Patent GB-1389003-A (GB)
Title: Plate filter press
IPC: B01D25/172
Filed: 1971-02-02
Abstract: 1389003 Filter press ENGLISH CLAYS LOVERING POCHIN & CO Ltd 25 Feb 1972 [2 Feb 1971] 3757/71 Heading B1D A filter press comprises an array of similar plates each defining an annular recess lined by an annular filter element 16 on, both faces, central duct 19 serving to deliver wet solids to be pressed to cavities 20 formed by the recesses, filtrate drainage ducts (Fig. 8, not shown) being provided in the lower halves of each plate to drain filtrate from the rear faces of elements 16 to apertures (182) in the plate peripheries, and a combined cake removal and plate separating means (Fig. 2, not shown) delivering blasts of compressed air through ducts 14 to separate successive plates during press opening and to remove cake therefrom. The plates have extensions (10) which slide along horizontal bars (3) on each side of the press, and ducts 14a and 14a' for example in one plate communicate with apertures (Fig. 9, not shown) in respective extensions. As shown in Fig. 5 aperture 14a leads to openings 15a beneath the filter element on the left-hand side of a plate and duct 14a' with openings 15a' beneath the element on the right-hand side of the plate. The cake removal and plate separating means comprises one each side of the press an endless chain 7 driven by a reversible hydraulic motor and carrying a device 9 comprising two spring-loaded pivoted pawls 91, 92, of which pawl 92 incorporates channel 93 through which air is delivered to a duct 14 when the pawls grip the corresponding extension 10 therebetween. The plates comprise basic annular members 11 with inner and outer rings 13, 12 bolted thereto and clamping elements 16 in place. Elements 16 may comprise a support and drainage cloth of nylon 0.02 inches thick and 22 threads per inch covered by a filter cloth (Figs. 8, 11, 13, not shown). Hub members 13 have radial surface grooves cooperating with the hub members of adjacent plates to connect the inlet duct 19 formed by the plates with spaces 20. Filtrate drainage ducts (Fig. 8) may communicate with both sides of a plate or separate ducts are provided for each side. In operation the press is closed by a ram (5) (Fig. 1 not shown), and slurry is delivered by pipe (6) to duct 19, a pressure of 100-150 psi being maintained for about three minutes and then being raised to 200-1500 p.s.i. to complete filtration. Pressure is released, and ram (5) withdraws the left-hand end plate (Fig. 1), and devices 9 are reciprocated by hydraulic motor (70) under cam control to move successive plates leftwards. Pawls 91 are first depressed by contacting extensions 10 but pawls 92 engage the extensions of the first plate 1a and pawls 91 and 92 then grip the extensions between them preventing devices 9 moving further rightwards. Motor (70) acts as its own slipping clutch. A high pressure blast followed by a low pressure blast of compressed air from one pawl 92 are delivered to duct 14a which displaces filter cake from the left-hand side of plate 1a, and similar blasts are then delivered through the other pawl to duct 14a' which breaks the seal between plates 1a and 1b so that subsequent leftward movement of devices 9 carries plate 1a therewith, leaving the filter cake from the right-hand side of plate 1a adhering to plate 1b. Pawl 92 is depressed by a fixed cam to release plate 1a when it reaches the withdrawn end plate and the cycle is repeated. When all plates have been moved leftwards the devices 9 engage stops at the righthand end of the press which lock pawls 91 in a depressed position (Fig. 4, not shown) allowing devices 9 to move past the plates to the left-hand end of the press, where the pawls 91 are released and devices 9 stop. Ram (5) then closes the press for the next pressing cycle.