CN111810253A - Double-end-face dry air sealing device for industrial steam turbine - Google Patents

Double-end-face dry air sealing device for industrial steam turbine Download PDF

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Publication number
CN111810253A
CN111810253A CN202010810467.8A CN202010810467A CN111810253A CN 111810253 A CN111810253 A CN 111810253A CN 202010810467 A CN202010810467 A CN 202010810467A CN 111810253 A CN111810253 A CN 111810253A
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China
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sealing
ring
sleeve
shaft
static
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徐冉
高立军
刘闯
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Individual
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    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01DNON-POSITIVE DISPLACEMENT MACHINES OR ENGINES, e.g. STEAM TURBINES
    • F01D11/00Preventing or minimising internal leakage of working-fluid, e.g. between stages
    • F01D11/02Preventing or minimising internal leakage of working-fluid, e.g. between stages by non-contact sealings, e.g. of labyrinth type
    • F01D11/04Preventing or minimising internal leakage of working-fluid, e.g. between stages by non-contact sealings, e.g. of labyrinth type using sealing fluid, e.g. steam
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01DNON-POSITIVE DISPLACEMENT MACHINES OR ENGINES, e.g. STEAM TURBINES
    • F01D11/00Preventing or minimising internal leakage of working-fluid, e.g. between stages
    • F01D11/02Preventing or minimising internal leakage of working-fluid, e.g. between stages by non-contact sealings, e.g. of labyrinth type
    • F01D11/04Preventing or minimising internal leakage of working-fluid, e.g. between stages by non-contact sealings, e.g. of labyrinth type using sealing fluid, e.g. steam
    • F01D11/06Control thereof
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01DNON-POSITIVE DISPLACEMENT MACHINES OR ENGINES, e.g. STEAM TURBINES
    • F01D25/00Component parts, details, or accessories, not provided for in, or of interest apart from, other groups
    • F01D25/005Selecting particular materials

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Materials Engineering (AREA)
  • Turbine Rotor Nozzle Sealing (AREA)

Abstract

A 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, a shaft shoulder is arranged in the middle of the shaft sleeve, two sides of the shaft shoulder are respectively provided with a movable ring, and a pneumatic pressure groove is formed in each movable ring. The static sealing assembly comprises a sealing sleeve fixed in the shell, and further comprises a pair of static rings and a pair of corrugated pipes which are respectively arranged on two sides of the shaft shoulder. Under the action of self elasticity, the corrugated pipe is pressed on the end face of the static ring on the same side to form a contact sealing structure. The static ring and the movable ring on the same side are arranged oppositely, and when the movable ring rotates along with the shaft of the steam turbine, a non-contact air film lubrication state is formed between the movable ring and the static ring. The dynamic ring and the static ring have self-adjusting capacity, so that stable air film lubrication non-contact sealing is formed between the dynamic ring and the static ring, high-pressure steam is sealed in the turbine, zero-leakage sealing of the steam in the turbine is realized, and the energy conversion efficiency of the steam turbine is greatly improved.

