety of the reaction system. The flushing fluid provided by the auxiliary sealing fluid system enters the reactor through the flushing fluid sealing chamber 6 and the throttling component 7 in sequence, continuously injecting a small flow of process water into the reactor to provide auxiliary sealing. During the reaction, the solid particles of the medium are flushed away to prevent the medium containing solid particles from entering the sealing end face of the medium side and causing damage to the mechanical seal 21.

[0044] The isolation fluid circulation pipeline forces the isolation fluid to circulate through the isolation fluid circulation pump 29. After being pressurized by the balance tank 30, the fluid enters the mechanical seal 21 assembly to provide sealing, cooling and lubrication, and then returns to the balance tank 30 for cooling and circulation. The flushing water pipeline continuously injects a small flow of process water into the reactor through the flushing water pump 25 via the mechanical seal 21 assembly to flush the material on the medium side sealing end face of the double-end mechanical seal 21.

[0045] In some embodiments, the flushing water pump 25 should be a plunger-type metering pump, and during operation, the flushing water pressure should be 0.1-0.2 MPa higher than the pressure inside the reactor, while being lower than the pressure of the isolation fluid.

[0046] In some embodiments, a remote liquid level interlocking system is provided on the flushing fluid pipeline. The remote liquid level interlocking system includes a remote liquid level gauge, a shut-off valve, and a replenishment pump 26.

[0047] A branch pipeline connected to the balance tank 30 is provided on the pipeline connecting the water tank 27 and the mechanical seal 21, and a replenishment pump 26 is provided on the branch pipeline;

[0048] A breather valve 13 is installed on the water tank 27, and a shut-off valve is installed on the pipeline connecting the water tank 27 and the breather valve 13.

[0049] Both water tank 27 and balance tank 30 are equipped with remote level gauges. The two remote level gauges, replenishment pump 26, and shut-off valve are electrically connected to the same controller. The controller has an automatic replenishment program; when the level falls below the set replenishment value, the controller activates the replenishment pump 26 and shut-off valve to achieve automatic replenishment. The balance tank 30 is replenished by the replenishment pump 26, and the water tank 27 is replenished by the shut-off valve. In one embodiment, the controller is configured as a DCS (Distributed Control System).

[0050] In some embodiments, the outlet of the isolation fluid is connected to a venting pipe, which is used to vent air from the pipe during the first operation to prevent air bubbles from damaging the sealing surface.

[0051] In some embodiments, both the water tank 27 and the oil tank 12 are equipped with a breather valve 13 and nitrogen sealing to ensure that moisture and oxygen in the air do not participate in the circulation of process water and oil.

[0052] In some embodiments, a first precision filter 22 is installed on the pipeline before the flushing fluid inlet, and a second precision filter 23 is installed on the pipeline before the isolation fluid inlet. A first flow meter 24 and a second flow meter 28 are respectively installed on the flushing water pipeline and the isolation fluid circulation pipeline. A remote pressure gauge is installed at each precision filter to monitor the operating flow rate or the pressure difference before and after the precision filter to confirm whether there is blockage, ensuring that the process water entering the mechanical seal 21 assembly is clean and free of foreign matter.

[0053] In some embodiments, the oil circuit system includes an oil tank 12, which is connected to an oil supply line and an oil return line.

[0054] A third precision filter 16 and an oil pump 18 are sequentially installed along the oil supply pipeline from the oil tank 12 to the balance tank 30, and an accumulator 19 is connected to the oil supply pipeline.

[0055] The return oil pipeline is connected to the section of the oil pump 18 to the accumulator 19 of the oil supply pipeline. The other end of the return oil pipeline is connected to the oil tank 12. A hydraulically controlled check valve 17, a pneumatic regulating valve 15, and a heat exchanger 14 are sequentially installed along the direction from the oil pump 18 to the oil tank 12. The hydraulically controlled check valve 17 is installed in the oil circuit system. When the oil pump 18 malfunctions during operation, the hydraulically controlled check valve 17 closes, maintaining the oil pressure supplied to the balance tank 30 and locking the isolation fluid pressure to prevent back pressure from damaging the sealing end face of the mechanical seal 21. The oil pressure is adjusted by the pneumatic regulating valve 15. This ensures that the isolation fluid pressure is always higher than the pressure inside the reactor, preferably 0.4-0.6 MPa higher.

[0056] In some embodiments, the oil supply line is provided with two sets of oil pumping lines before it is connected to the return line, and each oil pumping line is provided with a third precision filter 16 and an oil pump 18.

[0057] The auxiliary sealing system uses an oil pump 18 to pressurize the balance tank 30, and utilizes an accumulator 19 and a hydraulic control check valve 17 to ensure stable sealing pressure of the isolation liquid. At the same time, it uses mechanical measures to prevent abnormal back pressure of the sealing system during the reaction period from causing failure of the mechanical seal 21.

[0058] In the description of this utility model, it should be understood that the terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc., indicating the orientation or positional relationship are based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this utility model and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this utility model.

