Dry gas seal for ultra-high pressure gas injection centrifugal compressor

Abstract

The utility model discloses a kind of dry gas seals for superhigh pressure gas injection centrifugal compressor, it is related to dry gas seal structure field, and it includes: shaft sleeve, primary sealing mechanism, it is sleeved in the outside of shaft sleeve, primary sealing mechanism has primary seal leakage port in communication with atmosphere side, secondary sealing mechanism, block process medium that leaks from primary sealing mechanism but is not discharged from primary seal leakage port to atmosphere layer;Primary sealing mechanism includes first dynamic ring and first static ring, secondary sealing mechanism includes second dynamic ring and second static ring, first dynamic ring and second dynamic ring are made of silicon nitride, first static ring and second static ring are made of silicon carbide, diamond coating is coated on the sealing end face of first static ring.The utility model is by being arranged as silicon nitride material to dynamic ring, it is arranged as silicon carbide material to static ring, and diamond coating is coated on the sealing end face of static ring, to reach the purpose that process medium enters atmosphere when gas injection pressure reaches 45Mpa, is blocked.

Description

Technical Field

[0001] This utility model relates to the field of dry gas sealing structures, specifically to a dry gas seal for an ultra-high pressure gas injection centrifugal compressor. Background Technology

[0002] Ultra-high pressure dry gas seals are primarily used in centrifugal compressors for gas injection in oil and gas fields and natural gas storage facilities within the oil and gas industry. Oil and gas fields utilize the injection of fluid media underground to maintain formation pressure and improve oil and gas recovery rates, a process that has developed rapidly. Both natural gas storage facilities and oil and gas fields rely heavily on ultra-high pressure centrifugal compressor units for underground gas injection, with injection pressures typically exceeding 40 MPa. As a core component of centrifugal compressors, the development of dry gas seal technology significantly impacts the development and application of ultra-high pressure centrifugal compressors, thus hindering the development of the natural gas storage industry and the widespread application of injection technology in oil and gas fields. Currently, domestic dry gas seal products have design pressures ≤25 MPa, while those with design pressures >40 MPa lack complete design and manufacturing capabilities, with related products almost entirely monopolized by foreign companies. Furthermore, publicly available information indicates that there are no domestic technical cases or application records for dry gas seals with design pressures ≥45 MPa. However, in recent years, with the continuous development of domestic sealing technology, domestic dry gas seal technology has made corresponding breakthroughs in ultra-high pressure applications.

[0003] In view of the above, this application is hereby submitted. Summary of the Invention

[0004] The purpose of this invention is to provide a dry gas seal for an ultra-high pressure injection centrifugal compressor. By setting a double-end face seal, the moving ring is made of silicon nitride and the stationary ring is made of silicon carbide. A diamond coating is applied to the sealing end face of the stationary ring. This solves the problem that the existing dry gas seal structure has a large leakage when the injection pressure is greater than 40MPa, making it impossible to implement.

[0005] This utility model embodiment is achieved through the following technical solution: This utility model embodiment provides a dry gas seal for an ultra-high pressure gas injection centrifugal compressor, comprising:

[0006] The bushing is pressed against the unit shaft by the unit impeller and can rotate with the unit shaft.

[0007] The primary sealing mechanism is sleeved on the outside of the bushing and is used to form an air film to prevent the process medium from being discharged into the atmosphere. The atmospheric side of the primary sealing mechanism is connected to the primary sealing leak port, which is used to recover the leaked process medium.

[0008] The secondary sealing mechanism, located on the outside of the bushing, is used to form a gas film and prevent process media that leaks from the primary sealing mechanism but does not exit from the primary sealing leak port from being discharged into the atmosphere.

[0009] The primary sealing mechanism includes a first rotating ring and a first stationary ring, and the secondary sealing mechanism includes a second rotating ring and a second stationary ring. Both the first rotating ring and the second rotating ring are made of silicon nitride, and both the first stationary ring and the second stationary ring are made of silicon carbide. The sealing end face of the first stationary ring is coated with a diamond coating.

[0010] Optionally, the sealing surface of the second stationary ring is coated with a diamond coating.

[0011] Optionally, the primary sealing mechanism includes a first spring seat, a first rotating ring mounted on a bushing and capable of rotating with the bushing, and a first stationary ring mounted on the first spring seat.

[0012] Optionally, a first push ring and a first balance sleeve are also installed on the first spring seat.

[0013] Optionally, the secondary sealing mechanism includes a second spring seat, a second rotating ring mounted on the bushing and capable of rotating with the bushing, and a second stationary ring mounted on the second spring seat.

