Dry gas sealing structure

Abstract

The utility model belongs to the technical field of sealing, and particularly provides a dry gas sealing structure which comprises a rotating sleeve assembly, a first-stage sealing unit, a middle comb tooth seal and a second-stage sealing unit. The rotating sleeve assembly comprises a main rotating sleeve, an auxiliary rotating sleeve and a positioning sleeve; the first-stage sealing unit comprises a first-stage moving ring, a first-stage static ring and a first-stage seat sleeve; the second-stage seal comprises a second-stage moving ring, a second-stage static ring and a second-stage seat sleeve, and the end faces of the second-stage static ring and the second-stage moving ring are sealed; the positioning sleeve is fixed on the main rotating sleeve through a screw; and a push ring is mounted on one side of the secondary static ring and is in elastic compensation connection with the secondary seat sleeve through a spring. According to the novel dry gas seal, long-period operation of the dry gas seal is guaranteed under the high-temperature (high-pressure) working condition of a compressor, and the probability of failure of the dry gas seal is reduced especially in the starting pressurization and turning stages.

Description

Technical Field

[0001] The utility model belongs to the technical field of sealing, and specifically provides a dry gas seal structure. Background Technique

[0002] In the dry gas seal industry, users are concerned about the long-term operation of compressors, production shutdowns, product equipment failures, environmental pollution, etc. Therefore, there is an urgent need to develop a sealing mechanism with good sealing effect, safety and reliability. Content of the Utility Model

[0003] In view of the above problems, the utility model provides a dry gas seal structure, which includes a rotating sleeve assembly, a primary seal unit, an intermediate labyrinth seal, and a secondary seal unit. Among them,

[0004] The rotating sleeve assembly includes a main rotating sleeve, a secondary rotating sleeve, and a positioning sleeve; the main rotating sleeve is fixed on the compressor shaft through an elastic tolerance ring; the outer periphery of the main rotating sleeve is fixed with a secondary rotating sleeve through an elastic tolerance ring and a stop pin; the head ends of the main rotating sleeve and the secondary rotating sleeve extend outward to form an assembly cup; the positioning sleeve is fixed on the main rotating sleeve through an elastic tolerance ring screw, and the entire rotating sleeve assembly is tightened on the compressor rotating shaft through a compressor lock nut;

[0005] The primary seal unit includes a primary dynamic ring, a primary static ring, and a primary seat sleeve. The primary dynamic ring is installed in the assembly cup of the main rotating sleeve. The primary static ring and the push ring are installed in the primary seat sleeve. Among them, the primary seat sleeve is provided with convex ribs, and correspondingly, the primary static ring is provided with a static ring groove. The static ring groove and the convex ribs milled integrally on the primary seat sleeve cooperate to prevent rotation. The end faces of the primary static ring and the primary dynamic ring form a sealing friction pair; a push ring is arranged at the non-sealing end face of the primary static ring; a plurality of springs are evenly distributed along the circumferential direction on the push ring, and the other ends of the springs are placed in the grooves on the primary seat sleeve to realize the elastic compensation connection between the push ring and the primary seat sleeve; a primary seal gas injection port is arranged at the connection between the primary dynamic ring and the primary static ring;

[0006] The intermediate labyrinth seal is sleeved on the outer periphery of the assembly cup of the secondary rotating sleeve; a seal leakage gas outlet is arranged between the intermediate labyrinth seal and the primary seat sleeve;

[0007] The secondary seal includes a secondary dynamic ring, a secondary static ring, and a secondary seat sleeve. Among them, the secondary dynamic ring is installed in the assembly cup in the secondary rotating sleeve. The secondary static ring and the push ring are installed in the secondary seat sleeve. The static ring groove and the convex ribs milled integrally on the secondary seat sleeve cooperate to prevent rotation. The end faces of the static ring and the secondary dynamic ring form a secondary sealing friction pair; the positioning sleeve is fixed on the main rotating sleeve through a screw, and the positioning sleeve and the compressor shaft are prevented from rotating through a stop pin; a push ring is installed on one side of the secondary static ring, and the push ring and the secondary seat sleeve are elastically compensated and connected through a spring; a secondary seal gas injection inlet is arranged in the secondary seal unit.

