GB926290A - Vertical classifier - Google Patents

Abstract

926,290. Centrifugal separators. MICROCYCLOMAT CO. Jan. 2, 1962, No. 110/62. Class 23. [Also in Group XXVI] Dry pulverulent material; e.g. flour, is fed through an inlet 79 at the top of the rotor housing of a vertical classifier, Fig. 1, to the periphery of the rotor which is journalled at 17, 19 and has an air or gas inlet 57, Fig. 2, surrounding and substantially co-extensive with its classifying section 48, 49 through which the fine fraction of the material is centripetally extracted and discharged from an axial duet 50 through a discharge duct 83 via a fan housing 12 wherein the rotor carries pegs or rods 37. The rotor shaft 16 is driven by a belt 22 and is reinforced by a disc 26 and a tube 23 which is secured by rings 24, 25. An annular ring 29 supported on the ring 24 is provided with a number of vertical blades 30 which distributes the material feed uniformly and co-operates with a corrugated lining 31 in the housing cover 15 to break up agglomerates in the material. The classifying section of the rotor is supported between plates 46, 47 and consists of slotted vertical blades 48 interlocked with slotted, horizontal, spaced-apart discs 49. The blades 48 may be flat and disposed radially or at an angle to the rotor axis or, as shown, they may be curved. Rods 51 mounted between the plates 46, 47 form a cage around the classifying section. The duct 50 is formed between the tube 23 and the inner blade and disc peripheries. The effective length of the classifying section is varied by means of a selector disc 90 which is axially adjustable within the duet 50 in the manner described in Specification 923,331. The inlet air is introduced through a scroll housing 14 provided with vertical baffles 58, 59, 60 and one or more horizontal baffles 61 and is directed to the rotor periphery through louvres 63 which may be stationary or, as shown, of variable pitch which is adjustable through gearing 67, 68 by a crank 71 provided with a pivoted latch 72 engaging in an appropriate notch in a plate 73 on the housing. The housing cover 15 is removably clamped at 75 on the housing 14. The bottom plate 46 of the classifying section is supported by a ring 45 on a flanged ring 35 splined to members 36 screwed to the disc 26. The pegs or rods 37 extend through and are supported by the flanges 38, 39 of the ring 35 and by an annular plate 34 secured to the ring 25. An annular disc 41 mounted between the ring 45 and the flange 38 carries radial blades 42 which on rotation induce a slight negative pressure in an annular chamber 43 in which the material coarse particles enter from the space between the cage 51 and the louvres 63 and are thrown out centrifugally by the disc 41 towards discharge ducts 44 tangentially connected to the chamber. Provided between the chamber 43 and the interior of the fan housing 12 is a pneumatic seal chamber 85 into which air is drawn through damped inlet openings 88 due to the reduced pressure in the chamber 43 and flows out into the chamber 43 and the housing 12, thereby preventing accidental intermingling of the coarse and fine particles. In a modification, Fig. 4, the rods 37 are replaced by tubes 37A extending through the plate 34 and having at one end an adjustable cap 100 with a slot 101 through which air is forced into the tube as the rotor is rotated. Near its closed end the tube has a slot 102 in communication with a pneumatic seal chamber 105 bounded by resilient seals 104 at the peripheries of which the pressurized air flows into the chamber 43 and the fan housing 12. In operation, the material introduced at 79 falls by gravity on to the ring 29 which throws it centrifugally outwards. After being uniformly distributed by the blades 30 the material enters the classifying zone between the rotor and the louvres 63 where it is subjected to vortex action by the rods 51 and the blades 48. The fine particles pass through the blades into the duct 50 and into the fan housing where they are extracted through the duct 83. The coarse particles are thrown centrifugally outwards and fall by gravity on to the disc 41 where they are again acted on by centrifugal force and are withdrawn through the ducts 44 at the periphery of the chamber 43.