Dry gas sealing structure for ship oil-free compressor

Abstract

The utility model relates to the technical field of sealing structures, and discloses a dry gas sealing structure for a ship oil-free compressor, which is characterized in that a sealing shell is provided with a sealing gas inlet and a medium reflux inlet; the multi-stage carbon ring assembly is located on the inner side of the sealing shell and arranged on the rotating shaft in a sleeving mode, in the working state, after medium side gas passes through the multi-stage carbon ring assembly, the gas pressure is gradually reduced, and then the medium side gas enters the medium backflow opening; the dry gas sealing structure is located on the inner side of the sealing shell and comprises a spring seat and two dry gas sealing friction pairs, the two dry gas sealing friction pairs are arranged at the two ends of an inner cavity of the spring seat respectively, and in the working state, sealing gas entering from the sealing gas inlet passes through the corresponding dry gas sealing friction pairs respectively. The pressure of the sealing gas is larger than that of the gas on the medium side after passing through the multi-stage carbon ring assembly. The multi-stage carbon ring assembly has the advantages that the multi-stage carbon ring assembly prevents gas on the medium side from leaking from the compressor.

Description

Technical Field

[0001] This utility model relates to the technical field of sealing structures, specifically to a dry gas sealing structure for a marine oil-free compressor. Background Technology

[0002] LNG carriers are primarily used to transport liquefied natural gas (LNG), while BOG (evaporated gas) units are mainly used to recover and utilize BOG (evaporated gas) generated during the storage and transportation of LNG. The BOG unit compresses and cools the evaporated gas, reliquefying it and returning it to the LNG storage tank. This reduces LNG evaporation losses, improves the insulation of the storage tank, and thus lowers operating costs. BOG recovery units play a crucial role in LNG storage and transportation, especially in long-distance transport and large storage tanks, where their effectiveness is even more pronounced.

[0003] Currently, BOG compressors typically use packing seals to prevent the medium inside the compressor from flowing to the outside. Packing seals prevent medium leakage by filling the rotating shaft with soft materials (such as graphite, asbestos, etc.). However, both graphite and asbestos are easily worn, resulting in poor sealing performance and easy medium leakage. Utility Model Content

[0004] The technical problem this invention aims to solve is that current methods of preventing media leakage by filling the rotating shaft with graphite or asbestos have poor sealing effects and the media is prone to leakage. The purpose is to provide a dry gas sealing structure for marine oil-free compressors, which sets up a multi-stage carbon ring assembly so that the pressure of the medium gas entering the carbon ring assembly from the medium side is less than the pressure of the sealing gas, thereby preventing the gas on the medium side from leaking from the compressor. In addition, the dry gas sealing structure also prevents atmospheric gas from entering the compressor cavity, thus achieving a seal on the compressor cavity.

[0005] This utility model is achieved through the following technical solution:

[0006] A dry gas sealing structure for a marine oil-free compressor includes a sealing housing, a multi-stage carbon ring assembly, and a dry gas sealing structure. The sealing housing has a sealing gas inlet and a medium return port. The multi-stage carbon ring assembly is located inside the sealing housing and is sleeved on a rotating shaft. In operation, the gas pressure on the medium side gradually decreases after passing through the multi-stage carbon ring assembly before entering the medium return port. The dry gas sealing structure is located inside the sealing housing and includes a spring seat and two dry gas sealing friction pairs. The two dry gas sealing friction pairs are respectively disposed at both ends of the inner cavity of the spring seat. In operation, the sealing gas entering from the sealing gas inlet passes through the corresponding dry gas sealing friction pairs and then enters the medium return port and the atmospheric side, respectively. The pressure of the sealing gas is greater than the pressure of the gas on the medium side after passing through the multi-stage carbon ring assembly.