[0008] Further, on the end face of the push ring that contacts the primary static ring, an annular mounting groove is provided. A secondary static sealing ring is arranged in the mounting groove. The static sealing ring includes an elastic energy storage ring and a spring. The elastic energy storage ring is U-shaped. The spring is assembled inside the energy storage ring, and the opening diameter of the energy storage ring is smaller than the diameter of the spring to fix the spring.

[0009] Further, a recessed ring groove belt heel is provided on the bottom end face of the mounting groove, and a pressure relief hole is machined at the bottom of the mounting groove.

[0010] Further, on the contact end face between the primary seat sleeve and the push ring, a static sealing ring is provided through a mounting groove. The static sealing ring is of a spring-loaded energy storage ring structure.

[0011] Further, in the secondary sealing unit, a secondary sealing ring is also provided on the end face of the push ring that contacts the secondary static ring. A recessed ring groove belt heel is provided at the bottom of the mounting groove of the secondary sealing ring; on the secondary seat sleeve, a static sealing ring is also provided on the contact face with the push ring.

[0012] Further, evenly distributed spiral grooves are machined on the working faces of the dynamic ring or static ring in the primary sealing unit and the secondary sealing unit.

[0013] The purpose of the present utility model is to provide a new type of secondary series dry gas seal. The static seal and secondary seal of the dry gas seal generally use spring-loaded energy storage rings to ensure the long-term operation of the dry gas seal, reduce the failure of the dry gas seal under any working conditions, especially during the start-up pressurization process or the barring process, and the new structure of the groove cooperating with the spring-loaded energy storage ring reduces the failure of the dry gas seal during the compressor pressurization start-up and other processes. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 It is a schematic structural diagram of the seal body;

[0015] Figure 2 It is a schematic structural diagram of the push ring;

[0016] Figure 3 It is a schematic diagram of the end face pressure distribution of the spiral groove;

[0017] Figure 4 It is a schematic diagram of the position of the spiral groove;

[0018] Figure 5 It is a schematic diagram of the energy storage ring loading spring structure;

[0019] Figure 6 It is a schematic diagram of the cooperation between the integral milling rib and the static ring groove;

[0020] Figure 7 It is a schematic diagram of the friction pair structure;

[0021] Figure 8Schematic diagram of the gas flow direction for sealing

[0022] Among them, 1. Main rotating sleeve; 2. Auxiliary rotating sleeve; 3. First-stage dynamic ring; 4. First-stage static ring; 5. Thrust ring; 6. First-stage seat sleeve; 7. Secondary sealing ring; 8. Static sealing ring; 9. Spring; 10. Intermediate labyrinth seal; 11. Clip; 12. Pressure relief hole; 13. Elastic tolerance ring; 14. Second-stage dynamic ring; 15. Second-stage static ring; 16. Elastic energy storage ring; 17. Second-stage seat sleeve; 18. Positioning sleeve; 19. Anti-rotation pin; 20. Screw; 21. Spring part; 22. Helical groove; 23. Heel; 24. Compressor shaft; 25. Compressor lock nut; 26. Static ring groove; 27. Rib Specific embodiments

[0023] The principles and features of the present invention will be described below with reference to the accompanying drawings. The examples given are only for explaining the present invention and are not intended to limit the scope of the present invention.

[0024] Reference Figures 1-7 , the present invention provides a dry gas seal structure, including a rotating sleeve assembly, a first-stage sealing unit, an intermediate labyrinth seal 10 and a second-stage sealing unit. Among them,

[0025] The rotating sleeve assembly includes a main rotating sleeve 1, an auxiliary rotating sleeve 2 and a positioning sleeve 18; the main rotating sleeve 1 is fixed on the compressor shaft 24 through an elastic tolerance ring and an anti-rotation pin 19; an auxiliary rotating sleeve 2 is fixed on the outer periphery of the main rotating sleeve 1 through an elastic tolerance ring 13 and an anti-rotation pin 19; the head ends of the main rotating sleeve 1 and the auxiliary rotating sleeve 2 extend outward to form an assembly cup; the positioning sleeve is fixed on the main rotating sleeve through an elastic tolerance ring screw 20, and the entire rotating sleeve assembly is tightened on the compressor rotating shaft 24 through a compressor lock nut 25. The positioning sleeve 18 and the compressor shaft 24 are anti-rotated through an anti-rotation pin 19;

