CN111237468A

CN111237468A - Combined fluid dynamic pressure type rear-mounted isolation sealing device for turbine mechanical dry gas seal

Info

Publication number: CN111237468A
Application number: CN202010151720.3A
Authority: CN
Inventors: 杨惠霞; 陈嘉懿; 张小明; 郑毅
Original assignee: Shanghai Haomi Sealing Technology Co Ltd
Current assignee: Shanghai Haomi Sealing Technology Co Ltd
Priority date: 2020-03-06
Filing date: 2020-03-06
Publication date: 2020-06-05

Abstract

The invention relates to a combined fluid dynamic pressure type rear isolation sealing device for a turbine mechanical dry gas seal, which is arranged between a dry gas sealing component and a bearing box and comprises a carbon ring sealing unit and a fluid dynamic pressure type sealing unit, wherein the carbon ring sealing unit is arranged between the dry gas sealing component and the fluid dynamic pressure type sealing unit, the fluid dynamic pressure type sealing unit comprises a rotating component and a static component, the rotating component is sleeved outside a main shaft and rotates at a high speed along with the main shaft, the static component is arranged around the main shaft and is fixed with a shell, one end face of the rotating component is attached to one end face of the static component to form a sealing face, the sealing face is vertical to the axial direction of the main shaft, and a fluid dynamic pressure groove is arranged on the end face of the rotating component. Compared with the prior art, the sealing device of the application is applied to the turbine machinery, can realize zero leakage of bearing side lubricating oil to dry gas sealing, and has small loss of isolation gas.

Description

Combined fluid dynamic pressure type rear-mounted isolation sealing device for turbine mechanical dry gas seal

Technical Field

The invention relates to the technical field of mechanical sealing, in particular to a combined fluid dynamic pressure type rear-mounted isolation sealing device for a turbine mechanical dry gas seal.

Background

The turbo machinery comprises a turbo compressor (such as a centrifugal compressor and an axial flow compressor) and a turbo expander, which are high-speed rotating equipment and are key core equipment of devices such as petroleum and chemical engineering. At present, dry gas seal, namely dry running, gas lubrication and non-contact mechanical seal, is generally adopted by turbomachinery as shaft end seal. No matter the single-end face dry gas seal, the double-end face dry gas seal, the serial dry gas seal and the serial dry gas seal with the middle labyrinth are adopted, the rear isolation seal is needed to isolate the dry gas seal from the bearing box, and the condition that lubricating oil gas generated by the high-speed rotation of the main shaft in the bearing box pollutes the outer side seal of the dry gas seal through axial diffusion to cause failure of the dry gas seal is avoided.

The common sealing forms of the front and rear isolating seals are non-contact labyrinth seal (or comb seal) and split carbon ring seal. The labyrinth seal is realized by throttling and depressurizing, and has the advantages of non-contact, large working clearance and high reliability; but the defects are that the consumption of isolating gas is large, and the effect of plugging bearing lubricating oil gas is poor. The split carbon ring seal is also a throttling pressure reduction type seal, and is provided with a contact split carbon ring seal and a non-contact split carbon ring seal. However, the contact carbon ring seal has a certain running-in period at the initial stage of use, the carbon ring has certain abrasion in the running-in period, the abrasion amount is related to the dew point of the isolation gas nitrogen, and the lower the dew point, the drier the nitrogen is, the larger the abrasion amount is. Carbon graphite powder from time to time running under wear may cause failure of the outer seal of the dry gas seal.

The non-contact carbon ring seal has a large static leakage and the consumption of the barrier gas is very sensitive to the temperature at the carbon ring seal. For some special conditions, such as the bearing is too close to the dry gas seal axial distance; the position of the bearing oil drain port is unreasonable in design; the oil inlet pressure of the bearing is too high; the bearing box oil return port is too small, oil return flow is not smooth, and the labyrinth seal and the carbon ring seal are likely to have an isolation gas short circuit phenomenon, so that bearing lubricating oil or lubricating oil gas enters the outer side seal of the dry gas seal to pollute the dry gas seal, and the dry gas seal fails.

Disclosure of Invention

The invention aims to overcome the defects of the prior art and provide the combined type hydrodynamic pressure type rear isolation sealing device for the dry gas seal of the turbine machinery, which has good sealing effect.

In order to achieve the object of the present invention, the present application provides the following technical solutions.

