GB2034657A

GB2034657A - Valves for feeding to pneumatic conveyors

Info

Publication number: GB2034657A
Application number: GB7933609A
Authority: GB
Original assignee: FRIDHILL T
Current assignee: FRIDHILL T
Priority date: 1978-09-29
Filing date: 1979-09-27
Publication date: 1980-06-11
Also published as: DE2938746A1; DE2938746C2; SE7810233L; GB2034657B

Abstract

A valve arrangement in a suction conveyor intended for the transport of particulate material and having a transport conduit connected to a vacuum source, is disposed between the transport conduit and a discharge opening (5) in a hopper (1b) for particulate material. The valve arrangement comprises a pipe section (6b) which is fixedly connected to the hopper (1b) and, in its circumferential surface, has an aperture (8) which together with the discharge opening (5) makes a communication between the interior of the hopper (1b) and the interior of the pipe section (6b), and a pipe (7b) which is connected to the transport conduit and whose outer diameter is slightly less than the inner diameter of the pipe section (6b). The pipe (7b) passes through and is rotatably mounted in the pipe section (6b) and, in its circumferential surface, has an aperture (10) which in axial direction is disposed substantially opposite the aperture (8) in the circumferential surface of the pipe section. The pipe (7b) and the pipe section (6b) are so designed that there exists between the pipe section and the pipe a continuous annular gap (9) whose extent (a) between the aperture (8) in the circumferential surface of the pipe section (6b) and the aperture (10) in the circumferential surface of the pipe (7b) is adjustable by rotation of the pipe. <IMAGE>

Description

SPECIFICATION Valve arrangement in a suction conveyor for transporting particulate material The present invention relates to a valve arrangement in a suction conveyor intended for the transport of particulate material and having a transport conduit connected to a vacuum source, said valve arrangement being disposed between said transport conduit and a discharge opening in a hopper for particulate material and comprising a pipe section which is fixedly connected to said hopper and the circumferential surface of which is provided with an aperture which, together with said discharge opening, makes a communication between the interior of said hopper and the interior of said pipe section, and a pipe which is connected to said transport conduit and whose outer diameter is slightly less than the inner diameter of said pipe section, said pipe passing through and being rotatably arranged in said pipe section and provided, in its circumferential surface, with an aperature disposed axially substantially opposite said aperture in the circumferential surface of said pipe section.

In sand blast devices, for instance, it is known to collect the sand particles which have been used in the blasting operation, in hoppers which are connected by discharge openings to the transport conduit of a suction conveyor, which conduit is connected to a vacuum source and adapted to bring the particles back to different blasting units of the sand blast devices to permit reuse of the particles. If several succeeding hoppers are connected to one and the same transport conduit, all the hoppers must be supplied with used sand blast particles to substantially the same extent. if one or more of the hoppers are empty while the other hoppers contain varying amounts of used sand particles, air is in fact sucked into the transport conduit by the discharge openings of the empty hoppers, whereby the transport capacity of the suction conveyor is considerably reduced.

The object of the present invention thus is to provide a valve arrangement in a suction conveyor for transporting particulate material, which permits such series connection of a plurality of hoppers to a transport conduit, that the transport capacity of the suction conveyor is but insignificantly reduced in case one or more hoppers are empty.According to the invention, this object is achieved by the provision of a valve arrangement of the type defined in the introduction to the specification, wherein the discharge opening of said hopper and said aperture in the circumferential surface of said pipe section are provided in a lateral face of the hopper and of the pipe section, respectively, and wherein said pipe and said pipe section are of such a design that there is provided between said pipe section and said pipe a continuous annular gap whose extent between the aperture in the circumferential surface of said pipe section and the aperture in the circumferential surface of said pipe is adjustable by rotation of said pipe.

Between the pipe and the pipe section, there is thus a gap whose extent between the aperture in the circumferential surface of the pipe section and the aperture in the circumferential surface of the pipe can be adjusted by rotating the pipe. When a plurality of hoppers are connected in series to a transport conduit, the valve arrangement of each hopper is set such that the above-defined gap extent successively decreases in the different valve arrangements in the direction away from the vacuum source.Thus, if for instance the hopper adjacent the vacuum source, i.e. the hopper with the greatest gap extent, is empty, only a small amount of air is sucked into the transport conduit by the discharge opening of this hopper, the aperture in the circumferential surface of the pipe section, the gap, and the aperture in the circumferential surface of the pipe, and the transport capacity of the suction conveyor thus is reduced only insignificantly.