[0007] The beneficial effects of this utility model are as follows: by setting a dry gas sealing structure, the sealing gas (inert gas such as nitrogen with high atmospheric pressure) entering from the sealing gas inlet can pass through the two dry gas sealing friction pairs, preventing atmospheric gas from entering the compressor cavity; furthermore, by placing the multi-stage carbon ring assembly inside the sealing housing and sleeved on the rotating shaft, the medium gas entering the carbon ring assembly from the medium side can have its pressure reduced after passing through each carbon ring assembly, ultimately making the pressure of the medium gas entering the medium return port less than the pressure of the sealing gas, thereby preventing the medium gas from entering the dry gas sealing structure end (preventing the medium gas from leaking to the outside of the compressor), thus achieving sealing of the medium gas, replacing the filling seal, improving the sealing effect, and preventing the medium gas from leaking to the outside of the compressor.

[0008] In some embodiments, a bushing is further included, which is sleeved on the rotating shaft. Both dry gas sealing friction pairs are sleeved on the bushing. The spring seat has a through hole communicating with the sealing gas inlet. The two dry gas sealing friction pairs include a first dry gas sealing friction pair and a second dry gas sealing friction pair. The first dry gas sealing friction pair is located at the end of the spring seat away from the medium side, and the second dry gas sealing friction pair is located at the end away from the atmosphere side. By placing the first dry gas sealing friction pair at the end of the spring seat away from the medium side and the second dry gas sealing friction pair at the end away from the atmosphere side, it is convenient to prevent atmospheric air from entering the compressor interior through the sealing gas in cooperation with the first dry gas sealing friction pair, and to prevent the medium gas from leaking from the compressor interior through the sealing gas in cooperation with the second dry gas sealing friction pair.

[0009] In some embodiments, a stationary ring seat is connected to the end of the bushing away from the medium side. The first dry gas sealing friction pair includes a first combined push ring, a first moving ring, and a first stationary ring. A first compression spring is connected to the inner side of the stationary ring seat. The first combined push ring is connected to the inner cavity of the stationary ring seat. The first compression spring abuts against one side of the first combined push ring, and the other side of the first combined push ring abuts against one side of the first stationary ring. A convex ring is provided in the middle of the bushing. The first moving ring is connected to the side of the convex ring away from the medium side by an anti-rotation pin. Several dynamic pressure grooves are provided on the side of the first moving ring away from the convex ring and abut against the first stationary ring. By providing several dynamic pressure grooves on the side of the first moving ring away from the convex ring, the sealing gas forms a gas film when the dynamic pressure grooves rotate (the bushing drives the first moving ring to rotate). The sealing end face of the gas film seal is in a non-contact operating state (the mating point between the first moving ring and the first stationary ring), preventing external air from entering the compressor. The friction pair composed of the dry gas sealing moving and stationary rings is wear-free, ensuring stable and reliable operation of the sealing structure and extending its service life.

[0010] In some embodiments, the second dry gas sealing friction pair includes a second combined push ring, a second moving ring, and a second stationary ring. A second compression spring is connected to the end of the spring seat cavity away from the atmosphere. The second compression spring abuts against one side of the second combined push ring, and the other side of the second combined push ring abuts against one side of the second stationary ring. The second moving ring is connected to the side of the convex ring away from the first moving ring via an anti-rotation pin. Several dynamic pressure grooves are provided on the side of the second moving ring away from the convex ring and abut against the second stationary ring. By providing several dynamic pressure grooves on the side of the second moving ring away from the convex ring, the sealing gas forms a gas film when the dynamic pressure grooves rotate (the bushing drives the second moving ring to rotate). The sealing end face of the gas film seal is in a non-contact operating state (at the mating point of the second moving ring and the second stationary ring), preventing leakage of the medium gas from the compressor cavity. The friction pair composed of the dry gas sealing moving and stationary rings is wear-free, ensuring stable and reliable operation of the sealing structure and extending its service life.

[0011] In some embodiments, both ends of the outer side of the bushing are provided with external threads, and locking nuts are screwed onto each external thread. The ends of the two locking nuts abut against the first rotating ring and the second rotating ring, respectively. The axial movement of the first rotating ring and the second rotating ring is restricted by screwing the locking nuts onto the bushing.