In a first aspect, the present application provides a combined hydrodynamic pressure type rear isolation sealing device for a turbomachine dry gas seal, the rear isolation sealing device being located between a dry gas seal assembly and a bearing housing in the turbomachine, the turbomachine being provided with a main shaft rotating at a high speed, the rear isolation sealing device comprising a carbon ring seal unit and a hydrodynamic pressure type seal unit, wherein the carbon ring seal unit is disposed between the dry gas seal assembly and the hydrodynamic pressure type seal unit, the hydrodynamic pressure type seal unit comprises a rotating assembly and a stationary assembly, the main shaft is provided with a locking nut, wherein two ends of the rotating assembly are respectively clamped by the locking nut and a rotating portion of the dry gas seal assembly, the rotating assembly is sleeved outside the main shaft and rotates at a high speed with the main shaft, the stationary assembly is arranged around the main shaft, and the end surface of the rotating component is attached to the end surface of the static component to form a sealing surface, the sealing surface is axially vertical to the spindle, and the end surface of the rotating component is provided with a hydrodynamic groove.

In the application, when the turbine rotates at a high speed, the isolation gas is divided into two streams, one stream enters the carbon ring sealing unit to isolate the leakage of the outside seal in the dry gas seal, the other stream enters the hydrodynamic pressure type sealing unit, at the moment, the rotating component rotates at a high speed along with the main shaft under the clamping of the locking nut and the rotating part of the dry gas sealing component, and as the hydrodynamic pressure groove is arranged on the end surface of the rotating component, which is in contact with the static component, a micron-sized gas film is formed between the rotating component and the static component (namely a sealing surface) when the rotating component rotates at a high speed, so that the lubricating and isolating effects are realized on the sealing surface, and the sealed non-contact operation is realized. Because the rotating speed of the turbo machinery is very high, the rigidity of the extremely thin air film of the sealing surface is very high, the lubricating oil gas on the bearing side can be effectively isolated, and even if the air supply pressure of the isolation air is lower than the oil gas pressure of the bearing side, the zero leakage of the lubricating oil gas on the bearing side to the dry air seal can be ensured, so that the long-period stable operation of the dry air seal is ensured. The rotating part of the dry gas seal assembly described in the application can be a compressing sleeve and other parts of the dry gas seal assembly, can be selected according to different actual equipment, and is the prior art.

In a preferred scheme of the first aspect, the rotating assembly comprises a rotating ring, a shaft sleeve and a pressing sleeve, the shaft sleeve and the pressing sleeve are both annular and are sleeved outside the main shaft, wherein the shaft sleeve and the pressing sleeve are fixed through a hexagon socket head cap screw, the tail end of the shaft sleeve is abutted against a lock nut, the front end of the pressing sleeve is abutted against the rotating part of the dry gas sealing assembly, and the rotating ring is fixed with the shaft sleeve through a transmission pin and synchronously rotates.

In a preferred scheme of the first aspect, the axle sleeve includes first ring and the second ring of coaxial and integration setting, the tail end and the lock mother butt of second ring, the tail end integration of the front end of second ring and first ring are connected, the tail end of rotating ring and the laminating of the front end of second ring, through the transmission pin carries out the transmission, and is sealed through the sealing washer, the inner edge of rotating ring with the outer fringe butt of first ring.

In a preferred scheme of the first aspect, a groove is formed in a contact position of the tail end of the compression sleeve and the main shaft, the front end of the first ring is inserted into the groove and abutted against a groove wall, the bottom of the groove is fixed to the front end of the first ring through a hexagon socket head cap screw, and the tail end of the compression sleeve is abutted against the front end of the movable ring.

In a preferred version of the first aspect, a centering corrugated strip is provided between the inner edge of the rotating ring and the outer edge of the first ring. Since the rotating ring rotates at a high speed during operation, the very small eccentricity causes additional vibrations, which affect the dynamic performance of the entire device. This application adds the centering ripple area between rotating ring and first ring, can eliminate the gap between the two to guarantee that rotating ring and main shaft are with the axle center, ensure its operating stability. Preferably, the centering corrugated strip is a commercially available tolerance strip of a high alloy material.

In a preferred version of the first aspect, an O-ring is provided between the sleeve and the main shaft.

