CN111810251A - A split carbon ring type double-end dry gas seal device for industrial steam turbines - Google Patents

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 movable ring and the static ring have self-adjusting capacity, so that stable air film lubrication non-contact sealing is formed between the movable ring and the static ring, high-pressure steam is sealed in the turbine, energy consumption is reduced, and the energy conversion efficiency of the industrial steam turbine is improved.

Description

A split carbon ring type double-end dry gas seal device for industrial steam turbines

technical field

The invention relates to the technical field of mechanical seals, in particular to a split carbon ring type double-end dry gas seal device for industrial steam turbines.

Background technique

Steam turbine is one of the main equipment of steam power plant, which is a kind of rotary power machine that converts the energy of steam into mechanical work. The working principle of the steam turbine is that steam with a certain pressure and temperature enters the steam turbine, expands rapidly in the nozzle to obtain a high flow speed, and then the high-speed flowing steam impels the rotor blades of the steam turbine to rotate and perform work, thereby obtaining mechanical energy. The steam turbine is mainly composed of a rotating part, a fixed part and a control part.

Industrial steam turbines are equipment that uses steam as the motive power and are mainly used in chemical, petroleum, mining, metallurgy, paper, textile, sugar and other industrial enterprises. Industrial steam turbines drive various types of pumps, fans, compressors, presses or drive generators to obtain low-cost power and electricity. In advanced industrial countries, primary energy has been fully utilized since steam turbines have been used in industry. Small heat (electricity) cogeneration (small back pressure machine) can make full use of waste, waste gas, waste heat to produce steam, or use rich steam and steam pressure difference, and then convert it into mechanical energy through power steam turbine to directly drive mechanical equipment to do work, also The variable speed operation of mechanical equipment can be realized by adjusting the speed of the steam turbine. Since the energy conversion links are reduced, the energy conversion efficiency is increased, and expensive industrial electricity is saved, therefore, the application of industrial steam turbines as motive power equipment in production can achieve the purpose of energy conservation and efficiency enhancement. In addition, the extraction and exhaust steam of industrial steam turbines can also be used in the industrial production process or external supply of enterprises and institutions, thereby realizing the cascade utilization of energy. It is one of the effective measures for energy conservation and consumption reduction in enterprises and institutions. , with significant advantages in comprehensive economic benefits.

Due to the high pressure and high temperature of the working medium, the current industrial steam turbine usually adopts the form of comb-tooth labyrinth seal or carbon ring seal at the shaft end. Since both labyrinth seals and carbon ring seals are radial non-contact seals, in order to avoid friction between the main shaft or the shaft sleeve and the sealing parts during the whole working process, the radial sealing gap is generally relatively large (static or dynamic) , resulting in a large amount of axial steam leakage. Especially the back pressure type steam turbine, the seal chamber pressure is higher, and its shaft end seal leakage is larger. The leakage of steam will cause energy loss. In addition, the leaked steam needs to be cooled by cooling water, and the amount of cooling water is also very large. For medium-sized steam turbine units, the annual steam leakage, cooling water consumption, and subsequent operation and maintenance costs are equivalent to operating costs of more than one million yuan.

Different from the dynamic and static seals of general machinery, there are many factors affecting the shaft end seal of industrial steam turbines, and the situation is complicated. Affected by the high temperature and high pressure of the steam in the engine, as well as the thermal expansion, jumping, winding deformation and other factors when the steam turbine shaft rotates at a high speed, the leakage problem of the shaft end of the industrial steam turbine has been a technical problem that the industry wants to solve but cannot be solved for a long time. From the perspective of energy saving and efficiency improvement, there is an urgent need for a new type of sealing device that has high reliability and can significantly reduce the leakage of shaft end seals.

