Patent GB-1073925-A (GB)
Title: Air classifiers
IPC: B07B4/02
Filed: 1964-08-10
Abstract: 1,073,925. Centrifugal classifiers, pneumatic separators. KLOCKNER-HUMBOLDTDEUTZ A. G. Aug. 10, 1964 [Aug. 10, 1963], No. 32520/64. Headings B2H and B2P. Classifying air supplied via an inlet pipe 21, Fig. 1, to the bottom of a cylindrical and/or conical housing 1 of an air classifier flows upwardly through an outer annular chamber 15 supplied at the top with material to be classified by means of a device, e.g. a rotating distributor disc 18, and enters with a swirl into the upper region of an inner chamber 5 from which the substantially cleaned air is discharged through a central pipe 8, separated material being discharged through one or more apertures 6, 10 at the lower ends of the chamber 5 and of the housing 1. The air is drawn through the classifier by a fan connected to the pipe 8. The coarse particles fall, against the rising air stream in the chamber 15, along the inside of the housing 1 and are discharged by means of a pipe 11 and a chute 13 which is provided with a flap 14 acting as an air seal. The fine particles are entrained by the air stream which is swirled by guide plates 4 as it enters the chamber 15 where further separation takes place by centrifugal action and by deflection of the air around a baffle 9 before it enters the pipe 8 carrying with it only the finest particles. The finer particles are removed from the chamber 5 via the aperture 6 which may be divided into a number of passages each provided with an air-sealing flap 22. A guide member 7 causes uniform distribution of the finer particles in the chamber 15 so that the lightest of these particles are carried upwards in the rising air stream and again returned to the chamber 5 whereas the heaviest sink to the bottom and are removed with the coarse particles. Alternatively, a separate discharge may be connected to the bottom of the chamber 5 for separate collection of the fine particles. In Fig. 2, the air and finest particles are removed from the chamber 5<SP>1</SP> via a stepped pipe 24-26 from which four pipes, two of which are shown at 28, 30, branch off tangentially and obliquely downwards. These pipes are covered by a frusto-conical ishell 31 on the sloping surface of which the material to be classified fed from a chute 38 is distributed by a rotating disc 35. In a modification of Fig. 2, Fig. 4 (not, shown), the disc 35 is eliminated and the frusto-conical shell is replaced by a truly conical one on to the apex of which the material is dropped from the chute. In a further modification, Fig. 5 (not shown), the wall (42) of the inner chamber (45) is surrounded by an intermediate shell (56) which is parallel to the housing wall (41) and defines therewith an outer annular chamber (55) of constant width. The guide member (47) in that case is much wider and extends to the lower peripheral edge of the intermediate shell. Alternatively, the intermediate shell (56) is so constructed that the width of the annular chamber (55) decreases towards the top so that the cross-sectional area of the chamber (55) is substantially constant and hence the air velocity within the chamber is substantially constant.