Multi-stage floating carbon ring sealing structure

Abstract

The utility model belongs to the technical field of mechanical sealing, and particularly provides a multistage floating carbon ring sealing structure which comprises a sealing shell, and a sealing cavity is formed between the sealing shell and a main shaft. A first-stage sealing group, a second-stage sealing group and a third-stage sealing group are arranged in the sealing cavity; wherein the first-stage sealing group comprises two carbon ring sealing groups; the carbon ring sealing group comprises a sealing spacer bush and a sealing carbon ring; a pressure spring and an anti-rotating pin are arranged on the contact surface of the sealing carbon ring and the sealing spacer bush; the second-stage sealing group and the first-stage sealing group have the same structure, and an exhaust ring is arranged therebetween; the third-stage seal comprises a carbon ring seal group, and an exhaust ring is arranged between the third-stage seal and the second-stage seal; the end cover is fixed on the sealing shell; and the sealing shell is fixed on the compressor shell. The floating carbon ring provided by the utility model is a dry running and automatic compensation type sealing carbon ring, and no sealing assembly is arranged on the main shaft, so that no extra shaft vibration exists; extra-high-temperature media can be sealed, leakage of the high-temperature media is avoided, and a small amount of mixed gas is discharged safely.

Description

Technical Field

[0001] The utility model belongs to the technical field of mechanical seals, and particularly provides a multi-stage floating carbon ring seal structure. Background Art

[0002] In energy storage power generation projects, the operating conditions of the shafts of centrifugal compressors and steam turbines are mostly extremely high temperature and high-speed rotation. During operation, high-temperature gas media will be generated, and this part of the gas is harmful to production. Therefore, it is necessary to seal or collect the high-temperature media during the operation of the shaft. Content of the Utility Model

[0003] To solve the above technical problems, the utility model provides a multi-stage floating carbon ring seal structure for sealing the main shaft of a compressor, including a seal housing sleeved on the main shaft, and a seal cavity is formed between the inner wall of the seal housing and the main shaft; a first-stage seal group, a second-stage seal group and a third-stage seal group are arranged in the seal cavity, and the opening of the seal cavity is tightly fixed by an end cover; wherein,

[0004] The first-stage seal group includes two carbon ring seal groups arranged side by side axially and sleeved on the shaft; each carbon ring seal group includes a seal spacer and a seal carbon ring. Among them, a stepped surface is arranged on the end face of the seal spacer, and the seal carbon ring is located at the stepped surface; a compression spring and an anti-rotation pin are connected and arranged on the contact surface between the seal carbon ring and the seal spacer, and the two are arranged alternately;

[0005] The second-stage seal group has the same structure as the first-stage seal group, and an exhaust ring is installed between the two;

[0006] The third-stage seal includes a carbon ring seal group, and an exhaust ring is installed between it and the second-stage seal;

[0007] The exhaust ring is provided with through holes in the upper radial direction;

[0008] The end cover is arranged outside the third-stage seal unit and is fixed on the housing by screws;

[0009] The seal housing is fixed on the compressor housing. The seal housing is provided with a duct, and the through holes of the exhaust ring are communicated with the duct and the exhaust holes on the compressor housing, so as to discharge part of the high-temperature gas medium of the main shaft.

[0010] Furthermore, a plurality of anti-rotation pin holes are arranged on the stepped end face of the seal spacer, and a plurality of recessed grooves are arranged on the end face of the seal carbon ring; among them, anti-rotation pins are installed in the recessed grooves opposite to the anti-rotation pin holes, that is, part of the anti-rotation pin is located in the recessed groove and the other part is located in the anti-rotation pin hole to realize the connection and prevent rotation between the two; compression springs are installed in the recessed grooves corresponding to the stepped end face.

[0011] Further, a high-temperature resistant gasket is respectively arranged between one side of the primary seal and the outer shell, between the exhaust ring and the secondary seal, and between the tertiary seal and the end cover.

[0012] Further, a tension screw is arranged between the two carbon ring seal groups of the primary seal unit and the secondary seal unit and the exhaust ring.

[0013] Further, the sealing carbon ring is of a split structure, a spring installation groove is arranged on the outer periphery of the sealing carbon ring, and the outer peripheries of adjacent splits are tightly fixed by a tightening spring.