[0014] Optionally, a second push ring and a second balance sleeve are also installed on the second spring seat.

[0015] Optionally, spiral grooves are provided on the sealing end faces of both the first and second rotating rings.

[0016] Optionally, machining steps are provided on the contact surfaces of the first and second rotating rings with the bushing.

[0017] Optionally, a machining step is provided on the contact surface between the first stationary ring and the first push ring, and a machining step is provided on the contact surface between the second stationary ring and the second push ring.

[0018] Optionally, the secondary sealing mechanism is provided with a secondary sealing leak port on the atmospheric side.

[0019] Compared with the prior art, the embodiments of this utility model have the following advantages and beneficial effects:

[0020] The dry gas seal for an ultra-high pressure injection centrifugal compressor provided in this embodiment adopts a cartridge double-end face structure, and is combined with a hard-on-hard friction pair (liquid-phase toughened silicon nitride + diamond-coated silicon carbide) to achieve low leakage of the medium under high pressure. This structure allows for convenient installation and disassembly of the seal. The seal operates without contact, is energy-saving, safe and environmentally friendly, has reliable performance, is easy to operate, and has a long service life. The stable torque transmission and rotating ring centering structure ensure good seal stability, preventing the process medium from entering the atmosphere when the injection pressure reaches 45 MPa. Attached Figure Description

[0021] To more clearly illustrate the technical solutions of the embodiments of this utility model, the drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of this utility model and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0022] Figure 1 A schematic diagram of the dry gas sealing structure for an ultra-high pressure gas injection centrifugal compressor provided in this embodiment of the utility model;

[0023] Figure 2 for Figure 1 Enlarged view of the structure at point A;

[0024] Figure 3 for Figure 1 Enlarged view of the structure at point B;

[0025] Figure 4 A schematic diagram of the spiral groove structure provided for an embodiment of this utility model.

[0026] The attached diagram shows the markings and corresponding component names:

[0027] 1. Bushing; 2. Primary sealing leak port; 3. First rotating ring; 4. First stationary ring; 5. Second rotating ring; 6. Second stationary ring; 7. First spring seat; 8. First push ring; 9. First balance sleeve; 10. Second spring seat; 11. Second push ring; 12. Second balance sleeve; 13. Spiral groove; 14. Secondary sealing leak port; 15. Rotating ring seat; 16. Compression sleeve; 17. Split retaining ring; 18. Primary sealing gas inlet; 19. Machining step; 20. Secondary sealing gas inlet. Detailed Implementation

[0028] To make the objectives, technical solutions, and advantages of the embodiments of this utility model clearer, the technical solutions of the embodiments of this utility model will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this utility model, not all embodiments. The components of the embodiments of this utility model described and shown in the accompanying drawings can typically be arranged and designed in various different configurations.

[0029] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0030] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0031] In the description of this utility model, it should be noted that the terms "first", "second", "third", etc. are used only for distinguishing descriptions and should not be construed as indicating or implying relative importance. Example

[0032] like Figure 1 As shown, this utility model embodiment provides a dry gas seal for an ultra-high pressure gas injection centrifugal compressor, comprising: a bushing 1, pressed against the unit shaft by the unit impeller and capable of rotating with the unit shaft; a primary sealing mechanism, sleeved on the outside of the bushing 1, used to form a gas film and prevent the process medium from being discharged into the atmosphere, the atmospheric side of the primary sealing mechanism being connected to a primary sealing leak port 2, the primary sealing leak port 2 being used to recover the leaked process medium; a secondary sealing mechanism, disposed on the outside of the bushing 1, used to form a gas film and prevent the process medium leaking from the primary sealing mechanism but not discharged from the primary sealing leak port 2 from being discharged into the atmosphere; the primary sealing mechanism includes a first moving ring 3 and a first stationary ring 4, the secondary sealing mechanism includes a second moving ring 5 and a second stationary ring 6, the first moving ring 3 and the second moving ring 5 are both made of silicon nitride, the first stationary ring 4 and the second stationary ring 6 are both made of silicon carbide, and the sealing end face of the first stationary ring 4 is coated with a diamond coating.

