| 摘要 |
<p>1279606 Filter thickeners ENGLISH CLAYS LOVERING POCHIN & CO Ltd 22 Sept 1969 [27 Sept 1968] 46159/68 Heading BID A filter thickener comprises a tank enclosing a plurality of inward-flow flat filter elements operating in parallel and comprising nylon or polyethylene terephthalate, woven cloth bags internally supported by pervious packing which fills their internal volumes. The filter element in Fig. 3 is made by folding a single piece of filter cloth, stitching the two halves together up the sides, turning the resulting bag inside out and inserting perforated filtrate pipe 85 through gaps in the stitching adjacent the fold. The cloth is separated from the pipe by a similarly folded packing sheet of woven, splitfilm polypropylene fabric, and the ends of the cloth are tucked between the ends of the fabric and stitched in place at 94. Rows of stitching 88 extend through the cloth and fabric to prevent excess bowing of the cloth during backwashing. Figs. 1, 2 (not shown) illustrate similar flat filter elements with different filtrate outlet connections and made from two sheets of filter cloth separated by a single packing layer of fabric. Fig. 5 shows a filter thickener with an open tank 103 and flat filter elements 101 supported by floats 102 and chains 105 which prevent the elements descending to contact rotary rake 104. Pump 108 is driven by a reversible electric motor controlled by a timer, and alternately pumps filtrate from elements 101 to overflow tank 110 and returns filtrate to the elements to backwash them for specified periods. The tank in Fig. 6 (not shown) has a rotary mixer (204), and pump (208) delivers filtrate to an overhead vessel (210) from which some is returned to backwash the elements (201) when valves (221, 222) are appropriately adjusted. In Fig. 7 (not shown) liquid is supplied to closed filter tank (303) under a considerable head of pressure and no pumps are needed, an overhead filtrate tank (310) and valves (316, 321, 322) enabling the elements (301) to be backwashed. Packings may be made of other plastics than those above, and elements may be stitched to divide their areas into annular sections rather than strips as in Fig. 3.</p> |