SUMMARY OF THE INVENTION

In order to overcome the deficiencies in the background technology, the present invention discloses a split carbon ring type double-end dry gas sealing device for an industrial steam turbine, which adopts the following technical solutions:

A split carbon ring type double-end dry gas sealing device for industrial steam turbines, which is axially arranged between the casing and the casing, and radially between the casing and the journal of the steam turbine shaft, comprising a rotary seal assembly and a static sealing components;

The rotary seal assembly includes a shaft sleeve fixed on the shaft journal, a shaft shoulder is arranged in the middle part of the shaft sleeve, and a moving ring is arranged on both sides of the shaft shoulder; the end faces on both sides of the shaft shoulder are sealing surfaces, and both sides The moving ring of the moving ring is sealed with the sealing surface on the same side, and rotates with the shaft sleeve; a plurality of circumferentially distributed pneumatic pressure grooves are arranged on the end face of the moving ring on the side away from the shaft shoulder;

The static sealing assembly includes a sealing sleeve fixed in the casing and sealingly connected with the casing, and also includes a pair of static rings, a pair of carbon rings, a pair of push rings and a pair of inner rings respectively arranged on both sides of the shaft shoulder Wherein, the static ring, carbon ring and push ring on the same side are sleeved on the outer ring surface of the inner ring sleeve on the same side in turn, and the end of the inner ring sleeve on the same side away from the shaft shoulder is sealed with the sealing sleeve; the static ring is arranged on Between the carbon ring and the moving ring on the same side, and floatingly connected with the sealing sleeve through a stop pin; an axial compression spring is connected between the push ring and the sealing sleeve;

Under the elastic force of the axial compression spring, the push ring pushes the carbon ring on the same side against the static ring on the same side, and the end faces on both sides of the carbon ring form an axial contact seal with the corresponding static ring and the push ring. Structure, the inner ring surface of the carbon ring and the corresponding inner ring sleeve form a contact sealing structure in the radial direction; the static ring and the moving ring on the same side are arranged opposite to each other. Contact dry gas sealing structure; the sealing sleeve is provided with a main sealing cavity at the dry gas sealing structure part, and the main sealing cavity is communicated with the external main sealing gas through a pipeline; the main sealing gas is the filtered external steam.

Preferably, a centering coil spring is set on both sides of the shaft shoulder; the centering coil spring is in contact with the inner ring surface of the moving ring on the same side, and the moving ring has a certain amount of floating; on the sealing surface of the shaft shoulder There is a flexible graphite ring for sealing the moving ring, and a drive pin in the axial direction; the moving ring is provided with a pin shaft hole corresponding to the drive pin, the diameter of the pin shaft hole is larger than the diameter of the drive pin, and the shaft shoulder The moving rings on both sides are driven to rotate with the shaft sleeve through the transmission pin.

Preferably, the inner and outer surfaces of the sealing sleeve are multi-step surfaces, and the outer surface of the sealing sleeve is sealed with the casing through multiple sealing rings; the end of the inner ring sleeve away from the shaft shoulder is provided with an outer flange, The outer flange is matched and connected with a stepped surface of the inner sleeve surface of the sealing sleeve; the inner end face of the stepped surface is connected with a retaining ring for preventing the outer flange of the inner ring sleeve from coming out. A flexible graphite ring is arranged between the two, and the flexible graphite ring is used for sealing between the inner ring sleeve and the sealing sleeve.

Preferably, a front compression sleeve is connected to the inner end of the shaft sleeve, and the front compression sleeve is pressed against the inner shaft shoulder of the journal; the outer end of the shaft sleeve is connected with a rear compression sleeve, and the rear compression sleeve is A flexible graphite ring is arranged between it and the shaft sleeve; the outer end of the rear compression sleeve is back-tightened by a main shaft nut screwed on the shaft journal.

Preferably, a rear comb labyrinth sealing structure is arranged between the main shaft nut and the sealing sleeve; the sealing sleeve is provided with a venting cavity between the rear comb labyrinth sealing structure and the dry gas sealing structure close to the outside. , the venting cavity is communicated with the atmosphere through the venting port.

Preferably, there is a rear air barrier cavity between the labyrinth sleeve and the spindle nut, the rear air barrier chamber is arranged in the middle of the rear comb-shaped labyrinth seal structure, and the rear air barrier chamber is connected to the outside through the pipeline. Rear isolation gas communication.

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

Preferably, a ring groove is provided on the outer ring surface of the carbon ring, and a tension spring is installed in the ring groove; the carbon ring is a multi-lobed body structure, and the multi-lobed bodies are connected together by a tension spring; A ring is a group of carbocyclic rings.