[0012] In some embodiments, both the first and second combined push rings include a first push ring, a second push ring, a sealing ring sleeve, and a second tension spring. The sealing ring sleeve is fitted inside the cavity of the stationary ring seat. The first push ring is fitted on one side of the sealing ring sleeve, with the side of the first push ring away from the sealing ring sleeve abutting against a corresponding compression spring. The second push ring is connected to the other side of the sealing ring sleeve and located inside the first push ring. The second tension spring is connected to the sealing ring sleeve. By setting the compression spring to adjust the floating property of the corresponding stationary ring, and by connecting the sealing ring sleeve to the cavity of the stationary ring seat via the second tension spring, an axial static seal is achieved for the stationary ring seat. Furthermore, the first and second push rings are respectively connected to both sides of the sealing ring sleeve to achieve an axial seal for the first stationary ring and the stationary ring seat.

[0013] In some embodiments, the sealing ring sleeve is annular in shape and has a mounting groove. The second tension spring is sleeved within the mounting groove, and a tension spring limiting portion, which is a hook protruding towards the inside of the mounting groove, is provided on the side wall of the open end of the mounting groove. By providing a mounting groove on the sealing ring sleeve and a hook on the side wall of the mounting groove, the second tension spring is limited, preventing it from rolling during operation and affecting the sealing effect.

[0014] In some embodiments, the sealing ring sleeve is further provided with a push ring positioning part, which is a hook extending toward the center of the sealing ring sleeve. The second push ring is provided with a first groove, and the push ring positioning part cooperates with the first groove. A boss is provided on the outer periphery of the second push ring, and a second groove is provided on the inner cavity sidewall of the first push ring, which cooperates with the boss. By providing a hook on the sealing ring sleeve to cooperate with the first groove on the second push ring, and providing a second groove on the first push ring to cooperate with the boss on the second push ring, the three are connected together to achieve radial sealing of the first stationary ring and the stationary ring seat, or radial sealing of the second stationary ring and the spring seat.

[0015] In some embodiments, a carbon ring sealing seat is further included, located within the inner cavity of the sealing housing. The multi-stage carbon ring assembly is located within the inner cavity of the carbon ring sealing seat. The multi-stage carbon ring assembly includes at least two carbon ring assemblies, and several carbon ring assemblies are arranged sequentially along the length of the rotation axis. Each carbon ring assembly includes a carbon ring compression spring, a carbon ring seat, and a carbon ring. Both the carbon ring sealing seat and the carbon ring seat have countersunk holes. Several compression springs are respectively installed in corresponding countersunk holes, and the free ends of the compression springs abut against corresponding carbon rings. The restoring force of the corresponding compression springs pushes the end face of the corresponding carbon ring to fit against the end face of the corresponding carbon ring seat, causing the carbon ring located near the carbon ring pressure plate to fit against the carbon ring pressure plate, forming an end face seal to prevent the process medium from leaking in the radial direction. The process medium flows in the axial direction, and through the small clearance fit between the inner hole of the carbon ring assembly and the compressor rotation axis, the outflowing process medium is throttled and depressurized stage by stage.

[0016] In some embodiments, the system further includes a drive ring, a carbon ring pressure plate, and a positioning block. The drive ring is connected to the bushing by a set screw, and the positioning block is connected to the stationary ring seat by an internal hexagon screw. The outer periphery of the drive ring abuts against the lower part of the positioning block. The carbon ring pressure plate is fixedly connected to the end of the carbon ring sealing seat away from the end where the carbon ring compression spring is located. The carbon ring pressure plate is connected to the spring seat by an anti-rotation pin. The carbon ring pressure plate is provided with a through hole, which communicates with the medium return port. The drive ring is connected to the bushing with a set screw so that the drive ring can rotate synchronously with the rotating shaft. The positioning block is connected to the stationary ring seat with an internal hexagon screw, and the outer circumference of the drive ring abuts against the lower part of the positioning block to position the stationary ring seat and the spring seat. The carbon ring pressure plate is fixedly connected to the end of the carbon ring seal seat away from the end where the carbon ring compression spring is located. The carbon ring pressure plate is connected to the spring seat with an anti-rotation pin, thereby connecting the carbon ring seal seat and the spring seat together to prevent the carbon ring seal seat and the spring from rotating synchronously when the rotating shaft rotates. The carbon ring pressure plate is provided with a through hole that communicates with the medium return port, so that the medium gas and sealing gas can enter the medium return port.