[0014] Further, there is a gap of 0.01 - 0.04 mm between the inner diameter of the sealing carbon ring and the annular shaft sleeve.

[0015] Further, two sets of labyrinth seals are also sleeved on the outer side of the shaft sleeve and are respectively arranged on both sides of the sealing housing axially.

[0016] The novel floating ring carbon ring provided by the utility model has a reasonable structure and is convenient and simple to install. The floating seal carbon ring in this solution is a dry-running and self-compensating seal carbon ring. There is no sealing component on the main shaft, no additional shaft vibration, and the sealing carbon ring does not contact the shaft during operation - long service life; it can seal extremely high-temperature media, prevent high-temperature media from leaking, and a small amount of mixed gas (low temperature) can be safely discharged. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 is a schematic structural diagram of the utility model;

[0018] Figure 2 is Figure 1 an enlarged structural diagram of area A in

[0019] Figure 3 is Figure 1 an enlarged structural diagram of area B in

[0020] Wherein, 1, sealing carbon ring; 2, tightening spring; 3, compression spring; 4, sealing spacer sleeve; 5, gasket A; 6, exhaust ring A; 7, exhaust ring B; 8, end cover; 9, gasket B; 10, screw; 11, gasket C; 12, sealing ring; 13, sealing housing; 14, left labyrinth seal; 15, support sleeve; 16, tension screw; 17, compressor housing; 18, anti-rotation pin. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0021] The principles and features of the present utility model will be described below with reference to the accompanying drawings. The examples given are only for explaining the present utility model and are not intended to limit the scope of the present utility model.

[0022] The utility model relates to a multi-stage floating carbon ring seal structure, and particularly provides a new special working condition (extra-high temperature and high speed) floating carbon ring combined seal structure form, that is, a multi-stage floating carbon ring combined seal combined with a special structure secondary seal. It is mainly used for compressors and extra-high temperature working conditions of steam turbines, and solves the technical problems of carbon ring seal and secondary seal under extra-high temperature working conditions.

[0023] The floating carbon ring seal is a radial clearance type non-contact flow resistance type rotating shaft seal. Its sealing principle is: the sealing gas forms a gas film between the floating ring and the rotating shaft, generating throttling pressure reduction to prevent the gas on the high-pressure side from flowing to the low-pressure side. There is a certain clearance between the inner hole of the sealing carbon ring 1 and the outer diameter of the shaft (shaft sleeve). When the equipment is running, there is a pressure difference. Under the movement of the rotating shaft, the gas is driven into the eccentric wedge-shaped gap. A hydrodynamic pressure effect is generated in the wedge-shaped gap, causing the sealing carbon ring 1 to float and lift, and the inner wall of the ring to disengage from the shaft surface to form a non-contact state; in this state, the gas generates a pressure loss through the throttling action of the gap, thereby achieving the purpose of reducing leakage. The floating ring material is selected according to the magnitude of the buoyancy, and the buoyancy generated by the hydrodynamic pressure effect is equal to the weight of the floating ring, achieving dynamic balance. It is mainly applied to large shaft diameter equipment, high-speed and high-temperature turbine equipment and special working condition structure equipment.

[0024] Reference Figures 1-3 , the utility model provides a multi-stage floating carbon ring seal structure for sealing the main shaft of a compressor, including a sealing housing 13 sleeved on the main shaft, and a sealing cavity is formed between the inner wall of the sealing housing 13 and the main shaft; a primary seal group, a secondary seal group and a tertiary seal group are arranged in the sealing cavity, and the opening end of the sealing cavity is tightly fixed by an end cover; wherein,

[0025] The primary seal group includes two carbon ring seal groups arranged side by side axially and sleeved on the shaft; the carbon ring seal group includes a sealing spacer sleeve 4 and a sealing carbon ring 1. Wherein, a stepped surface is arranged on the end face of the sealing spacer sleeve 4, and the sealing carbon ring 1 is located at the stepped surface; a compression spring 3 and an anti-rotation pin 18 are connected and arranged on the contact surface between the sealing carbon ring 1 and the sealing spacer sleeve 4, and the two are arranged alternately.