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

Preferably, the material of the moving ring is silicon carbide, or silicon nitride, or a cemented carbide; the material of the static ring is graphite, or silicon carbide coated with a diamond-like film on the surface.

Due to adopting the above-mentioned technical scheme, compared with the background technology, the present invention has the following beneficial effects:

In the main sealing structure of the present invention, fixed sealing is achieved 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 The group and the inner ring sleeve form a contact sealing structure in the radial direction; a dry gas sealing structure is realized between the moving ring and the static ring. The secondary dry gas sealing structure seals the high-pressure steam in the machine, which reduces energy consumption and improves the energy conversion efficiency of the industrial steam turbine.

The dynamic ring and the static ring of the present invention have self-adjustment capabilities, and when the steam turbine shaft has thermal expansion, jumping, winding deformation, etc., a stable gas film can always be formed between the dynamic ring and the static ring, ensuring that the dry gas sealing structure can be Work reliably for long periods of time.

The invention adopts a double dry gas sealing structure. Under the same working conditions, the steam leakage of each dry gas sealing structure is only a few tenths to one percent of the existing sealing structure. The structure basically achieves zero leakage sealing. Since the steam no longer leaks, there is no need to set up an additional leakage steam cooling device, which greatly reduces the follow-up operation and maintenance costs of the industrial steam turbine, which can save nearly one million yuan in operating costs every year.

Dry gas seal was originally developed to solve the problem of high-speed centrifugal compressor shaft end seal, but in the steam turbine industry, it cannot be applied due to various factors. One of the important reasons is that industrial steam turbines are under complex working conditions. , it cannot guarantee a stable dry gas seal between the moving ring and the static ring. And the present invention, through long-term practical verification, stably realizes dry gas sealing between the dynamic ring and the static ring, and solves the technical problems that the industry has been trying to solve but cannot solve, and it is of great significance! In addition, the effect of the present invention in saving energy and improving efficiency is remarkable, and the economic value is huge.

Description of drawings

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

Figure 2 is a schematic diagram of the structure of the pneumatic pressure groove near the end of the moving ring outside the machine.

Figure 3 is a schematic diagram of the structure of the pneumatic pressure groove near the end of the moving ring in the machine.

In the figure: 1, journal; 2, casing; 3, shaft sleeve; 31, shaft shoulder; 4, front compression sleeve; 5, moving ring; 51, pneumatic pressure groove; 6, compression sleeve; 7, main shaft Nut; 8. Transmission pin; 9. Flexible graphite; 10. Centering coil spring; 11. Sealing sleeve; 12. Static ring; 13. Inner ring sleeve; 14. Carbon ring; 15. Shrinking spring; 16. Axial pressure Spring; 17, retaining ring; 18, push ring; 19, labyrinth sleeve; 20, main sealing chamber; 21, venting chamber; 22, front air barrier chamber; 23, rear air barrier chamber; 24, front comb Labyrinth seal structure; 25. Rear comb-like labyrinth seal structure; 26. Stop pin.

Detailed ways

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 used to explain the technical principle of the present invention, and are not intended to limit the protection scope of the present invention.

It should be noted that, in the description of the present invention, terms indicating directions or positional relationships such as "inside" and "outside" are based on the relative indicated directions or positional relationships centered on the main body of the industrial steam turbine, which are only for the convenience of description. It is not intended to indicate or imply that the device or element must have a particular orientation, be constructed and operate in a particular orientation, and therefore should not be construed as limiting the invention.

A split carbon ring type double-end dry gas seal device for an industrial steam turbine, as shown in Figure 1, is axially arranged between the casing 2 and the bearing housing, and radially between the casing 2 and the journal 1 of the turbine shaft Between them, including the rotary seal assembly and the static seal assembly, the sealing structure formed between the rotary seal assembly and the static seal assembly is the main sealing structure of the present invention.

The rotary seal assembly includes a bushing 3 fixed on the journal 1 . Specifically, a front compression sleeve 4 is connected to the inner end of the shaft sleeve 3 by bolts, and the front compression sleeve 4 abuts against the inner shaft shoulder 31 of the journal 1; the outer end of the shaft sleeve 3 is connected by bolts. The outer end of the compression sleeve 6 is backed by the main shaft nut 7 screwed on the journal 1, so that the sleeve 3 is fixed on the journal 1 and rotates with the turbine shaft. 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 compression sleeve 6 and the shaft sleeve 3 is achieved by the flexible graphite 9 ring.