[0017] Compared with the prior art, this utility model has the following advantages and beneficial effects:

[0018] 1. The multi-stage carbon ring assembly is designed so that the pressure of the medium gas entering the carbon ring assembly from the medium side is less than the pressure of the sealing gas, thereby preventing the gas on the medium side from leaking from the compressor. In addition, the dry gas sealing structure is designed to prevent atmospheric gas from entering the compressor cavity, thus achieving the sealing of the compressor cavity.

[0019] 2. Several dynamic pressure grooves are provided on one side of the rotating ring. When the sealing gas rotates in the dynamic pressure grooves, it forms a gas film (the bushing drives the rotating ring to rotate). The sealing end face of the gas film seal is in a non-contact operating state (the mating point between the rotating ring and the stationary ring), which prevents the medium gas from leaking from the compressor cavity. The friction pair composed of the dry gas seal rotating and stationary rings is wear-free, ensuring stable and reliable operation of the sealing structure and extending its service life. Attached Figure Description

[0020] The accompanying drawings, which are included to provide a further understanding of the embodiments of the present invention and form part of this application, do not constitute a limitation thereof. In the drawings:

[0021] Figure 1 This is a central sectional view of the present invention;

[0022] Figure 2 This utility model Figure 1 A magnified view of section K in the middle;

[0023] Figure 3 This is a center sectional view of the sealing ring jacket in this utility model;

[0024] Figure 4 This is a central cross-sectional view of the second push ring in this utility model;

[0025] Figure 5 This utility model Figure 4 Enlarged view of section I;

[0026] Figure 6 This is a central cross-sectional view of the first push ring in this utility model;

[0027] Figure 7 This is a side view of the moving ring in this utility model.

[0028] The attached diagram shows the markings and corresponding component names:

[0029] Carbon ring compression spring 1, carbon ring 2, O-ring 3, carbon ring seat 4, carbon ring sealing seat 5, anti-rotation pin 6, spring seat 8, first combination push ring 9, second combination push ring 19, locking nut 10, second stationary ring 11, second moving ring 12, first tension spring 13, first moving ring 16, dynamic pressure groove 161, first stationary ring 17, hex socket screw 20, positioning block 21, drive ring 23, set screw 24, stationary ring seat 26, bushing 34, carbon ring pressure plate 37, first compression spring 22, second compression spring 18, first push ring 30, second groove 301, limiting part 302, second push ring 31, first groove 311, boss 312, sealing ring sleeve 32, tension spring limiting part 322, push ring positioning part 321, second tension spring 33. Detailed Implementation

[0030] To make the objectives, technical solutions, and advantages of this utility model clearer, the present utility model will be further described in detail below with reference to the embodiments and accompanying drawings. The illustrative embodiments and descriptions of this utility model are only used to explain this utility model and are not intended to limit this utility model.

[0031] Throughout this specification, references to "an embodiment," "an example," or "an example" mean that a particular feature, structure, or characteristic described in connection with that embodiment or example is included in at least one embodiment of the present invention. Therefore, the phrases "an embodiment," "an example," "an example," or "an example" appearing in various places throughout the specification do not necessarily refer to the same embodiment or example. Furthermore, specific features, structures, or characteristics can be combined in one or more embodiments or examples in any suitable combination and / or sub-combination. Moreover, those skilled in the art will understand that the illustrations provided herein are for illustrative purposes and are not necessarily drawn to scale. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0032] In the description of this utility model, the terms "front", "rear", "left", "right", "up", "down", "vertical", "horizontal", "high", "low", "inner", and "outer" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limiting the scope of protection of this utility model.

