GB1239956A - Improved method of and apparatus for treating a mixture of materials - Google Patents

Abstract

1,239,956. Centrifugal separators. P. H. L. SAGET. 20 June, 1968 [21 June, 1967], No. 29358/68. Heading B2P. A mixture of materials is separated into its various constituents by flowing the mixture along a path while subjecting it to a centrifugal force acting substantially perpendicular to the general direction of the path and simultaneously suddenly diverting the mixture flow, at intervals along the whole of its path, from the general direction of the path in a direction which is substantially perpendicular to both the centrifugal force and the general direction of the path. The invention is applicable to the separation of liquids, of solids from liquids, of solid particles or liquid droplets from gases and of impure wash water from gases washed thereby. Separation is carried out in a platetype centrifuge in which the plates 8, Figs. 5 and 6, have orifices 9 which are angularly staggered from one plate to the next, the orifices and the spaces between the plates constituting zig-zag passages having a generally axial direction. Thus each time the mixture flow passes through an orifice it is diverted from its generally axial direction 10 along bends 11, 12 so that centrifugal forces f due to the deflection tend to propel the heavy constituent along trajectories 13 whereby it impinges on the plate opposite and is more efficiently moved radially outwardly by the centrifugal force F due to rotation of the plates. The plates 8 may, as shown, be flat annular discs in which the orifices are constituted by slots. The slots may be straight or curved; their width may vary from the centre to the periphery of the discs; they may extend radially or at an angle relative to the centrifuge axis; and they may or may not lead to the outer or inner peripheral edges of the discs. Instead of elongated slots, the orifices may consist of a series of holes formed in the discs. The deflection effect may be increased by providing the plates with turned back edges 17, Fig. 11, extending along the whole length of the slots 9 and projecting in the upstream direction and/or by shaping the unslotted portions 18 of the discs to form V sections pointing in the upstream direction. Instead of being flat, the discs may be conical. The discs may all be of the same dimensions to form a cylindrical stack or the inner and/or outer diameter of the discs may be different, e.g. the outer diameter may increase from the top and bottom of the stack of the discs towards the centre, Fig. 12 (not shown). By variations in the inner diameter of the discs or by cavities, zones 20, Fig. 13, may be formed to ensure, for example, collection of light sediments. The discs 8 may be assembled in a stack by tying them together at their inner edges by means of rings 14, Fig. 13, and fixing the stack by means of tie bars, to a lower widened portion of the hub 2 of the centrifuge bowl 1 the upper disc being connected to the hub radial arms 15. Instead of forming a rigid assembly with the bowl, the discs may be mounted on a support so that they may be driven at a speed different from that of the bowl. The bowl in this case may include a screw conveyor fixed to the stack of discs for the discharge of heavy products. The wall of the bowl may be imperforate or perforate, the latter type of bowl being used when separating liquid from solids, the liquid being evacuated both outwardly through the perforated wall and inwardly through the spaces between the discs.