[0033] Specifically, the primary sealing mechanism, sleeved on the outside of the bushing 1, includes a first rotating ring 3 and a first stationary ring 4. It forms a gas film to prevent the process medium from being discharged into the atmosphere. The primary sealing leak port 2 communicates with the atmospheric side of the primary sealing mechanism to recover leaked process medium. The secondary sealing mechanism, located on the outside of the bushing 1, includes a second rotating ring 5 and a second stationary ring 6. It prevents process medium leaking from the primary sealing mechanism but not discharged through the primary sealing leak port 2 from being discharged into the atmosphere. The working principle of the dry gas seal is a fluid dynamic and static pressure combined non-contact mechanical seal based on gas film lubrication. This embodiment of the invention solves the problem of large leakage in existing dry gas seal structures when the injection pressure is greater than 40 MPa. By setting a double-end face seal, using silicon nitride for the rotating ring and silicon carbide for the stationary ring, and coating the sealing end face of the stationary ring with a diamond coating, the sealing performance is enhanced, leakage is reduced, and the reliability and safety of the seal are improved. It is suitable for ultra-high pressure conditions, such as centrifugal compressors for injection in oil and gas fields and natural gas storage facilities in the oil and gas industry, where the injection pressure is generally greater than 40 MPa. Preferably, the sealing surface of the second stationary ring 6 is coated with a diamond coating. That is, this embodiment of the invention employs two pairs of hard-on-hard sealing friction pairs. The primary sealing mechanism withstands the entire process pressure, while the secondary sealing mechanism operates under low pressure for safety sealing. In the event of primary seal failure, it can withstand full pressure operation. Most of the medium leaked from the primary sealing mechanism is discharged and recovered through the primary sealing gas leak port. By setting the friction pairs to a hard-on-hard material of liquid-phase toughened silicon nitride + diamond-coated silicon carbide, low leakage of the medium under high pressure is achieved.

[0034] For example, such as Figure 1 As shown, a dry gas seal for an ultra-high pressure injection centrifugal compressor includes a shaft sleeve 1 and a clamping sleeve 16 pressed against the unit shaft by the unit impeller, rotating with the shaft. A first rotating ring 3 is mounted on the shaft sleeve 1 and rotates with the shaft along with a transmission lug machined on the shaft sleeve 1. A first stationary ring 4, a first push ring 8, and a first balance sleeve 9 are mounted on a first spring seat 7, together forming a primary seal. A second rotating ring 5 is mounted on a rotating ring seat 15, which is pressed against the shaft sleeve 1 by the clamping sleeve 16, rotating with the shaft. A second stationary ring 6, a second push ring 11, and a second balance sleeve 12 are mounted on a second spring seat 10, together forming a secondary seal.

[0035] The first moving ring 3 and the second moving ring 5 are both made of liquid-phase toughened silicon nitride, which has a dense and uniform structure. The compressive stress on its surface improves its strength and toughness, giving it higher strength under high pressure while also providing excellent wear resistance. The first stationary ring 4 and the second stationary ring 6 are both made of silicon carbide with a diamond coating. The diamond coating gives the silicon carbide higher hardness, a lower coefficient of friction, and better wear resistance at the end face. Together, they form a hard-on-hard sealing friction pair, which ensures that the parts themselves deform little under high pressure, thereby controlling the leakage of a small amount of medium from the end face of the sealing friction pair. Meanwhile, spiral grooves 13 (such as...) are engraved on the first moving ring 3 and the second moving ring 5. Figure 4 As shown), at the contact surface between the bushing 1 and the first moving ring 3 and the second moving ring 5 (as shown) Figure 2 As shown), the contact surface between the first stationary ring 4 and the first push ring 8, and the contact surface between the second stationary ring 6 and the second push ring 11 (as shown). Figure 3 As shown, steps 19 are machined to control the air film generated on the end face of the sealing friction pair, so as to achieve non-contact operation of the friction pair under high pressure. At the same time, the roughness of the contact surfaces of the bushing 1, the rotating ring seat 15 and the rotating ring, and the contact surfaces of the push ring and the stationary ring are ensured to ensure that these four static sealing points can withstand high pressure deformation and zero leakage.

[0036] The primary sealing gas enters the cavity through the primary sealing gas inlet 18. As the equipment shaft rotates, it drives the bushing 1 and the first moving ring 3 to rotate as well. Simultaneously, the end face of the first moving ring 3 is engraved with micro-grooves. The primary sealing gas flows through these micro-grooves, creating an air film between the end faces of the first moving ring 3 and the first stationary ring 4 during rotation, forming a non-contact end-face seal. If the leakage of the primary sealing mechanism is too large, it can be discharged through the primary sealing gas leak outlet.

