GB1279698A - Filter device - Google Patents

Abstract

1279698 Moving band filters MASCHINENFABRIK SACK GmbH 28 Nov 1969 [10 Dec 1968] 58331/69 Heading BID A filter comprises inlet chamber 7 and filtrate chamber 8 separated by a perforate plate 9 over which extend an upper coarse filtering band 18 of plastics or wire mesh and a lower fine filtering band 11 of cotton cloth. Both bands are movable by respective drives, the upper band 18 being moved more often than the lower band and serving to carry the filtr cake off the lower band. The lower band 11 is non-endless, and is moved a step from roller 14 to roller 15 during each movement of band 18. Band 18 is cleaned by scraper 38, roller brush 39 and air blower nozzle 41 during its movements. In Fig. 1, band 18 is non- endless and is drawn by motor 23 from plate 9, cleaned and drawn back again by motor 24 between nitration operations. In Figs. 2, 3 (not shown) the coarse band is endless and moves in one direction only, either passing back under chamber 8 or over chamber 7. Before band 18 is moved, the upper chamber 7 is emptied and the cake dried by delivering compressed air through line 35 to force the liquid remaining in chamber 7 through the cake. A buffer tank may be provided downstream of chamber 8 to even out supply of filtrate. To avoid tearing cloth 11 is moved or kept taut by air motors 24 or through slip clutches, and a similar motor tension band 18. Where bands 11, 18 enter and leave the chamber 7, they are sealed by doors 29, 31 which swing inwards and upwards to release the bands for movement. Incoming liquid passes through holes 28 in pipe 25 and is spread by grid 27. In Fig. 3 the whole apparatus is enclosed in a single housing (51). The fine band 11 has a pore size of 10 to 50 microns.