GB1314655A - Centrifugal air classifiers - Google Patents

Abstract

1314655 Air classifier FIVES LILLE-CAIL 6 July 1971 [7 July 1970] 31739/71 Headings B2H and B2P An air classifier for separating granular material into two fractions of different grain size comprises a vertical, cylindrical classifying chamber 12 provided with an outlet 35 at its upper portion, a rotary plate 24 for dispersing material to be classified situated in the chamber, a deflector 38 in the form of a cap-shaped member arranged coaxially in the chamber below the dispersion plate 24 so as to intercept a falling stream 52 of mainly large particles of the material, the peripheral surface of the deflector 38 flaring downwardly to a lower edge of a diameter smaller than that of the chamber 12 and situated above a wall element, e.g. the conical bottom 16 of the chamber, which narrows downwardly, and an air admission conduit 36 which opens out below the deflector 38 axially of the chamber. A second deflector in the form of an inverted truncated cone 42 is fixed to the classifying chamber casing 10 and has a frusto-conical plate 44 welded to its lower edge and to the casing so that the air current issuing from under the deflector 38 passes twice through the stream 52 and entrains with it any fine particles present therein. The material to be classified is fed through a supply conduit 32, falls on to the plate 24 and is projected by centrifugal force beyond the edge of the plate where it is met by the upward air current which carries the fine particles upwards towards outlets 35. Any large particles entrained by the air is removed as the air current passes through a bladed wheel 28 fixed on the plate 24. The outlets 35 are connected to cyclones 48 which are in turn connected to a fan 50 which recirculates particle-free air to the classifying chamber 12. Cold air or hot gases may be introduced into the chamber 12 with the recycled air to cool or dry the material. The deflectors 38 and 48 may alternatively be vertically adjustable.