CN212614900U

CN212614900U - Split carbon ring type double-end-face dry air sealing device for industrial steam turbine

Info

Publication number: CN212614900U
Application number: CN202021678429.3U
Authority: CN
Inventors: 徐冉
Original assignee: Individual
Current assignee: Individual
Priority date: 2020-08-13
Filing date: 2020-08-13
Publication date: 2021-02-26
Anticipated expiration: 2030-08-13

Abstract

A split carbon ring type double-end-face dry gas sealing device for an industrial steam turbine comprises a rotary sealing assembly and a static sealing assembly. The rotary sealing assembly comprises a shaft sleeve fixed on the shaft neck, the shaft sleeve is provided with a shaft shoulder, and two sides of the shaft shoulder are provided with movable rings. The static sealing assembly comprises a sealing sleeve fixed in the shell and a pair of inner ring sleeves, and the inner ring sleeves are connected with the sealing sleeve. Each inner ring sleeve is sleeved with a static ring, a carbon ring and a push ring. An axial pressure spring is connected between the push ring and the seal sleeve, and under the action of the axial pressure spring, the push ring pushes the carbon ring to be pressed on the static ring, so that the carbon ring, the static ring, the push ring and the inner ring sleeve form contact seal, and a non-contact air film lubrication state is formed between the static ring and the moving ring. The utility model discloses a rotating ring has self-adjusting ability with quiet ring, makes to form stable air film lubrication non-contact seal between rotating ring and the quiet ring to seal high-pressure steam in the built-in, reduced energy consumption, improved industrial steam turbine's energy conversion efficiency.

Description

Split carbon ring type double-end-face dry air sealing device for industrial steam turbine

Technical Field

The utility model belongs to the technical field of the mechanical seal technique and specifically relates to a split carbon ring type bi-polar face dry gas seal device for industrial steam turbine is related to.

Background

A steam turbine is one of the main equipments of a steam power plant, and is a rotary power machine that converts the energy of steam into mechanical work. The working principle of the steam turbine is that steam with certain pressure and temperature enters the steam turbine, the steam rapidly expands in a nozzle to obtain high flow speed, and then the steam flowing at high speed drives a rotor blade of the steam turbine to rotate and do work, so that the process of obtaining mechanical energy is achieved. The steam turbine mainly comprises a rotating part, a fixed part and a control part.

The industrial steam turbine is a motive power device using steam as impulse, and is mainly used in industrial enterprises of chemical industry, petroleum, mining, metallurgy, paper making, textile, sugar making and the like. Industrial turbines drive various pumps, fans, compressors, presses or drive generators, thereby producing low cost power and electricity. In advanced industrial countries, primary energy has been fully utilized since steam turbines have been used industrially. The small-sized heat (electricity) power cogeneration (small back press) can fully utilize waste materials, waste gases and waste heat to produce steam, or utilize rich steam and steam pressure difference, and then convert the rich steam into mechanical energy to directly drive mechanical equipment to do work through a power turbine, and can realize variable-speed operation of the mechanical equipment through regulating the rotating speed of the turbine. Because the energy conversion link is reduced, the energy conversion efficiency is increased, and the expensive industrial electricity is saved, the purpose of saving energy and improving efficiency can be achieved by using an industrial steam turbine as a motive power device in production. In addition, the steam extraction and exhaust of the industrial steam turbine can also be used for industrial production processes or external supply of enterprises and public institutions, so that the gradient utilization of energy is realized, the method is one of effective measures for energy conservation and consumption reduction of the enterprises and public institutions, and has the advantages of low investment, quick response and remarkable comprehensive economic benefit.

The current industrial steam turbine usually adopts a comb type labyrinth seal or a carbon ring seal form at the shaft end because of high pressure and high temperature of working medium. Because labyrinth seal and carbon ring seal all belong to radial non-contact seal, in order to ensure to avoid appearing main shaft or axle sleeve and sealed position collision and rub in whole working process, its radial seal clearance is all bigger (static or dynamic), leads to the leakage volume of axial steam to be great. In particular, the back pressure turbine has higher sealing cavity pressure and larger shaft end sealing leakage amount. The leakage of steam causes energy loss, and the leaked steam needs to be cooled by circulating cooling water, so that the consumption of the cooling water is large. For medium-sized steam turbine units, the annual leakage of steam, the consumption of cooling water, and the subsequent operating and maintenance costs thereof, equate to operating costs in excess of one million dollars.

