RU2443926C2 - Heat-resistant gate valve - Google Patents

Abstract

FIELD: machine building.

SUBSTANCE: heat-resistant gate valve includes body and damper with feedthrough holes, sleeve seats in the housing pockets, which are provided with end and radial seals, stock, packing gland, cover plate and flywheel. At that, sleeve seats are provided with skirts, with radial seals on their outer surfaces, which are installed with possibility of end contact with the housing and sleeve seat; at that, sleeve seats are installed in the housing pockets so that manufacturing clearance is formed between them and the housing, the size of which is accepted equal as to the value to thermal change of transverse sizes of gate vale and linear sizes of sleeve seats. In the gate valve there made is a bore in which a sleeve is installed with possibility of forming the clearance between stock and damper, kinematic connection with lower end of stock connected to it by means of a pin.

EFFECT: invention provides the possibility of sealing the high-temperature medium, and structural elements and seals are maintained, at multiple cycles of opening - closing, heating and cooling of damper, as well as the possibility of supporting optimum contact stresses.

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Description

The invention relates to the field of valve engineering and is intended for wellhead valves, mainly for steam injection wells of oil fields.

Known gate valve (see US Pat. RF №2.378547, IPC F16K 3/02, publ. 10.01.2010), comprising a housing with a through hole installed in the housing with a drive gate, sealing seats, bushings on both ends of the gate installed with the possibility of pressing the seats to the end surface of the gate.

Design disadvantages:

- such a design of the valve will not allow it to be used if a high-temperature medium, for example, hot oil, water or steam, is pumped through it, since there is a temperature difference between the parts installed inside the body and the body itself.

This will result in a thermal elongation of the sleeve and seat, and also increase the transverse dimensions of the gate. This will lead to a sharp increase in contact stresses at the saddle - end surface of the gate, which can lead to jamming.

The connection of the rod with the gate through the thread requires high precision manufacturing of the mating parts and can lead to uneven contact stresses at the saddle - gate interface during assembly and the occurrence of bending moment on the rod.

Sealing the annular gaps between the sleeve, the seat and the body, using highly elastic sealing rings limits the scope of such valves to a temperature of T = 100 ° C.

Known gate valve (see US Pat. RF No. 2208731, IPC ⁷ F16K 41/04, publ. 07.20.2003).

The design of the valve includes a housing with a cover, a gate connected to the stem, seats with mechanical and radial seals, and stem seals.

Design disadvantages:

- the use of radial and mechanical seals mounted on saddles implies their execution from elastomeric materials, for example rubber, which simplifies the design of the sealing assembly, but at the same time narrows the scope of application, if necessary, to seal the high-temperature medium;

- pressing the saddle to the end of the gate with Belleville springs.

Known gate valve (see US Pat. RF No. 2128308, IPC ⁶ F16K 3/20, publ. 03/27/1999), adopted by the authors as a prototype.

The gate valve comprises a housing with passage openings. Inside the housing there is a gate, movable saddles with a sealing element and independent supporting bushings, each of which forms an annular gap with a corresponding movable saddle. The sealing element of the movable seat on the side facing the gate is made along the radius to increase the reliability and durability of the work. The saddles are pressed to the gate with springs located in the nests around the perimeter.

Design disadvantages:

- the complexity of the design, high precision manufacturing of the mating parts of the saddles and their interaction with the gate are necessary;

- according to the application text, the saddles are pressed to the gate by springs, but in the figure (see figure 2) the rings pressing the seal are connected to the saddle by a bolt connection, which means that the springs can be installed only in the holes from the end part facing the inner surface of the housing .

To obtain sufficient axial force from the springs to ensure sealing of the gap between the seat and the gate, it is possible with a sufficiently large overall dimensions of the structure:

- The main axial force directed to the compression of the seat seal from the gate surface is created by the perception of the pressure drop acting on the end face of the seat from the side of the installation of radial sealing rings, which, judging by the figure, have a larger diameter than the diameter of the sealing rings at the end of the seats.

- Ensuring a tight contact at the boundary of the end of the gate - the end of the supporting sleeve is more than problematic, since it is created due to the perception of the pressure of the medium being sealed on the end face of the saddle, which has a significantly smaller diameter than the diameter of the supporting sleeve. That is, the specific contact stress at the interface between the gate and the support ring will be much less than that necessary to ensure sealing of the medium being sealed.

From the figures attached to the patent, it is absolutely unclear how the installation of saddles and support rings inside the body is ensured.

- The use of elastic sealing elements both at the end of the seats, and radial limits the scope of such valves on the temperature of the medium being sealed, i.e. the scope of this design depends on the thermal resistance of the elastic seals.

