US2887178A - Apparatus for separating pneumatically conveyed material - Google Patents

Description

May 19, 1959 G. LARSSON ET AL APPARATUS FOR SEPARATING PNEUMATICALLY CONVEYED MATERIAL Filed Sept. so, 1957 ed States Patent APPARATUS FOR SEPARATIN G PNEUMATICALLY 'CONVEYED MATERIAL Gustaf Larsson and Sven Wallin, Jonkoping, Sweden,

assignors to Aktiebolaget Svenska Fliiktfabriken, Stockholm, Sweden The present invention relates to improvements in ap paratus for separating pneumatically conveyed material consisting of a cyclone having a tangential inlet, an outlet at the bottom for separated material and an outlet for the transporting medium in form of a tube (central tube) coaxially arranged in the cyclone casing.

In pneumatic conveying plants it is necessary to use some type of separating device for separating the material from the transporting air. Such devices are usually designed as cyclones, where the material is discharged at the bottom of the cyclone and the transporting air is discharged through an outlet tube arranged in the centre of the cyclone. In pneumatic conveying plants of this kind it is also desirable to be able to regulate the quantity of transporting air and for this purpose it has been the practice to use volume governors arranged in one of the pipes of the conveying system. It is an object of the invention to combine these separate means to one single apparatus.

The apparatus according to the invention consists of a cyclone having a tangential inlet, an outlet at the bottom for separated material and an outlet for the transporting medium in form of a tube (central tube), being coaxially arranged in the cyclone casing and is characterized by a volume governor arranged in said central tube and provided with a floating body, actuated by the discharging transporting medium. The governor operates automatically to regulate the quantity of transporting medium being discharged, and when it is in a position corresponding to a predetermined minimum quantity of the transporting medium it actuates a breaking means or switch, which in turn controls the feed means for supplying material to the pneumatic conveying system. A suitable embodiment of the apparatus is characterized in that the volume governor is designed in accordance with the Swedish patent specification 133,723 and the corresponding U.S. Patent No. 2,765,812, and consists of a transverse partition arranged in the central tube at its outlet end and having a central opening with a tubular floating body therein.

2,887,178 Patented May 19, 1959 The invention will now be described more in detail with reference to the accompanying drawing, illustrating by way of example one embodiment of an apparatus according to the invention.

In the drawing, a cylindrical casing 1 of a cyclone is provided with an inlet 2 for the mixture of material and transporting air and with an outlet 3 for separated material. The transporting air discharges through a central tube 4 which terminates in a chamber 5 arranged above the cyclone and provided with a preferably tangential outlet 6. some distance above the outlet of the central tube, said disk being fastened by means of rods 7:: to the roof of the cyclone proper.

A volume governor is mounted in the tube 4. The. floating body 8 of the volume governor, which is designed in accordance with the U.S. Patent 2,765,812, is mounted forvertical movement in an opening 10 of a disk 9. The body 8 consists of a horizontal annular disk 8a and a cylindrical tubular part 8b joined with said disk. By the dynamic pressure of the discharging transporting air acting upon the disk 8a, the floating body 8 will approach to a greater or lesser extent the disk 7 and thereby regulate the outlet opening between said disk and the upper 'ice end of the cylindrical part 8b of the floating body. The

' body of said volume governor is arranged to actuate a The body is mounted for vertical movement in the opening and substantially seals against the edges of the opening. The body is provided with an annular plate facing the medium current and is operable to be moved by the dynamic pressure of the medium current to a greater or lesser extent towards a fixed plate spaced above the out let of the central tube and which functions as a valve seat for the tubular body.

According to still another feature of the invention, there is a second tube fixedly mounted in the lower part of the cyclone. A suitably conical valve disk is mounted within the secondtube for closing the upper end of the tube, said valve disk being movably suspended and arranged to be forced downwards by material which may, on occasion, accumulate in the cyclone. The downward movement is opposed by the action of a biasing force tending to keep the disk in its closing position, and, in its lower limit position, actuates said circuit breaking means.

lever 14 by means of the lower end 11b of said rod when the body is in a position corresponding to a predetermined minimum quantity of air. The lever in the illustrated embodiment is pivoted at the point 15 outside the casing 1 of the cyclone and is arranged to actuate a microswitch 43 or similar breaking means inserted in a control circuit for the driving means of the device for feeding the material into the transporting medium.

In the lower part of the cyclone there is a conical disk 18 mounted for vertical movement in a cylinder 19. The disk will be pressed downwards by the material which may, on occasion, accumulate in the lower part of the cyclone. A rod 17 suspends the disk 18 from the above mentioned lever 14, so that it may operate the switch 43 in the same manner as the volume governor. In order to counteract the weight of the disk 18, the lever 14 is held in a neutral position by means of a spring 16.

In the described apparatus the quantity of air passing through the cyclone, by means of the volume governor, may be maintained constant or may be varied in accord ance with variations in the quantity of material supplied to the apparatus, and the supply of material will furthermore by cut off if the quantity of transporting air by any reason should decrease so that its velocity falls below a suitable value for conveying said material. One form of apparatus for controlling and/or cutting oif the supply of material to the cyclone is disclosed in our copending patent application, Serial No. 687,275, filed September 30, 1957. Furthermore the interruptions caused by supplying too much material or by defects in the operation of the discharge device will be prevented by the operation of the disk 18.

What we claim is:

1. In a pneumatic material-conveying system, a cyclone for separating the material from the transport medium comprising an upright cylindrical casing, a tangential inlet in the upper portion of said casing for said medium and the entrained material, a central tube mounted coaxially in the upper portion of said casing and depending below said inlet to constitute an exhaust outlet for said transport medium, an outlet at the bottom of said casing for the In said chamber there is a disk 7 spaced at material separated from said transport medium, and a volume governor in said tube having a floating body supported for movement between upper and lower limit positions by the medium flowing through said exhaust outlet and means cooperable with said body to regulate the flow of said medium in accordance with the position of said body so as to maintain the flow of said medium substantially constant, and switch means operated by said volume governor when the body is in its lower limit position.

2. Apparatus according to claim 1 wherein the volume governor consists of a transverse partitionmounted in the central tube at its upper end and provided with a central opening, and a tube-likemember: carried by said floating body andv vertically displaceable in the opening in substantially sealingengagementwith the edges of the opening, said body having an annular plate facing the medium currentand being operable to bemoved vertically by the dynamic: pressureof the medium flowing therethrough, and a transverse-plate mounted above the outlet of the centraltube-cooperable with said tube-like member as a valveseat so as to regulate the flow of the medium in accordance with the clearance between said tube and said plate.

3. Apparatus according to claim 1 including a vertical tube mounted in the lower part of the casing and having an annular upper end wall, and a conical valve disk mounted in said tube and cooperable with said end wall to close the upper end of the tube, bias means tending to keep the disk in its closing position, said valve disk being suspended for vertical displacement to be forced downwards by material accumulated in the cyclone against said bias means, and connections to said switch means to oper ate the same when the disk is in its lower limit position.

References Cited in the file of this patent UNITED STATES PATENTS 2,496,180 Smith Jan. 31, 1950 2,731,102 James Jan. 17, 1956 2,776,725 Wood Jan. 8, 1957 2,830,674 Dolf et al Apr. 15, 1958 FOREIGN PATENTS 697,328 Great Britain Sept. 23, 1953

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