GB1075469A - An air classifier - Google Patents

Abstract

1,075,469. Pneumatic separators. KLOCKNER-HUMBOLDT-DEUTZ A.G. July 1, 1964 [Aug. 2, 1963], No. 27171/64. Heading B2H. In an air classifier comprising a vertical chamber 1, e.g. of rectangular cross-section, through which a current of air flows from the bottom upwards and into which the material to be classified is fed through an opening 6 in one side of the chamber, an inclined grid 2 is arranged below the opening 6 and extends to the opposite side of the chamber where a discharge aperture 10 for the coarse particles is provided substantially at the level of the grid, the grid forming one or more gaps (5), Fig. 2 (not shown) extending in the same direction as the grid itself. The material to be classified is fed from a hopper 9 via a bucket wheel 8 which also serves as an air seal. The coarse particles are discharged through a conduit 11 provided with a bucket wheel 12 also forming an air seal. The air is fed at 3 and evacuated at 4. The grid bars are tear-shaped in cross-section so that the gaps between them widen towards the top. The width of the gaps, the grain size of the material to be classified and the air velocity in the vicinity of the grid are adapted to one another in such a manner that the course particles do not fall through the gaps and are not carried away by the air current but remain in suspension in the gaps or just above the grid and move towards the discharge aperture 10. The fine particles are carried by the air towards the aperture 4. In a modification, Fig. 3 (not shown), the material to be classified is introduced with the air through a bent pipe (13). A pivotable guide plate (15) guides that part of the stream, which due to the effect of centrifugal force in the bend (14) contains the material, towards the inlet opening (6') and the other part of the stream, i.e the bulk of the air, into the air inlet (3') below the grid (2').