A shaft shoulder 31 is arranged in the middle part of the shaft sleeve 3 , and a moving ring 5 is arranged on each side of the shaft shoulder 31 . The end faces on both sides of the shaft shoulder 31 are both sealing faces, and flexible graphite 9 rings for sealing the moving ring 5 are respectively provided on the sealing faces on both sides of the shaft shoulder 31 , and a drive pin 8 in the axial direction is also provided. The movable ring 5 is provided with a pin shaft hole corresponding to the transmission pin 8, the transmission pin 8 is floatingly connected with the pin shaft hole of the movable ring 5, and the shaft shoulder 31 drives the movable ring 5 on both sides through the transmission pin 8 to rotate together with the turbine shaft. .

The static sealing assembly includes a sealing sleeve 11 fixed in the casing 2 and sealingly connected with the casing 2 . Since the main sealing structure penetrates the sealing sleeve 11, the sealing sleeve 11 has a longer axial dimension. In order to reduce the difficulty of processing and at the same time facilitate assembly and maintenance, the sealing sleeve 11 is formed by connecting three parts. The inner and outer surfaces of the sealing sleeve 11 are all multi-step surface structures, and the outer surface of the sealing sleeve 11 is sealedly connected with the casing 2 through multiple sealing rings.

The static seal assembly also includes a pair of static rings 12 , a pair of carbon rings 14 , a pair of push rings 18 , a pair of inner ring sleeves 13 , a pair of static rings 12 , a pair of carbon rings 14 , a pair of static rings 12 , a pair of carbon rings 14 , which are respectively arranged on both sides of the shaft shoulder 31 . , a pair of push rings 18 and a pair of inner ring sleeves 13 are symmetrically arranged with respect to the shaft shoulder 31 . Due to the symmetrical arrangement of the two sides, for the convenience of description, only the static ring 12, the dynamic ring 5, the carbon ring 14, the push ring 18 and the inner ring sleeve 13 on one side of the shoulder 31 are described, and the static ring 12, the dynamic ring 12 on the other side, and the dynamic ring 13 are described. The installation positions and corresponding relationships of the ring 5, the carbon ring 14, the push ring 18 and the inner ring sleeve 13 are the same as on this side.

The static ring 12 , the carbon ring 14 and the push ring 18 on the same side are sequentially sleeved on the outer ring surface of the inner ring sleeve 13 , and the end of the inner ring sleeve 13 away from the shaft shoulder 31 is sealed with the sealing sleeve 11 . Specifically, one end of the inner ring sleeve 13 away from the shaft shoulder 31 is provided with an outer flange, and the outer flange is matched and connected with a stepped surface of the inner sleeve surface of the sealing sleeve 11 . A retaining ring 17 for preventing the outer flange of the inner ring sleeve 13 from coming out is connected to the inner end surface of the stepped surface, and a flexible graphite 9 ring is arranged between the retaining ring 17 and the outer flange of the inner ring sleeve 13 . The retaining ring 17 presses the flexible graphite 9 on the inner end surface of the stepped surface through bolts, so as to realize the sealing between the inner ring sleeve 13 and the sealing sleeve 11 . A countersunk hole for accommodating the axial compression spring 16 is provided on the inner end face of the stepped surface. One end of the axial compression spring 16 is located in the countersunk hole, and the other end is connected to the outer end of the push ring 18 for pushing the push ring 18 An axial thrust is applied to the shoulder 31 side. The static ring 12 is arranged between the carbon ring 14 and the moving ring 5, and is floatingly connected to the sealing sleeve 11 through the stopper pin 26 to prevent the static ring 12 from rotating. The static ring 12, the carbon ring 14 and the push ring 18 are sequentially fitted on the outer ring surface of the inner ring sleeve 13, and the static ring 12, the carbon ring 14 and the push ring 18 are radially limited, which can prevent the steam in the machine from turbulent flow. Vibration caused to static ring 12, carbon ring 14 and push ring 18.

