Sealing device for associated gas double-screw compressor

Abstract

The sealing device for the associated gas double-screw compressor comprises a labyrinth seal and a double-end-face mechanical seal, the labyrinth seal comprises a first sealing seat, a labyrinth seal groove is formed in the inner circumferential wall of the first sealing seat, and two annular grooves are further formed in the inner wall of the first sealing seat and used for dividing the labyrinth seal groove into three parts. The side wall of the first sealing seat is provided with an air inlet channel and an air outlet channel which communicate with the two annular grooves correspondingly. The double-end-face mechanical seal is of a packaging type structure and comprises a second sealing seat and a shaft sleeve, a main static ring and an auxiliary static ring are arranged at the two ends of an inner cavity of the second sealing seat respectively, the shaft sleeve is in transmission connection with the rotating shaft, the shaft sleeve is sleeved with a movable ring, and the two ends of the movable ring abut against the main static ring and the auxiliary static ring respectively. According to the sealing device for the associated gas double-screw compressor, through a combined sealing mode, sealing of working medium gas can be achieved, liquid media can be effectively sealed, and the overall sealing performance is stable and reliable.

Description

Technical Field

[0001] This utility model relates to the field of mechanical seal technology, and more specifically, to a sealing device for a twin-screw compressor with associated gas. Background Technology

[0002] Associated gas refers to natural gas extracted simultaneously during oil extraction. It is usually found alongside oil, existing in the upper part of the reservoir or dissolved in crude oil, hence the name associated gas or dissolved gas. Associated gas mainly consists of methane, carbon dioxide, hydrogen sulfide, nitrogen, helium, etc. These complex gases pose potential threats to safety and the environment.

[0003] Twin-screw compressors for associated gas have multiple applications in the oil and gas industry. Firstly, they are primarily used for gas transportation and compression, especially in the processing of associated gas from oil fields. Through a highly efficient compression process, twin-screw compressors can compress and transport these associated gases to storage or processing facilities, ensuring the effective utilization of resources. Simultaneously, the units can also be used for the extraction and pressurization of associated gas. They draw pressure from the unit into a negative pressure, causing the large amount of light hydrocarbon components in the crude oil to rapidly vaporize. Then, through compression and cooling, light oil is extracted, thereby eliminating unstable components in the crude oil, avoiding hazards during transportation and storage, and improving economic efficiency.

[0004] The commonly used shaft seal types and their characteristics for associated gas twin-screw compressors are as follows:

[0005] 1. Labyrinth seal: Simple structure, requires no lubrication, and is easy to maintain; however, it often leads to a high leakage rate under high pressure.

[0006] 2. Carbon ring seal: Suitable for medium and low pressure applications, with low manufacturing cost, simple structure, and easy installation and disassembly.

[0007] 3. Oil seal: Suitable for low-pressure applications, simple structure, easy installation, easy replacement, and low maintenance cost.

[0008] 4. Mechanical seals are the most commonly used shaft seal type in twin-screw compressors. However, since the associated gas mainly consists of methane, carbon dioxide, hydrogen sulfide, nitrogen, helium, etc., these complex gases are collectively referred to as working gases. Due to their complex composition, traditional single-end or double-end mechanical seals often cannot handle the situation well without special structural design.

[0009] Therefore, twin-screw compressors operating under associated gas conditions require specially developed mechanical seals. Utility Model Content

[0010] To overcome at least one of the defects in the prior art, this utility model provides a sealing device for a twin-screw compressor with associated gas. Through a combined sealing method, it can achieve both sealing of the working gas and effective sealing of the liquid medium, with stable and reliable overall sealing performance.

[0011] The technical solution adopted by this utility model is to provide a sealing device for a twin-screw compressor with associated gas:

[0012] The system includes a labyrinth seal and a double-end mechanical seal, which are sequentially fitted around the rotating shaft along the axial direction, with the labyrinth seal located near the medium end. The labyrinth seal includes a first sealing seat connected to the compressor mounting cavity. The inner circumferential wall of the first sealing seat has a labyrinth sealing groove extending along its axial direction. The inner wall of the first sealing seat also has two annular grooves to divide the labyrinth sealing groove into three parts. The side wall of the first sealing seat has an inlet channel and an outlet channel that communicate with the two annular grooves respectively. The double-end mechanical seal is a cartridge structure, which includes a second sealing seat and a bushing. The two ends of the inner cavity of the second sealing seat are respectively provided with a main stationary ring and a secondary stationary ring. The bushing is located radially inside the second sealing seat and is drivenly connected to the rotating shaft. A rotating ring is fitted around the outside of the bushing. One end of the rotating ring rotatably abuts against the main stationary ring to form a main seal, and the other end rotatably abuts against the secondary stationary ring to form a secondary seal.

