Mechanical sealing system of screw compressor

Abstract

The utility model discloses a screw compressor mechanical sealing system which comprises a mechanical sealing shell, an oil supply buffer tank and an oil outlet pipeline, and further comprises a movable ring, a static ring, a transmission sleeve and a multi-spring structure, a notch is formed in the outer ring of the sealing face of the movable ring, and the axial depth of the notch is 1 mm; the lubricating oil buffer tank is connected with the oil inlet of the mechanical seal shell through an oil inlet pipeline, the oil outlet pipeline is connected with the oil outlet of the mechanical seal shell, and a filter is arranged on the oil outlet pipeline. Lubricating oil can be stored in the notch, so that the lubricating effect of the sealing surface is improved; impurity particles entering the notch can be thrown out through the notch, so that a self-cleaning effect is achieved; impurity particles gathered in the mechanical seal can be intercepted at the filter of the oil outlet pipeline and are prevented from entering an air inlet of the compressor to damage a rotor of the compressor. Therefore, the damage of fine sand grains in shale gas to the mechanical seal can be reduced, the lubricating oil buffer tank can separate gas released in the pressure reduction process of diluted lubricating oil, and the failure rate of the mechanical seal is reduced.

Description

TECHNICAL FIELD

[0001] The utility model relates to a compressor technical field especially relates to a screw compressor mechanical seal system. BACKGROUND

[0002] Shale gas reservoir has the characteristics of low porosity and low permeability, and currently a hydraulic fracturing technology is mostly used to form an artificial fracture network to release shale gas. Fracturing sand is injected into the fracture as a supporting agent in the hydraulic fracturing process to prevent the fracture from closing and maintain the flow channel to improve the yield. In the shale gas exploitation process, the fracturing sand is extracted together with the gas. Although the sand is filtered through a sand remover and a separator, a large number of fine sand particles with a particle size of 5-15 um still pass through the filter into the compressor and are brought to the mechanical seal by the flow of lubricating oil, causing the compressor seal to wear and leak.

[0003] The screw compressor has a high exhaust pressure, and the hydrocarbon gas has a strong dilution capacity on the lubricating oil. The pressure of the lubricating oil at the mechanical seal liquid film is reduced to atmospheric pressure, at which time a part of the gas is precipitated. The part of the gas can destroy the liquid film, causing the mechanical seal to be poorly lubricated, the edge to be damaged, and the leakage to occur.

[0004] In view of the above technical problems, the conventional and commonly used processing methods include:

[0005] 1. A 3-5 um high-precision filter element is used to filter the lubricating oil to ensure that solid particles do not enter the mechanical seal working cavity. However, due to the high filtering precision, the lubricating oil filter element is very easy to be blocked, and the filter element needs to be frequently replaced. In severe cases, a plurality of filter elements need to be replaced in one day to ensure the normal operation of the lubricating oil system.

[0006] 2. A hard-on-hard mechanical seal is selected, and the dynamic ring and the static ring are respectively made of silicon carbide and tungsten carbide to increase the wear resistance. However, the actual situation still has a large number of phenomena of rapid wear and leakage of the mechanical seal.

[0007] 3. A synthetic lubricating oil with strong anti-dilution capacity is selected. However, such a lubricating oil is usually expensive, and the problem of gas precipitation cannot be solved.

[0008] 4. A separate lubricating oil supply system is provided for the mechanical seal, which needs to include an oil pump, a heat exchanger, an oil tank, and an adjusting valve, which greatly increases the complexity of the system. UTILITY MODEL CONTENTS

[0009] In view of the above deficiencies, the technical problem to be solved by the utility model is to provide a screw compressor mechanical seal system, which can reduce the damage of fine sand particles in shale gas to the mechanical seal, can separate the released gas from the lubricating oil in the decompression process through a lubricating oil buffer tank, and can reduce the failure rate of the mechanical seal.