Since the discharge opening of the hopper and the aperture in the circumferential surface of the pipe section are formed in a lateral face of the hopper and of the pipe section, respectively, the particulate material from the hopper cannot fill and plug the pipe.

The invention will be described in greater detail hereinbelow with reference to the accompanying drawing, in which: Figure 1 shows a series of hoppers which are each connected to a suction conveyor by a respective valve arrangement according to the invention; and Figure 2. on a larger scale, is a cross-section along the line ll-ll in Figure 1.

In Figure 1 of the drawing, there are shown four hoppers la, 1 b, icand ldforcollecting particulate material, such as used sand blast particles to be re-used. The hoppers la-id are covered by a grating 2 through which the particulate material falls down into the hoppers. The hoppers la-ld are each connected by a valve arrangement 3a, 3b, 3c and 3d, respectively, to the transport conduit 4 of a suction conveyor that is connected to a vacuum source. Each hopper 1 a, 1 b, 1 c, id has an opening 5 for the discharge of particulate material.

Each valve arrangement 3a-3d has a stationary pipe section 6a-6d and a pipe 7a-7d passing through the pipe section 6a-6d and rotatably mounted therein. The pipe section 6a-6d is welded to the hopper ia-id about the discharge opening 5 and has in its circumferential surface an aperture 8 which is disposed in the discharge opening 5. The outer diameter of the pipe 7a-7d is slightly less than the inner diameter of the pipe section 6a-6d such that a gap is provided between the pipe section and the pipe. The pipe 7a-7d has in its circumferential surface an aperture 10 which in axial direction is disposed substantially opposite the aperture 8 in the circumferential surface of the pipe section 6a-6d and which extends over approximately 1/4 of the circumference of the pipe 7a-7d.Sealing rings 11,11' are mounted at the ends of the pipe sections 6a-6d around the pipes 7a-7d for sealingly enclosing the interior of the pipe sections 6a-6d. The pipes 7a-7d are connected to each other and to the transport conduit 4 by couplings 12 serving at the same time as fixing means for axial and radial fixation of the pipes. The positions of rotation of the pipes 7a-7d in the pipe sections 6a-6d are releasably fixable by means of locking screws 13a-13d.

The extent a of the gap 9 between the aperture 10 in the circumferential surface of each pipe 7a-7d and the aperture 8 in the circumferential surface of each pipe section 6a-6d can be adjusted in that the pipe is rotated with respect to the fixed pipe - sction. The valve arrangement 3a of the hopper adjacent the vacuum source is then set such that the gap extent a is relatively great, which means that only a very small amount of air is sucked into the transport conduit 4 by the valve arrangement 3a when the hopper 1 a is empty. The valve arrangements 3b-3d of the other hoppers 1 b-id are so set that the gap extent a successively slightly decreases in the direction away from the vacuum source. By such an adjustment of the valve arrangements 3a-3d, the problems discussed above can be eliminated and the transport capacity of the suction conveyor can be maintained even if one or more hoppers la-ld are empty.

Claims

1. A valve arrangement in a suction conveyor intended for the transport of particulate material and having a transport conduit connected to a vacuum source, said valve arrangement being disposed between said transport conduit and a discharge opening in a hopper for particulate material and comprising a pipe section which is fixedly connected to said hopper and the circumferential surface of which is provided with an aperture which, together with said discharge opening, makes a communication between the interior of said hopper and the interior of said pipe section, and a pipe which is connected to said transport conduit and whose outer diameter is slightly less than the inner diameter of said pipe section, said pipe passing through and being rotatably arranged in said pipe section and provided, in its circumferential surface, with an aperture disposed axially substantially opposite said aperture in the circumferential surface of said pipe section, wherein the discharge opening of said hopper and said aperture in the circumferential surface of said pipe section are provided in a lateral face of the hopper and of the pipe section, respectively, and wherein said pipe and said pipe section are of such a design that there is provided between said pipe section and said pipe a continuous annular gap whose extent between the aperture in the circumferential surface of said pipe section and the aperture in the circumferential surface of said pipe is adjustable by rotation of said pipe.

2. Valve arrangement as claimed in claim 1, wherein the aperture in the circumferential surface of said pipe extends over about 1/4 of the circumference of the pipe.

3. Valve arrangement as claimed in claim 1 or 2, wherein a fixing means is provided for fixation of said pipe in different positions of rotation relative to said pipe section.

4. Valve arrangement in a suction conveyor for transporting particulate material, constructed substantially as hereinbefore described and claimed with particular reference to the accompanying figures.