[0033] The terms "first," "second," etc., used in this utility model are merely for clarity of description and are not intended to limit any order or emphasize importance. Furthermore, the term "connection" as used herein, unless otherwise specified, can refer to a direct connection or an indirect connection via other components. Example

[0034] like Figures 1-7 As shown, this embodiment provides a dry gas sealing structure for a marine oil-free compressor, including a sealing housing, a multi-stage carbon ring 2 assembly, and a dry gas sealing structure. The sealing housing is provided with a sealing gas inlet and a medium return port. The multi-stage carbon ring 2 assembly is located inside the sealing housing and is sleeved on a rotating shaft. In the working state, the gas pressure on the medium side gradually decreases after passing through the multi-stage carbon ring 2 assembly before entering the medium return port. The dry gas sealing structure is located inside the sealing housing and includes a spring seat 8 and two dry gas sealing friction pairs. The two dry gas sealing friction pairs are respectively disposed at both ends of the inner cavity of the spring seat 8. In the working state, the sealing gas entering from the sealing gas inlet passes through the corresponding dry gas sealing friction pairs and then enters the medium return port and the atmospheric side respectively. The pressure of the sealing gas is greater than the pressure of the medium side gas after passing through the multi-stage carbon ring 2 assembly.

[0035] See Figure 1 The system also includes a bushing 34, which is fitted onto the rotating shaft. Both dry gas sealing friction pairs are fitted onto the bushing 34. The spring seat 8 has a through hole communicating with the sealing gas inlet. The two dry gas sealing friction pairs include a first dry gas sealing friction pair and a second dry gas sealing friction pair. The first dry gas sealing friction pair is located at the end of the spring seat 8 away from the medium side, and the second dry gas sealing friction pair is located at the end away from the atmosphere side. By placing the first dry gas sealing friction pair at the end of the spring seat 8 away from the medium side and the second dry gas sealing friction pair at the end away from the atmosphere side, it is convenient to prevent atmospheric air from entering the compressor interior through the sealing gas in conjunction with the first dry gas sealing friction pair, and to prevent the medium gas from leaking from the compressor interior through the sealing gas in conjunction with the second dry gas sealing friction pair.

[0036] See Figure 1The bushing 34 is connected to a stationary ring seat 26 at one end away from the medium side. The first dry gas sealing friction pair includes a first combined push ring 9, a first moving ring 16, and a first stationary ring 17. A first compression spring 22 is connected to the inner side of the stationary ring seat 26. The first combined push ring 9 is connected to the inner cavity of the stationary ring seat 26. The first compression spring 22 abuts against one side of the first combined push ring 9, and the other side of the first combined push ring 9 abuts against one side of the first stationary ring 17. A convex ring is provided in the middle of the bushing 34. The first moving ring 16 is connected to the side of the convex ring away from the medium side by an anti-rotation pin 6. The side of the first moving ring 16 away from the convex ring is provided with several dynamic pressure grooves 161 and abuts against the first stationary ring 17. By providing several dynamic pressure grooves 161 on the side of the first moving ring 16 away from the convex ring, the sealing gas forms a gas film when the dynamic pressure grooves 161 rotate (the bushing 34 drives the first moving ring 16 to rotate). The sealing end face of the gas film seal is in a non-contact operating state (the mating point between the first moving ring 16 and the first stationary ring 17), preventing external air from entering the inside of the compressor. The friction pair composed of the dry gas sealing moving and stationary rings is wear-free, ensuring stable and reliable operation of the sealing structure and extending its service life.

[0037] See Figures 1-7 The second dry gas sealing friction pair includes a second combined push ring 19, a second moving ring 12, and a second stationary ring 11. A second compression spring 18 is connected to one end of the inner cavity of the spring seat 8 away from the atmosphere. The second compression spring 18 abuts against one side of the second combined push ring 19, and the other side of the second combined push ring 19 abuts against one side of the second stationary ring 11. The second moving ring 12 is connected to the side of the convex ring away from the first moving ring 16 by an anti-rotation pin 6. The side of the second moving ring 12 away from the convex ring is provided with several dynamic pressure grooves 161 and abuts against the second stationary ring 11. By providing several dynamic pressure grooves 161 on the side of the second moving ring 12 away from the convex ring, the sealing gas forms a gas film when the dynamic pressure grooves 161 rotate (the bushing 34 drives the second moving ring 12 to rotate). The sealing end face of the gas film seal is in a non-contact operating state (the mating point between the second moving ring 12 and the second stationary ring 11), preventing the medium gas from leaking from the compressor cavity. The friction pair composed of the dry gas sealing moving and stationary rings is wear-free, ensuring stable and reliable operation of the sealing structure and extending its service life.

