CN215333597U

CN215333597U - Dry air sealing device for-196 ℃ low-temperature centrifugal pump

Info

Publication number: CN215333597U
Application number: CN202121710049.8U
Authority: CN
Inventors: 袁子予
Original assignee: Chengdu Shilun Sealing Co ltd
Current assignee: Chengdu Shilun Sealing Co ltd
Priority date: 2021-07-26
Filing date: 2021-07-26
Publication date: 2021-12-28
Anticipated expiration: 2031-07-26

Abstract

The utility model discloses a dry gas sealing device for a low-temperature centrifugal pump at-196 ℃, which comprises a rotating assembly and a static ring compensation assembly, wherein the rotating assembly comprises a rotating ring and a copper gasket; the static ring compensation assembly comprises a static ring, a static ring seat, an inner sheath, a static ring seat, a metal corrugated pipe and a metal corrugated pipe seat, an energy storage sealing ring is arranged between the static ring and the static ring seat, and a dynamic pressure groove is arranged on the end face of the rotating ring. The utility model provides preset closing force for the sealing surface of the rotating ring and the static ring through the compression value of the metal corrugated pipe; after the cryogenic pump is finished, liquid gas enters the pump, and the dry gas seal becomes a shutdown seal by the combined force of the preset closing force and the acting force of the medium on the sealing surface before the pump is started, so that the cryogenic medium is prevented from leaking; after the pump is started, the friction heat between the sealing surfaces leads the liquid film to be heated and vaporized, the dynamic pressure groove introduces vaporized gas to generate axial thrust between the sealing surfaces of the rotating ring and the static ring, and when the push-away force and the closing force of the mechanical seal are balanced, the contact type mechanical seal becomes a non-contact type dry gas seal.

Description

Dry air sealing device for-196 ℃ low-temperature centrifugal pump

Technical Field

The utility model relates to a dry air sealing device for a low-temperature centrifugal pump at the temperature of-196 ℃, and belongs to the technical field of mechanical sealing of cryogenic low-temperature centrifugal pumps.

Background

The low-temperature centrifugal pump at the temperature of-196 ℃ is important equipment for conveying liquefied gases such as liquid oxygen, liquid nitrogen, liquid argon, LNG and the like.

The technology of the cryogenic low-temperature centrifugal pump is originated in Europe and America, the technology is widely used in industrial production for less than one hundred years, and the special low-temperature pump is reformed and enters China. In China, air separation plant production enterprises such as Hangzhou oxygen, Xinya and three-well are from imitation to self-design production of the pumps, but the quality difference with products in Europe and America is very large, and the Europe and America are still in absolute monopoly on the technology and market of domestic cryogenic pumps.

For a considerable part of continuously working (non-stop) cryogenic pumps for conveying liquid gas (such as process pumps in the air separation industry), the dry gas seal used is a product in Europe and America.

The dry gas seal for the cryogenic pump has the advantages of long service life (over 12000 hours), small leakage, strong reliability and high economic benefit, which is an obvious fact.

As with the dry gas seal in the mechanical seal for the ordinary pump, one end (hard ring) between the sealing surfaces which are jointed by the dry gas seal for the cryogenic pump is provided with a hydrodynamic pressure groove. The groove shape has asymmetry (such as arc groove, spiral groove, etc.), it has rotation direction requirement to pump shaft or the pump shaft rotation direction determines the rotation direction of dynamic pressure groove, it is called unidirectional groove in industry.

Another type of dynamic pressure groove is symmetrical, (e.g., T-shaped, rectangular, christmas tree, etc.), which in use does not require rotational orientation of the pump shaft, and is known in the industry as a bi-directional groove.

From the perspective of practitioners producing a dry gas seal for a cryogenic pump, a dry gas seal for a pump of the bi-directional tank type is better than a dry gas seal of the unidirectional tank type, since simplicity is efficiency, which is an economic benefit.

The dry gas seal for the low-temperature pump works in liquid gas, when the dry gas seal works, friction is generated between a seal rotating ring and a stationary ring under the action of axial compression elastic force of a corrugated pipe and medium pressure, heat generated by friction enables liquid between sealing surfaces and around to be vaporized (certainly, temperature rise caused by stirring heat is also generated), gas with saturated vapor pressure is introduced into a hydrodynamic groove, and due to the existence of a dynamic groove dam, gas is introduced into a position of a weir to be blocked to generate thrust between the sealing surfaces. When the thrust force is balanced with the axial compression elasticity of the corrugated pipe and the closing pressure of the medium acting sealing surface, the closed sealing surface is opened. The open sealing surfaces form a rigid film of gas therebetween that is sufficiently rigid to withstand the pressure of the liquid gas in the pump so that it cannot leak out of the separated sealing surfaces. Meanwhile, the sealing end face rubs with gas, friction heat is reduced, rigidity of a rigid gas film is reduced, and the sealing face has a fitting trend under the action of axial elasticity of the corrugated pipe and pressure of the medium acting on the sealing face. When the distance between the sealing surfaces is small enough, the friction heat is increased, the gap between the sealing surfaces is increased … …, the dry gas sealing is self-balancing sealing, and the thickness of the rigid gas film between the sealing surfaces is changed uninterruptedly.