In a preferred scheme of the first aspect, a wear-resistant layer is attached to the end face of the front end of the moving ring in a spraying or surfacing mode, an annular hydrodynamic pressure groove is formed in the inner side of the wear-resistant layer, the hydrodynamic pressure groove is a one-way rotation groove type or a two-way rotation groove type, the one-way rotation groove type comprises an arc groove, a spiral groove and the like, and the two-way rotation groove type comprises a U-shaped groove, a T-shaped groove and the like. The rotating member base material preferably recommends high-strength precipitation hardening stainless steel, and martensite stainless steel or dual-phase steel can be selected for the working condition that the rotating speed is not very high; the wear-resistant layer can be made of the hard alloy sprayed by supersonic flame and can also be made of the hard alloy subjected to surface overlaying.

In a preferred version of the first aspect, the outer side of the wear resistant layer is a slotless dam region.

In a preferable mode of the first aspect, the hydrodynamic grooves have a groove depth of 3 to 20 μm.

In a preferable mode of the first aspect, a radial width of the dam region located at the outer side is 0.2 to 0.7 of a width of the sealing surface. When the width of the dam area is too small, an air film formed by the fluid dynamic pressure groove is too thick, and isolation air easily leaks outwards over the dam area, so that the sealing performance is reduced; when the width of the dam area is too large, the radial width of the hydrodynamic groove is small, an air film is not easy to form, and the service life and the performance of sealing are also influenced.

In a preferred version of the first aspect, the stationary assembly includes a spring seat, a spring, a push ring and a stationary ring, and the spring seat is fixed to the housing by a socket head cap screw; the end face of the tail end of the static ring is attached to the end face of the front end of the movable ring to form a sealing face, the front end of the push ring is attached to the rear end of the spring, and the front end of the spring is attached to the end face of the bottom of the spring hole in the spring seat. And sealing rings are arranged at the matching positions of the push ring, the static ring and the spring seat. The joint of the end face of the static ring and the end face of the moving ring is realized by the axial pressing force of the spring and the gas pressure of the isolation gas. More preferably, the material of the static ring is high-quality resin-impregnated carbon graphite or antimony-impregnated carbon graphite.

In a preferred aspect of the first aspect, an isolation gas passage is provided in the spring seat, and the isolation gas enters the inner diameter of the stationary ring through the isolation passage. . The isolating gas from the spring seat isolating gas channel is divided into two streams, one stream enters a cavity between the inner diameter of the static ring and the outer diameter of the compression sleeve and then enters the hydrodynamic groove, and the isolating gas at the inner diameter is pumped outwards by utilizing the hydrodynamic effect generated by the hydrodynamic groove, so that a layer of micron-order gas film is formed between sealing surfaces, the lubricating and isolating effects are realized on the sealing surfaces, and the sealed non-contact operation is realized.

In a preferred aspect of the first aspect, a pin is provided between the spring seat and the push ring, and the pin prevents rotation between the spring seat and the push ring. More preferably, the push ring is provided with a limiting structure in the axial direction, so that the static assembly is convenient to mount, and the push ring and the O-shaped ring are prevented from being pushed out of the spring seat by the spring during assembly.

In a preferred arrangement of the first aspect, a pin is provided between the push ring and the stationary ring, and rotation between the push ring and the stationary ring is prevented by the pin. The arrangement ensures that the static ring and the push ring are kept static in the working state.

In a preferable mode of the first aspect, the matching surfaces of the push ring and the stationary ring with the spring seat are provided with O-rings.

In a preferred aspect of the first aspect, the mating surface of the spring seat and the housing is provided with an O-ring.

In a preferred version of the first aspect, the rear end of the spring seat is flared, which arrangement facilitates the removal of lubricant.

In a preferred embodiment of the first aspect, the housing is provided with an oil slinger, and the lock nut is provided with an oil slinger, which can prevent or reduce the diffusion or splashing of the bearing-side lubricating oil to the rear isolation seal.

In an optimal selection scheme of the first aspect, the carbocycle sealing unit includes split carbocycle and gland, and is a plurality of split carbocycle outer wall is banded through extension spring and is the ring form, the inner wall of split carbocycle with compress tightly the cover cooperation, the gland is fixed with the spring holder through hexagon socket head cap screw, just be equipped with O type circle between gland and the spring holder, the terminal surface of split carbocycle front end and the terminal surface laminating of gland tail end, there is a small clearance in order to guarantee the floatability of split carbocycle the terminal surface of split carbocycle tail end and spring holder terminal surface axial to prevent through the round pin that split carbocycle and spring holder from taking place to rotate. The isolation gas coming out of the spring seat isolation gas channel is divided into two streams, one stream enters the outer side sealing leakage cavity of the dry gas seal through a small gap between the split carbon ring and the pressing sleeve, and the isolation effect of the outer side sealing leakage gas of the dry gas seal is achieved.