Different from the dynamic and static sealing of general machinery, the sealing of the shaft end of the industrial steam turbine is influenced by a plurality of factors and the situation is complex. Under the influence of high temperature and high pressure of steam in the steam turbine and factors such as thermal expansion, jumping, flexible deformation and the like when a shaft of the steam turbine rotates at high speed, the problem of shaft end leakage of the industrial steam turbine is a technical problem which is wanted to be solved and cannot be solved in the industry for a long time. From the perspective of energy conservation and efficiency improvement, a novel sealing device which is high in reliability and can obviously reduce the leakage amount of shaft end sealing is urgently needed.

Disclosure of Invention

In order to overcome not enough among the background art, the utility model discloses an industry is split carbon ring type bi-polar face dry gas sealing device for steam turbine adopts following technical scheme:

a split carbon ring type double-end-face dry air sealing device for an industrial steam turbine is axially arranged between a casing and radially arranged between the casing and a shaft neck of a steam turbine shaft, and comprises a rotary sealing component and a static sealing component;

the rotary sealing assembly comprises a shaft sleeve fixed on the shaft neck, a shaft shoulder is arranged in the middle of the shaft sleeve, and two movable rings are respectively arranged on two sides of the shaft shoulder; the end surfaces of two sides of the shaft shoulder are sealing surfaces, and the movable rings of the two sides are respectively connected with the sealing surfaces at the same side in a sealing way and rotate along with the shaft sleeve; a plurality of pneumatic pressure grooves distributed circumferentially are arranged on the end face of the movable ring on the side far away from the shaft shoulder;

the static sealing assembly comprises a sealing sleeve which is fixed in the shell and is in sealing connection with the shell, and also comprises a pair of static rings, a pair of carbon rings, a pair of push rings and a pair of inner ring sleeves which are respectively arranged at two sides of the shaft shoulder; the static ring, the carbon ring and the push ring on the same side are sequentially sleeved on the outer ring surface of the inner ring sleeve on the same side, and one end, far away from the shaft shoulder, of the inner ring sleeve on the same side is in sealing connection with the sealing sleeve; the static ring is arranged between the carbon ring and the movable ring on the same side and is in floating connection with the sealing sleeve through the stop pin; an axial pressure spring is connected between the push ring and the sealing sleeve;

under the action of the elastic force of the axial pressure spring, the push ring pushes the carbon ring on the same side to press against the stationary ring on the same side, the end surfaces on the two sides of the carbon ring respectively form an axial contact sealing structure with the corresponding stationary ring and the push ring, and the inner ring surface of the carbon ring and the corresponding inner ring sleeve form a radial contact sealing structure; the static ring and the movable ring on the same side are arranged oppositely, and a non-contact dry gas sealing structure is formed between the static ring and the movable ring when the movable ring rotates along with the shaft of the steam turbine; the sealing sleeve is provided with a main sealing cavity at the position of the dry gas sealing structure, and the main sealing cavity is communicated with the external main sealing gas through a pipeline; the main seal gas is the filtered off-machine steam.

Preferentially, two sides of the shaft shoulder are respectively sleeved with a centering ring spring; the centering coil spring is contacted with the inner ring surface of the movable ring at the same side, and the movable ring has a certain floating amount; a flexible graphite ring for sealing the movable ring and a transmission pin in the axial direction are arranged on the sealing surface of the shaft shoulder; the rotating ring is provided with a pin shaft hole corresponding to the transmission pin, the diameter of the pin shaft hole is larger than that of the transmission pin, and the shaft shoulders drive the rotating rings on two sides to rotate along with the shaft sleeve through the transmission pin.

Preferably, the inner sleeve surface and the outer sleeve surface of the sealing sleeve are multi-step surfaces, and the outer sleeve surface of the sealing sleeve is in sealing connection with the shell through a plurality of sealing rings; the end of the inner ring sleeve, which is far away from the shaft shoulder, is provided with an outward flange, and the outward flange is matched and connected with a stepped surface on the inner sleeve surface of the sealing sleeve; the inner side end face of the stepped surface is connected with a check ring for preventing the outward flange of the inner ring sleeve from separating, a flexible graphite ring is arranged between the check ring and the outward flange of the inner ring sleeve, and the flexible graphite ring is used for sealing between the inner ring sleeve and the sealing sleeve.

Preferably, the inner side end of the shaft sleeve is connected with a front pressing sleeve, and the front pressing sleeve abuts against the shoulder of the shaft on the inner side of the shaft neck; the outer side end of the shaft sleeve is connected with a rear pressing sleeve, and a flexible graphite ring is arranged between the rear pressing sleeve and the shaft sleeve; the outer side end of the rear pressing sleeve is backed up by a spindle nut screwed on the shaft neck.