[0026] The first-stage sealing unit includes a first-stage dynamic ring 3, a first-stage static ring 4, and a first-stage seat sleeve 6. The first-stage dynamic ring 3 is installed in the assembly cup, and the first-stage static ring 4 is installed in the first-stage seat sleeve 6 and on the outer periphery of the auxiliary rotating sleeve 2. Reference Figure 6 , the static ring groove of the first-stage static ring 4 is matched with the integrally milled rib of the first-stage seat sleeve 6 to prevent the static ring from rotating circumferentially; the axial movement of the static ring is limited by a clip 11; the end faces of the first-stage static ring 4 and the first-stage dynamic ring 3 form a first-stage sealing friction pair; a thrust ring 5 is provided at the non-sealing end face of the first-stage static ring 4; a plurality of springs 9 are evenly distributed along the circumferential direction on the thrust ring 5, and the other ends of the springs 9 are placed in the grooves on the first-stage seat sleeve 6 to make the static ring have followability in axial movement; a first-stage sealing gas injection port is provided at the connection between the first-stage dynamic ring 3 and the first-stage static ring 4.

[0027] The intermediate labyrinth seal 10 is sleeved on the outer periphery of the right end of the assembly cup of the auxiliary rotating sleeve 2; a sealing leakage gas outlet is provided between the labyrinth seal 10 and the first-stage seat sleeve 6.

[0028] The secondary seal includes a secondary rotating ring 14, a secondary stationary ring 15, and a secondary seat sleeve 17. The secondary rotating ring 14 is installed in the assembly cup in the auxiliary rotating sleeve 2. The secondary stationary ring and the thrust ring are installed in the secondary seat sleeve. The stationary ring groove and the integral milling rib of the secondary seat sleeve cooperate to prevent rotation. The end faces of the stationary ring and the secondary rotating ring form a secondary seal friction pair. The positioning sleeve 18 is fixed to the main rotating sleeve 1 by screws 20, and the positioning sleeve 18 and the anti-rotation pin 19 on the compressor shaft prevent rotation. A thrust ring 5 is installed on one side of the secondary stationary ring 15, and the thrust ring 5 and the secondary seat sleeve 17 are elastically compensated and connected by a spring 9. A secondary seal gas injection is provided inside the secondary seal unit.

[0029] As an improvement of the solution, an installation annular groove is provided on the end face of the thrust ring 5 in contact with the primary stationary ring 4. A secondary sealing ring 7 is provided in the installation groove. The secondary sealing ring 7 includes an elastic energy storage ring 16 and a spring member 21. The elastic energy storage ring 16 is U-shaped, and the spring member 21 is assembled inside the energy storage ring 16. The opening diameter of the energy storage ring 16 is smaller than the diameter of the spring member 21 to fix the spring member 21. The performance of the spring member 21 loading the energy storage ring 16 must meet the requirement of being consistent with the original performance after stretching and rebounding. Spring-loaded energy storage rings are generally used for the static seal and secondary seal of dry gas seals to ensure the long-term operation of dry gas seals under the high-temperature and high-pressure conditions of compressors.

[0030] As an improvement of the solution, a recessed ring groove belt 23 is provided on the bottom end face of the installation groove to prevent the spring member 21 from protruding the energy storage ring 16, causing the carbon ring to get stuck and preventing seal failure. A pressure relief hole is machined at the bottom of the installation groove. During the operation of the dry gas seal, when the compressor stops and then starts, due to the charging process of the compressor, the dry gas seal fails due to the jamming of the thrust ring 5 of the dry gas seal. The reason for the jamming is that the spring member 21 loading the energy storage ring 16 comes out of the installation groove, causing the thrust ring 5 to jam. The new structure of the sealing groove of the spring member 21 loading the energy storage ring, and a pressure relief hole 12 is machined at the bottom of the installation groove of the spring member loading the energy storage ring to timely discharge the leaked gas of the sealing ring, ensuring that no back pressure is generated due to jamming.

[0031] As an improvement of the solution, a static sealing ring 8 is provided on the contact end face of the primary seat sleeve 6 and the thrust ring 5 through an installation groove. The static sealing ring 8 is a spring 9 loaded energy storage ring structure.