[0026] The secondary seal group has the same structure as the primary seal group, and an exhaust ring A6 is installed between the two;

[0027] The tertiary seal includes a carbon ring seal group, and an exhaust ring B7 is installed between the tertiary seal and the secondary seal; through holes are radially arranged on the exhaust ring;

[0028] The end cover 8 is arranged outside the tertiary seal unit and is fixed on the housing by screws 10;

[0029] The sealed housing 13 is fixed on the compressor housing 17. There are channels provided on the sealed housing 13. The through holes of the exhaust ring are communicated with the channels and are also communicated with the exhaust holes on the compressor housing 17, which is used to discharge part of the high-temperature gas medium of the main shaft.

[0030] As an improvement of the solution, a plurality of anti-rotation pin 18 holes are provided on the stepped end face of the sealing spacer sleeve 4, and a plurality of recessed grooves are provided on the end face of the sealing carbon ring 1. Among them, anti-rotation pins 18 are installed in the recessed grooves facing the anti-rotation pin 18 holes, that is, a part of the anti-rotation pin 18 is located in the recessed groove, and the other part is located in the anti-rotation pin 18 hole, so as to realize the connection between the two to prevent rotation; compression springs 3 are installed in the recessed grooves corresponding to the stepped end face to realize axial elastic compensation. The special structure carbon ring anti-rotation pins occupy less space, have a reasonable structure, and do not disengage at high temperatures.

[0031] As an improvement of the solution, a high-temperature resistant sealing gasket A5 is respectively provided between one side of the primary seal and the sealed housing 13, between the exhaust ring and the secondary seal, and between the tertiary seal and the end cover 8.

[0032] Furthermore, a tension screw 16 is provided between the two carbon ring seal groups of the primary seal unit and the secondary seal unit and the exhaust ring.

[0033] As an improvement of the solution, the sealing carbon ring 1 is of a split structure, and the outer peripheries of adjacent splits are tightly fixed by a tightening spring 2. The ring-segment floating ring seal, as a radial seal with an automatic compensation function, is in a non-contact state with the shaft and can well offset the shaft expansion and shaft runout under high-temperature and high-speed working conditions.

[0034] As an improvement of the solution, it also includes two sets of labyrinth seals sleeved outside the shaft sleeve, which are respectively arranged on both sides of the sealed housing 13 axially. There are gaps between the labyrinth seals at both ends and the sealed housing 13 axially. The left labyrinth seal 14 is fixed on the support sleeve 15 by screws, and a sealing ring 12 is provided between the left labyrinth seal 14 and the support sleeve 15; the outer circle of the support sleeve 15 is connected to the housing of the compressor by an anti-rotation pin 18. The right labyrinth seal is fixed on the compressor housing 17.

[0035] As an improvement of the solution, there are 2 stepped surfaces on the outer periphery of the sealed housing 13. When it is assembled with the compressor housing 17, sealing gaskets B9 and C11 are provided on the vertical contact connection surfaces.

[0036] Working principle: For the installation of the first-stage seal group, first install the gasket and the sealing spacer sleeve 4 into the sealing cavity of the shell in sequence, and make marks (hole-to-hole). Then install the first group of sealing carbon rings 1 (i.e., the sealing carbon ring 1, the tightening tension spring 2, the axial compression spring 3, and the positioning pin) at the step surface of the sealing spacer sleeve 4. After installing the two groups of sealing spacer sleeves 4 and the sealing carbon rings 1, install the intermediate exhaust ring, and screw in the tightening screw 16. This tightening screw 16 fixes the first-stage seal group to the shell and compresses the gasket. Install the second-stage and third-stage seal groups in the same way. Install the end cover, and fix the end cover 8 to the shell by tightening the screws with a certain torque to make the gasket fit tightly. Check whether there is any jamming in the axial and radial movement of the seal.

[0037] Install the labyrinth seal and the sealing ring into the support sleeve 15 and tighten them with screws.

[0038] In this solution, the labyrinth seal on the right side is set at the outlet end of the compressor main shaft to seal the high-temperature gas medium in the compressor. However, some high-temperature medium will flow out from the labyrinth seal. Therefore, a through-hole S is provided on the compressor housing. Then the high-temperature gas coming out of the compressor passes through the gap between the labyrinth seal and the sealing housing 13, and then through the through-hole S. In addition, a balance pipe is connected between the through-hole S and the inlet end of the compressor, and the gases on both sides are connected to achieve a balance. Then the gas at the S interface returns to the compressor inlet through the balance pipe.