[0059] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this utility model, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0060] In this utility model, unless otherwise explicitly specified and limited, the terms "installation," "connection," "joining," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection, an electrical connection, or a connection that allows communication between them; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise explicitly limited. Those skilled in the art can understand the specific meaning of the above terms in this utility model according to the specific circumstances.

[0061] In this utility model, unless otherwise explicitly specified and limited, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature is in indirect contact with the second feature through an intermediate medium. Furthermore, "above," "on top of," and "over" the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0062] In this utility model, the terms "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to a specific feature, structure, material, or characteristic described in connection with that embodiment or example, which is included in at least one embodiment or example of this utility model. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Furthermore, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0063] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. A combined mechanical seal for a medium- and high-pressure reaction polymerization reactor, characterized in that, The device includes a stirring shaft and a housing fitted outside the stirring shaft. A cartridge-type double-end mechanical seal is installed on the stirring shaft. The cartridge-type double-end mechanical seal includes a stationary ring assembly, a rotating ring assembly, and a throttling assembly. The rotating ring assembly is located inside the stationary ring assembly and has a sealing cavity for a separating fluid for lubrication and sealing of both ends. A clamping assembly is provided at the end of the cartridge-type double-end mechanical seal facing the inside of the reactor. The throttling assembly is located between the clamping assembly and the housing. A flushing fluid sealing cavity is provided between the housing, the stirring shaft, and the clamping assembly. A flushing fluid channel is provided on the housing and is connected to the flushing fluid sealing cavity, the throttling assembly, and the inside of the reactor.

2. The combined mechanical seal for a medium- and high-pressure reaction polymerization reactor as described in claim 1, characterized in that, A flow gap is formed between the clamping component and the housing to allow the flushing liquid to flow into the reactor after passing through the throttling component.

3. The combined mechanical seal for a medium- and high-pressure reaction polymerization reactor as described in claim 1, characterized in that, The housing is provided with an isolation liquid inlet channel and an isolation liquid return channel that are connected to the isolation liquid sealing cavity, and the included angle between the isolation liquid inlet channel and the isolation liquid return channel is 180 degrees.

4. The combined mechanical seal for a medium- and high-pressure reaction polymerization reactor as described in claim 3, characterized in that, The flushing fluid channel and the isolation fluid return channel are set at a 90-degree angle.

5. The combined mechanical seal for a medium- and high-pressure reaction polymerization reactor as described in claim 1, characterized in that, A flow gap is formed between the stirring shaft and the housing in the section from the flushing liquid channel to the flushing liquid sealing cavity, so that the flushing liquid can flow from the flushing liquid channel to the flushing liquid sealing cavity.

6. An auxiliary sealing liquid system using the combined mechanical seal for a medium-high pressure reaction polymerization reactor as described in any one of claims 1 to 5, characterized in that, Includes a mechanical seal, which is connected to a flushing fluid line and a barrier fluid circulation line; The flushing fluid pipeline includes a water tank, which is connected to the flushing fluid inlet of the mechanical seal via a pipe. A flushing water pump is installed on the pipe connecting the water tank and the mechanical seal. The isolation fluid circulation pipeline includes a balance tank, which is connected to the isolation fluid inlet of the mechanical seal via a pipeline, and the balance tank is connected to the isolation fluid outlet pipeline of the mechanical seal. An isolation fluid circulation pump is installed on the pipeline connecting the balance tank and the isolation fluid inlet. The balance tank is connected to an oil circuit system for controlling the pressure of the balance tank.

7. The auxiliary sealing liquid system as described in claim 6, characterized in that, The flushing fluid pipeline is equipped with a remote liquid level interlocking system, which includes a remote liquid level gauge, a shut-off valve, and a replenishment pump. The pipeline connecting the water tank and the mechanical seal is equipped with a branch pipeline that connects to the balance tank, and a replenishment pump is installed on the branch pipeline. A breather valve is installed on the water tank, and a shut-off valve is installed on the pipeline connecting the water tank and the breather valve; Both the water tank and the balance tank are equipped with remote level gauges.

8. An auxiliary sealing liquid system as described in claim 6, characterized in that, A first precision filter is installed on the pipeline before the flushing fluid inlet, and a second precision filter is installed on the pipeline before the isolation fluid inlet.

9. An auxiliary sealing liquid system as described in claim 6, characterized in that, The oil circuit system includes an oil tank, which is connected to an oil supply line and an oil return line; The oil supply pipeline is equipped with a third precision filter and an oil pump in sequence from the oil tank to the balance tank, and the oil supply pipeline is connected to an accumulator. The return oil pipeline is connected to the oil pump to accumulator section of the oil supply pipeline, and the other end of the return oil pipeline is connected to the oil tank. A hydraulic check valve, a pneumatic regulating valve and a heat exchanger are sequentially arranged along the direction from the oil pump to the oil tank.

10. An auxiliary sealing liquid system as described in claim 9, characterized in that, Before the oil supply line is connected to the return line, two sets of oil pumping lines are installed, and each oil pumping line is equipped with the third precision filter and the oil pump.

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