| 摘要 |
<p>1443353 Moving bed filter SIMON-HARTLEY Ltd 11 July 1974 [25 Aug 1973] 40368/73 Heading BID Granular filter medium such as sand is fed into the filtering zone past a baffle edge 14 so as to form a free inclined upper surface 26 into which liquid, such as sewage effluent, to be filtered flows from inlet 27. If the sand includes grains of various sizes, the baffle edge 14 causes coarse grains to form an upper layer adjacent surface 26 with the finer grains forming the intermediate part of the bed. A baffle 36 may be provided to create a similar coarse layer adjacent to nitrate outlet 29, 30; otherwise the left-hand side of the bed will remain unclassified. Medium may be discarded after leaving the lower end of the bed, but as shown an air lift pump 32 recycles medium up pipe 31 to chamber 19 where it is washed by a fraction of the incoming unfiltered liquid diverted through valve 34 and discharging at 35. Alternatively the medium may be washed with filtrate. The bed movement may be continuous or intermittent. It is possible to backwash the bed by delivering liquid to outlet 30 or to the bottom of the bed. In Fig. 1 the bed has a rectangular horizontal section, but in Fig. 2, not shown, an annular bed is formed with an inverted conical inlet surface 26 by a conical baffle (38) into whose interior the unfiltered liquid is delivered. Several air lift pumps are circumferentially spaced.</p> |