A ring groove is provided on the outer ring surface of the carbon ring 14, and a tension spring 15 is installed in the ring groove. The carbon ring 14 is a multi-lobed body structure, and the multi-lobed bodies are connected together by a tension spring 15 hooped on the outer diameter to form an annular whole. Every two carbon rings cooperate with each other to form a group of carbon rings. In this embodiment, the carbon ring 14 on the inner side is divided into six lobes, and the carbon ring 14 on the outer side is divided into three lobes. The lateral incision is staggered from the radial incision of the outer three-valve annulus. Under the elastic force of the axial compression spring 16 , the push ring 18 pushes the carbon ring group to press against the outer end surface of the static ring 12 , so that a certain contact pressure is maintained between the static ring 12 and the moving ring 5 . The end faces on both sides of the carbon ring group form an axial contact sealing structure with the static ring 12 and the push ring 18 respectively, and the inner ring surface of the carbon ring group and the inner ring sleeve 13 form a radial contact sealing structure.

The sealing sleeve 11 is provided with a main sealing cavity 20 at the dry gas sealing structure part, and the main sealing cavity 20 communicates with the external main sealing gas through a pipeline. The main sealing gas can be high-pressure clean steam, or high-pressure nitrogen or instrument air, the pressure of which is greater than the pressure of the steam in the machine. A plurality of circumferentially distributed pneumatic pressure grooves 51 are provided on the end surface of the moving ring 5 on the side away from the shaft shoulder 31 . The pneumatic pressure groove 51 may be a unidirectional rotating groove, or a bidirectional rotating groove. It can be a one-way arc groove, a spiral groove, a triangular groove, or a two-way, such as a hammer-shaped two-way groove. In this embodiment, the pneumatic pressure groove 51 is a one-way spiral groove. Figure 2 shows a schematic diagram of the rotation direction of the one-way helical groove on the outer end face of the moving ring 5 close to the outer side of the turbine and the rotation direction of the turbine shaft when viewed from the X direction. Figure 3 shows a schematic diagram of the rotation direction of the one-way helical groove on the outer end face of the moving ring 5 close to the inner side of the turbine and the rotation direction of the turbine shaft when viewed from the Y direction. It can be seen from Figures 2 and 3 that the rotation direction of the one-way spiral groove on the outer end face of the moving ring 5 close to the machine and the moving ring 5 near the outside of the machine is the same as that of the turbine shaft, and the one-way spiral groove automatically The inner part of the outer end surface of the ring 5 extends spirally in the outer radial direction, and is opened to the outer ring surface of the movable ring 5 . Along the direction of helical extension, the cross-sectional area of the one-way helical groove gradually increases. The groove depth of the one-way helical groove is 19 μm, and the width of the dam area of the pneumatic pressure groove 51 is 0.6 times the width of the outer end face of the moving ring 5 . When the moving ring 5 rotates with the turbine shaft, the pressure of the main sealing gas is greater than that of the steam in the machine, and the main sealing gas enters the one-way spiral groove and produces a hydrodynamic pressure effect, so that the main sealing gas at the outer ring surface is pumped inward, As a result, a layer of micron-scale gas film is generated between the outer end face of the moving ring 5 and the inner end face of the static ring 12 to form a dry gas sealing structure. On the one hand, the main sealing gas blocks the leakage of steam and generates a gas film between the moving ring 5 and the static ring 12, and on the other hand cools the moving ring 5 and the static ring 12, and takes away the heat generated by the dry gas sealing structure.

The dry gas sealing structure also functions to lubricate and isolate the sealing surface between the moving ring 5 and the static ring 12 . Due to the very high speed of the steam turbine shaft, the rigidity of the gas film is very large, and the opening force formed by the gas film is balanced with the axial elastic force of the bellows, which not only realizes the non-contact of the sealing surface between the moving ring 5 and the static ring 12 It runs and seals the steam inside the machine. The amount of steam leaked through the dry gas seal structure is only a few tenths to one percent of that of the comb-tooth labyrinth seal or the carbon ring 14 seal under the same working conditions. In the present invention, two dry gas sealing structures are arranged inside and outside the main sealing structure, and the dry gas sealing structure located on the outer side seals the steam leaked from the inner dry gas sealing structure again, basically realizing zero leakage sealing of steam. . Since the steam no longer leaks, there is no need to set an additional leakage steam cooling device, so that the subsequent operation and maintenance costs of the industrial steam turbine are significantly reduced.

