Cyclone

Details Cyclone Cyclone

1997-11-20

1999-06-29

Woo, Jay H.

Gas separation

Deflector

Fixed gas whirler or rotator means

96384, B01D 4512

Patent

active

059170654

DESCRIPTION:

BRIEF SUMMARY
The present invention relates to a cyclone for treating a gas flow containing dust, said cyclone having a cyclone chamber of circular cross-section and a vertical axis, said chamber having a gas flow inlet for substantially horizontal injection of the gas flow into the cyclone chamber, and a lower dust outlet for removing dust, which is separated from the gas flow in the cyclone chamber, and a central tube of circular cross-section, which is coaxially arranged in the upper portion of the cyclone chamber and whose lower end forms a lower gas flow inlet and whose upper end forms an upper gas flow outlet.
A cyclone of this type is used as, for example, dust separator in plants for drying paper pulp or some other fibrous pulp, an air flow containing particles, such as fibres, being passed through the cyclone so as to be relieved of particles.
In operation, the cyclone is subjected to strong vibrations, which, especially if the cyclone is large, may cause its shaking to pieces. These vibrations are probably caused by a flow phenomenon which is called PVC (Precessing Vortex Core) and is described in more detail by A K Gupta, D G Lilley and N Syred in "Swirl Flows", pp 191-198, published in 1984 by ABACUS PRESS, Massachusetts, USA.
The object of the present invention is to provide a cyclone, in which the PVC phenomenon and, thus, the problem of vibrations are eliminated or at least reduced to a considerable extent.
According to the invention, this object is achieved by a cyclone, which is of the type mentioned by way of introduction and characterised in that an elongate insert element, which is vertically inserted in the central tube, is so designed and extends in such a manner downwards in the central tube from the upper end thereof that a circumferential gap exists between the insert element and the central tube, said gap having a preferably constant cross-sectional area that does not increase in the direction of the gas flow.
In a preferred embodiment, the insert element projects a distance above the central tube.
Preferably, the insert element extends down to the lower end of the central tube.
In a preferred embodiment, the insert element is rotationally symmetrical and suitably coaxially inserted in the central tube.
The insert element suitably is hollow. The hollow insert element can have a closure at its upper and/or lower end.
The invention will now be described in more detail with reference to the accompanying drawing, which is a schematic longitudinal section of a cyclone according to the present invention in the axial direction.
The cyclone illustrated in the drawing comprises a cyclone chamber 1 of circular cross-section and having a vertical axis. A horizontal inlet pipe 2, which forms an upper gas flow inlet, extends substantially tangentially into the cyclone chamber 1 in the upper portion thereof. A fan (not shown) is arranged to inject, via the inlet pipe 2, a dust-containing gas flow F, for example an air flow containing fibres, into the cyclone chamber 1.
The cyclone chamber 1 comprises, in the shown embodiment, a circular-cylindrical portion 3, a truncated conical portion 4, which is connected to the lower part of the circular-cylindrical portion 3, a circular-cylindrical portion 5; which is connected to the lower part of the truncated conical portion 4, and a truncated conical portion 6, which is connected to the upper part of the circular-cylindrical portion 3 and forms the top of the cyclone chamber 1. The cyclone chamber portions 3, 4, 5 and 6 are coaxially arranged. The lower portion 5 forms a lower dust outlet for removing dust or particles, e.g. fibres, which are separated from the gas flow in the cyclone chamber 1.
A central tube 7 of circular cross-section is coaxially arranged in the circular-cylindrical portion 3 of the cyclone chamber 1 and extends, via the truncated conical portion 6 thereof, out of the cyclone chamber 1. The central tube 7 comprises a circular-cylindrical tubular portion 8 and, connected to the lower end thereof, a truncated conical tubular portion 9. The central

REFERENCES:
patent: 1265763 (1918-05-01), Fender
patent: 2034023 (1936-03-01), Cheltnam et al.
patent: 3405803 (1968-10-01), Bahr et al.
patent: 3970335 (1976-07-01), Curington et al.
patent: 4842145 (1989-06-01), Boadway

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