[0010] To solve the above technical problems, the technical scheme of the utility model is

[0011] A screw compressor mechanical seal system, including machine seal shell, the middle of machine seal shell is provided with transmission shaft, the outside of transmission shaft is provided with transmission sleeve, dynamic ring and static ring, the one end of dynamic ring is inserted into transmission sleeve and is resisted on transmission sleeve through spring, the one end of static ring is fixed on machine seal shell, the other end of static ring and the other end of dynamic ring form sealing surface;Machine seal shell, transmission sleeve, dynamic ring, static ring jointly enclose machine seal cavity, oil inlet and oil outlet are arranged on machine seal shell, oil inlet and oil outlet are communicated with machine seal cavity respectively;The outer circle of one end of dynamic ring located sealing surface is provided with at least one notch, and the axial depth of each notch is 1mm;The system further includes lubricating oil buffer tank, lubricating oil buffer tank is connected with oil inlet through oil inlet pipeline, machine seal shell is connected with host computer air inlet through oil outlet pipeline, and filter is arranged on oil outlet pipeline.

[0012] Preferably, the oil outlet pipeline is also provided with a throttle one-way valve.

[0013] Preferably, the oil inlet and the oil outlet are staggered, and the oil inlet is arranged close to the sealing surface side.

[0014] Preferably, each notch is a circular arc notch, the circular arc angle is 75°, and / or the radial depth of each notch is 1 / 3 of the thickness of the sealing surface.

[0015] Preferably, the outer circle of one end of the dynamic ring located the sealing surface is uniformly provided with 12 notches.

[0016] Preferably, the hole diameter of the oil inlet is larger than the hole diameter of the oil outlet.

[0017] Preferably, the material of the dynamic ring is silicon carbide, and the material of the static ring is hard alloy tungsten carbide.

[0018] Preferably, an O-ring is arranged between the static ring and the machine seal shell, and / or the O-ring is made of fluorine rubber.

[0019] Preferably, an O-ring is arranged between the dynamic ring and the transmission shaft, and / or the O-ring is made of fluorine rubber.

[0020] After adopting the above technical scheme, the utility model has the beneficial effects that:

[0021] This utility model discloses a screw compressor mechanical seal system, including a mechanical seal housing, a drive shaft disposed in the middle of the mechanical seal housing, a drive sleeve, a rotating ring, and a stationary ring disposed on the outer side of the drive shaft, one end of the rotating ring extending into the drive sleeve and pressed against the drive sleeve by a spring, one end of the stationary ring being fixed to the mechanical seal housing, and a sealing surface being formed between the other end of the stationary ring and the other end of the rotating ring; the mechanical seal housing, drive sleeve, rotating ring, and stationary ring together form a mechanical seal cavity, the mechanical seal housing being provided with an oil inlet and an oil outlet, which are respectively connected to the mechanical seal cavity; the outer ring of the rotating ring located at the sealing surface has at least one groove, each groove having an axial depth of 1mm; the system also includes a lubricating oil buffer tank, the lubricating oil buffer tank being connected to the oil inlet via an oil inlet pipe, the lubricating oil buffer tank being connected to the oil outlet via an oil outlet pipe, and a filter being disposed on the oil outlet pipe. Because the grooves on the rotating ring can store lubricating oil, the lubrication effect on the sealing surfaces, especially the inner sealing surfaces, is increased. Furthermore, because the axial depth of the grooves is much greater than the diameter of the impurity particles, impurity particles entering the grooves can be thrown out, providing a self-cleaning effect. The lubricating oil buffer tank can separate the gas released from the lubricating oil, and impurity particles accumulated inside the mechanical seal can be intercepted at the filter in the oil outlet pipeline, preventing them from entering the compressor inlet and causing damage to the compressor rotor. Therefore, the screw compressor mechanical seal system of this invention can reduce the damage to the mechanical seal caused by fine sand particles in shale gas. It can separate the gas released during the decompression process of diluted lubricating oil through the lubricating oil buffer tank, reducing the mechanical seal failure rate of shale gas screw compressors. It has strong adaptability to conditions in shale gas applications containing a large number of solid particles, with high exhaust pressure and severely diluted lubricating oil, and can improve the service life of the mechanical seal under such conditions. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of the mechanical seal system of the screw compressor in the embodiment;