When the steam turbine shaft rotates at high speed, phenomena such as thermal expansion, jumping, and winding deformation will inevitably occur at the journal 1. The dry gas seal structure requires a strict parallel relationship between the sealing surfaces of the moving ring 5 and the static ring 12, so at least one of the moving ring 5 and the static ring 12 must have self-adjustment capability. To this end, a centering coil spring 10 is set on both sides of the shaft shoulder 31, and the centering coil spring 10 is in contact with the inner ring surface of the moving ring 5 on the same side; the diameter of the pin shaft hole is larger than the diameter of the transmission pin 8, preventing transmission The pin 8 restricts the floating of the moving ring 5. These measures make the moving ring 5 have a certain amount of floating, and realize the self-adjustment of the moving ring 5 .

In order for the static ring 12 to have the freedom of self-adjustment following the moving ring 5 , the axial compression spring 16 exerts a certain axial force on the static ring 12 to ensure that the sealing surface of the static ring 12 does not detach from the sealing surface of the moving ring 5 . Sealing contact with a small gap is reserved between the inner ring surface of the carbon ring group and the inner ring sleeve 13, and the contact width between the inner ring surface of the carbon ring group and the inner ring sleeve 13 is reduced to ensure that the carbon ring group has a certain floating amount. Similarly, a large gap is set between the inner annular surfaces of the static ring 12 and the push ring 18 and the inner ring sleeve 13 . In addition, a radially open long groove is provided on the outer ring surface of the static ring 12, and the static ring 12 is connected with the stop pin 26 by a gap through the long groove, so that the static ring 12 has a certain floating value while preventing the static ring 12 from rotating. quantity. In this way, while ensuring that the static ring 12 has the ability to follow the moving ring 5 for self-adjustment, the end faces on both sides of the carbon ring group can always be kept in contact and sealing with the static ring 12 and the push ring 18 . When thermal expansion, jumping, and winding deformation occur at the journal 1, a parallel gas film is always formed between the moving ring 5 and the static ring 12, which can ensure the normal operation of the dry gas sealing structure.

When the steam turbine is working, the moving ring 5 rotates at a high speed with the steam turbine shaft, so there is a high requirement on the strength of its material; due to long-term work in a high-temperature and high-pressure steam environment, the physical There are also high requirements for mechanical performance; in addition, during the starting and stopping process, the sealing surface between the moving ring 5 and the static ring 12 will have slight contact wear, so the surface tribological characteristics of the moving ring 5 and the static ring 12 are affected. There are also high demands. Therefore, the moving ring 5 can be made of high-hardness and high-wear-resistant materials such as silicon carbide, silicon nitride or cemented carbide with high strength, good tribological properties and relatively high hardness, or stainless steel can be used as the substrate. The surface is prepared by spraying or surfacing with a high-hardness wear-resistant coating. The static ring 12 can be prepared by using graphite with good self-lubrication, or silicon carbide with diamond-like carbon film (DLC) plated on the surface of silicon carbide. The use of DLC coating technology can improve the surface tribological properties of hard-to-hard friction pairs. Extending the service life of the moving ring 5 and the static ring 12 can greatly reduce the maintenance cost of the steam turbine.

To sum up, in the main sealing structure of the device, fixed sealing is achieved between the casing 2 and the sealing sleeve 11, and between the sealing sleeve 11 and the inner ring sleeve 13; the carbon ring groups on both sides and the static ring 12, The push ring 18 forms a contact sealing structure in the axial direction, the carbon ring groups on both sides and the inner ring sleeve 13 form a contact sealing structure in the radial direction; the dynamic ring 5 and the static ring 12 on both sides realize a double dry gas seal Therefore, the high-pressure steam is enclosed in the machine, the energy consumption is reduced, and the energy conversion efficiency of the industrial steam turbine is improved.

