Patent GB-764500-A (GB)
Title: Coutinuous filter and method of operation thereof
IPC: B01D33/00
Filed: 1954-06-29
Abstract: 764,500. Filters; gravity separation apparatus; treating waste effluents. PETERSON FILTERS & ENGINEERING CO. June 29, 1954 [July 16, 1953], No. 19049/54. Classes 46 and 111.  Liquid is clarified for re-use or to prevent stream pollution in the apparatus shown. A tank 10, Fig. 1, is maintained full of liquid to be filtered within which is rotated clockwise a filter comprising leaves 30 to which suction is applied through outlet 40 and conduits 32, Fig. 2, and valve 37 from just after the " 12 o'clock " position to the " 8 o'clock " position. At the " 9 o'clock " position atmospheric air is drawn from inlet 38 through a conduit 35, Fig. 2, and conduit 34 communicating with the outside edges of the leaves, through the leaf interiors, through conduit 32 and through an appropriate opening in the stationary plate of valve 37 by vacuum applied at 42, thus draining the leaves at that position. Back pressure is then applied through conduits 35 and 34 from the same inlet 38 and through conduit 32 from an appropriate opening in the valve 37 to remove the cake. At the " 10 o'clock " position pressure is shut off and at the " 12 o'clock " position vacuum is applied for a short period at 33, Fig. 2, for withdrawal of cloudy filtrate. Thereafter the cycle is repeated. The cakes fall through a region of the tank which, after a time, constitutes three zones : a settling zone A, a barrier zone B, and a compacting zone C. In zone C a series of impellers 22 on a rotating shaft 20 blends the cakes, and coarse particles not formed in the cake, into a homogeneous mass which is withdrawn through a check valve 46, Fig. 1, by a diaphragm pump 45. In Fig. 7 (not shown) the pump 45 is dispensed with and the solid mass withdrawn by a screw conveyer mounted in a conduit located under the oblique wall of the tank 10. In Fig. 9 (not shown) an endless conveyer instead of a screw conveyer is 'provided in the same location. In Fig. 8 an air jet 73 introduces compressed air into a delivery pipe 70a, decreasing the density of the thickened mass from the tank sump, and hydrostatic pressure thereupon elevates it to a discharge point above the level of liquid in the tank. In Fig. 10 the air is discharged from the lower end of the impeller shaft 80, which is hollow. The space between axially-adjacent sectors may be reduced by providing one or more restraining strips clipped on each sector, by inserting rods in pockets along the filter medium or by covering each sector with a coarse mesh wire screen, these devices serving to prevent bulging of the filter medium during cake removal. In Fig. 14 sets of tubular filtering elements 106 are radially arranged on a rotatable shaft 108 with which is associated a plate valve 114 having inlet and outlet connections 115 and 117 respectively. A tank inlet 101 and overflow 103 are provided, while a solids discharge outlet 118 is connected to a pump similar to the pump 45 in Fig. 1. The filter medium on each element is held in place by a wire wrapping 107 or by two diametricallyopposed axially-extending rods, Fig. 15 (not shown).