GB1186229A - Improvements relating to Apparatus for Separating Particles from a Gas Stream into Classified Groups. - Google Patents

Abstract

1,186,229. Centrifugal separators. VICKERS Ltd. 6 Dec., 1968 [23 Oct., 1967], No. 48065/67. Heading B2P. [Also in Division F2] A separator/classifier unit, Fig. 3, for separating particles of finely divided material from an air stream according to size and/or specific gravity, comprises a passage 12 along which the particle-laden air stream is caused to flow and a motor-driven fan 22 for imparting a whirling motion to the air stream in a section of the passage in which the fan is mounted whereby particles of material are thrown by centrifugal force via one or more apertures in the wall of the passage into each of two or more axially-spaced circumferential collecting channels 15, 16 which surround the said section of the passage and which are provided with discharge ducts 18 for the separated particles. The heavier and/or coarser particles will be thrown out first to be collected in the first collecting channel 15 whilst the lighter and/or finer particles will move outwardly less quickly so that they are carried further forward axially and collect in the channel 16. The fan 22 and its motor 24 are mounted at the end of a hollow shaft which is axially adjustable by means of a screw and nut arrangement 26, 27. Axial adjustment of the fan and speed adjustment of the motor provide a control of the classification. The blades 21 of the fan 22 are radial and may comprise bunches or brushes of metal wire or natural or synthetic fibre. Electricallyinsulating material, such as plastics fibre may be used for the fan blades to produce an augmented separation effect due to the electrostatic charge built up on the fibres by friction with the air stream and which will attract particles on to the blades from which they will subsequently break away as agglomerates. The motor may be of the pneumatic, hydraulic or eleotric type and is supplied through leads 29 extending through the hollow shaft. Each channel 15 (16) communicates with the ducts 18 through a tangential opening 17, Fig. 2. Each duct 18 communicates with discharge spout 41 through an air-lock device in the form of a double-beat valve 19 comprising a particle holding chamber 40 in which two closure ball members 34, 35 are urged apart towards their seatings 32, 33, by a spring 36 and are operated in sequence through rockers 37, 38 by a hydraulically, pneumatically or solenoid-actuated double-acting plunger 39 for cyclically opening and closing the valve intermittently or continuously. Fig. 1 shows a cascade installation comprising individual separator/classifier units 10A- 10E connected in a closed air-flow circuit. The air is circulated by a centrifugal fan 13 and is directed to the first unit 10A via a venturi section 30 into which the particulate material is fed through a funnel 31. A bleed port controlled by a tap 42 is provided ahead of the section 30. The unit 10A is connected through branches 60, 61 to units 10B, 10C to which are respectively connected the discharge spouts 41 associated with the collecting channels 15, 16. Thus the classified outputs discharged from the unit 10A and containing a proportion of incompletely separated coarse/heavy and fine/ light particles are subjected to further classification in the units 10B, 10C'. The units 10B, 10C are connected by branches 62, 63 to further units 10E, 10D respectively which are connected via a single duct 64 to the fan 13. The discharge spouts 41 of the upstream collecting channels 15B, 15C of units 10B, 10C are connected to the unit 10D while the discharge spouts of the downstream collecting channels are connected to the unit 10E. The outputs from the upstream and downstream collecting channels 15D, 15E and 16D, 16E of the units 10D, 10E are delivered into storage hoppers 68, 69 as the classified end products. Two other cascade installations are described and illustrated.