[0037] The secondary sealing mechanism employs a second moving ring 5 and a second stationary ring 6 with the same structural dimensions as the primary sealing mechanism. A spiral groove 13 is engraved on the second moving ring 5. Steps 19 are machined on the contact surfaces of the moving ring seat 15 and the second moving ring 5, and on the contact surfaces of the second stationary ring 6 and the second push ring 11, to control the gas film generated at the end faces of the sealing friction pair. This achieves non-contact operation of the friction pair under high pressure. Preferably, a secondary sealing leak port 14 is provided on the atmospheric side of the secondary sealing mechanism. During normal operation, the gas pressure of the secondary sealing mechanism must be lower than that of the primary sealing mechanism, ensuring non-contact operation of both mechanisms. Even if the primary sealing mechanism fails, the secondary sealing mechanism, with its identical structure, can still operate under high pressure.

[0038] Overall, in this embodiment of the invention, the sealing structure composed of a primary sealing mechanism and a secondary sealing mechanism can achieve low leakage of the medium under high pressure conditions, and can also cope with frequent start-ups and shutdowns of equipment under high pressure.

[0039] The above description is merely a preferred embodiment of this utility model and is not intended to limit the utility model. Various modifications and variations can be made to this utility model by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this utility model should be included within the protection scope of this utility model. It should be noted that the structures or components illustrated in the accompanying drawings are not necessarily drawn to scale, and descriptions of well-known components, processing techniques, and processes are omitted to avoid unnecessarily limiting the utility model.

Claims

1. A dry gas seal for an ultra-high pressure gas-injection centrifugal compressor, characterized in that, include: The bushing (1) is pressed against the unit shaft by the unit impeller and can rotate with the unit shaft; A primary sealing mechanism is sleeved on the outside of the bushing (1) to form a gas film and block the process medium from being discharged into the atmosphere. The atmospheric side of the primary sealing mechanism is connected to a primary sealing leak port (2), which is used to recover the leaked process medium. The secondary sealing mechanism is located on the outside of the bushing (1) and is used to prevent the process medium that leaks from the primary sealing mechanism but is not discharged from the primary sealing leak port (2) from being discharged into the atmosphere after the gas film is formed. The primary sealing mechanism includes a first moving ring (3) and a first stationary ring (4), and the secondary sealing mechanism includes a second moving ring (5) and a second stationary ring (6). The first moving ring (3) and the second moving ring (5) are both made of silicon nitride, and the first stationary ring (4) and the second stationary ring (6) are both made of silicon carbide. The sealing end face of the first stationary ring (4) is coated with a diamond coating.

2. The dry gas seal for an ultra-high pressure gas-injection centrifugal compressor according to claim 1, characterized in that, The sealing surface of the second stationary ring (6) is coated with a diamond coating.

3. A dry gas seal for an ultra-high pressure gas-injection centrifugal compressor according to claim 1 or 2, characterized in that, The primary sealing mechanism includes a first spring seat (7), a first moving ring (3) mounted on the bushing (1) and capable of rotating with the bushing (1), and a first stationary ring (4) mounted on the first spring seat (7).

4. A dry gas seal for an ultra-high pressure gas-injection centrifugal compressor according to claim 3, characterized in that, The first spring seat (7) is also equipped with a first push ring (8) and a first balance sleeve (9).

5. A dry gas seal for an ultra-high pressure gas-injection centrifugal compressor according to claim 1 or 2, characterized in that, The secondary sealing mechanism includes a second spring seat (10), a second moving ring (5) mounted on the bushing (1) and capable of rotating with the bushing (1), and a second stationary ring (6) mounted on the second spring seat (10).

6. A dry gas seal for an ultra-high pressure gas-injection centrifugal compressor according to claim 5, characterized in that, The second spring seat (10) is also equipped with a second push ring (11) and a second balance sleeve (12).

7. A dry gas seal for an ultra-high pressure gas-injection centrifugal compressor according to claim 1, characterized in that, Both the first moving ring (3) and the second moving ring (5) have spiral grooves (13) on their sealing end faces.

8. A dry gas seal for an ultra-high pressure gas-injection centrifugal compressor according to claim 4, characterized in that, The first moving ring (3) and the second moving ring (5) are both provided with machining steps (19) on their contact surfaces with the bushing (1).

9. A dry gas seal for an ultra-high pressure gas-injection centrifugal compressor according to claim 8, characterized in that, A machining step (19) is provided on the contact surface between the first stationary ring (4) and the first push ring (8), and a machining step (19) is provided on the contact surface between the second stationary ring (6) and the second push ring (11).

10. A dry gas seal for an ultra-high pressure gas-injection centrifugal compressor according to claim 1, characterized in that, The secondary sealing mechanism is provided with a secondary sealing leak port (14) on the atmospheric side.

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