GB839205A - Improvements in and relating to continuous vacuum filters - Google Patents

Abstract

839,205. Filters. COAL INDUSTRY (PATENTS) Ltd. Nov. 21, 1957 [Nov. 30, 1956], No. 36721/56. Class 46. [Also in Group XXIX] A chamber 1, Fig. 1, which is connected to a source of compressed-air, has an outlet controlled by a plate lift-valve closure 3 seating on a ring 4 of rubber or similar resilient material or a metal seat ; the closure 3 is formed with a hollow stem 15 having an end member 14 whilst in the stem is a spring 5, the ends of which abut the closure 3 and a shoulder 6 on a rod 7 connected to a diaphragm 10; more than one spring 5 may be used and the diaphragm 10 is supplied with air from chamber 1. Upon admitting air to the diaphragm 10 the closure 3 is rapidly opened by the rod 7 and/or the spring 5, the closure movement being stopped by a rubber or like resilient buffer 13; air from chamber 1 flows into a further chamber 16 having both a connection 17 to a continuous vacuum filter and a one-way valve 45 for relieving partial vacuum in the filter whilst the air blast ports of any given section of the filter are opening and prior to unseating of the closure 3. The rod 7 passes through a seal 18 in the wall of chamber 16. After the closure 3 has been unseated the supply of air to the diaphragm 10 is interrupted and the latter is connected to atmosphere whilst a spring 19 returns the parts to the positions shown. In a modification (not shown) the spring 19 is disposed on the closure side of diaphragm, a greaser is provided for the seal 18, and the valve 45 comprises an annular closure movable on a central journal to and from an annular seat extending round a ring of apertures in the valve housing. The sequential supply and exhaust of air to and from the diaphragm to produce blasts of air in the connection 17 is obtained by means of a four-lobed cam 22, Fig. 3, with four arms 28 by which the cam is rotated by pegs 20 on the filter drum 19 ; each cam controls the operation of a valve 23 having a compressed air inlet 25, a diaphragm connection 26 and an atmospheric connection 27 ; a spring plunger 24 is interposed between each valve and its cam. The timing of the air blast is adjustable by varying the position, form, dwell or radial length of the cam. A regulating valve (not shown) may be inserted in the exhaust connection of valve 23 to enable the diaphragm to be maintained in the operative position thereby keeping the valve 3 open ; the regulating valve may be partially closed to reduce the rate of discharge from the diaphragm. In a modification (not shown) the valve 23 is actuated by levers rotated by the stops 20. In another modification, the diaphragm is replaced by a solenoid and an adjustable stop is provided to enable the closure to be permanently held open when desired. The energisation of the solenoid is controlled by the cam 22 and electrical relay switches may be used. An alternative form of the valve 23 comprises an oil bath 50, Fig. 4, housing a cam 51 on a shaft 52 to which is secured an arm 53 supporting an adjustable return weight 55; coacting with the cam is a hollow follower 56 containing a spring 58 loading a plunger 59 which via plungers 60, 61 operates a spring-loaded liftvalve closure 62 controlling the passage of air from the inlet 25 to the diaphragm connection 26. When the closure 62 is unseated the plunger 61 closes the passage between connection 26 and atmospheric connection 27; when the closure 62 is seated connections 26, 27 are in communication to open the diaphragm chamber to atmosphere. The valve casing 65 is adjustably attached to the filter frame. In a final modification, the closure 3, Fig. 1, may be operated by a flexible control cable.