[0039] Correspondingly, a high-temperature gas recovery port A, a mixed gas discharge port B, and a cooling gas inlet E are also provided at the upper end of the compressor housing. The cooling gas inlet E is used to introduce cooling isolation gas into the entire shaft and seal structure. A condensate drain through-hole P is provided at the lower end of the compressor housing to drain the condensate in the seal structure.

[0040] For the high-temperature medium in the process, part of the throttled leakage gas of the first-stage seal passes through the exhaust ring and is then recovered through the A port; the other part of the throttled leakage gas of the second-stage seal is mixed with the low-temperature isolation instrument air passing through the third stage and passes through the exhaust ring, and then is safely discharged through the mixed gas discharge port B. The isolation instrument air enters the carbon ring seal through the labyrinth seal to isolate the bearing oil and air.

[0041] The innovative new seal structure is a multi-stage and multi-group distinguishable carbon ring seal + high-temperature static seal combination. The carbon ring is a split type, balanced carbon ring, with the design structure of axial springs and circumferential tightening tension springs 2. The high-temperature static gasket combination is in the sealing cavity, which can seal extremely high-temperature media, making the high-temperature media leak-free, and a small amount of mixture (low temperature) can be safely discharged.

[0042] 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 in the protection scope of the present invention.

Claims

1. A multi-stage floating carbon ring sealing structure for sealing the main shaft of a compressor, characterized in that: It includes a sealing shell sleeved on the main shaft, a sealing cavity is formed between the sealing shell and the main shaft; a primary sealing group, a secondary sealing group and a tertiary sealing group are arranged in the sealing cavity, and the opening of the sealing cavity is pressed and fixed by an end cover; wherein, The primary sealing group includes two carbon ring sealing groups which are axially arranged side by side and sleeved on the shaft; the carbon ring sealing group includes a sealing spacer and a sealing carbon ring, wherein a step surface is arranged on the end surface of the sealing spacer, and the sealing carbon ring is located on the step surface; a compression spring and an anti-rotation pin are arranged on the contact surface between the sealing carbon ring and the sealing spacer, and the two are arranged in a staggered manner; The secondary sealing group has the same structure as the primary sealing group, and an exhaust ring is installed between the two; The third-stage seal includes a carbon ring seal group with an exhaust ring installed between the second-stage seal; An exhaust ring, with a through hole radially arranged on the upper side; The end cover is arranged on the outside of the three-stage sealing unit and fixed to the sealing housing by screws; The sealed shell is fixed on the compressor casing. A plurality of channels are arranged on the sealed shell. The two exhaust ring through holes are respectively connected with the channels and then connected with a plurality of exhaust holes on the compressor casing.

2. A multi-stage floating carbon ring seal structure as claimed in claim 1, characterized in that: in, A plurality of anti-rotation pin holes are arranged on the step end face of the sealing spacer, and a plurality of recessed grooves are arranged on the end face of the sealing carbon ring; wherein an anti-rotation pin is installed in the recessed groove directly opposite to the anti-rotation pin hole, that is, a part of the anti-rotation pin is located in the recessed groove, and the other part is located in the anti-rotation pin hole, so that the two are connected to prevent rotation; a compression spring is installed in the recessed groove corresponding to the step end face.

3. The multi-stage floating carbon ring sealing structure according to claim 1, characterized in that: A high temperature resistant sealing gasket is respectively arranged between one side of the primary seal and the external shell, between the exhaust ring and the secondary seal, and between the tertiary seal and the end cover.

4. The multi-stage floating carbon ring sealing structure according to claim 1, characterized in that: A tightening screw is arranged between the two carbon ring sealing groups of the primary sealing unit and the secondary sealing unit and the exhaust ring.

5. The multi-stage floating carbon ring sealing structure according to claim 1, characterized in that: The sealing carbon ring is a petal structure, and a tension spring installation groove is arranged on the outer periphery of the sealing carbon ring. The outer peripheries of adjacent petals are tightly fixed by tightening the tension springs.

6. The multi-stage floating carbon ring seal structure according to claim 1, characterized in that: There is a gap of 0.01 to 0.04 mm between the inner diameter of the sealing carbon ring and the annular sleeve.

7. The multi-stage floating carbon ring seal structure according to claim 1, characterized in that: It also includes two groups of comb teeth sealing sleeves connected to the outside of the shaft sleeve and respectively arranged on both sides of the sealing shell in the axial direction.

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