[0038] See Figure 1 Both ends of the outer side of the bushing 34 are provided with external threads, and locking nuts 10 are screwed onto each of the external threads. The ends of the two locking nuts 10 abut against the first rotating ring 16 and the second rotating ring 12, respectively. The axial movement of the first rotating ring 16 and the second rotating ring 12 is restricted by screwing the locking nuts 10 onto the bushing 34.

[0039] See Figures 1-7The first combined push ring 9 and the second combined push ring 19 each include a first push ring 30, a second push ring 31, a sealing ring sleeve 32, and a second tension spring 33. The sealing ring sleeve 32 is fitted inside the cavity of the stationary ring seat 26. The first push ring 30 is fitted on one side of the sealing ring sleeve 32, with the side of the first push ring 30 away from the sealing ring sleeve 32 abutting against the corresponding compression spring. The second push ring 31 is connected to the other side of the sealing ring sleeve 32 and located inside the first push ring 30. The second tension spring 33 is connected to the sealing ring sleeve 32. By setting the floating property of the stationary ring corresponding to the compression spring, and by connecting the sealing ring sleeve 32 to the cavity of the stationary ring seat 26 through the second tension spring 33, an axial static seal is achieved on the stationary ring seat 26. Furthermore, the first push ring 30 and the second push ring 31 are respectively connected to both sides of the sealing ring sleeve 32, achieving an axial seal on the first stationary ring 17 and the stationary ring seat 26.

[0040] See Figures 1-7 The sealing ring sleeve 32 is annular in shape and has a mounting groove. The second tension spring 33 is fitted into the mounting groove. A tension spring limiting part 322, which is a hook protruding towards the inside of the mounting groove, is provided on the side wall of the open end of the mounting groove. By providing a mounting groove on the sealing ring sleeve 32 and a hook on the side wall of the mounting groove, the second tension spring 33 is limited, preventing it from rolling during operation and affecting the sealing effect.

[0041] See Figures 1-7 The sealing ring sleeve 32 is further provided with a push ring positioning part 321, which is a protrusion extending toward the center of the sealing ring sleeve 32. The second push ring 31 is provided with a first groove 311, and the push ring positioning part 321 cooperates with the first groove 311. The outer periphery of the second push ring 31 is provided with a boss 312. The inner cavity sidewall of the first push ring 30 is provided with a second groove 301, which cooperates with the boss 312. By providing a protrusion on the sealing ring sleeve 32 to cooperate with the first groove 311 on the second push ring 31, and providing a second groove 301 on the first push ring 30 to cooperate with the boss 312 of the second push ring 31, the three are connected together to achieve radial sealing of the first stationary ring 17 and the stationary ring seat 26, or radial sealing of the second stationary ring 11 and the spring seat 8.

[0042] See Figure 1The system also includes a carbon ring sealing seat 5, located within the inner cavity of the sealing housing. The multi-stage carbon ring 2 assembly is located within the inner cavity of the carbon ring sealing seat 5. The multi-stage carbon ring 2 assembly includes at least two carbon ring 2 assemblies, which are sequentially arranged along the length of the rotation axis. Each carbon ring 2 assembly includes a carbon ring compression spring 1, a carbon ring seat 4, and a carbon ring 2. Both the carbon ring sealing seat 5 and the carbon ring seat 4 have countersunk holes. Several compression springs are respectively installed in the corresponding countersunk holes, and the free ends of the compression springs abut against the corresponding carbon ring 2. The restoring force of the corresponding compression spring pushes the end face of the corresponding carbon ring 2 to fit against the end face of the corresponding carbon ring seat 4, causing the carbon ring 2 located near the carbon ring pressure plate 37 to fit against the carbon ring pressure plate 37, forming an end face seal to prevent the process medium from leaking radially. The process medium flows axially, and through the small clearance fit between the inner hole of the carbon ring 2 assembly and the compressor rotation axis, the outflowing process medium is throttled and depressurized step by step.