The dry gas seal for the low-temperature pump is soaked in liquid gas under saturated pressure to work, the friction temperature rise of the sealing surface is vaporized into gas corresponding to the saturated vapor pressure, and blocking gas or buffer gas does not need to be introduced into the sealing surface, so that the dry gas seal has the unique advantage. But the current low-temperature centrifugal pump at the temperature of-196 ℃ has the problem of low-temperature medium leakage.

SUMMERY OF THE UTILITY MODEL

In order to overcome the problems in the prior art, the utility model provides a dry air sealing device for a low-temperature centrifugal pump at the temperature of-196 ℃.

The technical scheme provided by the utility model for solving the technical problems is as follows: the dry gas sealing device for the low-temperature centrifugal pump at the temperature of 196 ℃ below zero comprises a rotating component and a static ring compensation component, the rotating component comprises a rotating ring and a copper gasket, the static ring compensation component comprises a static ring, a static ring seat, an inner sheath, a static ring seat, a metal corrugated pipe and a metal corrugated pipe seat, the left end and the right end of the metal corrugated pipe are respectively welded on the metal corrugated pipe seat and the static ring seat, the static ring is welded on the static ring seat, an energy storage sealing ring is arranged between the static ring and the static ring seat, the static ring and the static ring seat form static sealing with the end surface of the part by the energy storage sealing ring, the inner sheath is fixed in the inner hole of the metal corrugated pipe seat, the metal corrugated pipe seat is welded in the inner hole of the static ring seat, the static ring seat is provided with an anti-rotation pin for preventing the static ring from rotating, the end face of the rotating ring is attached to the end face of the static ring to form a sealing face, and the end face of the rotating ring is uniformly provided with a plurality of dynamic pressure grooves.

The further technical scheme is that the number of the dynamic pressure grooves is 6-20.

The further technical scheme is that a sealing gasket is arranged on the static ring seat.

The further technical scheme is that the static ring seat is provided with a static ring axial limiting shaft clamp.

The further technical scheme is that the stationary ring seat, the metal corrugated pipe seat and the stationary ring seat are all made of 304 stainless steel.

The further technical scheme is that the metal corrugated pipe is made of high-nickel elastic alloy.

The further technical proposal is that the bidirectional groove for the dynamic pressure groove on the rotating ring.

The utility model has the following beneficial effects: the utility model provides preset closing force for the sealing surface of the rotating ring and the static ring through the compression value of the metal corrugated pipe; after the cryogenic pump completes purging and precooling, liquid gas enters the pump, and the dry gas seal becomes a shutdown seal by the combined force of the preset closing force and the acting force of the medium on the sealing surface before the pump is started, so that the cryogenic medium is prevented from leaking; after the pump is started, the friction heat between the sealing surfaces leads a liquid film between the sealing surfaces to be heated and vaporized, the dynamic pressure groove introduces vaporized gas to generate axial thrust between the sealing surfaces of the rotating ring and the static ring, and when the pushing-away force and the closing force of the mechanical seal are balanced, the contact type mechanical seal becomes a non-contact type dry gas seal.

Drawings

FIG. 1 is a schematic structural view of the present invention;

FIG. 2 is a schematic view showing the structure of the rotating ring in the embodiment.

Detailed Description

The technical solutions of the present invention will be described clearly and completely with reference to the accompanying drawings, and it should be understood that the described embodiments are some, but not all embodiments of the present invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings, and are only for convenience of description and simplicity of description, but do not indicate or imply that the device or element being referred to must have a particular orientation, be constructed and operated in a particular orientation, and thus, should not be construed as limiting the present invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance.

In the description of the present invention, it should be noted that, unless otherwise explicitly specified or limited, the terms "mounted," "connected," and "connected" are to be construed broadly, e.g., as meaning either a fixed connection, a removable connection, or an integral connection; may be a mechanical connection. The specific meanings of the above terms in the present invention can be understood in specific cases to those skilled in the art.

In addition, the technical features involved in the different embodiments of the present invention described below may be combined with each other as long as they do not conflict with each other.