[0013] Compared with the prior art, the sealing device for an associated gas twin-screw compressor of this utility model has the following advantages:

[0014] This utility model discloses a sealing device for a twin-screw compressor with associated gas. It is a sealing structure specifically designed for compressors operating under associated gas conditions. It is a combined sealing structure, and within the labyrinth-shaped sealing structure, two annular grooves divide the labyrinth sealing groove into three sections axially. The middle section is circulated with isolation gas, and the pressure of this isolation gas is typically greater than the working gas pressure at the medium end. This prevents the working gas inside the screw rotor cavity from escaping into the sealing cavity, ensuring effective operation of the seal in a fully liquid film environment. Furthermore, the mechanical seal is a double-end-faced, modular structure, which not only provides stable sealing performance but also facilitates easy assembly and disassembly.

[0015] Furthermore, the second sealing seat includes a stationary ring seat and an end cap. The inner side of one end of the stationary ring seat is provided with a first mounting groove. The end of the main stationary ring away from the rotating ring is slidably fitted in the first mounting groove along the axial direction, and a first elastic element is provided between the end of the main stationary ring and the bottom of the first mounting groove. The end cap is connected to the other end of the stationary ring seat, and a second mounting groove is provided on the end cap. The end of the secondary stationary ring away from the rotating ring is slidably fitted in the second mounting groove along the axial direction, and a second elastic element is provided between the end of the secondary stationary ring and the bottom of the second mounting groove.

[0016] Furthermore, the first elastic element and the second elastic element have the same structure, each including multiple springs evenly distributed along the circumference. The bottom of the first mounting groove and the second mounting groove are provided with multiple spring holes. One end of each spring is inserted into the corresponding spring hole, and the other end abuts against the end of the main stationary ring or the auxiliary stationary ring.

[0017] As an improvement, the bottom of the first mounting groove and the second mounting groove are provided with a number of anti-rotation pins extending axially, and the ends of the main stationary ring and the auxiliary stationary ring are provided with a number of anti-rotation pin grooves that respectively cooperate with each of the anti-rotation pins, and the outer end of each of the anti-rotation pins is fitted with a nylon protective sleeve.

[0018] In a further improvement, a positioning protrusion is formed on the outer wall of the bushing, and the end of the moving ring near the auxiliary stationary ring abuts against the positioning protrusion. A retaining spring is fitted on the outer wall of the bushing near the main stationary ring, and the retaining spring abuts against the other end of the moving ring.

[0019] In a further improvement, the outer peripheral wall of the stationary ring seat is provided with a first annular groove and a second annular groove that are staggered along the axial direction. The bottom of the first annular groove is provided with a plurality of liquid inlet holes that communicate with the inner cavity of the stationary ring seat, and the inner end of each liquid inlet hole faces the position of the main seal. The bottom of the second annular groove is provided with a liquid outlet hole that communicates with the inner cavity of the stationary ring seat, and the inner end of the liquid outlet hole faces the position of the secondary seal.

[0020] In a further improvement, an annular positioning groove is provided on the outer peripheral wall of the end of the bushing away from the main seal, and multiple circumferentially distributed limiting blocks are detachably connected to the outer end face of the end cover. The radial inner ends of each limiting block are respectively inserted into the annular positioning groove, so that the stationary ring seat, main stationary ring, bushing, rotating ring, auxiliary stationary ring and end cover are pre-assembled into an integral structure.

[0021] The aforementioned improvements and advantages of this invention will be set forth in detail in the following specific embodiments, and will be apparent in part from the description, or may be learned by practicing the invention. The objectives and other advantages of this invention can be realized and obtained through the structures particularly pointed out in the description and drawings. Attached Figure Description

[0022] Figure 1 This is an axial front view of the sealing device for a twin-screw compressor with associated gas according to the present invention;

[0023] Figure 2 for Figure 1 Sectional view along line AA in the middle;

[0024] Figure 3 for Figure 1 BB-direction sectional view in the middle;

[0025] Figure 4 for Figure 3 Another perspective view of the structure;

[0026] Figure 5 This is a schematic diagram of the first sealing seat structure in this utility model;

[0027] Figure 6 for Figure 2 A magnified structural diagram at point X in the diagram.

