GB718922A - Improvements in or relating to cell filter - Google Patents

Abstract

718,922. Filters. LAMLA, V. May 9, 1952 [May 12, 1951], No. 11820/52. Class 46 A rotary drum filter incorporating a plurality of cells and adapted to have suction applied both internally and externally of the drum is characterized in that the filtering drum comprises a filter carrier in the form of a circular ring inc'uding a plurality of narrow axially-directed filter channels closed at one end, an end wall through which the filter channels extend, two filter cloths extending respectively over the inner and outer sides of the filter carrier and covering the channels to form the cells, a stationary control ring formed with an annular control channel which is closed by the end wall and communicates with the filter channels, and plugs arranged so as to subdivide the control channel into a plurality of zones. A control ring 5, Fig. 2, having an annular control channel 6 is secured by a flange 42 to a vat 1. Mounted in the hub 44 of the control ring 5 is the shaft 45 of a filtering drum consisting of a wall 46, an annular filter carrier 2, and a ring 48, the shaft being driven by a toothed wheel 29. The carrier 2 may comprise bars 9, Fig. 5, forming channels z on the inside and outside which are closed to form cells by filter cloths 11 secured as by stitching, the inner one being held in place by a sieve 12. Alternatively the carrier may comprise perforate tubes 10, Fig. 9, or of alternate tubes and flat bars, of an annular corrugated sheet or of a cast member grooved on both sides. The cells z extend through the end wall 46 into the control channel 6, which is subdivided into zones by plugs 16a-c, Fig. 1, and to which vacuum is applied at 6a and 6b and atmospheric air at 54. The cake 15 formed is removed by scrapers 3, 4, Fig. 1, the cake from the inner side of the drum being moved to the outer end by a screw conveyer 8, Fig. 2. Where the filter carrier comprises perforate tubes 10 they may be arranged in groups, each group communicating with a sector-shaped chamber 30, Fig. 9, in the ring 57. Washing agent fed to a central control head 55 by a pipe 19 is forced through pipes 18, 18a to the chambers 30 and thus into the tubes 10. Compressed air for cake removal may also be supplied at 19. Several (imperforate) tubes in the filter carrier may be connected alternatively at either end to form a continuous coil Fig. 11 (not shown), connected by pipes to the drum hub and communicating with a stationary control head similar to 55, Fig. 9, to and from which heating or cooling agent is supplied and discharged. The whole carrier may comprise a number of such coils; small extension tubes communicating with the channel 6 to connect the cells z to the channel. The drum may be frusto-conical rather than cylindrical. Two concentric cylindrical drums secured together may rotate in a single vat against concentric control channels in a single control ring. In Fig. 19, however, the outer drum 26 rotates in a vat 1, its outer cake being returned to the vat, while its inner cake falls into an inner vat 27 into which also falls the outer cake from the inner drum 63. The drums are secured together as before. There may be a stirrer 7a in each vat. Where two drums rotate in a single vat they may be cylindrical but of unequal lengths, or frusto-conical but tapering in opposite directions.