Description

Double-end-face dry air sealing device for industrial steam turbine
Technical Field
The invention relates to the technical field of mechanical sealing, in particular to a double-end-face dry air sealing device for an industrial steam turbine.
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. According to statistics, for a medium-sized steam turbine set, the annual leakage amount of steam, the consumption amount of cooling water and subsequent operation and maintenance costs thereof are reduced to the operation cost of more than one million yuan.
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 the defects in the background art, the invention discloses a double-end-face dry gas sealing device for an industrial steam turbine, which adopts the following technical scheme:
a double-end-face dry air sealing device for an industrial steam turbine is axially arranged between a casing and a bearing box and radially arranged between the casing and a journal 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 and a pair of corrugated pipes which are respectively arranged at two sides of the shaft shoulder; the end surface of the corrugated pipe, which is far away from the shaft shoulder, is in sealing connection with the sealing sleeve; the static ring is arranged between the corrugated pipe and the dynamic ring and is in floating connection with the sealing sleeve through a stop pin; under the action of self elasticity, the end face of the corrugated pipe close to one side of the shaft shoulder is pressed against the end face of one side of the static ring to form a contact sealing structure; the end face of the other side of the static ring is opposite to the end face of the side of the dynamic ring, which is far away from the shaft shoulder, and when the dynamic ring rotates along with the shaft of the steam turbine, a non-contact dry gas sealing structure is formed between the dynamic ring and the static ring; 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.
Preferably, the static sealing assembly further comprises a pair of damping sleeves for radially limiting the static ring and the corrugated pipe, the outer sleeve surface of each damping sleeve is in contact connection with the inner sleeve surface of the sealing sleeve through a centering ring spring, and the inner sleeve surface of each damping sleeve is in contact connection with the outer surfaces of the static ring and the corrugated pipe respectively.
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 through the transmission pin.
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 labyrinth sleeve is arranged between the main shaft nut and the sealing sleeve, and a rear comb-shaped labyrinth sealing structure is arranged on the labyrinth sleeve; the seal cover is provided with a vent cavity between the rear comb labyrinth seal structure and the corrugated pipe 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, a front air-isolating cavity for preventing steam in the machine from entering is arranged on the inner side of the sealing sleeve of the machine shell, 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, the inner sleeve surface and the outer sleeve surface of the sealing sleeve are both multi-step surfaces; the outer sleeve surface of the sealing sleeve is in sealing connection with the machine shell through a plurality of sealing rings, and the inner sleeve surface of the sealing sleeve is in sealing connection with the outer sleeve surface of the labyrinth sleeve through the sealing rings and is in sealing connection with one end, far away from the shaft shoulder, of the pair of corrugated pipes through the flexible graphite ring.
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.
Due to the adoption of the technical scheme, compared with the background technology, the invention has the following beneficial effects:
the invention realizes the static seal between the casing and the sealing sleeve, and between the sealing sleeve and the corrugated pipe, and realizes the contact seal between the corrugated pipe and the static ring, and the air film lubrication non-contact seal between the dynamic ring and the static ring. The two-stage dry gas structure seals high-pressure steam in the turbine, so that energy consumption is reduced, and the energy conversion efficiency of the industrial steam turbine is improved.
The movable ring and the static ring have self-adjusting capacity, and when the shaft of the steam turbine has the phenomena of thermal expansion, jumping, flexible deformation and the like, a stable air film can be formed between the movable ring and the static ring all the time, so that the dry gas sealing structure can work reliably for a long time.
The invention adopts double dry gas sealing structures, under the same working condition, the steam leakage amount of each dry gas sealing structure is only one tenth to one hundredth of the existing sealing structure, and the double dry gas sealing structure basically realizes zero leakage sealing. 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. The invention stably realizes dry gas sealing between the dynamic ring and the static ring through long-term practice verification, solves the technical problem which is always solved but can not be solved in the industry, and has great significance! In addition, the invention has obvious effect of energy saving and efficiency improvement and great economic value.
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 rear pressing sleeve; 7. a spindle nut; 8. a bellows; 9. a stationary ring; 10. sealing sleeves; 11. a damping sleeve; 12. a centering coil spring; 13. a labyrinth sleeve; 14. a drive pin; 15. a retaining pin; 16. flexible graphite; 17. a front comb labyrinth seal structure; 18. a comb-shaped labyrinth seal structure is arranged at the rear part; 19. a primary seal cavity; 20. a front air-isolating cavity; 21. a rear air-isolating cavity; 22. and (4) placing the cavity.
Detailed Description
Preferred embodiments of the present invention are 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 indicating 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.
A double-end-face dry air sealing device for an industrial steam turbine is axially arranged between a casing 2 and a bearing box (not shown in the figure) and is radially arranged between the casing 2 and a shaft neck 1 of a steam turbine shaft, and comprises a rotary sealing assembly and a static sealing assembly, wherein a sealing structure formed between the rotary sealing assembly and the static sealing assembly is a main sealing structure of the invention.