As shown in figure 1, the dry gas sealing device for the-196 ℃ low-temperature centrifugal pump comprises a rotating assembly and a static ring compensation assembly. The rotating assembly comprises a rotating ring 9 and a copper gasket 11; the static ring compensation component comprises a static ring 8, a static ring seat 5, an inner sheath 1, a static ring seat 4, a metal corrugated pipe 3 and a metal corrugated pipe seat 2, the left end and the right end of the metal corrugated pipe 3 are respectively welded on the metal corrugated pipe seat 2 and the static ring seat 5, the static ring 8 is welded on the static ring seat 5, an energy storage sealing ring 6 is arranged between the static ring 8 and the static ring seat 5, the static ring 8 and the static ring seat 5 form static sealing with the end surface of the part 8 by the energy storage sealing ring 6, the inner sheath 1 is fixed in the inner hole of the metal corrugated pipe seat 2, the metal corrugated pipe seat 2 is welded in the inner hole of the static ring seat 4, an anti-rotation pin 10 for preventing the static ring 8 from rotating is arranged on the static ring seat 4, an axial limiting shaft clamp 7 for the static ring 8 is arranged on the static ring seat 5, and the static ring component is positioned by a thread M and fastened on the end face of the volute of the cryogenic pump (but not limited to a threaded connection mode); the rotating ring 9 and the copper gasket 11 are mounted on the pump shaft and synchronously rotate with the pump shaft under the screw tightening pressure of the pressing sleeve 13, the rotating ring 9 is attached to the end face of the stationary ring 8 to form a sealing face, and 8 dynamic pressure grooves 14 are axially arranged on the rotating ring 9.

In this embodiment, a sealing gasket 12 is disposed on the stationary seat 4.

In this embodiment, the inner jacket 1, the metal bellows seat 2, the metal bellows 3, the stationary ring seat 4, the stationary ring seat 5, the energy storage sealing ring 6, the shaft clamp 7, the stationary ring 8, and the rotation preventing pin 10 form a dry gas sealing stationary ring assembly. The copper gasket 11 is pressed tightly on the step of the pump shaft phi of 58mm under the axial force of the pressing sleeve 13, and the copper gasket 11 becomes a static seal to form a dry gas seal rotating ring assembly.

The stationary ring assembly compresses the sealing gasket 12 (flexible graphite +304+ flexible graphite) against the end face of the volute casing of the pump head by 6-M5 hexagon socket head cap bolts.

When the device is installed, the metal corrugated pipe compresses a set value to provide preset closing force for the sealing surfaces of the rotating ring and the static ring.

After the cryogenic pump finishes 'purging' and 'precooling', liquid gas enters the pump, and the resultant force of the preset closing force and the acting force of the medium on the sealing surface enables the dry gas seal to become a shutdown seal, so that the cryogenic medium is ensured not to leak.

After starting the automobile, the low-temperature mechanical seal is changed from a contact type parking seal to a non-contact type mechanical seal with an opened sealing surface.

After the product of the figure is driven on site, the output pressure reaches 3.8 MPa.

The low-temperature dry gas seal is used on a low-temperature process pump which runs continuously or does not stop for a long time, so that the low-temperature dry gas seal has great economic effect on air separation enterprises and is a development trend.

Although the present invention has been described with reference to the above embodiments, it should be understood that the present invention is not limited to the above embodiments, and those skilled in the art can make various changes or modifications to the equivalent embodiments without departing from the scope of the present invention, and all simple modifications (such as dynamic pressure groove shape with other symmetrical and asymmetrical shapes), equivalent changes and modifications to the above embodiments according to the technical essence of the present invention are within the scope of the present invention.

Claims

1. The dry gas sealing device for the low-temperature centrifugal pump at the temperature of-196 ℃ comprises a rotating component and a static ring compensation component, wherein the rotating component comprises a rotating ring and a copper gasket, and is characterized in that the static ring compensation component comprises a static ring, a static ring seat, an inner sheath, a static ring seat, a metal corrugated pipe and a metal corrugated pipe seat, the left end and the right end of the metal corrugated pipe are respectively welded on the metal corrugated pipe seat and the static ring seat, the static ring is welded on the static ring seat, an energy storage sealing ring is arranged between the static ring and the static ring seat, the static ring and the static ring seat form end face static sealing with a part by the energy storage sealing ring, the inner sheath is fixed in an inner hole of the metal corrugated pipe seat, the metal corrugated pipe seat is welded in the inner hole of the static ring seat, an anti-rotating pin for preventing the static ring from rotating is arranged on the static ring seat, and the end faces of the rotating ring and the static ring are jointed to form a sealing face, and a plurality of dynamic pressure grooves are uniformly distributed on the end surface of the rotating ring.

2. The dry gas sealing device for a-196 ℃ low temperature centrifugal pump according to claim 1, wherein the number of the dynamic pressure grooves is 8.

3. The dry gas sealing device for a-196 ℃ low-temperature centrifugal pump according to claim 1, wherein a sealing gasket is arranged on the static ring seat.

4. The dry gas sealing device for the-196 ℃ low-temperature centrifugal pump according to claim 1, wherein a shaft clamp for axially limiting the stationary ring is arranged on the stationary ring seat.

5. The dry gas sealing device for the centrifugal pump at-196 ℃ C is characterized in that the static ring seat, the metal corrugated pipe seat and the static ring seat are all made of 304 stainless steel.

6. The dry gas sealing device for a-196 ℃ low-temperature centrifugal pump according to claim 1, wherein the material of the metal corrugated pipe is high-nickel elastic alloy.