The analysis of technical solutions showed that the gate valve is known (see US Pat. RF No. 2244862, Mcl. F16 41/07, publ. 20.01.2005), which is the closest technical solution.

The valve comprises a housing with passage channels, a gate with a passage hole, movable sleeve seats located in the housings, sealing elements, springs, a spindle with stuffing box packing, a cover and a flywheel.

The node connecting the rod to the gate is made in the form of a T-shaped groove in the gate, into which the response T-shaped finger is inserted, which allows for a limited mutual movement of the gate relative to the rod by the amount of the technological gap formed during the manufacture and installation of the mating parts.

The disadvantage of this design is the significant operating costs associated with the complexity of the design.

The technical result that can be obtained by implementing the invention:

- the ability to seal a high-temperature medium, while maintaining the integrity of structural elements and seals with multiple opening cycles - closing, heating and cooling of the gate;

- the ability to maintain optimal contact stresses at the boundary: mechanical seal of the saddle - mechanical surface of the gate while maintaining the elastic properties of the sealing elements made of heat-resistant material;

- the ability to compensate for thermal changes in the sizes of the gate and seats, while maintaining the necessary contact stresses on the sealing surface of the gate;

- the ability to provide self-centering of the gate between the end surfaces of the seats, with the exception of the transmission of axial load to the rod.

The technical result is achieved by the fact that the heat-resistant gate valve comprises a body and a gate with passage holes, sleeve seats in the housing sockets equipped with mechanical and radial seals, a stem, stuffing box, cover and a flywheel. In this case, the sleeve seats are equipped with skirts, with radial seals on their outer surface, installed with the possibility of mechanical contact with the body and the sleeve seat, and the sleeve seats are installed in the housing sockets, with the formation of a technological gap between them and the body, the size of which is assumed to be equal to the thermal changing the transverse dimensions of the gate and the linear dimensions of the sleeve seats, and in the gate there is a bore in which the sleeve is installed, with the possibility of a gap between the rod and take, kinematic connection with the lower end of the rod associated with it with a pin.

The design of the heat-resistant gate valve is illustrated by the drawings:

- figure 1 the design of the slide gate valve in the context, in the open position;

- figure 2 in the context of the design of the node connecting the rod with the gate.

The gate valve consists of a housing 1, with through holes 2 and sockets 3 for sleeve seats 4, equipped with skirts 5.

The sleeve seats 4 are installed in the sockets of the housing 1, with the formation of a gap 6 with it.

On the outer surface of the skirts 5 installed packages of heat-resistant radial seals 7, pressed by the end surface of the sleeve seats 4 to the end surface in the slots of the housing 1.

On the end surface of the sleeve seats 4, facing the surface of the gate 8, there are annular grooves 9 in which end seals 10 are installed, which are in end contact with the sealing surface of the gate 8.

In the upper part of the gate 8, perpendicular to its end surface, a cylindrical bore 11 is made (see FIG. 2), in which a sleeve 12 with a thread 13 is installed for communication with the lower end of the rod 14 (see FIG. 2). Perpendicular to the axis in the rod 14, a hole is made in which a pin 15 is passed, rigidly connected to the sleeve 12.

Between the body of the rod 14 and the gate 8, above the location of the sleeve 12, a gap 16 is formed (see figure 2).

The body of the rod 14, in the upper part, is covered by a package of sealing cuffs 17 installed in the cover 18 and pushed from below, through the nut 19, the packing follower 20.

A collar 21 is made on the outer surface of the rod 14, with which it interacts with the packing follower 20 in its highest position.

Heat-resistant slide gate valve operates as follows:

A package of heat-resistant radial seals 7 is installed on the outer surface of each of the skirts 5 of the sleeve seats 4, and when the gate 8 is inserted into the gap between the sleeve seats 4, the material is pre-compressed of the heat-resistant radial seals 7, while maintaining elastic properties. At the same time, a gap 6 is formed between the body of the sleeve saddles 4 and the inner surface of the body 1, the size of which is determined from the conditions for its elimination, with a thermal change in the transverse dimensions of the gate 8 and the linear dimensions of the sleeve seats 4, with axial load closing 1. The technological gap existing during installation between the skirt 5 and the body 1 of each of the sleeve seats 4 is determined from the condition of maintaining its minimum value, with a thermal increase in the diametrical dimensions of the skirts 5, in the case of neniya thermostable slide gate valves for passing and sealing of the high-temperature environment, such as steam. The sealing of the gate 8 is carried out by maintaining contact stresses in the mechanical seals 10 located in the annular grooves 9 of the sleeve seats 4.