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 of the shaft neck 1; the outer side end of the shaft sleeve 3 is connected with a rear pressing sleeve 6 through a bolt, and the outer side end of the rear 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 16 ring is arranged between the rear compression sleeve 6 and the shaft sleeve 3, and the flexible graphite 16 ring not only has good sealing performance, but also has high temperature resistance. The axial seal between the rear clamping sleeve 6 and the shaft sleeve 3 is realized by a flexible graphite ring 16.
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 surfaces of the two sides of the shaft shoulder 31 are sealing surfaces, and the sealing surfaces of the two sides of the shaft shoulder 31 are respectively provided with a flexible graphite 16 ring for sealing the movable ring 5 and a transmission pin 14 in the axial direction. The rotating ring 5 is provided with a pin shaft hole corresponding to the driving pin 14, and the driving pin 14 is connected with the pin shaft hole of the rotating ring 5 in a floating mode. The shoulder 31 carries the two side rings 5 with the drive pin 14 to rotate with the turbine shaft.
The stationary seal assembly comprises a gland 10 secured within the interior of the housing 2 and sealingly connected to the housing 2. The gland 10 has a longer axial dimension due to the primary seal structure extending through the gland 10. In order to reduce the processing difficulty and facilitate the assembly and maintenance, the sealing sleeve 10 is formed by connecting three parts. The inner and outer sleeve surfaces of the sealing sleeve 10 are both of a multi-step surface structure, and the outer sleeve surface of the sealing sleeve 10 is connected with the casing 2 in a sealing manner through a plurality of sealing rings.
The stationary seal assembly further comprises a pair of stationary rings 9 and a pair of bellows 8 disposed on either side of the shoulder 31. The pair of stationary rings 9 and the pair of bellows 8 are symmetrically arranged about the shaft shoulder 31, wherein the end surfaces of the pair of bellows 8 far away from the shaft shoulder 31 are fixed on the inner stepped table surface of the sealing sleeve 10 through bolts, and are in sealing connection with the sealing sleeve 10 through flexible graphite 16 rings. The static ring 9 is arranged between the corrugated pipe 8 and the dynamic ring 5 and is in floating connection with the sealing sleeve 10 through a stop pin 15. In this embodiment, the corrugated pipe 8 is a high temperature resistant stainless steel corrugated pipe 8, which is not only resistant to high temperature corrosion, but also has good elasticity. The bellows 8 is flexible and generates a certain axial elastic force when being pressed. Under the action of self axial elasticity, the end surface of the corrugated pipe 8 close to the shaft shoulder 31 is pressed against the end surface of the static ring 9 on the same side, so that a contact sealing structure between the corrugated pipe 8 and the static ring 9 is formed. The other end face of the static ring 9 is opposite to the end face of the movable ring 5 far from the shaft shoulder 31, and under the action of the axial elasticity of the corrugated pipe 8, a certain contact pressure is kept between the static ring 9 and the movable ring 5 on the same side.
The seal sleeve 10 is provided with a main seal cavity 19 communicated with a dry gas seal structure at the shaft shoulder 31 of the shaft sleeve 3, and the main seal cavity 19 is communicated with an 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 12 μm, and the width of the dam area of the pneumatic pressure groove 51 is 0.5 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 9, 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 9, and cools the static ring 9 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 plays a role in lubricating and isolating the sealing surface between the movable ring 5 and the static ring 9. 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 8 reach balance, and the non-contact operation of the sealing surface between the movable ring 5 and the static ring 9 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 a comb-tooth type labyrinth seal or a carbon ring seal under the same working condition. The main sealing structure is internally provided with an inner dry gas sealing structure and an outer dry gas sealing structure, and the dry gas sealing structure positioned at the outer side is used for sealing steam leaked from the inner dry gas sealing structure again, so that zero leakage sealing of the steam is basically realized. 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. And the dry gas sealing structure requires that the sealing surface between the dynamic ring 5 and the static ring 9 has strict parallel relation. Thus, at least one of the movable ring 5 and the stationary ring 9 is ensured to have a self-adjusting capability. Therefore, two sides of the shaft shoulder 31 are respectively sleeved with a centering coil spring 12, and the centering coil springs 12 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 14, so that the driving pin 14 is prevented from limiting the floating of the movable ring 5; a certain gap is reserved between the movable ring seat and the outer ring surface 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 provide the static ring 9 with the freedom of self-adjustment following the movable ring 5, a long groove with a radial opening is arranged on the outer ring surface of the static ring 9, the static ring 9 is in clearance connection with a stop pin 15 through the long groove, the rotation of the static ring 9 is prevented, but the floating of the static ring 9 is not limited. Bellows 8 applys certain axial force to quiet ring 9, guarantees that the sealed face of quiet ring 9 does not deviate from the sealed face of rotating ring 5, and bellows 8 self has certain universal flexibility moreover, guarantees that bellows 8 carries out the sealed face of perpendicular to rotating ring 5 all the time to the axial force that quiet ring 9 was applyed, makes quiet ring 9 have the degree of freedom that follows rotating ring 5 and carry out the self-regulation all the time. Thus, 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 9, 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 high-temperature high-pressure steam generator works in a high-temperature high-pressure steam environment for a long time, so that the high-temperature high-pressure steam generator has high requirements on the physical properties of the materials of the moving environment 5 and the static environment 9; furthermore, the sealing surfaces between the rotating ring 5 and the stationary ring 9 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 9 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 9 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 9 is prolonged, and the maintenance cost of the steam turbine can be greatly reduced.