Preferably, a rear comb labyrinth seal structure is arranged between the main shaft nut and the seal sleeve; the seal cover is provided with a vent cavity between the rear comb labyrinth seal structure and the dry gas seal structure close to the outer side, and the vent cavity is communicated with the atmosphere through a vent hole.

Preferably, a rear air-isolating cavity is arranged between the labyrinth sleeve and the spindle nut, the rear air-isolating cavity is arranged in the middle of the rear comb-shaped labyrinth seal structure, and the rear air-isolating cavity is communicated with external rear isolating air through a pipeline.

Preferably, the casing is provided with a front air-isolating cavity for preventing steam in the casing from entering the casing on the inner side of the sealing sleeve, and front isolating air is introduced into the front air-isolating cavity; the pressure of the front isolation gas is greater than the pressure of steam in the machine and less than the pressure of the main sealing gas.

Preferably, an annular groove is arranged on the outer annular surface of the carbon ring, and a tension spring is arranged in the annular groove; the carbocycle is of a multi-petal body structure, and the multi-petal bodies are connected together through tension springs; each two carbocycles are a set of carbocycles.

Preferably, the pneumatic pressure groove is a one-way groove or a two-way groove; the depth of the one-way groove is 3-20 μm, and the width of the dam area of the pneumatic groove pressing is 0.25-0.75 times of the width of the sealing surface.

Preferably, the movable ring is made of silicon carbide, silicon nitride or hard alloy; the static ring is made of graphite or silicon carbide with a diamond-like film plated on the surface.

Owing to adopt above-mentioned technical scheme, compare the background art, the utility model discloses following beneficial effect has:

in the main sealing structure of the utility model, fixed sealing is realized between the casing and the sealing sleeve and between the sealing sleeve and the inner ring sleeve; the carbon ring group, the static ring and the push ring form an axial contact sealing structure, and the carbon ring group and the inner ring sleeve form a radial contact sealing structure; and a dry gas sealing structure is realized between the dynamic ring and the static ring. The secondary dry gas sealing structure seals high-pressure steam in the steam turbine, so that energy consumption is reduced, and the energy conversion efficiency of the industrial steam turbine is improved.

The utility model discloses a rotating ring has self-adjusting ability with quiet ring, when phenomena such as thermal energy appears in the steam turbine axle, beats, flexible deformation, can form stable air film all the time between rotating ring and quiet ring, guarantees that dry gas seal structure can work reliably for a long time.

The utility model discloses a two dry gas seal structure, under same operating mode condition, every dry gas seal structure's steam leakage volume is only for the tenths to the hundredth of current seal structure, and two dry gas seal structure has accomplished zero basically and has leaked sealedly. Because steam no longer leaks, therefore also need not to set up extra leakage steam cooling device for the subsequent operation maintenance cost of industrial steam turbine reduces by a wide margin, can save nearly million yuan of operation cost annually.

The dry gas seal is originally developed to solve the problem of shaft end sealing of a high-speed centrifugal compressor, but cannot be applied in the industry of steam turbines due to various factors, wherein one important reason is that the industrial steam turbines cannot ensure that a stable dry gas seal is formed between a moving ring and a static ring under complex working conditions. And the utility model discloses a long-term practice is verified, has realized steadily that dry gas is sealed between rotating ring and the quiet ring, has solved the difficult technical problem who wants to solve always in the trade and can't solve, and its meaning is great! Furthermore, the utility model discloses the effect of effect is showing to energy-conservation, and economic value is huge.

Drawings

Fig. 1 is a schematic structural diagram of the present invention.

FIG. 2 is a schematic structural view of the pneumatic pressure groove near the end of the outer rotating ring.

FIG. 3 is a schematic structural view of the pneumatic pressure groove near the end of the inner rotating ring.

In the figure: 1. a journal; 2. a housing; 3. a shaft sleeve; 31. a shaft shoulder; 4. a front compression sleeve; 5. a moving ring; 51. pneumatic groove pressing; 6. a compression sleeve; 7. a spindle nut; 8. a drive pin; 9. flexible graphite; 10. a centering coil spring; 11. sealing sleeves; 12. a stationary ring; 13. an inner ring sleeve; 14. a carbocyclic ring; 15. the spring is contracted; 16. an axial pressure spring; 17. a retainer ring; 18. a push ring; 19. a labyrinth sleeve; 20. a primary seal cavity; 21. placing the cavity; 22. a front air-isolating cavity; 23. a rear air-isolating cavity; 24. a front comb labyrinth seal structure; 25. a comb-shaped labyrinth seal structure is arranged at the rear part; 26. a retaining pin.