[0043] See Figure 1 It also includes a drive ring 23, a carbon ring pressure plate 37, and a positioning block 21. The drive ring 23 is connected to the bushing 34 by a set screw 24. The positioning block 21 is connected to the stationary ring seat 26 by an internal hex screw 20. The outer periphery of the drive ring 23 abuts against the lower part of the positioning block 21. The carbon ring pressure plate 37 is fixedly connected to the end of the carbon ring sealing seat 5 away from the end where the carbon ring compression spring 1 is located. The carbon ring pressure plate 37 is connected to the spring seat 8 by an anti-rotation pin 6. The carbon ring pressure plate 37 is provided with a through hole, which communicates with the medium return port. The drive ring 23 is connected to the bushing 34 by a set screw 24, allowing the drive ring 23 to rotate synchronously with the rotating shaft. The positioning block 21 is connected to the stationary ring seat 26 by an internal hex screw 20, and the outer periphery of the drive ring 23 abuts against the lower part of the positioning block 21 to position the stationary ring seat 26 and the spring seat 8. The carbon ring pressure plate 37 is fixedly connected to the end of the carbon ring sealing seat 5 away from the end where the carbon ring compression spring 1 is located. The carbon ring pressure plate 37 is connected to the spring seat 8 by an anti-rotation pin 6, thereby connecting the carbon ring sealing seat 5 and the spring seat 8 together to prevent the carbon ring sealing seat 5 and the spring from rotating synchronously when the rotating shaft rotates. The carbon ring pressure plate 37 is provided with a through hole that communicates with the medium return port, so that the medium gas and sealing gas can enter the medium return port.

[0044] See Figure 1 Specifically, a first tension spring 13 and an O-ring 3 are provided on the inner side of the bushing 34 to adjust the alignment of the second rotating ring 12 and provide a back seal. Multiple O-rings 3 are also provided on the outer circumference of the bushing 34 to prevent the process medium inside the unit from leaking from the rotating shaft to the atmosphere. By providing the first tension spring 13 and O-rings 3 on the inner side of the second rotating ring 12, the second rotating ring 12 is adjusted for alignment and a back seal is provided.

[0045] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of this utility model. It should be understood that the above description is only a specific embodiment of this utility model and is not intended to limit the scope of protection of this utility model. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this utility model should be included within the scope of protection of this utility model.

Claims

1. A dry gas sealing structure for a marine oil-free compressor, characterized in that, include: A sealing housing, wherein a sealing gas inlet and a medium return outlet are provided on the sealing housing; A multi-stage carbon ring assembly is located inside the sealing housing and is sleeved on the rotating shaft. In the working state, the gas pressure on the medium side gradually decreases after passing through the multi-stage carbon ring assembly and then enters the medium return port. A dry gas sealing structure is located inside the sealing housing. The dry gas sealing structure includes a spring seat and two dry gas sealing friction pairs. The two dry gas sealing friction pairs are respectively disposed at both ends of the inner cavity of the spring seat. In the working state, the sealing gas entering from the sealing gas inlet passes through the corresponding dry gas sealing friction pairs and then enters the medium return port and the atmospheric side respectively. The pressure of the sealing gas is greater than the pressure of the medium side gas after passing through the multi-stage carbon ring assembly.

2. The dry gas sealing structure for a marine oil-free compressor according to claim 1, characterized in that, It also includes a bushing, which is sleeved on the rotating shaft. Both dry gas sealing friction pairs are sleeved on the bushing. The spring seat is provided with a through hole, which communicates with the sealing gas inlet. The two dry gas sealing friction pairs include a first dry gas sealing friction pair and a second dry gas sealing friction pair. The first dry gas sealing friction pair is located at the end of the spring seat away from the medium side, and the second dry gas sealing friction pair is located at the end away from the atmosphere side.

