GB2121141A

GB2121141A - Valve for the flow control of a fluid comprising solid particles

Info

Publication number: GB2121141A
Application number: GB08215706A
Authority: GB
Inventors: Kessel Matheus Maria Van
Original assignee: Shell Internationale Research Maatschappij BV
Current assignee: Shell Internationale Research Maatschappij BV
Priority date: 1982-05-28
Filing date: 1982-05-28
Publication date: 1983-12-14

Abstract

Valve for controlling the flow of a fluid comprising solid particles having a valve housing 2 with an inlet 3 and an outlet 4, a valve body 5 and a valve seat 6. To allow uniform wear of the sealing surfaces 10 and 11 of the valve body 5 and the valve seat 6, the valve body 5 and the valve seat 6 are both substantially rotational- symmetric, and the valve body 5 is displaceably and separately rotatably arranged in the valve housing 2. <IMAGE>

Description

SPECIFICATION Valve for the flow control of a fluid comprising solid particles The invention relates to a valve for controlling the flow of a fluid comprising solid particles, said valve comprising a valve housing having an inlet and an outlet, a valve body movably arranged within the valve housing and a valve seat adapted to cooperate with the valve body.

One of the most important requirements for valves is that the risk of leakage between the valve body and the valve seat is minimal.

A great variety of valves are known and commercially applied on a large scale. The known valves can be subdivided into two groups, viz.

those having a continuous contact between the sealing surfaces of the valve body and the valve seat, wherein the valve body is rotated for opening or closing the valve, and those having a noncontinuous contact between the sealing surfaces of the valve body and the valve seat, wherein the valve body is displaced for opening or closing the valve. All these known valves are however not suitable for controlling the flow of fluids comprising solid particles.

A disadvantage of valves of the type having a non-continuous contact between the valve body and the valve seat consists herein that prior to closing such a valve the sealing surfaces of the valve body and the valve seat should be intensively cleaned to avoid entrapment of solids, which can easily result in wear and consequently leakage of the valve. In practice such a thorough cleaning of the sealing surfaces during operation of the valve has found to be not sufficient enough to avoid any entrapment of solids.

The above problem of solids entrapment between the sealing surfaces occurs to a much less extent in valves of the above-mentioned continuous contact type. However, once solids have been entrapped between the sealing surfaces of this type of valves, which sooner or later will inevitably occur, the relative movement between the valve body and the valve seat necessary for closing or opening the valve, will cause non-uniform wearing of the sealing surfaces due to scratching by the entrapped solids. Erosion at the scratch points on the sealing surfaces caused by process differential pressures across the valve will subsequently accelerate wear, resulting in a rapid increase of the leakage in the valve.Further, it should be noted that corrosion of the material(s) forming the sealing surfaces will also lead to non-uniformities of the sealing surfaces, resulting in a decrease of the sealing and therefore leakage of the valve.

The object of the present invention is to overcome the problems with the known valves when used for controlling the flow of fluids comprising solid particles, by providing a valve wherein the sealing properties are hardly effected by the adverse influence of solids passing through the valve.

The valve for controlling the flow of a fluid comprising solid particles thereto comprises according to the invention a valve housing having an inlet and an outlet, a substantially rotationalsymmetric valve body being displaceably and separately rotatably arranged within the valve housing and a substantially rotational-symmetric valve seat arranged within the valve housing, the valve body and the valve housing having substantially coinciding axes, and being provided with sealing surfaces adapted to cooperate with one another.

The arrangement of a rotational-symmetric valve seat in combination with a rotationalsymmetric, displaceable and separately rotatable valve body allows a uniform wear of the sealing surfaces by rotation of the valve body over the valve seat. Such a uniform wear of the sealing surfaces is compensated by displacing the valve body towards the valve seat, so that sealing contact between the valve body and the valve seat is guaranteed even in a particles rich environment.

The invention will now be described by way of example only with reference to the accompanying drawing showing a suitable embodiment of the invention.

The drawing shows a valve, generally indicated with reference numeral 1 , for controlling the flow of a fluid comprising solid particles. The valve 1 is composed of a valve housing 2 having an inlet 3 and an outlet 4, a valve body 5 and a valve seat 6, arranged within the valve housing 2. The valve housing 2 is provided with flanges 7 and 8, at the inlet 3 and the outlet 4, respectively, for incorporating the valve into for example a pipeline system (not shown). The valve body 5 and the valve seat 6 are both rotational-symmetric, the valve body 5 being circle-cylindrical and the valve seat 6 being annular. Further, the valve body 5 is so mounted in the valve housing 2 that it can be displaced in axial direction and that it can be separately rotated. The valve seat 6 is fixedly mounted in the valve housing 2, against an inclined shoulder 9 thereof.The valve body 5 and the valve seat 6 are each provided with frustoconically shaped sealing surface 10 and 11, respectively, adapted to cooperate with one another for closing the valve. As shown in the drawing the sealing surfaces 10 and 11 form part of a cone having an apex pointing away from the valve body 5.