Detailed Description

Preferred embodiments of the present invention will be described below with reference to the accompanying drawings. It should be understood by those skilled in the art that these embodiments are only for explaining the technical principle of the present invention, and are not intended to limit the scope of the present invention.

It should be noted that in the description of the present invention, the terms "inside", "outside", etc. indicating directions or positional relationships are based on relative indications of directions or positional relationships centering on the main body of the industrial steam turbine, which are merely for convenience of description, and do not indicate or imply that the device or element must have a specific orientation, be constructed and operated in a specific orientation, and thus should not be construed as limiting the present invention.

The utility model provides a split carbon ring type bi-polar face dry gas seal device for industrial steam turbine, as shown in figure 1, the axial setting is between casing 2 and bearing box, radially between casing 2 and the axle journal 1 of steam turbine axle, including rotary seal subassembly and static seal subassembly, the seal structure that forms between rotary seal subassembly and the static seal subassembly, does the utility model discloses a main seal structure.

The rotary seal assembly comprises a sleeve 3 fixed to the journal 1. Specifically, the inner side end of the shaft sleeve 3 is connected with a front pressing sleeve 4 through a bolt, and the front pressing sleeve 4 abuts against the inner side shaft shoulder 31 of the shaft neck 1; the outer end of the shaft sleeve 3 is connected with a pressing sleeve 6 through a bolt, and the outer end of the pressing sleeve 6 is backed up by a spindle nut 7 screwed on the shaft neck 1, so that the shaft sleeve 3 is fixed on the shaft neck 1 and rotates along with the shaft of the steam turbine. A flexible graphite 9 ring is arranged between the pressing sleeve 6 and the shaft sleeve 3, and the flexible graphite 9 ring not only has good sealing performance, but also has high temperature resistance. The axial sealing between the pressing sleeve 6 and the shaft sleeve 3 is realized by a flexible graphite 9 ring.

A shaft shoulder 31 is arranged at the middle part of the shaft sleeve 3, and two movable rings 5 are respectively arranged at two sides of the shaft shoulder 31. The end faces of the two sides of the shaft shoulder 31 are sealing faces, and the sealing faces of the two sides of the shaft shoulder 31 are respectively provided with a flexible graphite 9 ring for sealing the movable ring 5 and a transmission pin 8 in the axial direction. The rotating ring 5 is provided with a pin shaft hole corresponding to the transmission pin 8, the transmission pin 8 is connected with the pin shaft hole of the rotating ring 5 in a floating mode, and the shaft shoulder 31 drives the rotating rings 5 on two sides to rotate along with the shaft of the steam turbine through the transmission pin 8.

The stationary seal assembly comprises a gland 11 secured within the housing 2 and sealingly connected to the housing 2. The gland 11 has a longer axial dimension due to the primary seal arrangement extending through the gland 11. In order to reduce the processing difficulty and facilitate the assembly and maintenance, the sealing sleeve 11 is formed by connecting three parts. The inner and outer sleeve surfaces of the sealing sleeve 11 are both in a multi-step surface structure, and the outer sleeve surface of the sealing sleeve 11 is connected with the casing 2 in a sealing way through a plurality of sealing rings.

The static seal assembly further comprises a pair of static rings 12, a pair of carbon rings 14, a pair of push rings 18 and a pair of inner sleeves 13 which are respectively arranged at two sides of the shaft shoulder 31, wherein the pair of static rings 12, the pair of carbon rings 14, the pair of push rings 18 and the pair of inner sleeves 13 are symmetrically arranged around the shaft shoulder 31. Because the two sides are symmetrically arranged, for convenience of description, only the stationary ring 12, the movable ring 5, the carbon ring 14, the push ring 18 and the inner ring sleeve 13 on one side of the shaft shoulder 31 are described, and the mounting positions and corresponding relationships of the stationary ring 12, the movable ring 5, the carbon ring 14, the push ring 18 and the inner ring sleeve 13 on the other side are the same as those on the other side.