[0023] Figure 2 This is a partial structural schematic diagram of the mechanical seal system of the screw compressor in this utility model;

[0024] Figure 3 This is a schematic diagram of the structure of the dynamic ring sealing surface in this utility model;

[0025] In the diagram: 1-Transmission sleeve, 2-Dynamic ring, 20-Slot, 3-Stationary ring, 4-Spring, 5-Dynamic ring O-ring, 6-Stationary ring O-ring, 7-Lubricating oil buffer tank, 8-Filter, 9-Throttle check valve, 10-Oil supply shut-off valve, 11-Vent shut-off valve, 12-Transmission shaft, 13-Oil inlet, 14-Oil outlet, 15-Mechanical seal housing, 16-Mechanical seal cavity. Detailed Implementation

[0026] In order to make the purpose, technical scheme and advantages of the utility model clearer and more apparent, the utility model will be further described in detail below in combination with the drawings and examples.

[0027] It should be noted that, in the description of the utility model, the terms "upper", "lower", "left", "right", "inner", "outer" and the like indicate the direction or positional relationship terms based on the direction or positional relationship shown in the drawings, which is merely for the convenience of description, and is not intended to indicate or imply that the device or element must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the utility model.

[0028] In addition, it should also be noted that, in the description of the utility model, unless otherwise explicitly specified and limited, the terms "mounting", "connection" and "connection" should be understood broadly, for example, it can be fixedly connected, or it can be detachably connected, or integrally connected; it can be mechanically connected, or it can be electrically connected; it can be directly connected, or it can be indirectly connected through an intermediate medium, or it can be connected inside two elements. For those skilled in the art, the specific meaning of the above terms in the utility model can be understood according to the specific circumstances.

[0029] As shown in Figure 1 , Figure 2 and Figure 3 , a screw compressor mechanical sealing system is an internally mounted multi-spring balanced mechanical seal, and the leakage direction is an internal flow type; the screw compressor mechanical sealing system comprises a mechanical seal shell 15, a transmission shaft 12 is arranged in the middle of the mechanical seal shell 15, a transmission sleeve 1, a movable ring 2 and a static ring 3 are arranged on the outer side of the transmission shaft 12, one end of the movable ring 2 extends into the transmission sleeve 1 and abuts against the transmission sleeve 1 through a spring 4, one end of the static ring 3 is fixed on the mechanical seal shell 15, the other end of the static ring 3 abuts against the other end of the movable ring 2, and a sealing surface is formed between the static ring 3 and the movable ring 2; a static ring O-ring 6 is arranged between the static ring 3 and the mechanical seal shell 15, and / or the static ring O-ring 6 is made of fluorine rubber material; a movable ring O-ring 5 is arranged between the movable ring 2 and the transmission shaft 12, and / or the movable ring O-ring 5 is made of fluorine rubber material;

[0030] As shown in Figure 1 and Figure 2 , the mechanical seal shell 15, the transmission sleeve 1, the movable ring 2 and the static ring 3 jointly enclose a mechanical seal cavity 16, and the mechanical seal shell 15 is provided with an oil inlet 13 and an oil outlet 14, and the oil inlet 13 and the oil outlet 14 are respectively communicated with the mechanical seal cavity 16.

[0031] As shown in Figure 3As shown, the dynamic ring 2 is located at one end of the sealing surface, and the outer circle is provided with at least one notch 20; in the embodiment, the outer circle of the dynamic ring 2 located at one end of the sealing surface is uniformly provided with 12 notches 20, and in a preferred scheme, each notch 20 is a circular-arc notch 20, the circular-arc angle is 75°, and / or the radial depth of each notch 20 is 1 / 3 of the thickness of the sealing surface, and / or the axial depth of each notch 20 is 1 mm. Because the deep notch 20 provided on the dynamic ring 2 can store lubricating oil, the lubricating effect of the sealing surface, especially the inner sealing surface, is increased; and because the axial depth of the notch 20 is much greater than the diameter of the impurity particles, the impurity particles entering the notch 20 can be thrown out, and the self-cleaning effect is achieved.