More preferably, the surface of the compressing sleeve corresponding to the inner side split carbon ring is subjected to wear-resistant coating spraying treatment, so that the wear of the split carbon ring is reduced, and the service life is prolonged. The inside carbon ring seal can increase the axial compression spring, further improve the stability of the carbon ring seal work and reduce the leakage amount of the carbon ring seal.

Compared with the prior art, the invention has the beneficial effects that:

(1) the combined form of the carbon ring seal and the hydrodynamic seal is arranged between the dry gas seal assembly and the bearing box, so that the structure of a static ring and a dynamic ring in the purely hydrodynamic seal is simplified, and the dry gas seal assembly is particularly suitable for occasions with smaller radial space;

(2) because the clearance between the static ring and the dynamic ring is extremely small, and the sealing pressure difference is low, the consumption of the isolating gas is extremely small, namely, the zero leakage of the lubricating oil gas at the bearing side to the dry gas seal of the turbine machinery can be ensured only by the extremely low consumption of the isolating gas through the fluid dynamic pressure type rear isolating sealing device;

(3) even if the pressure of the isolation gas fluctuates and even the pressure of the isolation gas is lower than that of lubricating oil gas on the bearing side, the rear isolation sealing device can work normally, and the dry gas seal is ensured not to be polluted by the oil gas and fail.

Drawings

FIG. 1 is a schematic view of the construction of a seal of the present application;

FIG. 2 is a schematic view showing the shape of a unidirectional rotation groove type hydrodynamic groove provided at the front end of a rotating ring in the present application;

FIG. 3 is a schematic view showing the shape of another unidirectional rotation groove type hydrodynamic groove provided at the front end of the rotating ring in the present application;

fig. 4 is a schematic view showing the shape of a bidirectional rotating groove type hydrodynamic groove provided at the front end of the rotating ring in the present application.

In the drawing, 1 is a shaft sleeve, 2 is a transmission pin, 3 is a movable ring, 4 is a stationary ring, 5 is a spring seat, 6 is a spring, 7 is a pressing sleeve, 8 is an O-ring, 9 is an O-ring, 10 is a centering corrugated strip, 11 is a lock nut, 12 is a push ring, 13 is an O-ring, 14 is an O-ring, 15 is a pin, 16 is a pin, 17 is an inner hexagonal screw, 18 is a tension spring, 19 is a split carbon ring, 20 is a gland, 21 is an inner hexagonal screw, 22 is an oil retainer ring, 23 is an inner hexagonal screw, 24 is a washer, 25 is a main shaft, 26 is a housing, 27 is a first ring, 28 is a second ring, 29 is an oil slinger, 30 is a hydrodynamic groove, and 31 is an outer dam region.

Detailed Description

Unless otherwise defined, technical or scientific terms used herein in the specification and claims should have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. All numerical values recited herein as between the lowest value and the highest value are intended to mean all values between the lowest value and the highest value in increments of one unit when there is more than two units difference between the lowest value and the highest value.

While specific embodiments of the invention will be described below, it should be noted that in the course of the detailed description of these embodiments, in order to provide a concise and concise description, all features of an actual implementation may not be described in detail. Modifications and substitutions to the embodiments of the present invention may be made by those skilled in the art without departing from the spirit and scope of the present invention, and the resulting embodiments are within the scope of the present invention.

In the present description, all leading ends are the media side of fig. 1, i.e., the side where the dry gas seal assembly is located, and all trailing ends are the bearing side of fig. 1, i.e., the side where the bearing housing is located.

Examples

The following will describe in detail the embodiments of the present invention, which are implemented on the premise of the technical solution of the present invention, and the detailed embodiments and the specific operation procedures are given, but the scope of the present invention is not limited to the following embodiments.

Example 1

A combined type hydrodynamic pressure type rear isolation sealing device for a dry gas seal of turbine machinery is structurally shown in figure 1, is arranged between a dry gas sealing assembly and a bearing box and comprises a carbon ring sealing unit and a hydrodynamic pressure type sealing unit, wherein the hydrodynamic pressure type sealing unit consists of a rotating assembly and a static assembly.