[0028] Explanation of reference numerals in the attached figures:

[0029] 1. First sealing seat; 2. Labyrinth sealing groove; 3. Annular groove; 4. Air inlet channel; 5. Air outlet channel; 6. Bushing; 7. Main stationary ring; 8. Secondary stationary ring; 9. Rotary ring; 10. Stationary ring seat; 11. End cap; 12. First mounting groove; 13. Second mounting groove; 14. Anti-rotation pin; 15. Positioning protrusion ring; 16. Snap ring; 17. First annular groove; 18. Second annular groove; 19. Liquid inlet through hole; 20. Liquid outlet through hole; 21. Annular positioning groove; 22. Limiting block; 23. Set screw; 24. Retaining ring. Detailed Implementation

[0030] First, those skilled in the art should understand that these embodiments are merely used to explain the technical principles of the embodiments of this application and are not intended to limit the scope of protection of the embodiments of this application. Those skilled in the art can make adjustments as needed to adapt to specific application scenarios.

[0031] In the description of the embodiments of this application, it should be noted that, unless otherwise explicitly specified and limited, the terms "assembly" and "connection" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms in the embodiments of this application based on the specific circumstances.

[0032] The present application will now be described in further detail with reference to the accompanying drawings and specific embodiments.

[0033] See Figures 1-6 As shown in the figure, this application discloses a sealing device for a twin-screw compressor with associated gas, including a labyrinth seal and a double-end mechanical seal that are sequentially fitted around the outside of the rotating shaft along the axial direction. The labyrinth seal is close to the medium end and is a combined sealing structure. The mechanical seal part also adopts a double-end form, which is essentially a multi-seal form, effectively improving the sealing stability.

[0034] Specifically, the labyrinth seal includes a first sealing seat 1 connected to the compressor mounting cavity. A stepped mounting cavity is provided inside the compressor mounting cavity, and the first sealing seat 1 has a T-shaped cross-section, including an axial sleeve structure and a radially arranged circular flange. The axial sleeve part is axially fitted in the mounting cavity, and the flange part is fitted and positioned on the stepped surface of the mounting cavity, and it is connected to the bottom of the mounting cavity by multiple connecting bolts. In addition, a labyrinth sealing groove 2 extending axially is provided on the inner peripheral wall of the first sealing seat 1. Two annular grooves 3 are also provided on the inner wall of the first sealing seat 1 to divide the labyrinth sealing groove 2 into three parts. An air inlet channel 4 and an air outlet channel 5 communicating with the two annular grooves 3 are provided on the side wall of the first sealing seat 1. An air inlet and an air outlet are respectively provided at corresponding positions on the compressor cavity. When in use, isolation gas is injected through the air inlet and flows out through the air outlet to achieve circulation. That is, a labyrinth seal filled with isolation gas is formed in the middle part of the labyrinth channel. The pressure of the isolation gas is usually greater than the working gas pressure at the medium end, which can prevent the working gas in the screw rotor cavity from running into the sealing cavity, so as to ensure the effective operation of the seal in a full liquid film environment.

[0035] In this embodiment, the double-end mechanical seal is a cartridge structure, comprising a second sealing seat and a bushing 6. The inner ends of the second sealing seat are respectively provided with a main stationary ring 7 and a secondary stationary ring 8. The bushing 6 is located radially inside the second sealing seat and is connected to the rotating shaft. Specifically, a sealing ring is provided between the inner wall of the bushing 6 near the main stationary ring 7 and the outer wall of the rotating shaft. Multiple circumferentially distributed and radially extending set screws 23 are provided on the side wall of the other end of the bushing 6. The transmission connection is achieved through the tight fit between the set screws and the rotating shaft. A rotating ring 9 is fitted outside the bushing 6. One axial end of the rotating ring 9 rotatably abuts against the main stationary ring 7 to form a main seal, and the other end of the rotating ring 9 rotatably abuts against the secondary stationary ring 8 to form a secondary seal. This fit creates a sealed isolation cavity between the inner wall of the stationary ring seat 10 and the main and secondary seals. Preferably, a first annular groove 17 and a second annular groove 18 are provided on the outer peripheral wall of the stationary ring seat 10, which are staggered along the axial direction. The bottom of the first annular groove 17 is provided with a plurality of liquid inlet holes 19 that communicate with the inner cavity of the stationary ring seat 10, and the inner end of each liquid inlet hole 19 faces the position of the main seal. The bottom of the second annular groove 18 is provided with a liquid outlet hole 20 that communicates with the inner cavity of the stationary ring seat 10, and the inner end of the liquid outlet hole 20 faces the position of the secondary seal. This unique flushing channel design allows the flushing fluid to first flush and cool the main seal, and then exit from the sealing surface close to the secondary seal, which increases the operational reliability of the main seal and also ensures sufficient lubrication of the secondary seal, thus extending the life of the mechanical seal.