[0032] As shown in Figure 1 , the system further comprises a lubricating oil buffer tank 7, the lubricating oil buffer tank 7 is connected with the oil inlet 13 through an oil inlet pipeline, the lubricating oil buffer tank 7 is connected with the oil outlet 14 through an oil outlet pipeline, and a filter 8 and an oil return throttling one-way valve 9 are arranged in series on the oil outlet pipeline, and in the embodiment, the filter 8 is a large-capacity Y-type filter. In use, the impurity particles gathered in the mechanical seal cavity can be intercepted at the Y-type filter 8 of the oil outlet pipeline, so that the impurity particles are prevented from entering the compressor inlet and causing damage to the compressor rotor; at the same time, the oil return throttling one-way valve 9 prevents the lubricating oil in the mechanical seal cavity 16 from being blown out by the compressor inlet airflow when the unit is started and stopped, so that the problem of insufficient oil in the mechanical seal cavity 16 when the unit is started next time is solved. Moreover, the lubricating oil buffer tank 7 in the utility model can separate the released gas in the decompression process of the diluted lubricating oil, so that the mechanical seal failure rate of the shale gas screw compressor is reduced.

[0033] As shown in Figure 1 and Figure 2 , in the embodiment, the oil inlet 13 and the oil outlet 14 are arranged staggered, the oil inlet 13 is arranged close to the sealing surface side, and the oil outlet 14 is arranged away from the sealing surface. This structure can reduce the flow dead zone in the mechanical seal cavity 16. In a preferred scheme, the mechanical seal cavity is supplied with oil by increasing the diameter of the oil inlet. By this design, the impact of the lubricating oil on the mechanical seal is reduced by reducing the flow rate of the lubricating oil, and the diameter of the oil inlet 13 is greater than the diameter of the oil outlet.

[0034] In the embodiment, the material of the dynamic ring 2 is silicon carbide with small density, and the following property of the dynamic ring 2 is improved, and the material of the static ring 3 is tungsten carbide hard alloy. At the same time, because the dynamic ring 2 needs to have very high following property, a large gap is designed between the dynamic ring 2 and the transmission sleeve 1 in the utility model, and this design greatly reduces the problem that the dynamic ring 2 is stuck because of the impurity particles entering the gap.

[0035] As shown in Figure 1 , Figure 2 and Figure 3 , the working principle of the utility model is as follows:

[0036] The transmission sleeve 1, the dynamic ring 2, the spring 4, the sealing ring and the transmission shaft 12 are matched together, rotate with the transmission shaft 12, the static ring 3, the sealing ring and the mechanical seal shell 15 are matched together, under the joint action of spring force and lubricating oil pressure, the dynamic ring 2 and the static ring 3 sealing surface form a gap of 3-5um liquid film, the liquid film blocks the medium leakage in the mechanical seal cavity 16.

[0037] The compressor lubricating oil is throttled and decompressed through the oil supply stop valve 10 and enters the buffer tank, in the buffer tank, the gas is gathered in the upper part and returns to the compressor inlet through the gas discharge stop valve 11, the lubricating oil is gathered in the middle and lower parts and enters the mechanical seal oil inlet hole through the oil supply pipe.

[0038] The utility model discloses a mechanical seal system of shale gas screw compressor, through the mechanical seal system, can reduce the damage of fine sand in shale gas to mechanical seal, the design of lubricating oil buffer tank 7 can separate the released gas in the decompression process of dilution lubricating oil, to reduce the mechanical seal failure rate of shale gas screw compressor.