The rotating assembly comprises a moving ring 3, a shaft sleeve 1, a pressing sleeve 7, a centering corrugated belt 10, a plurality of O-shaped rings, a transmission pin 2, a plurality of inner hexagonal screws and the like, wherein the pressing sleeve 7 is connected with the shaft sleeve 1 into a whole through the inner hexagonal screws 17, specifically, the shaft sleeve 1 comprises a first ring 27 and a second ring 28 which are coaxially and integrally arranged, a groove is arranged at the tail end of the pressing sleeve 7 and is in contact with a main shaft 25, the front end of the first ring 27 is inserted into the groove and is abutted against the groove wall, the groove bottom of the groove is fixed with the front end of the first ring 27 through the inner hexagonal screws 17, the front end of the second ring 28 is integrally connected with the tail end of the first ring 27, the tail end of the moving ring 3 is fixed with the front end of the second ring 28 through the transmission pin 2, the inner edge of the moving ring 3 is abutted against the outer edge of the first ring 27, the centering corrugated belt 10 is arranged between the inner edge of the moving ring and the outer edge of the first ring 27, and secured by a pin 16. Through the axial compression of the dry gas sealing assembly and the lock nut 11, torque is transmitted to the shaft sleeve 1 and the compression sleeve 7, so that the shaft sleeve 1, the compression sleeve 7 and the main shaft 25 rotate together at a high speed. The sleeve 1 in turn transmits torque to the moving ring 3 via the drive pin 2, causing the moving ring 3 to rotate at high speed with the sleeve 1. The moving ring 3 is made of metal pieces, a high-hardness wear-resistant coating is sprayed or surfacing welded on the sealing end face, and micrometer-level fluid dynamic pressure grooves 30 which are uniformly distributed along the circumferential direction are machined on the coating or surfacing layer in a special machining mode; in the present embodiment, the hydrodynamic grooves 30 are unidirectional spiral grooves, and as shown in fig. 2 or fig. 3, the outer sides of the hydrodynamic grooves 30 are outer dams 31 without grooves. An O-ring 8 is provided between the sleeve 1 and the main shaft 25, and an O-ring 9 is provided between the rotating ring 3 and the second ring 28.

In other embodiments, the hydrodynamic grooves may also be of a bi-directional rotating groove type, as shown in fig. 4, a T-shaped groove.

The static assembly is composed of a static ring 4 made of carbon graphite, a push ring 12, a spring 6, a plurality of O-shaped rings, a spring seat 5, a plurality of pins and a plurality of hexagon socket head cap screws, and the end face of the static ring 4 is attached to the end face of the moving ring 3 by means of axial pressing force of the spring 6 and gas pressure of isolation gas. Specifically, the spring seat 5 is fixed to the housing 26 by a socket head cap screw, and an O-ring is provided therebetween. A push ring 12, a spring 6 and a static ring 4 are arranged in the spring seat 5, wherein the front end of the push ring 12 is attached to the rear end of the spring 6, and the front end of the spring 6 is attached to the bottom of a spring hole in the spring seat 5; the tail end of the push ring 12 is abutted against the front end of the stationary ring 4, and the matching surface of the push ring 12, the stationary ring 4 and the spring seat 5 is provided with an O-shaped ring 13, and one end of the stationary ring 4 close to the axis of the main shaft 25 (namely the inner diameter of the stationary ring) is positioned at the inlet position of the hydrodynamic groove 30. The tail end of the static ring 4 is jointed with the front end of the dynamic ring 3 to form a sealing surface.

In this embodiment, the carbocycle sealing unit includes split carbocycle 19 and gland 20, and 19 outer walls of a plurality of split carbocycles are banded through extension spring 18 and are the ring form, split carbocycle 19 the inner wall with compress tightly the cover laminating, gland 20 is fixed with spring holder 5 through hexagon socket head cap screw 21, and the terminal surface of 19 front ends of split carbocycle and the terminal surface laminating of 20 tail ends of gland, the terminal surface of 19 tail ends of split carbocycle has a small clearance in order to guarantee the floatability of split carbocycle with the 5 terminal surface axial of spring holder. In the present embodiment, the split carbon ring 19, the spring seat 5, the push ring 12 and the stationary ring 4 are retained by the pin 15 to prevent rotation therebetween. An O-ring 14 is provided between the gland 20 and the spring seat 5.