The dry gas seal has high requirements on the cleanliness of the gas at the high pressure end. Otherwise, the dirty high pressure end gas will contaminate the end face of the friction pair of the dry gas seal, resulting in premature failure of the seal. To this end, the casing 2 is provided with a front air isolation cavity 22 between the front comb-shaped labyrinth sealing structure 24 and the sealing sleeve 11 , and a front isolation gas is introduced into the front air isolation cavity 22 . It should be noted that the pre-comb-shaped labyrinth sealing structure 24 is a self-contained sealing structure of the existing steam turbine, which has a large amount of steam leakage, but is not affected by thermal expansion. The device only utilizes the existing structure to perform primary sealing on the steam in the engine.

The pre-isolation gas can be high-pressure and high-temperature steam drawn from the inlet of the steam turbine, or the externally drawn steam whose pressure and temperature meet the requirements. In this case, the pressure of the front isolation gas is required to be greater than the steam pressure in the machine, and the front isolation gas is returned to the machine through the front comb-shaped labyrinth sealing structure 24 to prevent the unfiltered visceral steam from contaminating the dry gas sealing structure. At the same time, the heat generated by the dry gas sealing structure is taken away. If the cleanliness of the steam medium in the steam turbine itself meets a certain quality standard, it can also be directly used as the front isolation gas to enter the front air isolation chamber 22 through the front comb-shaped labyrinth sealing structure 24. At this time, the front air isolation chamber 22 The external channel is closed.

In order to generate a pressure difference between the inside and outside of the dry gas seal, the casing 2 is provided with a main sealing cavity 20 at the position of the shaft shoulder 31 , and the main sealing cavity 20 communicates with the main sealing gas through a pipeline. The main sealing gas is the external steam that has been filtered and whose pressure and temperature meet certain requirements. Since the pneumatic pressure groove 51 used in this embodiment is a one-way spiral groove with an outer high pressure, the pressure of the main sealing gas entering the main sealing cavity 20 is greater than the pressure of the front isolation gas entering the front air blocking cavity 22 . The main sealing gas can also be of the same source as the front insulation gas, but the front insulation gas entering the front gas insulation chamber 22 needs to be decompressed so as to generate a pressure difference between the inside and outside of the dry gas seal.

In order to prevent the lubricating oil in the bearing housing (outside the labyrinth sleeve 11, not shown in the figure) from contaminating the dry gas seal structure through diffusion, a labyrinth sleeve 19 is provided between the spindle nut 7 and the seal sleeve 11, and the seal sleeve 11 The inner surface of the labyrinth is sealed with the outer surface of the labyrinth sleeve 19 through a sealing ring. The labyrinth sleeve 19 is provided with a plurality of comb-shaped inner ring teeth, and the inner ring teeth and the spindle nut 7 form an external comb-shaped labyrinth seal structure 25 . The sealing sleeve 11 is provided with a venting cavity 21 between the rear comb labyrinth sealing structure 25 and the dry gas sealing structure close to the outside, and the venting cavity 21 communicates with the atmosphere through the venting port. In this way, the rear comb-shaped labyrinth sealing structure 25 can seal off most of the lubricating oil gas in the casing 2, and a small amount of lubricating oil gas leaking from the rear-mounted comb-shaped labyrinth sealing structure 25 is emptied through the vent, preventing the lubricating oil gas from drying out. Contamination of hermetic structures. Similarly, a very small amount of steam leaking from the dry gas sealing structure is also vented through the venting port after entering the venting cavity 21 . Meanwhile, between the labyrinth sleeve 19 and the main shaft nut 7, a rear air barrier cavity 23 is provided, and the rear air barrier chamber 23 is arranged in the middle part of the rear comb-shaped labyrinth sealing structure 25, and the rear air barrier cavity 23 passes through. The pipeline is communicated with the rear isolation gas of the outside world. The rear isolation gas is nitrogen or instrument air. After the nitrogen or instrument air enters the air isolation chamber, the lubricating oil gas entering the rear comb labyrinth sealing structure 25 is blocked. The excess nitrogen or instrument air enters the venting cavity 21 and is vented through the venting port.

The parts of the present invention that are not described in detail are prior art. Although embodiments of the present invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, and substitutions can be made in these embodiments without departing from the principle and spirit of the invention and modifications, the scope of protection of the present invention is defined by the appended claims and their equivalents.

Claims (10)

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;

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.

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.

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