3. The dry gas sealing structure for a marine oil-free compressor according to claim 2, characterized in that, The end of the bushing away from the medium side is connected to a stationary ring seat. The first dry gas sealing friction pair includes a first combined push ring, a first moving ring, and a first stationary ring. A first compression spring is connected to the inner side of the stationary ring seat. The first combined push ring is connected to the inner cavity of the stationary ring seat. The first compression spring abuts against one side of the first combined push ring, and the other side of the first combined push ring abuts against one side of the first stationary ring. A convex ring is provided in the middle of the bushing. The first moving ring is connected to the side of the convex ring away from the medium side by an anti-rotation pin. The side of the first moving ring away from the convex ring is provided with several dynamic pressure grooves and abuts against the first stationary ring.

4. The dry gas sealing structure for a marine oil-free compressor according to claim 3, characterized in that, The second dry gas sealing friction pair includes a second combined push ring, a second moving ring, and a second stationary ring. A second compression spring is connected to one end of the inner cavity of the spring seat away from the atmosphere. The second compression spring abuts against one side of the second combined push ring, and the other side of the second combined push ring abuts against one side of the second stationary ring. The second moving ring is connected to the side of the convex ring away from the first moving ring by an anti-rotation pin. The side of the second moving ring away from the convex ring is provided with several dynamic pressure grooves and abuts against the second stationary ring.

5. The dry gas sealing structure for a marine oil-free compressor according to claim 3, characterized in that, Both ends of the outer side of the bushing are provided with external threads, and locking nuts are screwed onto the external threads. The ends of the two locking nuts abut against the first rotating ring and the second rotating ring, respectively.

6. The dry gas sealing structure for a marine oil-free compressor according to claim 3, characterized in that, Both the first and second combined push rings include a first push ring, a second push ring, a sealing ring sleeve, and a second tension spring. The sealing ring sleeve is fitted inside the cavity of the stationary ring seat. The first push ring is fitted on one side of the sealing ring sleeve, and the side of the first push ring away from the sealing ring sleeve abuts against the corresponding compression spring. The second push ring is connected to the other side of the sealing ring sleeve and located inside the first push ring. The second tension spring is connected to the sealing ring sleeve.

7. The dry gas sealing structure for a marine oil-free compressor according to claim 6, characterized in that, The sealing ring sleeve is circular in shape and has an installation groove. The second tension spring is sleeved in the installation groove. A tension spring limiting part is provided on the side wall of the opening end of the installation groove. The tension spring limiting part is a protruding hook that protrudes towards the inside of the installation groove.

8. The dry gas sealing structure for a marine oil-free compressor according to claim 6, characterized in that, The sealing ring sleeve is also provided with a push ring positioning part, which is a protrusion extending toward the center of the sealing ring sleeve. The second push ring is provided with a first groove, and the push ring positioning part cooperates with the first groove. The outer periphery of the second push ring is provided with a boss, and the inner cavity sidewall of the first push ring is provided with a second groove, which cooperates with the boss.

9. The dry gas sealing structure for a marine oil-free compressor according to claim 7, characterized in that, It also includes a carbon ring sealing seat, which is located in the inner cavity of the sealing housing. The multi-stage carbon ring assembly is located in the inner cavity of the carbon ring sealing seat. The multi-stage carbon ring assembly includes at least two carbon ring assemblies, and several carbon ring assemblies are arranged sequentially along the length of the rotation axis. Each carbon ring assembly includes a carbon ring compression spring, a carbon ring seat, and a carbon ring. Both the carbon ring sealing seat and the carbon ring seat are provided with countersunk holes. Several compression springs are respectively installed in the corresponding countersunk holes, and the free ends of the compression springs abut against the corresponding carbon rings.

10. The dry gas sealing structure for a marine oil-free compressor according to claim 9, characterized in that, It also includes a drive ring, a carbon ring pressure plate, and a positioning block. The drive ring is connected to the bushing by a set screw, and the positioning block is connected to the stationary ring seat by an internal hexagon screw. The outer periphery of the drive ring abuts against the lower part of the positioning block. The carbon ring pressure plate is fixedly connected to the end of the carbon ring sealing seat away from the end where the carbon ring compression spring is located. The carbon ring pressure plate is connected to the spring seat by an anti-rotation pin. The carbon ring pressure plate is provided with a through hole, which communicates with the medium return port.

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