The spring seat 5 is fixed to the housing 26 by a socket head cap screw 23 and a washer 24, an oil slinger 22 is provided on the housing 26, an oil slinger 29 is provided on the lock nut 11, and the tail end of the spring seat 5 is formed in a bell mouth shape, so that the bearing-side lubricating oil is prevented or reduced from spreading or splashing to the hydrodynamic seal unit and can be discharged in time.

When the turbomachinery works, the rotating ring rotates at a high speed, and the isolating gas passes through an isolating gas channel arranged in the spring seat, then is divided into two parts, and respectively enters the carbon ring sealing unit and the fluid dynamic pressure type sealing unit. The isolating gas entering the carbon ring sealing unit enters the outer side sealing leakage cavity of the dry gas seal through a small gap between the split carbon ring and the pressing sleeve, and the isolating effect of the outer side sealing leakage gas of the dry gas seal is achieved. The isolating gas entering the hydrodynamic pressure type sealing unit enters the hydrodynamic pressure groove through a cavity between the static ring and the pressing sleeve, and the isolating gas at the inner diameter is pumped outwards by utilizing the hydrodynamic pressure effect generated by the hydrodynamic pressure groove, so that a layer of micron-order gas film is formed between the sealing end surfaces, the lubricating and isolating effects are realized on the sealing end surfaces, and the sealed non-contact operation is realized. In the view of fig. 1, the isolating gas enters the spring seat from a point A, is divided into two parts at a point B, one part of the isolating gas passes through the split carbon ring to reach a point C, is leaked to the inner side through the carbon ring seal, is mixed with the leakage gas of the outer side seal of the dry gas seal, and is discharged from a point E to perform high-point emptying; the other strand enters the hydrodynamic groove through the point D to generate an air film, so that the lubrication and the isolation of the lubricating oil gas are realized. Because the rotating speed of the turbo machinery is very high, the rigidity of the extremely thin air film on the sealing end face is very high, the micron-level air films on the groove area and the dam area at the outer side can effectively isolate lubricating oil gas at the bearing side, and even if the air supply pressure of isolating air is lower than the oil gas pressure at the bearing side, zero leakage of the lubricating oil gas at the bearing side to dry air sealing can be ensured, so that the long-period stable operation of the dry air sealing is ensured. Because the end surface clearance is extremely small and the sealing pressure difference is low, the consumption of the isolating gas is extremely small, namely, the lubricating oil gas on the bearing side can be ensured to leak to the dry gas seal of other turbine machinery only by the extremely low consumption of the isolating gas by the fluid dynamic pressure type rear isolating sealing device. Even if the pressure of the isolation gas fluctuates and even the pressure of the isolation gas is lower than that of lubricating oil gas on the bearing side, the rear isolation sealing device can work normally, and the dry gas seal is ensured not to be polluted by the oil gas and fail.

The embodiments described above are intended to facilitate the understanding and appreciation of the application by those skilled in the art. It will be readily apparent to those skilled in the art that various modifications to these embodiments may be made, and the generic principles described herein may be applied to other embodiments without the use of the inventive faculty. Therefore, the present application is not limited to the embodiments herein, and those skilled in the art who have the benefit of this disclosure will appreciate that many modifications and variations are possible within the scope of the present application without departing from the scope and spirit of the present application.

Claims

1. A combined type fluid dynamic pressure type rear isolation sealing device for a turbine mechanical dry gas seal is arranged between a dry gas sealing component and a bearing box in the turbine machine, the turbine machine is provided with a main shaft rotating at a high speed, and the rear isolation sealing device is characterized by comprising a carbon ring sealing unit and a fluid dynamic pressure type sealing unit, wherein the carbon ring sealing unit is arranged between the dry gas sealing component and the fluid dynamic pressure type sealing unit, the fluid dynamic pressure type sealing unit comprises a rotating component and a static component, a lock nut is arranged on the main shaft, two ends of the rotating component are respectively clamped by the lock nut and a rotating part of the dry gas sealing component, the rotating component is sleeved on the outer side of the main shaft and rotates along with the main shaft at a high speed, the static component is arranged around the main shaft and is fixed with a shell of the turbine machine, one end face of the rotating component is attached to one end face of the static component to form a sealing face, the sealing face is perpendicular to the axial direction of the spindle, and a hydrodynamic groove is formed in the end face of the rotating component.