Because the disturbance of the steam airflow in the machine can cause vibration to the static ring 9 and the corrugated pipe 8, even the static ring 9 and the corrugated pipe 8 are eccentrically unstable, the technical scheme is further improved, and the static sealing assembly further comprises a pair of damping sleeves 11 for radially limiting the static ring 9 and the corrugated pipe 8. The damping sleeve 11 is made of a high-temperature resistant metal material, and in this embodiment, the damping sleeve 11 is made of stainless steel. The outer ring surface of each damping sleeve 11 is in contact connection with the inner ring surface of the sealing sleeve 10 through a two-stage centering ring spring 12, and the inner ring surface is in contact connection with the outer surfaces of the static ring 9 and the corrugated pipe 8 respectively. It is to be noted here that the damping sleeve 11 is not fixed in the inner sleeve surface of the sealing sleeve 10, but is connected in contact with the inner sleeve surface of the sealing sleeve 10 by means of a two-stage centering coil spring 12. The two-stage centering coil spring 12 provides the damping sleeve 11 with a certain floating amount, so that the damping sleeve 11 does not prevent the static ring 9 from always having a degree of freedom to self-adjust following the dynamic ring 5, although it radially restrains the static ring 9 and the bellows 8.
In conclusion, the invention realizes the sealing of the casing 2 and the sealing sleeve 10; the sealing of the sealing sleeve 10 and the corrugated pipes 8 at the inner side and the outer side is realized; the contact sealing between the corrugated pipes 8 at the two sides and the static ring 9 at the same side is realized; a steam lubrication non-contact sealing state is formed between the inner side moving ring 5 and the outer side moving ring 9. The two-stage dry gas structure seals high-pressure steam in the turbine, so that 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 bellows loses elasticity and compensation capacity, so that the seal fails prematurely. For this purpose, the casing 2 is provided with a front air-isolating chamber 20 between the front comb labyrinth seal structure 17 and the sealing sleeve 10, and front isolating air is introduced into the front air-isolating chamber 20. The pre-comb labyrinth seal structure 17 is a seal structure of the existing steam turbine, and the seal structure 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 isolation 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 air isolation cavity 20 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, the front isolation gas returns to the machine through the front comb-shaped labyrinth seal structure 17, dirty steam in the machine which is not filtered is prevented from polluting the dry gas seal structure, and 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 separation cavity 20 through the front comb-shaped labyrinth seal structure 17, and at the moment, an external pipeline of the front air separation cavity 20 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 19 at the position of the shaft shoulder 31, and the main seal cavity 19 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 19 is greater than the pressure of the front barrier gas entering the front barrier chamber 20. The main seal gas may also be homologous to the front barrier gas, but the front barrier gas entering the front gas barrier chamber 20 needs to be depressurized in order 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 box (not shown in the figure) from polluting the dry gas sealing structure through diffusion, a labyrinth sleeve 13 is arranged between the spindle nut 7 and the sealing sleeve 10, and the inner sleeve surface of the sealing sleeve 10 is in sealing connection with the outer sleeve surface of the labyrinth sleeve 13 through a sealing ring. A plurality of comb-shaped inner ring teeth are arranged on the labyrinth sleeve 13, and a rear comb-shaped labyrinth sealing structure 18 is formed by the labyrinth sleeve and the spindle nut 7. The sealing sleeve 10 is provided with a vent cavity 22 between the rear comb labyrinth type sealing structure 18 and the corrugated pipe 8 close to the outer side, and the vent cavity 22 is communicated with the atmosphere through a vent. Thus, most of the lubricating oil gas in the casing 2 can be sealed off by the rear comb-shaped labyrinth seal structure 18, and a small amount of lubricating oil gas leaked from the rear comb-shaped labyrinth seal structure 18 is discharged through the vent, so that the pollution of the lubricating oil gas to the dry gas seal structure is avoided. Similarly, a very small amount of steam leaking from the dry gas seal is vented through the vent after entering the vent cavity 22. Meanwhile, a rear air-isolating cavity 21 is arranged between the labyrinth sleeve 13 and the spindle nut 7, the rear air-isolating cavity 21 is arranged in the middle of the rear comb-shaped labyrinth seal structure 18, and the rear air-isolating cavity 21 is communicated with external rear air-isolating through a pipeline. The rear isolation gas is nitrogen or instrument wind, and the nitrogen or the instrument wind enters the air isolation cavity and blocks the lubricating oil gas entering the rear comb-shaped labyrinth sealing structure. Excess nitrogen or meter air enters the vent cavity 22 and vents through the vent.
The present invention is not described in detail in the 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 (10)