[0032] As an improvement of the solution, in the secondary seal unit, a secondary sealing ring 7 is also provided on the end face of the thrust ring 5 in contact with the secondary stationary ring 15. A recessed ring groove belt is provided at the bottom of the installation groove of the secondary sealing ring 7; on the secondary seat sleeve 17, a static sealing ring 8 is also provided on the contact face with the thrust ring 5.

[0033] As an improvement of the solution, refer to Figure 4, helical grooves 22 evenly distributed are machined on the working surfaces of the dynamic rings of the primary sealing unit and the secondary sealing unit.

[0034] As an improvement to the solution, an elastic tolerance ring 13 is provided between the main rotating sleeve and the compressor shaft, and between the main rotating sleeve and the auxiliary rotating sleeve / positioning sleeve, so as to better transmit torque and achieve better centering.

[0035] Dry gas seal working principle

[0036] Dry gas seal is a balance of static pressure and hydrodynamic force. The static fluid force acting on the seal is generated by the medium pressure and the spring 9 force, and exists both when rotating and at rest. The fluid dynamic force only occurs when the seal rotates. When the seal rotates, the viscous shear force generated by the dynamic ring drives the sealing gas into the helical grooves 22. From the outer diameter towards the center, the radial component flows towards the sealing dam, and the sealing dam restricts the gas flow to the low-pressure side. Thus, the gas is compressed, the pressure increases, the sealing surfaces separate, and a gas film with a certain thickness is formed. The opening force formed by the gas film force and the closing force formed by the spring force and the medium force reach equilibrium, so that the seal operates in a non-contact manner. The gas film formed between the sealing surfaces of the dry gas seal has a certain positive stiffness, which ensures the stability of the seal operation and can also lubricate the friction pair. In order to obtain the necessary hydrodynamic effect, the hydrodynamic grooves must be opened on the high-pressure side.

[0037] The dynamic ring in the seal pair and the shaft sleeve (main rotating sleeve / auxiliary rotating sleeve / positioning sleeve) are installed on the compressor rotating shaft. The static ring and the seat sleeve are installed in the sealing cavity on the compressor housing. When the compressor shaft rotates, a gas film is formed between the end faces of the dynamic ring and the static ring, enabling the seal to operate in a non-contact state. This unique sealing method depends on helical grooves evenly distributed being machined on the working surfaces of the dynamic ring or the static ring. Refer to Figure 2 , Figure 7 .

[0038] When the compressor is working, the dynamic ring rotates with the compressor shaft, and the helical grooves 22 on the end face of the dynamic ring of the seal pair generate a pumping effect, causing the sealing gas to flow to the root of the helical grooves 22. Hindered by the sealing weirs and dams on the end face of the dynamic ring of the seal pair, the gas pressure increases, generating a force (opening force) that separates the dynamic ring and the static ring. And a gap is generated between the dynamic ring and the static ring. When the opening force FO is equal to the closing force FC, this gap will maintain dynamic equilibrium. The end face pressure distribution of the helical grooves 22 is as Figure 3 shown. That is to say, when the closing force generated by the sealing gas pressure is equal to the opening force generated by the hydrodynamic effect, a stable gap between the sealing surfaces is established.

[0039] The balance gap between the sealing surfaces has a self-adjusting characteristic. When external disturbances cause the sealing gap to tend to decrease, the hydrodynamic pressure effect of the spiral grooves will increase, and the opening force FO generated by the spiral grooves will tend to increase to prevent the sealing gap from decreasing, that is, the opening force is greater than the closing force (FO > FC). Conversely, the hydrodynamic pressure effect of the spiral grooves weakens, and the opening force generated by the spiral groove surface tends to decrease, that is, the closing force will be greater than the opening force (FC > FO). In this way, the sealing gap is always maintained in a dynamic equilibrium state. The typical balance gap is about 0.002 - 0.006 mm. The gas film in the tiny gap has extremely high stiffness (109 N / m), preventing the process medium from leaking and external disturbances. This enables the sealing pair to be separated from contact and yet play a good sealing role.

[0040] In this solution, sealing gas is introduced into the compressor through the primary sealing gas inlet. This gas seals the medium gas in the compressor. A part of the gas leaks through the primary sealing end face in the compressor and is discharged to the flare (or a safe place) through the primary leakage gas outlet; a part of the gas entering from the secondary sealing gas inlet flows to the left and is discharged to the flare (or a safe place) through the primary sealing leakage gas outlet after passing through the labyrinth seal 10 (where it converges with the primary sealing end face leakage gas), and a part of the gas is discharged to a safe place after leaking through the secondary sealing end face.

