GB311359A - Improvements in rotary filters - Google Patents

Abstract

311,359. British Rotary Filter Go., Ltd., and Joyce, A. G. E. Feb. 10, 1928. Rotary filters.-The cells a<4>, Fig. 2, formed beneath the filtering medium of a rotary drum suction filter, are shallow, the walls of each cell converging towards a sump a<3>, the cross-section of the outlet of which is substantially equal to that of the discharge passage b<3> communicating with it. The object of this construction is to facilitate the efficient discharge of the filtrate and thus secure a dry cake. The side walls a<5>, a<6> of each cell may be sloped as shown in Fig. 3, the sump a<3> being situated near to the trailing side a<5> of the cell, so that the cell is drained when it rises to a position level with the axis of rotation of the filter. The discharge passages b<3> from the cells are formed in a web B which is in one with, or bolted to, a trunnion C. With the object of further facilitating the drainage of the the passages b<3> may be inclined in a slightly backward direction as indicated by the lines b<5>, Fig. 3, instead of being strictly radial. The passages b<3> are continued as passages c<3> in the trunnion, and, as the filter rotates, each of these communicates successively with ports in a fixed valve head P through which the mother liquor and wash liquor are separately discharged and air or other gas or liquid is supplied to assist the detachment of the cake. The trunnion is held in engagement with the valve head P by a spring p<2> on a stud p<1>, the spring bearing against a sleeve washer p<3> a flange on which bears against an internal flange on the head P. The filter cloth is supported over the cells by perforated plates a', the over-lapping ends of the cloth being gripped between bars. fitting in a recess a<10>, Fig. 3. An extension shaft E is bolted to the hub of the web B. The trunnion C and the shaft E turn in bearings D, F, respectively, the shaft E carrying a worm wheel e<3> engaging with a worm j<3> on a shaft J driven by bevel gearing from a main driving shaft j<9> which is pro- -vided with fast and loose pulleys j<12>, j<13>. The vessel G to which the material under treatment is supplied and into which the filter dips, is provided with an agitator H suspended by arms h' and oscillated by means of crank and lever mechanism from the shaft J. The perforated plates a<7> which support the filter cloth may be replaced by longitudinal and transverse, ribs carried from the inner walls of the cells, and bent rigid or flexible rubber pipes may be used instead of the web B for connecting the cells with the passages in the trunnion. Fig. 8 shows apparatus in which two elements are bolted together end-to-end, each element being discharged through its own trunnion C.