1. A kind of industry steam turbine uses the dry air sealing device of the double end, the axial is set up between casing and bearing box, radially between casing and journal of the steam turbine shaft, its characteristic is: 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 and a pair of corrugated pipes which are respectively arranged at two sides of the shaft shoulder; the end surface of the corrugated pipe, which is far away from the shaft shoulder, is in sealing connection with the sealing sleeve; the static ring is arranged between the corrugated pipe and the dynamic ring and is in floating connection with the sealing sleeve through a stop pin; under the action of self elasticity, the end face of the corrugated pipe close to one side of the shaft shoulder is pressed against the end face of one side of the static ring to form a contact sealing structure; the end face of the other side of the static ring is opposite to the end face of the side of the dynamic ring, which is far away from the shaft shoulder, and when the dynamic ring rotates along with the shaft of the steam turbine, a non-contact dry gas sealing structure is formed between the dynamic ring and the static ring; 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.
2. The double-end-face dry gas seal assembly of claim 1, wherein: the static sealing assembly further comprises a pair of damping sleeves for radially limiting the static ring and the corrugated pipe, the outer ring sleeve surface of each damping sleeve is in contact connection with the inner sleeve surface of the sealing sleeve through a centering ring spring, and the inner ring sleeve surface of each damping sleeve is in contact connection with the outer surfaces of the static ring and the corrugated pipe respectively.
3. A double-ended dry gas seal assembly for an industrial steam turbine as claimed in claim 1 or claim 2 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 through the transmission pin.
4. A double-ended dry gas seal assembly as claimed in claim 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 double-end-face dry gas seal assembly of claim 4, wherein: a labyrinth sleeve is arranged between the main shaft nut and the seal sleeve, and a rear comb-shaped labyrinth seal structure is arranged on the labyrinth sleeve; the seal cover is provided with a vent cavity between the rear comb labyrinth seal structure and the corrugated pipe close to the outer side, and the vent cavity is communicated with the atmosphere through a vent hole.
6. The double-ended dry gas seal assembly of 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 double-end-face dry gas seal assembly of claim 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. A double-ended dry gas seal assembly for an industrial steam turbine as claimed in claim 5 or 6 or 7 wherein: the inner and outer sleeve surfaces of the sealing sleeve are multi-step surfaces; the outer sleeve surface of the sealing sleeve is in sealing connection with the machine shell through a plurality of sealing rings, and the inner sleeve surface of the sealing sleeve is in sealing connection with the outer sleeve surface of the labyrinth sleeve through the sealing rings and is in sealing connection with one end, far away from the shaft shoulder, of the pair of corrugated pipes through the flexible graphite ring.
9. The double-end-face dry gas seal assembly 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. A double-ended dry gas seal assembly for an industrial steam turbine as claimed in 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.
CN202010810467.8A 2020-08-13 2020-08-13 Double-end-face dry air sealing device for industrial steam turbine Pending CN111810253A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
CN202010810467.8A CN111810253A (en) 2020-08-13 2020-08-13 Double-end-face dry air sealing device for industrial steam turbine

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
CN202010810467.8A CN111810253A (en) 2020-08-13 2020-08-13 Double-end-face dry air sealing device for industrial steam turbine

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CN111810253A true CN111810253A (en) 2020-10-23

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Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN111335968A (en) * 2020-03-06 2020-06-26 西华大学 Sealing device for high-speed rotating impeller machine
CN117167285A (en) * 2023-11-01 2023-12-05 江苏新世界泵业有限公司 Rapid assembly type fluorine material axial flow pump with dry gas seal and use method thereof

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN111335968A (en) * 2020-03-06 2020-06-26 西华大学 Sealing device for high-speed rotating impeller machine
CN111335968B (en) * 2020-03-06 2022-05-27 西华大学 Sealing device for high-speed rotating impeller machine
CN117167285A (en) * 2023-11-01 2023-12-05 江苏新世界泵业有限公司 Rapid assembly type fluorine material axial flow pump with dry gas seal and use method thereof

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