[0039] Compared with the prior art, the utility model has the following advantages:

[0040] I. The dynamic ring 2 and the transmission sleeve 1 adopt large gap design, further improve the followability of the dynamic ring 2, greatly reduce the problem that the dynamic ring 2 is stuck because of impurity particles entering the gap;

[0041] II. The deep groove 20 on the dynamic ring 2 sealing surface can store lubricating oil, increase the lubricating effect of the sealing surface, especially the inner sealing surface, at the same time, the axial depth of the groove 20 is 1mm, which is much larger than the diameter of the impurity particles, so that the impurity particles entering the groove 20 can be thrown out, and the self-cleaning effect is achieved;

[0042] III. The mechanical seal oil supply and oil outlet hole adopt staggered design, the oil inlet 13 is on the sealing surface side, and the oil outlet 14 is away from the sealing surface side, so that the flow dead zone in the mechanical seal cavity 16 can be reduced;

[0043] IV. The lubricating oil buffer tank 7 is arranged on the mechanical seal oil supply side to separate the gas separated from the lubricating oil, the impurity particles gathered in the mechanical seal can be intercepted at the Y-type filter 8 of the oil outlet pipeline, so that the compressor rotor is prevented from being damaged due to the impurity particles entering the compressor inlet, and the throttling check valve 9 is arranged on the mechanical seal return oil pipeline, so that the lubricating oil in the mechanical seal cavity 16 is prevented from being blown out by the compressor inlet gas flow when the unit starts and stops, and the problem of insufficient oil in the mechanical seal cavity 16 when starting next time is solved.

[0044] The above merely describes the preferred embodiments of the present application and is not intended to limit the present application, and any modification, equivalent improvement, etc. made within the spirit and principle of the present application should be included in the protection scope of the present application.

Claims

1. A mechanical seal system for a screw compressor, comprising a mechanical seal housing, a drive shaft disposed in the middle of the mechanical seal housing, a drive sleeve, a rotating ring and a stationary ring disposed on the outer side of the drive shaft, one end of the rotating ring extending into the drive sleeve and abutting against the drive sleeve by a spring, one end of the stationary ring being fixed to the mechanical seal housing, and a sealing surface being formed between the other end of the stationary ring and the other end of the rotating ring; The mechanical seal housing, the transmission sleeve, the rotating ring, and the stationary ring together form a mechanical seal cavity. The mechanical seal housing is provided with an oil inlet and an oil outlet, which are respectively connected to the mechanical seal cavity. Its characteristic is... The moving ring has at least one groove on the outer ring of one end of the sealing surface, and the axial depth of each groove is 1 mm. The system also includes a lubricating oil buffer tank, which is connected to the oil inlet via an oil inlet pipe. The mechanical seal housing is connected to the main unit's air inlet via an oil outlet pipe, and a filter is installed on the oil outlet pipe.

2. The screw compressor mechanical seal system according to claim 1, characterized in that, A throttling check valve is also installed on the oil outlet pipeline.

3. The screw compressor mechanical seal system according to claim 1, characterized in that, The oil inlet and the oil outlet are staggered, with the oil inlet located closer to the sealing surface.

4. The screw compressor mechanical seal system according to claim 1, characterized in that, Each of the slots is an arc-shaped slot with an arc angle of 75°, and / or the radial depth of each slot is 1 / 3 of the thickness of the sealing surface.

5. The screw compressor mechanical seal system according to claim 1, characterized in that, The outer ring of the moving ring located at one end of the sealing surface has 12 slots evenly distributed.

6. The screw compressor mechanical seal system according to claim 1, characterized in that, The diameter of the oil inlet is larger than the diameter of the oil outlet.

7. The screw compressor mechanical seal system according to claim 1, characterized in that, The moving ring is made of silicon carbide, and the stationary ring is made of cemented carbide tungsten carbide.

8. The screw compressor mechanical seal system according to claim 1, characterized in that, A stationary O-ring is provided between the stationary ring and the mechanical seal housing, and / or the stationary O-ring is made of fluororubber.

9. The screw compressor mechanical seal system according to claim 1, characterized in that, An O-ring is provided between the moving ring and the drive shaft, and / or the moving ring O-ring is made of fluororubber.

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