The stationary ring 12, the carbon ring 14 and the push ring 18 on the same side are sequentially sleeved on the outer annular surface of the inner ring sleeve 13, and one end of the inner ring sleeve 13, which is far away from the shaft shoulder 31, is hermetically connected with the sealing sleeve 11. Specifically, an outward flange is arranged at one end of the inner ring sleeve 13 far away from the shaft shoulder 31, and the outward flange is connected with a stepped surface of the inner sleeve surface of the sealing sleeve 11 in a matching manner. A retaining ring 17 for preventing the outward flange of the inner ring sleeve 13 from separating is connected on the end surface of the inner side of the stepped surface, and a flexible graphite 9 ring is arranged between the retaining ring 17 and the outward flange of the inner ring sleeve 13. The retainer ring 17 presses the flexible graphite 9 ring on the inner side end face of the stepped surface through a bolt, so that the inner ring sleeve 13 and the sealing sleeve 11 are sealed. A counter bore for accommodating the axial pressure spring 16 is arranged on the end surface of the inner side of the stepped surface, one end of the axial pressure spring 16 is positioned in the counter bore, and the other end of the axial pressure spring is connected with the outer end of the push ring 18 and is used for applying axial thrust to one side of the shaft shoulder 31 to the push ring 18. The stationary ring 12 is arranged between the carbon ring 14 and the movable ring 5, and is in floating connection with the sealing sleeve 11 through the stop pin 26, so that the stationary ring 12 is prevented from rotating. Quiet ring 12, carbocycle 14 and push away the ring 18 suit in proper order on the outer anchor ring of inner ring cover 13, have carried out radial spacing to quiet ring 12, carbocycle 14 and push away ring 18, can prevent that built-in steam vortex from to quiet ring 12, carbocycle 14 and push away the tremble that ring 18 caused.

An annular groove is formed in the outer annular surface of the carbon ring 14, and a tension spring 15 is installed in the annular groove. The carbon ring 14 is a multi-petal body structure, and the multi-petal bodies are connected together through a tension spring 15 hooped on the outer diameter to form a ring-shaped whole. Every two carbocycles mutually support and form a set of carbon ring group, and in this embodiment, the carbocycle 14 that leans on the inboard divides into six lamella, and the carbocycle 14 that leans on the outside divides into three lamella, and the radial incision of the ring of the six valve of inboard and the radial incision of the ring of the three lamella of outside stagger during the installation. Under the action of the elastic force of the axial compression spring 16, the push ring 18 pushes the carbon ring set to press against the outer end face of the static ring 12, so that a certain contact pressure is kept between the static ring 12 and the dynamic ring 5. The end surfaces of two sides of the carbon ring set respectively form an axial contact sealing structure with the static ring 12 and the push ring 18, and the inner ring surface of the carbon ring set and the inner ring sleeve 13 form a radial contact sealing structure.

The seal cartridge 11 is provided with a main seal chamber 20 at the dry gas seal structure, and the main seal chamber 20 is communicated with the external main seal gas through a pipeline. The main seal gas can be high-pressure clean steam, or high-pressure nitrogen or instrument wind, and the pressure of the main seal gas is greater than that of the steam in the machine. A plurality of circumferentially distributed pneumatic grooves 51 are provided on the end face of the rotating ring 5 remote from the shoulder 31. The pneumatic groove 51 may be a groove type rotating in one direction or a groove type rotating in two directions. Can be a unidirectional arc groove, a spiral groove, a triangular groove, or a bidirectional groove, such as a hammer-shaped bidirectional groove. In this embodiment, the pneumatic groove 51 is a one-way spiral groove. Fig. 2 shows a schematic view of the spiral direction of the unidirectional spiral groove on the outer end surface of the rotor ring 5 near the outer side of the turbine and the spiral direction of the turbine shaft, as viewed in the X direction. Fig. 3 is a schematic view showing the spiral direction of the unidirectional spiral groove on the outer end surface of the rotor ring 5 near the inner side of the turbine and the spiral direction of the turbine shaft, as viewed in the Y direction. As can be seen from fig. 2 and 3, the rotating direction of the unidirectional spiral groove on the outer end surface of the rotating ring 5 near the inside and the rotating ring 5 near the outside is the same as the rotating direction of the turbine shaft, and the unidirectional spiral groove extends spirally from the inside of the outer end surface of the rotating ring 5 in the outer radial direction and opens on the outer annular surface of the rotating ring 5. The cross-sectional area of the unidirectional helical groove increases gradually along the direction of helical extension. The depth of the one-way spiral groove is 19 μm, and the width of the dam area of the pneumatic pressure groove 51 is 0.6 times of the width of the outer side end face of the movable ring 5. When the moving ring 5 rotates along with the shaft of the steam turbine, the pressure of the main seal gas is greater than that of steam in the steam turbine, the main seal gas enters the one-way spiral groove and generates a fluid dynamic pressure effect, the main seal gas at the outer ring surface is pumped inwards, and therefore a layer of micron-order gas film is generated between the outer side end face of the moving ring 5 and the inner side end face of the static ring 12, and a dry gas sealing structure is formed. The main sealing gas blocks the leakage of steam on one hand, generates an air film between the movable ring 5 and the static ring 12, and cools the static ring 12 of the movable ring 5 on the other hand, so as to take away the heat generated by the dry gas sealing structure.