2. The combined hydrodynamic pressure type rear isolation seal device for turbomachinery dry gas seal according to claim 1, wherein said rotating assembly comprises a rotating ring, a shaft sleeve and a pressing sleeve, said shaft sleeve and pressing sleeve are both ring-shaped and are both sleeved outside said main shaft, wherein said shaft sleeve and pressing sleeve are fixed by hexagon socket head cap screws, the tail end of said shaft sleeve is abutted with a lock nut, the front end of said pressing sleeve is abutted with the rotating part of the dry gas seal assembly, and said rotating ring is fixed with said shaft sleeve by a driving pin and rotates synchronously.

3. The combined hydrodynamic pressure type rear isolation seal for turbomachinery dry gas seal as claimed in claim 2, wherein said sleeve comprises a first ring and a second ring coaxially and integrally provided, a tail end of said second ring is abutted with said lock nut, a front end of said second ring is integrally connected with a tail end of said first ring, a tail end of said rotating ring and a front end of said second ring are fixed by said driving pin, and an inner edge of said rotating ring is abutted with an outer edge of said first ring;

a groove is formed in the contact part of the tail end of the compression sleeve and the main shaft, the front end of the first ring is inserted into the groove and is abutted against the groove wall, the groove bottom of the groove is fixed with the front end of the first ring through a hexagon socket head cap screw, and the tail end of the compression sleeve is abutted against the front end of the movable ring;

a centering corrugated belt is arranged between the inner diameter of the movable ring and the outer edge of the first ring;

an O-shaped ring is arranged between the shaft sleeve and the main shaft.

4. The combined hydrodynamic pressure type rear isolation seal device for turbomachinery dry gas seal according to claim 3, wherein a wear-resistant layer is attached to the end face of the front end of the rotating ring by means of spraying or build-up welding, and an annular hydrodynamic pressure groove is provided inside the wear-resistant layer, the hydrodynamic pressure groove being a groove type of unidirectional rotation or a groove type of bidirectional rotation;

and the outer side of the wear-resistant layer is a slotless dam area.

5. The combined hydrodynamic pressure type rear isolation seal for turbomachinery dry gas seal as claimed in claim 4, wherein said hydrodynamic groove has a groove depth of 3 to 20 μm;

the radial width of the dam area positioned on the outer side is 0.2-0.7 of the width of the sealing surface.

6. The combined hydrodynamic pressure type rear isolating seal for turbomachinery dry gas seal as claimed in claim 4, wherein said stationary member comprises a spring seat, a spring, a push ring and a stationary ring, said spring seat being fixed to the casing by a hexagon socket head cap screw; the end face of the tail end of the static ring is attached to the end face of the front end of the movable ring to form a sealing surface, the front end of the static ring is attached to the tail end of the push ring, the front end of the push ring is attached to the rear end of the spring, the spring seat is provided with a spring hole, and the front end of the spring is attached to the end face of the bottom of the spring hole.

7. The combined hydrodynamic pressure type rear isolating seal for a turbomachinery dry gas seal as claimed in claim 6, wherein said spring seat is provided with an isolating gas passage through which isolating gas enters said stationary ring inner diameter.

8. The combined hydrodynamic pressure type rear isolation seal for turbomachinery dry gas seal as claimed in claim 6, wherein a pin is provided between said spring seat and said push ring, and rotation between said spring seat and said push ring is prevented by said pin;

a pin is arranged between the push ring and the static ring, and the push ring and the static ring are prevented from rotating through the pin;

the matching surface of the push ring and the static ring on the spring seat is provided with an O-shaped ring;

and an O-shaped ring is arranged on the matching surface of the spring seat and the shell.

9. The combined hydrodynamic pressure type rear isolation seal for turbomachinery dry gas seal as claimed in claim 6, wherein said spring seat has a bell mouth shape at its rear end;

the oil slinger is arranged on the shell, and the oil slinger is arranged on the lock nut.

10. The turbomachinery dry gas seal of claim 6 is with combination formula hydrodynamic pressure type rearmounted isolation sealing device, characterized in that, carbocycle sealing unit includes split carbocycle and gland, and a plurality of split carbocycle outer wall is banded and is the ring form through extension spring, the inner wall of split carbocycle with compress tightly the cover cooperation, the gland passes through hexagon socket head cap screw and spring holder fixed, just be equipped with O type circle between gland and the spring holder, the terminal surface of split carbocycle front end and the terminal surface laminating of gland tail end, there is a little clearance in order to guarantee the floatability of split carbocycle between the terminal surface of split carbocycle tail end and the spring holder terminal surface axially to prevent through the round pin that the split carbocycle from taking place to rotate with the spring holder between.