[0036] More specifically, as a preferred structure in this embodiment, the second sealing seat includes a stationary ring seat 10 and an end cap 11. The inner side of the stationary ring seat 10 near the end of the first sealing seat 1 is provided with a first mounting groove 12. The end of the main stationary ring 7 away from the rotating ring 9 is slidably fitted in the first mounting groove 12 along the axial direction. A first elastic element is provided between the end of the main stationary ring 7 and the bottom of the first mounting groove 12. An auxiliary sealing ring is provided between the inner side of the main stationary ring 7 and the inner wall corresponding to the first mounting groove 12. The end cap 11 is connected to the other end of the stationary ring seat 10. The end cap 11 is provided with a second mounting groove 13. The end of the secondary stationary ring 8 away from the rotating ring 9 is slidably fitted in the second mounting groove 13 along the axial direction. A second elastic element is provided between the end of the secondary stationary ring 8 and the bottom of the second mounting groove 13. Similarly, an auxiliary sealing ring is also provided between the inner wall of the secondary stationary ring 8 and the side wall corresponding to the second mounting groove 13.

[0037] In the above structure, the first and second elastic elements have the same structure, both including multiple springs evenly distributed circumferentially (not shown in the figure). Multiple spring holes are provided at the bottom of the first mounting groove 12 and the second mounting groove 13. One end of each spring is inserted into the corresponding spring hole, and the other end abuts against the end of the main stationary ring 7 or the auxiliary stationary ring 8. In this application, both the main seal and the auxiliary seal are stationary ring compensation structures, meaning the elastic compensation elements are all located at the stationary ring end. This stationary seal can be used for high-speed rotation. Under normal operating conditions, the compressor operates at approximately 4500 rpm. Placing the springs on the stationary side avoids problems such as untimely or inadequate compensation due to vibration at high speeds and large shaft diameters. Simultaneously, the springs also avoid stress fatigue and extend the service life of the mechanical seal.

[0038] In this embodiment, to prevent the main stationary ring 7 and the auxiliary stationary ring 8 from rotating together with the auxiliary moving ring 9, the bottom of the first mounting groove 12 and the second mounting groove 13 are provided with several anti-rotation pins 14 extending axially. The ends of the main stationary ring 7 and the auxiliary stationary ring 8 are provided with several anti-rotation pin 14 grooves that respectively cooperate with each anti-rotation pin 14, and the outer end of each anti-rotation pin 14 is fitted with a nylon protective sleeve. In this structure, the main seal and the auxiliary seal share a single moving ring 9, which saves costs and shortens the axial dimension. At the same time, the use of silicon carbide for both the moving and stationary rings improves the PV value, which can better cope with the high PV value brought about by high speed. In addition, the use of nylon protective sleeves on the anti-rotation pins 14 avoids wear on the metal pins and silicon carbide grooves, making the transmission and anti-rotation more effective.

[0039] See appendix Figure 6 The outer wall of the bushing 6 has a protruding positioning ring 15. One end of the rotating ring 9 near the auxiliary stationary ring 8 abuts against the positioning ring 15. A retaining ring 16 is fitted on the outer wall of the bushing 6 near the main stationary ring 7, and the retaining ring 16 is positioned and abuts against the other end of the rotating ring 9. In addition, auxiliary sealing rings are provided at both ends of the inner cavity of the rotating ring 9. One end of the sealing ring abuts against the positioning ring 15, and the sealing ring at the end away from the positioning ring 15 is axially limited by the retaining ring 24. In this way, the retaining ring 16 abuts against and is limited on the outer wall of the retaining ring 24, thus realizing the installation and positioning of the rotating ring 9 and the bushing 6.

[0040] Additionally, in this embodiment, see Appendix Figure 4An annular positioning groove 21 is provided on the outer peripheral wall of the end of the bushing 6 away from the main seal. Multiple circumferentially distributed limiting blocks 22 are detachably connected to the outer end face of the end cover 11. The radial inner ends of each limiting block 22 are respectively inserted into the annular positioning groove 21, so that the stationary ring seat 10, the main stationary ring 7, the bushing 6, the rotating ring 9, the auxiliary stationary ring 8, and the end cover 11 are pre-assembled into an integral structure. The integral structure facilitates its quick installation into the compressor cavity without on-site assembly, thus improving installation efficiency. However, it should be noted that the limiting block 22 structure is only used for axial limiting when pre-installing the double-end mechanical seal. After it is installed into the compressor cavity as a whole, it needs to be removed because the bushing 6 needs to rotate synchronously with the rotating shaft during actual operation. The operation cannot proceed without removing the limiting block 22.