The dry gas sealing structure also has the functions of lubricating and isolating the sealing surface between the movable ring 5 and the static ring 12. Because the rotating speed of the shaft of the steam turbine is very high, the rigidity of the air film is very high, the opening force formed by the air film and the axial elastic force of the corrugated pipe reach balance, and the non-contact operation of the sealing surface between the movable ring 5 and the static ring 12 is realized, and the sealing of steam in the steam turbine is realized. The steam quantity leaked through the dry gas sealing structure is only one tenth to one hundredth of that of the comb-tooth type labyrinth seal or the carbon ring 14 seal under the same working condition. And the utility model discloses set up inside and outside two dry gas seal structures in main seal structure, the dry gas seal structure that is located the outside seals the steam that the inside dry gas seal structure leaked again, has realized basically that the zero of steam leaks sealedly. Because the steam is not leaked any more, an additional leakage steam cooling device is not needed, and the subsequent operation and maintenance cost of the industrial steam turbine is obviously reduced.

When the shaft of the steam turbine rotates at high speed, the phenomena of thermal expansion, jumping, flexible deformation and the like inevitably occur at the journal 1 part. The dry gas sealing structure requires that the sealing surfaces between the movable ring 5 and the static ring 12 have strict parallel relation, so that at least one of the movable ring 5 and the static ring 12 is ensured to have self-adjusting capacity. Therefore, two sides of the shaft shoulder 31 are respectively sleeved with a centering coil spring 10, and the centering coil springs 10 are contacted with the inner ring surface of the same side moving ring 5; the diameter of the pin shaft hole is larger than that of the driving pin 8, so that the driving pin 8 is prevented from limiting the floating of the movable ring 5. These measures provide a certain floating amount for the movable ring 5, and realize the self-adjustment of the movable ring 5.

In order to enable the static ring 12 to have the freedom degree of self adjustment along with the movable ring 5, the axial pressure spring 16 applies a certain axial force to the static ring 12 to ensure that the sealing surface of the static ring 12 does not separate from the sealing surface of the movable ring 5. And a small gap is reserved between the inner ring surface of the carbon ring set and the inner ring sleeve 13 for sealing contact, and the contact width between the inner ring surface of the carbon ring set and the inner ring sleeve 13 is reduced, so that the carbon ring set is ensured to have a certain floating amount. Similarly, a large gap is arranged between the inner ring surfaces of the stationary ring 12 and the push ring 18 and the inner ring sleeve 13. In addition, the outer annular surface of the stationary ring 12 is provided with a long groove with a radial opening, and the stationary ring 12 is in clearance connection with the stop pin 26 through the long groove, so that the stationary ring 12 is prevented from rotating and has a certain floating amount. Thus, the static ring 12 can be self-adjusted along with the movable ring 5, and the end faces of the two sides of the carbon ring group can be always kept in contact and sealed with the static ring 12 and the push ring 18. When the phenomena of thermal expansion, jumping, flexible deformation and the like occur at the position of the shaft neck 1, a layer of parallel air film is always formed between the movable ring 5 and the static ring 12, and the normal work of the dry air sealing structure can be ensured.

When the steam turbine works, the movable ring 5 rotates at a high speed along with the shaft of the steam turbine, so that the material has high requirements on the strength; the device works in a high-temperature and high-pressure steam environment for a long time, so that the physical properties of the materials of the moving environment 5 and the static environment 12 are also high; furthermore, the sealing surfaces between the rotating ring 5 and the stationary ring 12 are subject to slight contact wear during starting and stopping, so that the surface tribological properties of the materials of the rotating ring 5 and the stationary ring 12 are also highly required. Therefore, the moving ring 5 can be made of high-hardness and high-wear-resistance materials such as silicon carbide, silicon nitride or hard alloy materials with high strength, good tribological characteristics and relatively high hardness, and can also be made of stainless steel materials as a substrate, and a high-hardness wear-resistance coating is sprayed or surfacing-welded on the surface of the substrate. The stationary ring 12 may be made of graphite having a good self-lubricating property, or silicon carbide with a diamond-like carbon film (DLC) plated on the surface thereof. With the DLC coating technique, the surface tribological properties of the hard-to-hard friction pair pairing can be improved. The service life of the dynamic ring 5 and the static ring 12 is prolonged, and the maintenance cost of the steam turbine can be greatly reduced.

