GB2032582A

GB2032582A - Improvements relating to apparatus for handling bulk or fluent materials

Info

Publication number: GB2032582A
Application number: GB7842359A
Authority: GB
Original assignee: Westinghouse Brake and Signal Co Ltd
Current assignee: Siemens Mobility Ltd
Priority date: 1978-10-28
Filing date: 1978-10-28
Publication date: 1980-05-08
Also published as: GB2032582B

Abstract

Fluidised material can be handled generally in the same manner as normal fluids but particular problems arise in the operation of isolating or shut-off valves due to the granular nature of bulk material. The isolating valve described is of a double shutter type in which the upstream valve 8 is first closed to substantially cut-off the material flow and the downstream valve 9 subsequently closed to provide a gas-tight seal. <IMAGE>

Description

SPECIFICATION Improvements relating to apparatus for handling bulk or fluent materials This invention relates to apparatus for handling bulk or fluent materials Particulate and granulate bulk materials are conveniently handled by fluidising the material, that is by forcing air or other suitabie gas through a mass of the material to cause it to assume fluid like properties. The fluidised material can then be conveyed to its destination through a pipe and its flow therein controlled by special valves. A problem which arises in such valves is combining the functions of shutting off the material flow and providing a gas-tight seal. The present invention seeks to provide an isolating valve which overcomes these problems by separating the functions of shutting-off the material flow and providing the gas-tight seal.

According to the present invention, an isolating valve for controlling or shutting-off the flow of bulk material in a pipe-line comprises a valve body having inlet and outlet ports and an intermediate region or chamber lying therebetween, a first or upstream valve means operable to interrupt the flow of material through the inlet port into the intermediate chamber, and a second or downstream valve means operable to provide a gas-tight seal between the intermediate chamber and the outlet port.

Preferably the operating mechanisms of the valves are not linked so that the valves may be operated independently, normally the upstream valve is closed to shut-off material flow before the downstream valve is closed to provide the gas tight seal.

Further features of the invention will be apparent from the following description of the preferred embodiment in which reference will be made to the accompanying drawing, which shows a longitudinal section through a double shutter isolating valve.

The double shutter isolating valve shown in the drawing comprises a generally cylindrical hollow valve body having at one end an inlet port 1 and at the opposite end an outlet port 2. The inlet and outlet ports communicate with an intermediate chamber 3 within the valve through a first or upstream shutter valve 4 and a second or downstream shutter valve 5 respectively. The shutter valves 4 and 5 are independently operable by means qf operating mechanisms 6 and 7 respectively. The valve shutters 8 and Sare both disposed within the intermediate chamber 3 and may be moved into position against valve seats 10 and 11 respectively to seal off the intermediate chamber 3 from the inlet or outlet port as appropriate.

In operation, with the valves 4 and 5 open, fluidised bulk material enters the valve through inlet port 1 in the direction of arrow 12, passes through the intermediate chamber 3, through the open valve 5 and the outlet port 2. To interrupt the flow of material and isolate the inlet port 1 from the outlet port 2, the valve 4 is first closed so the valve shutter 8 moves into position against the valve seat 10 and halts the flow of bulk material without necessarily providing a gas-tight seal, subsequently the valve 5 is closed and the shutter 9 is moved into position against the valve seat 11 to provide a gas-tight seal.Thus, in operation, the function of shutting-off material flow is separated in space and time from the function of providing a gas-tight seal so that interference between the two functions is reduced as, for example, might occur if only one valve is used and the valve seat is contaminated by bulk material debris. Since the upstream valve 4 substantially halts the flow of bulk material when closed, the downstream valve 5 which provides the gas-tight seal, operates in a relatively clean environment and may be further assisted in providing a gas-tight seal by purging of the valve seat 11 with air or other suitable gas blown in through a purge vent or vents, one of which is shown at reference 13.The valve shutters 8 and 9 are both housed entirely within the intermediate chamber 3 in both their open and closed positions so that no change in internal volume of the chamber 3 is involved when one or both of the valves is operated.

In the particular example being described, the valve body is cast in two complementary halves 14 and 1 5 which are bolted together by means of centre flanges 16, 17, respectively, to form a composite valve body, further end f!anges 18, 19 are provided for connection of the valve into a conveyor pipe line. The particular valve is intelded for operation in a high temperature environment and each half 14, 1 5 of the valve body is provided with a refractory ceramic liner 21, respectively.

The valve seats 10, 11 are also formed of special hard material to obviate wear. Silicon carbide seats are made by slip-casting an initial valve seat member which after a preliminary firing may be machined to its final size. The material is such that, after final firing, it assumes its hard properties without any further change in dimensions. The valve seat can then be pressed into the valve body.It will also be seen from the drawing that the seating faces of both valves are towards the intermediate chamber so that material flowing through the valve may impinge on the seating face of the downstream valve 5, thus the internal diameter of the downstream valve 5 is preferably larger than that of the upstream valve 4 so that the main flow through the valve passes through the centre portion of the downstream valve without impinging on the valve seat face and avoiding excessive wear of the seat face.

Although it has been previously mentioned in connection with the operating mechanisms 6 and 7 for the valves that there is no mechanical linkage between them, it is clearly preferable that at least some form of interlock is incorporated in the control mechanism so that the downstream valve 5 is not closed or an attempt made to close it until the upstream valve 4 has substantially shut-off the flow of bulk material. Such an interlock may be built into the control or actuating means for the valve operating mechanisms 6 and 7.

Claims

1. An isolating valve for controlling or shuttingoff the flow of bulk material in a pipe-line comprises a valve body having inlet and outlet ports and an intermediate chamber lying therebetween, first or upstream valve means operable to interrupt the flow of material through the inlet port into the intermediate chamber and second or downstream valve means operable to provide a gas-tight seal between the intermediate chamber and the outlet port.

2. An isolating valve according to Claim 1, wherein one or more purge vents are formed in the valve body for directing a gas jet towards the seat of the second or downstream valve means.

3. An isolating valve according to either Claim 1 or Claim 2, wherein the first and second valve means are independently operable.

4. An isolating valve according to any preceding claim including valve operating means operative to close the first or upstream valve means in advance of the second or downstream valve means.

5. An isolating valve according to any preceding claim, wherein the inlet and outlet ports, and the upstream and downstream valve seats are axially aligned.

6. An isolating valve according to any preceding claim wherein the valve means comprise shutter valves.

7. An isolating valve according to Claim 6, wherein the valve shutters are disposed within the intermediate chamber.

8. An isolating valve according to any of Claims 5, 6 or 7, wherein the valve seat diameter of the downstream valve means is greater than the valve seat diameter of the upstream valve means.

9. An isolating valve according to any preceding claim, wherein the valve seats are formed of hard material.

10. An isolating valve according to Claim 9, wherein the hard material is silicon carbide.

11. An isolating valve according to any preceding claim, wherein the interior of the valve body is lined with refractory ceramic material extending at least between the valve ports and each respective valve seat.

12. An isolating valve according to any preceding claim, wherein the valve body comprises separately formed parts of complementary configuration, each of which includes a valve means and associated port.

13. An isolating valve substantially as described herein with reference to the accompanying drawing.