[0041] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A dry gas sealing structure, characterized in that: It includes a rotating sleeve assembly, a primary sealing unit, an intermediate comb seal and a secondary sealing unit, wherein: The rotating sleeve assembly comprises a main rotating sleeve, a secondary rotating sleeve and a positioning sleeve; wherein the main rotating sleeve is fixed on the compressor shaft through an elastic tolerance ring; the outer periphery of the main rotating sleeve is fixed with the secondary rotating sleeve through an elastic tolerance ring, and a stop pin is fixed with the secondary rotating sleeve; the head ends of the main rotating sleeve and the secondary rotating sleeve extend toward the outer periphery to form an assembly cup; the positioning sleeve is fixed to the main rotating sleeve through an elastic tolerance ring screw, the entire rotating sleeve assembly is tightened on the compressor shaft through a compressor tightening nut, and the positioning sleeve and the compressor shaft are stopped by a stop pin; The primary sealing unit comprises a primary moving ring, a primary stationary ring and a primary seat cover, wherein the primary moving ring is installed in the main rotating sleeve assembly cup, and the primary stationary ring and the push ring are installed in the primary seat cover, wherein the primary seat cover is provided with a convex rib, and a corresponding stationary ring groove is provided on the primary stationary ring, and the stationary ring groove cooperates with the convex rib milled integrally on the primary seat cover to stop rotation, and the stationary ring and the end face of the primary moving ring form a sealing friction pair; a push ring is provided at the non-sealing end face of the primary stationary ring; a plurality of springs are evenly arranged on the push ring along the circumferential direction, and the other end of the spring is placed in the groove on the primary seat cover to realize the elastic compensation connection between the push ring and the primary seat cover; a primary sealing gas injection port is provided at the connection between the primary moving ring and the primary stationary ring; The middle comb seal is sleeved on the outer periphery of the assembly cup of the auxiliary rotating sleeve; a sealing leakage gas outlet is provided between the middle comb seal and the first-level seat sleeve; The secondary seal includes a secondary dynamic ring, a secondary static ring and a secondary seat sleeve, wherein the secondary dynamic ring is installed in the assembly cup inside the secondary rotating sleeve, the secondary static ring and the push ring are installed in the secondary seat sleeve, the static ring groove and the integrally milled ribs of the secondary seat sleeve cooperate to stop rotation, and the static ring and the end face of the secondary dynamic ring form a secondary sealing friction pair; the positioning sleeve is fixed to the main rotating sleeve by screws, and the positioning sleeve and the compressor shaft are stopped by a stop pin; a push ring is installed on one side of the secondary static ring, and the push ring is connected to the secondary seat sleeve by spring elastic compensation; a secondary sealing gas injection port is provided in the secondary sealing unit.

2. A dry gas sealing structure according to claim 1, characterized in that: A push ring is provided with an annular mounting groove on the end face in contact with the primary static ring. A secondary sealing ring is arranged in the mounting groove. The secondary sealing ring includes an elastic energy storage ring and a spring. The elastic energy storage ring is U-shaped. The spring is assembled inside the energy storage ring, and the opening diameter of the energy storage ring is smaller than the diameter of the spring to fix the spring.

3. A dry gas sealing structure according to claim 2, characterized in that: The bottom end surface of the installation groove is provided with a recessed annular groove with a heel, and a pressure relief hole is processed at the bottom of the installation groove.

4. A dry gas sealing structure according to claim 2, characterized in that: A static sealing ring is arranged on the contact end surface between the first-stage seat sleeve and the push ring through a mounting groove, and the static sealing ring is a spring-loaded energy storage ring structure.

5. A dry gas sealing structure according to claim 1, characterized in that: In the secondary sealing unit, a secondary sealing ring is also arranged on the end face of the push ring in contact with the secondary static ring, and a recessed ring groove with a heel is arranged at the bottom of the installation groove of the secondary sealing ring; a static sealing ring is also arranged on the contact surface with the push ring on the secondary seat sleeve.

6. A dry gas sealing structure according to claim 1, characterized in that: Evenly distributed spiral grooves are machined on the working surfaces of the dynamic ring or the static ring of the primary sealing unit and the secondary sealing unit.

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