GB2079709A

GB2079709A - Improvements in or relating to rotary valves

Info

Publication number: GB2079709A
Application number: GB8023097A
Authority: GB
Original assignee: Coal Industry Patents Ltd
Current assignee: Coal Industry Patents Ltd
Priority date: 1980-07-15
Filing date: 1980-07-15
Publication date: 1982-01-27
Also published as: GB2079709B

Abstract

A rotary valve (1) having a bladed rotor (6) is provided with cleaning members in the form of chains (16) associated with the pockets (10). During discharge of material from the pockets (10), the chains (16) descend thereby scouring the sides of the pockets (10). <IMAGE>

Description

SPECIFICATION Improvements in or relating to rotary valves This invention concerns improvements in or relating to valves.

Conventional rotary valves include a bladed rotor mounted for rotation within a housing having an inlet and discharge outlet. Pockets are defined between the blades of the rotor which extend at their free extremities into close proximity to the interior walls of the housing. Such valves are employed in solids material systems either for metering solids flow out of a storage hopper or for an air seal in a pneumatic conveying scheme. In particular, valves can be used in coal handling systems in which flow of industrial grades of solid fuel are to be conveyed or metered. One of the problems attendant upon rotary valves is that there is a tendency for the base of the pockets adjacent to the spindle of the rotor to become blocked with fines and this reduces the volume of the pockets thus adversely affecting the performance of the valve.The problem becomes particularly acute when wet solids are being handled through the valve as the build-up of fines occurs rapidly thereby necessitating frequent maintenance.

Furthermore, the build up of fines in the pockets of a valve used for metering purposes gives rise to inaccuracy as the volume of the pockets is constantly changing, thus resulting in variable feed rates.

An object of the present invention is to provide an improved rotary valve with a self-cleaning facility.

Accordingly the invention provides a rotary valve including a rotor on which is mounted a plurality of blades defining pockets therebetween, a housing in which the rotor is mounted for rotation, and inlet and a discharge outlet in the housing, and a cleaning member associated with each pocket and capable, in use, of moving from the base of the pocket towards the extremity of the blades during at least the time when the pocket registers with the discharge outlet.

The cleaning member may be flexible and elongate in form. For example, the member may be a length of chain links attached at each end to a blade of the rotor such that the chain extends substantially the whole length of the associated pocket. The weight of the chain is such that it can move under the force of gravity from a position adjacent the base of the pocket to the extremity of the blades as and when the pocket registers with the discharge outlet.

As an alternative the cleaning member may be elongate and of a lightly sprung material which upon entry of material into the pocket, the member assumes a position adjacent the base of the pocket under the weight of the material but springs outwardly when the weight is relieved, as for example during discharge.

The effect of the movement of the cleaning member is to scourge the pocket of any material adhering to the sides of the blades. In addition, the cleaning member lies or assumes a position in the base of the pocket during receipt of material and in so doing prevents any substantial build-up of fine material in that region. Any fine material which does reach the base of the pocket does not have any significant compaction force applied to it by further incoming material and thus adherence is minimised enabling such fine material to discharge freely with the bulk of the material.

Each blade may have at least one cleaning member attached thereto. Conveniently, each side of each rotor blade has a cleaning member.

By way of example, two forms of rotary valve according to the present invention are described below with reference to the accompanying drawings in which: Figure lisa diagrammatic sectional end view of a first form of rotary valve; Figure 2 is a side elevation of the rotor of the valve; and Figure 3 is a sectional end view of a second form of rotary valve.

Referring to Figures 1 and 2, a rotary valve 1 has a housing 2 with an inlet 4, and an inline discharge outlet 5 disposed vertically below the inlet. A rotor 6 is located within the housing 2 and mounted for rotation. The rotor 6 has a plurality of blades 8 defining therebetween pockets 10 which are adapted in useto receive incoming material 12 through the inlet 4, to carry the material 12 through the housing to discharge same through outlet 5, the rotation of the rotor 6 indicated by arrow 14.

To each side of each blade 8 is attached a cleaning member in the form of a length of chain 16 which under the action of gravity hangs in catenary fashion as seen in Figure 2.

The chains 16 lie adjacent the base of the pocket 10 when, in use, material is received through inlet 4 and remain there under the weight of that material, until discharge takes place upon the relevant pocket register with the outlet 5. The presence of the chains 16 in the base of the pocket 10 effectively prevents all but fine particles from penetrating to the base. Any particles which do reach the base are, however, not subject to the compaction occasioned by the rest of the material in the pocket 10 and can thus be released easily with the bulk of material upon discharge. Once the material vacates the pocket 10, the chains 16 fall under gravity toward the edge of the blades 8 thereby taking with them any material adhering to the sides of the pocket 10.As the rotor 6 rotates further during the cycle, the chains 16 again assume the position adjacent the base of the now empty pocket 10. The respective positions of the chains 16 are to be seen in Figure 2.

With regard to Figure 3, it will be appreciated that in this embodiment, the discharge outlet 5 is angled in relation to the outlet 4. The cleaning members 16 operate in essentially the same way, except that the trailing face of the pocket 10 is scourged more effectively as the blade 8' will be vertical when the material starts to discharge from the pocket 10. The chain 16 on the trailing side of each blade 8' can upon further rotation of rotor 6 fall against the leading side of the trailing face of the pocket, thus giving enhanced impact to the blade resulting in an effective scourging action on the blade.

The cleaning action of the chains 16 thus ensures that the pockets 10 are cleaned during and subsequent to discharge prior to further filling. The rotary valve can therefore operate more efficiently and effectively. In particular, when such a valve is employed as a metering device, reliance can be placed upon the amounts of material passing through the valve.

The invention has particular, but not exclusive application for particulate fuel but it will be understood that the valve is suitable for all materials in particulate, granular, powder or discrete form.

Claims

1. A rotary valve including a rotor on which is mounted a plurality of blades defining pockets therebetween, a housing in which the rotor is mounted for rotation, an inlet and a discharge outlet in the housing, and a cleaning member associated with each pocket capable, in use, of moving from the base of the pocket towards the extremities of the blades during at least the time when the pocket registers with the discharge outlet.

2. A rotary valve according to claim 1 in which the cleaning member is flexible and elongate in form.

3. A rotary according to claim 2 in which each cleaning member is a length of chain attached at at least one end to a side of the associated blade.

4. A rotary according to claim 3 in which the length of chain is attached at each end to a side of the associated blade such that under the action of gravity the chain hangs in catenary form.

5. A rotary valve according to any one of the preceding claims in which a cleaning member is provided on each side of each blade of the rotor.

6. A rotary valve according to any one of the preceeding claims in which the inlet and discharge outlet are aligned.

7. A rotary valve according to any one of claims 1 to 5 in which the discharge outlet is angularly offset in relation to the inlet.

8. A rotary valve substantially as hereinbefore described with reference to Figures 1 and 2, or 3 of the accompanying drawings.

New claims or amendments to claims filed on 29.5.81 Superseded claims 1 New or amended claims: Remaining claims renumbered

1. A rotary valve including a rotor on which is mounted a plurality of blades defining pockets therebetween, a housing in which the rotor is mounted for rotation, an inlet and a discharge outlet in the housing, and a flexible elongate cleaning member associated with each pocket capable, in use, of moving from the base of the pocket towards the extremities of the blades during at least the time when the pocket registers with the discharge outlet.