The sealing surface 10 of the valve body 5 forms the outer surface of an annular shoulder 1 2 arranged on top of the valve body 5. The annular shoulder 12 and the valve seat 6 are suitably formed of different materials wherein the one material wears preferentially to the other material.

Suitable materials are for example stellite, wolfram carbide, silicon nitride, silicon carbide and alumina.

For moving the valve body 5, a rod-shaped element 13, arranged in a recess 14, is secured to the valve body 5. The rod-shaped element 1 3 can be provided with not shown means, for example a handle, enabling easily manoeuvring the rodshaped element 1 3 and therefore the valve body 5. Further the rod-shaped element 13 can be connected to a circuit enabling automatic operation of the valve in response to, for example, pressure changes in a pipeline system in which the valve has been incorporated.

The operation of the valve shown in the drawing is as follows. When a mass of solid particles or a fluid containing solid particles is to be transferred through a pipeline system, the shown valve can advantageously be incorporated in the system for controlling the flow therein. The inlet 3 and the outlet 4 of the valve 2 are connected to transfer conduits for example by means of bolted flange constructions. For allowing matter to pass through the valve, the rod-shaped element 1 3 and therefore the valve body 5 are held in a retracted position to uncover the outlet 4.

In this position matter can flow from the inlet 3 via the interior of the valve housing 2 into the outlet 4. When the fluid flow has to be stopped, the rodshaped element 1 3 and therefore the valve body 5 are moved inwardly until the sealing surfaces 10 and 11 are in a mating position. In this position the valve body 5 is rotated via the rod-shaped element 13. By the rotation of the sealing surface 1 0 over the fixed sealing surface 11 of the valve seat 6, the solid particles entrapped between the valve body 5 and the valve seat 6 are removed by a grinding action and sealing of the surfaces 10 and 11 is achieved.Provided that the sealing surfaces are sufficiently hard with respect to the solids in the valve and suitably cooperative with one another, wear of the sealing surfaces will be uniform due to the rotation, so that the sealing of the valve is not adversely affected.

Although the actual wear of the sealing surfaces in the proposed valve may be greater than in known types of valves, this wear will be of a uniform nature, owing to the rotational symmetricity and the relative rotation of the valve body 5 and the valve seat 6. By choosing a material for the shoulder 12 of the valve body 5 which wears preferentially to the valve seat 6, it is ensured that the sealing of the valve after excessive wear can be easily corrected by removing the valve body 5 from the housing 2 and replacing the annular shoulder thereof.

It should be noted that the invention is not restricted to a valve provided with a separate rodshaped element for moving the valve body 5. In an alternative embodiment of the invention for example the valve body itself may be extended to a location outside the valve housing, so that the valve body can be directly moved.

Further, the valve may be provided with a plurality of outlets instead of a single outlet as shown in the drawing. Such a plurality of outlets are advantageously uniformly distributed over the circumference of the valve housing.

The invention is not restricted to a valve having sealing surfaces formed of any of the materials mentioned in the above. Any other suitable material may be applied provided that such a material is sufficiently hard compared to the solids transferred through the valve. Examples of such materials are for example ceramic materials and hard plastics materials.

Finally it should be noted that the invention is not restricted to a valve with the particular position of the valve body as shown in the drawing. It is also possible to arrange the valve body upstream of the valve seat in the inlet of the valve.

Claims

1. Valve for controlling the flow of a fluid comprising solid particles, comprising a valve housing having an inlet and an outlet, a substantially rotational-symmetric valve body being displaceably and separately rotatably arranged within the valve housing, and a substantially rotational-symmetric valve seat arranged within the valve housing, the valve body and the valve seat having substantially coinciding axes and being provided with sealing surfaces adapted to cooperate with each other.

2. Valve as claimed in claim 1, wherein the sealing surfaces are substantially frusto-conically shaped.

3. Valve as claimed in claim 2, wherein the sealing surfaces each form part of a cone having an apex pointing away from the valve body.

4. Valve as claimed in any one of the claims 1-3, wherein the sealing surfaces are each formed of a hard metailic material.

5. Valve as claimed in any one of the claims 1-4, wherein the sealing surfaces are formed of materials chosen from the group consisting of stellite, wolfram carbide, silicon nitride, silicon carbide and alumina.

6. Valve as claimed in any one of the claims 1-3, wherein the sealing surfaces are each formed of a ceramic material.

7. Valve as claimed in any one of the claims 1-6, wherein the sealing surfaces are formed of materials having different wearing properties.

8. Valve as claimed in claim 7, wherein the sealing surface of the valve body preferentially wears to the sealing surface of the valve seat.

9. Valve for controlling the flow of a fluid comprising solid particles substantially as described with particular reference to the accompanying drawing.