The mechanical seals 10 of the sleeve seats 4 extend beyond their end surfaces by an estimated value determined on the basis of the known technological properties of the material from which they are made, as well as taking into account the factor of thermal change in the dimensions of the mating parts, gate 8 and sleeve seats 4.

Such material, in our case, is determined by the GRAFLEX material (see Ilyin ET “Russian high-performance seals GRAFLEX.” Materials of the industry meeting of the chief mechanics of oil refining and petrochemical enterprises in Russia and the CIS. Kirishi, 2002, pp. 59-266 ), as well as Domashnev A.D., Khmelniker V.P. “Stuffing box packing for NPP valves”. M., Atomizdat, 1980, p. 112 pp.).

From informational materials “The influence of the use of GRAFLEX seals on the construction of stuffing box assemblies of centrifugal and piston pumps”. Avdeev V.V., Ilyin E.T., Ulanov G.A.), published on the website (http://unichimtek.ru/publications/publications-herm 94.html), it is known that, along with the high temperature resistance of GRAFLEX It has a low coefficient of friction K = 0.02-0.12 and high thermal conductivity. Moreover, the residual elasticity of this material is K _y = 8-12% with a good compressibility index, which is K _c = 20-60%. Based on these data, the height of the mechanical seal 10 in the annular grooves 9 of the sleeve seats 4 and the size of their outlet above their end surfaces are determined.

With a known depth of the annular groove 9, the height of the mechanical seal 10 is determined as follows

h _k.u = h _k · k _y ,

where h _KU - the height of the output of the mechanical seal 9 above the end surface of the sleeve seats 4;

h _to - the depth of the annular groove 8, mm;

k _y - coefficient of residual elasticity of the material.

When a high-temperature medium is supplied through a slide gate valve, under the influence of temperature, the transverse dimensions of the gate 8 and the linear dimensions of the sleeve seats 4 are thermally changed, which eliminates the gap 6 and the end contact of the sleeve seats 4 with the housing 1.

This solution is aimed at protecting the package of heat-resistant radial seals 7 from additional compressive axial loads, which may exceed the heat-resistant seals allowed for the material.

When the through holes 2 of the housing 1 are blocked by the gate body 8, the latter, under the influence of a pressure differential, is pressed against the end surface of the sleeve seat 4 and moves it until it contacts the body of the housing 1, without transmitting the axial compressive load to the package of heat-resistant radial seals 7 on the skirt 5 of the sleeve seat 4 located on the right.

At the same time, the package of heat-resistant radial seals 7 on the skirt 5 of the sleeve seat 4, located on the left, presses the mechanical seal 10 against the surface of the gate 8 under the action of excessive pressure, while maintaining tight contact.

The gate 8 moves towards the end surface of the sleeve seat 4, and its upper end moves relative to the lower end of the rod 14, connected by a thread with the sleeve 12 by the size of the technological gap 16. This eliminates the transmission of bending moment to the rod 14 and uneven load on the package sealing cuffs 17.

The specifics of mounting sleeve seats 4 with a skirt 5, on which a package of heat-resistant seals 7 is installed in the socket 3 of the housing 1, is that when mounting sleeve saddles 4 with a package of heat-resistant seals 7 on skirts 15, the latter are pre-compressed by axial load until a tight contact with the inner surface of the nest 3 of the housing 1 and the transfer of radial compressive load on the outer surface of the skirt 5. The wall thickness of the skirt 5 is determined from the condition of ensuring its elastic deformation while maintaining the integrity of the ma material of heat-resistant radial seals 7 and maintaining the necessary contact stresses on the surface of the skirt 5 and in the socket 3 of the housing 1.

When the diametrical dimensions of the skirt 5 are thermally changed, the internal stresses in the material of the heat-resistant radial seals 7 are compensated, with the contact stresses on the sealing surfaces in the nests 3 of the housing 1 and the skirts 5 of the sleeve seats 4 being preserved, as well as the safety and performance of the heat-resistant radial seals 7.

Claims (1)

Heat-resistant gate valve, comprising a housing and a gate with passage openings, sleeve seats in the housing sockets equipped with mechanical and radial seals, a stem, stuffing box, cover and a flywheel, characterized in that the sleeve seats are equipped with skirts with radial seals on their outer surface, installed with the possibility of face contact with the housing and the sleeve seat, and the sleeve seats are installed in the housing sockets with the formation of a technological gap between them and the housing, the size of which is accepted It is equal in magnitude to the thermal change in the transverse dimensions of the gate and the linear dimensions of the sleeve seats, and in the gate there is a bore in which the sleeve is installed, with the possibility of forming a gap between the rod and the gate, kinematic connection with the lower end of the rod connected with it by a pin.

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