In summary, in the main sealing structure of the device, fixed sealing is realized between the casing 2 and the sealing sleeve 11, and between the sealing sleeve 11 and the inner annular sleeve 13; the carbon ring groups on the two sides, the static ring 12 and the push ring 18 form an axial contact sealing structure, and the carbon ring groups on the two sides and the inner ring sleeve 13 form a radial contact sealing structure; the dynamic ring 5 and the static ring 12 on the two sides realize a double dry gas sealing structure, so that high-pressure steam is sealed in the turbine, the energy consumption is reduced, and the energy conversion efficiency of the industrial steam turbine is improved.

The cleanliness requirement of the dry gas seal on the gas at the high-pressure end is high, otherwise, the dirty gas at the high-pressure end can pollute the friction pair end face of the dry gas seal, and the seal fails prematurely. For this purpose, the casing 2 is provided with a front air-isolating chamber 22 between the front comb labyrinth seal 24 and the gland 11, and front isolating air is introduced into the front air-isolating chamber 22. It should be noted that the pre-comb labyrinth seal 24 is a seal provided in the conventional steam turbine, and the seal has a large steam leakage amount but is not affected by thermal expansion. The device only utilizes the prior structure to carry out primary sealing on the steam in the machine.

The front insulating gas can be high-pressure high-temperature steam led out from the inlet of the steam turbine or externally led steam with pressure and temperature meeting requirements, and enters the front insulating gas cavity 22 through a pipeline after being properly cooled, decompressed and filtered. In this case, the pressure of the front isolation gas is required to be larger than the steam pressure in the machine, and the front isolation gas returns to the machine through the front comb-shaped labyrinth seal structure 24, so that the pollution of dirty steam in the machine, which is not filtered, to the dry gas seal structure is prevented, and the heat generated by the dry gas seal structure is taken away. If the cleanliness of the steam medium in the steam turbine meets a certain quality standard, the steam medium can also be directly used as front isolation gas to enter the front air isolation cavity 22 through the front comb-shaped labyrinth seal structure 24, and at the moment, an external pipeline of the front air isolation cavity 22 is in a closed state.

In order to generate a pressure difference between the inside and the outside of the dry gas seal, the housing 2 is provided with a main seal cavity 20 at the position of a shaft shoulder 31, and the main seal cavity 20 is in gas communication with the main seal through a pipeline. The main seal gas is filtered off-machine steam with pressure and temperature meeting certain requirements. Since the pneumatic pressure groove 51 used in this embodiment is a one-way spiral groove with high pressure on the outside, the pressure of the main seal gas entering the main seal chamber 20 is greater than the pressure of the front barrier gas entering the front barrier chamber 22. The main seal gas may also be co-sourced with the front barrier gas, but the front barrier gas entering the front barrier chamber 22 requires a pressure reduction to create a pressure differential between the interior and exterior of the dry gas seal.

In order to prevent the lubricating oil gas in the bearing housing (outside the labyrinth sleeve 11, not shown in the figure) from polluting the dry gas seal structure by diffusion, a labyrinth sleeve 19 is arranged between the spindle nut 7 and the gland sleeve 11, and the inner sleeve surface of the gland sleeve 11 is in sealing connection with the outer sleeve surface of the labyrinth sleeve 19 through a seal ring. A plurality of comb-shaped inner ring teeth are arranged on the labyrinth sleeve 19, and the inner ring teeth and the spindle nut 7 form an external comb-shaped labyrinth seal structure 25. The seal sleeve 11 is provided with a cavity 21 between the rear comb labyrinth seal structure 25 and the dry gas seal structure close to the outer side, and the cavity 21 is communicated with the atmosphere through a vent. Like this, most lubricated oil gas in the casing 2 can be sealed off to rearmounted comb labyrinth seal structure 25, and a small amount of lubricated oil gas that leaks from rearmounted comb labyrinth seal structure 25 passes through drain unloading, has avoided the pollution of lubricated oil gas to dry gas seal structure. Similarly, a very small amount of steam leaking from the dry gas seal is vented through vent after entering vent chamber 21. Meanwhile, a rear air-isolating cavity 23 is arranged between the labyrinth sleeve 19 and the spindle nut 7, the rear air-isolating cavity 23 is arranged in the middle of the rear comb-shaped labyrinth seal structure 25, and the rear air-isolating cavity 23 is communicated with external rear isolating air through a pipeline. The rear isolation gas is nitrogen or instrument air, and the nitrogen or the instrument air enters the air isolation cavity and then blocks the lubricating oil gas entering the rear comb-shaped labyrinth seal structure 25. Excess nitrogen or meter air enters the vent cavity 21 and vents through the vent.

