Patent GB-1021331-A (GB)
Title: Horizontal plate filter
IPC: B01D25/26
Filed: 1963-01-01
Abstract: 1,021,331. Plate filters. W. B. HOELSCHER. Jan. 1, 1963, No. 68/63. Heading BID. A horizontal plate filter with external clamping means 4, comprises horizontal filter plates 1 arranged in vertically superposed relationship and secured to a cover plate 3 and a bottom plate 2, the filter plates 1 having intermediate bottoms 1<SP>1</SP> impervious to liquids slightly inclined towards the outlet side, and provided with screens 5 supported on projections 6, inlet and outlet apertures 7, 8 above and below the intermediate bottoms, arranged in opposite relationship thereto and having substantially the same free cross-sectional area, thus forming main inlet and outlet passages integral with the filter plates, cover and bottom plates, and a sheet of filter paper or other sheet filter medium 9 placed on each screen the sheets having cutouts communicating with the apertures 7 and 8. As shown, Fig. 2, the inlet and outlet passages may be incorporated in the circular cross-sectional area of the plates, lateral pins 30 and centering pins 31 facilitating the assembly of the plates. Rigidly or removably secured deflecting members 12 may be provided at the rear of the inlet apertures to prevent washing away of the filter bed and to assist in the filtration of low viscosity liquids. Liquid to be filtered enters the bottom plate 2 from the side via valve 13, sight-glass 14<SP>1</SP> and tube 14, reaches the inlet passage 7 and hence enters the plates 1 through holes 10. The apparatus may be modified to enable liquid to enter the bottom plate 2 from below, or the cover plate 3 from the side or the top, or one of filter plates 1 from the side. Prior to filtration the apparatus is deaerated at both the raw liquid and filtrate sides through air-relief cocks 5 and 6, and after filtration gas may be admitted to the apparatus through cock 15 to force out remaining liquid. After its passage through the filter medium 9 and screens 5, liquid accumulates on the intermediate bottoms 1<SP>1</SP> and passes through the exit holes 11 to outlet passages 8 and main outlet tube line 17 having a valve 18. Tube lines 14 and 17 may be connected either to the bottom plate 2 as shown, or to the cover plate 3, or to one of the filter plates 1. The plates of Fig. 3 (not shown) are each provided with a separate outlet passage having an individual exit and a shut-off valve 19, enabling various filter media to be tested experimentally. Double filtration, useful for liquids of high solids content, may be effected by using a set of plates, Fig. 4 (not shown), including a flowreversing plate 20, which is fitted with a valve 21 for adding measured quantities of filter aids, and an air-relief valve 22 for the filtrate side of the second filtration stage. Where the last residue of the liquid has to be filtered out without thinning, or where the solids have to be reclaimed in a dry state, draining plates 23, 24, Fig. 5 (not shown) are provided to enable the apparatus to be emptied by air. Filter plate 23 has an outlet passage 8 shut off at the lower end, and a lateral connection for the main outlet tube line 27 of the filtrate. Bottom plate 24 connects to an inlet passage 7 closed at the upper end as well as to outlet valve 28 at a low point to remove the residual filtrate. Fig. 6 (not shown) shows a combination of draining plates 24, 25, 26 having inlets 29 and outlets 28 that may be shut off. Plate 25 has an inlet passage closed at its lower end and having connections for flexible feed lines 29 which lead to draining plate 26 and can be shut off. Plate 26 is similar to plate 23 of Fig. 5 but has a connection for feed line 29. Bottom plate 24 is similar to that of Fig. 5. When a preliminary deposit is required, the draining plates are operated in conjunction with the standard filter plates 1, connector 28 interconnecting the outlet passage to the main filtrate outlet 27. During filtration the draining plates are shut off and thus kept in stand-by position for the draining process.