GB1093174A - Filter apparatus - Google Patents

Abstract

1,093,174. Filter. AJEM LABORATORIES Inc. Dec. 4, 1964 [Dec. 6, 1963], No. 49529/64. Heading B1D. Filter apparatus comprises at least one suction box disposed within a tank for containing liquid to be filtered, the or each suction box being connectable to a source of suction and having a pervious filter face through which liquid enters the box, an endless pervious conveyor belt disposed about the suction box or boxes so as to be movable across the filter face or faces thereof, said conveyor belt supporting a strip of filter medium on its outside with respect to the suction box or boxes, and edgesealing means pressing on the outside of the filter medium at opposite edges thereof so as to press said edges against the belt which is thereby pressed against the or each suction box at opposite lateral edges of its filter face. In Figs. 1 and 3, the filter apparatus comprises suction boxes 30, 32 each having a pervious filter face, an endless pervious conveyor belt 19 which is moved at intervals on rails 23 across the pervious face while supporting a strip of filter medium 12, and edge sealing means comprising belts 22 which bear down on the filter medium 12. The boxes are connected via duct 36, 38 and a three way valve 34 (Fig. 4) to suction pump 32. Rails 23 may be made of neoprene, polytetrafluoroethylene or nylon. Water jet 41 stirs up the sedimented solid so that it is removed on the filter medium. In operation, suction is first applied via line 38 to upper box 30 up to a predetermined pressure differential across the filter element caused by clogging, which differential operates switch 48 (Fig. 4) to alter valve 34 to transfer the suction to line 36 and lower box 32 and to energize time delay switch 54. Switch 54 causes switch 48 to cut off suction from box 32, and then allows water to filter into the box to reduce the vacuum before energizing motor 27 to rotate roller 28, and pull-rolls 50 and hence move conveyor belt 19 and the filter medium 12 on by a distance equal to the length of the pervious filter face of the upper box. The time delay switch 54 then activates switch 48 to allow suction via valve 34 and line 38 to upper box 30.