The part of the utility model not detailed is prior art. Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that changes, modifications, substitutions and alterations can be made in these embodiments without departing from the principles and spirit of the invention, the scope of which is defined in the appended claims and their equivalents.

Claims

1. The utility model provides an industry is split carbon ring type bi-polar face dry gas seal device for turbine, the axial sets up between casing and casing, radially between casing and the journal of turbine axle, characterized by: comprises a rotary sealing component and a static sealing component;

2. The split carbon ring type double-end-face dry gas seal device of claim 1, wherein: two sides of the shaft shoulder are respectively sleeved with a centering ring spring; the centering coil spring is contacted with the inner ring surface of the movable ring at the same side, and the movable ring has a certain floating amount; a flexible graphite ring for sealing the movable ring and a transmission pin in the axial direction are arranged on the sealing surface of the shaft shoulder; the rotating ring is provided with a pin shaft hole corresponding to the transmission pin, the diameter of the pin shaft hole is larger than that of the transmission pin, and the shaft shoulders drive the rotating rings on two sides to rotate along with the shaft sleeve through the transmission pin.

3. The split carbon ring type double-end-face dry gas seal device of claim 1, wherein: the inner and outer sleeve surfaces of the sealing sleeve are multi-step surfaces, and the outer sleeve surface of the sealing sleeve is in sealing connection with the shell through a plurality of sealing rings; the end of the inner ring sleeve, which is far away from the shaft shoulder, is provided with an outward flange, and the outward flange is matched and connected with a stepped surface on the inner sleeve surface of the sealing sleeve; the inner side end face of the stepped surface is connected with a check ring for preventing the outward flange of the inner ring sleeve from separating, a flexible graphite ring is arranged between the check ring and the outward flange of the inner ring sleeve, and the flexible graphite ring is used for sealing between the inner ring sleeve and the sealing sleeve.

4. The split carbon ring type double-ended dry gas seal assembly for an industrial steam turbine as claimed in claim 1, 2 or 3, wherein: the inner side end of the shaft sleeve is connected with a front pressing sleeve which is propped against the shoulder part of the shaft neck at the inner side; the outer side end of the shaft sleeve is connected with a rear pressing sleeve, and a flexible graphite ring is arranged between the rear pressing sleeve and the shaft sleeve; the outer side end of the rear pressing sleeve is backed up by a spindle nut screwed on the shaft neck.

5. The split carbon ring type double-end-face dry gas seal device for an industrial steam turbine according to claim 4, wherein: a postposition comb-shaped labyrinth sealing structure is arranged between the main shaft nut and the sealing sleeve; the seal cover is provided with a vent cavity between the rear comb labyrinth seal structure and the dry gas seal structure close to the outer side, and the vent cavity is communicated with the atmosphere through a vent hole.

6. The split carbon ring type double-end-face dry gas seal device for an industrial steam turbine according to claim 5, wherein: a rear air isolating cavity is arranged between the labyrinth sleeve and the spindle nut, the rear air isolating cavity is arranged in the middle of the rear comb-shaped labyrinth sealing structure, and the rear air isolating cavity is communicated with external rear isolating air through a pipeline.

7. The split carbon ring type double-ended dry gas seal assembly for an industrial steam turbine as claimed in claim 1, 5 or 6, wherein: the inner side of the sealing sleeve of the shell is provided with a front air-isolating cavity for preventing steam in the shell from entering, and front isolating air is introduced into the front air-isolating cavity; the pressure of the front isolation gas is greater than the pressure of steam in the machine and less than the pressure of the main sealing gas.

8. The split carbon ring type double-end-face dry gas seal device of claim 1, wherein: the outer ring surface of the carbon ring is provided with a ring groove, and a tension spring is arranged in the ring groove; the carbocycle is of a multi-petal body structure, and the multi-petal bodies are connected together through tension springs; each two carbocycles are a set of carbocycles.

9. The split carbon ring type double-end-face dry gas seal device of claim 1, wherein: the pneumatic pressure groove is a one-way groove or a two-way groove; the depth of the one-way groove is 3-20 μm, and the width of the dam area of the pneumatic groove pressing is 0.25-0.75 times of the width of the sealing surface.

10. The split carbon ring type double-end-face dry gas seal device for an industrial steam turbine according to claim 1 or 9, wherein: the movable ring is made of silicon carbide, silicon nitride or hard alloy; the static ring is made of graphite or silicon carbide with a diamond-like film plated on the surface.