[0041] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A sealing device for a twin-screw compressor containing associated gas, characterized in that: The system includes a labyrinth seal and a double-end mechanical seal, which are sequentially fitted around the outside of the rotating shaft along the axial direction, with the labyrinth seal located near the medium end. The labyrinth seal includes a first sealing seat (1) connected to the compressor mounting cavity. The inner circumferential wall of the first sealing seat (1) has a labyrinth sealing groove (2) extending axially. The inner wall of the first sealing seat (1) also has two annular grooves (3) to divide the labyrinth sealing groove (2) into three parts. The side wall of the first sealing seat (1) has intake channels that communicate with the two annular grooves (3) respectively. 4) and an exhaust channel (5); the double-end mechanical seal is a cartridge structure, and it includes a second sealing seat and a bushing (6). The two ends of the inner cavity of the second sealing seat are respectively provided with a main stationary ring (7) and a secondary stationary ring (8). The bushing (6) is located on the radial inner side of the second sealing seat, and the bushing (6) is connected to the rotating shaft for transmission. The bushing (6) is fitted with a rotating ring (9) on its outer side. One end of the rotating ring (9) is rotatably abutted against the main stationary ring (7) to form a main seal, and the other end is rotatably abutted against the secondary stationary ring (8) to form a secondary seal.

2. The sealing device for a twin-screw compressor with associated gas according to claim 1, characterized in that: The second sealing seat includes a stationary ring seat (10) and an end cap (11). The inner side of one end of the stationary ring seat (10) is provided with a first mounting groove (12). The end of the main stationary ring (7) away from the moving ring (9) is slidably fitted in the first mounting groove (12) along the axial direction. A first elastic element is provided between the end of the main stationary ring (7) and the bottom of the first mounting groove (12). The end cap (11) is connected to the other end of the stationary ring seat (10). A second mounting groove (13) is provided on the end cap (11). The end of the auxiliary stationary ring (8) away from the moving ring (9) is slidably fitted in the second mounting groove (13) along the axial direction. A second elastic element is provided between the end of the auxiliary stationary ring (8) and the bottom of the second mounting groove (13).

3. The sealing device for a twin-screw compressor with associated gas according to claim 2, characterized in that: The first elastic element and the second elastic element have the same structure, both including multiple springs evenly distributed along the circumference. The bottom of the first mounting groove (12) and the second mounting groove (13) are provided with multiple spring holes. One end of each spring is inserted into the corresponding spring hole, and the other end abuts against the end of the main stationary ring (7) or the auxiliary stationary ring (8).

4. The sealing device for a twin-screw compressor with associated gas according to claim 2, characterized in that: The bottom of the first mounting groove (12) and the second mounting groove (13) are provided with a number of anti-rotation pins (14) extending along the axial direction. The ends of the main stationary ring (7) and the secondary stationary ring (8) are provided with a number of anti-rotation pin (14) grooves that respectively cooperate with each of the anti-rotation pins (14). The outer end of each anti-rotation pin (14) is fitted with a nylon protective sleeve.

5. The sealing device for a twin-screw compressor with associated gas according to claim 1, characterized in that: The bushing (6) has a convex positioning ring (15) formed on its outer wall. The end of the moving ring (9) near the auxiliary stationary ring (8) abuts against the positioning ring (15). A retaining ring (16) is fitted on the outer wall of the bushing (6) near the main stationary ring (7). The retaining ring (16) is limited and abuts against the other end of the moving ring (9).

6. The sealing device for a twin-screw compressor with associated gas according to claim 2, 3, or 4, characterized in that: The outer peripheral wall of the stationary ring seat (10) is provided with a first annular groove (17) and a second annular groove (18) that are offset along the axial direction. The bottom of the first annular groove (17) is provided with a plurality of liquid inlet holes (19) that communicate with the inner cavity of the stationary ring seat (10), and the inner end of each liquid inlet hole (19) faces the position of the main seal. The bottom of the second annular groove (18) is provided with a liquid outlet hole (20) that communicates with the inner cavity of the stationary ring seat (10), and the inner end of the liquid outlet hole (20) faces the position of the secondary seal.

7. The sealing device for a twin-screw compressor with associated gas according to claim 6, characterized in that: The bushing (6) has an annular positioning groove (21) on its outer peripheral wall away from the main seal. The end cover (11) has multiple circumferentially distributed limiting blocks (22) detachably connected to its outer end face. The radial inner ends of each limiting block (22) are respectively inserted into the annular positioning groove (21) so that the stationary ring seat (10), main stationary ring (7), bushing (6), moving ring (9), auxiliary stationary ring (8) and end cover are pre-assembled as an integral structure.

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