Patent GB-807932-A (GB)
Title: Improvements in or relating to gas-filtering devices
IPC: B01D46/04
Filed: 1956-09-03
Abstract: 807,932. Gas filters. PREPARATION INDUSTRIELLE DES COMBUSTIBLES. Sept. 3, 1956 [Nov. 8, 1955], No. 26930/56. Addition to 700,782. Class 8(2). In a gas filtering apparatus as claimed in the parent Specification and wherein dust-laden air entering the hopper portion of the filter casing 1, Fig. 2, is drawn through a plurality of filter sleeves into an outlet 33 and wherein the open end of each sleeve is secured to the hopper and the other closed end is secured to the movable end plate of a bellows 25 subjected to a source of alternating pneumatic pressure in a pipe 24 to effect shaping of the sleeves, the latter are arranged in groups within compartments formed by radial walls 11, Fig. 1 (not shown), and each group is dissconnected in turn from the suction circuit during a sleeve-shaping period by a single rotary distributor. The latter comprises a fixed head 17 open at 18 to a source of pulsating air pressure, and a rotary portion having an upper chamber 22 serving to connect the pulsating pressure with the pipe 24 of each filtering compartment in turn through a pipe 23, and having a lower chamber 27 separated from the upper chamber by a partition 21 and driven by a pneumatic or hydraulic cylinder 38 through gearing 35. The lower chamber 27 has an aperture 28 by which each filtering compartment in turn is connected to atmosphere thereby causing a reverse flow of scavenging air whenever the end 29 of chamber 27 registers with the outlet 30 of a filtering compartment. In a modification the fixed head 40, Fig. 3 of the distributor body 46 has an annular space 42 open at 43 to a source of pulsating pressure and connected by an annular space 52 and duct 53 of the upper portion 47 of the body 46 to a duct 54 which in turn is connected to the filter shaking bellows of the compartment being cleaned. Axial ducts 41, 56 of the head 40 and body portion 47 connect a source of suction through an arm 57 integral with a lower body portion 48 to an annular bellows 58 by which the distributor is rotated. To this end a bottom plate 75 of the bellows is secured to a vertical sleeve 76 having slots 77 through which pass the arm 57 and a venting arm 60 of an axial duct 59 of the distributor and also having two stops 80 each engaging a helical groove 81 cut in the internal cylindrical face of a pinion 82 mounted for rotation in one direction on a bearing 83 ; a pawl 85 and external teeth 84 serving to prevent rotation of the pinion in the direction opposite to that of the distributor. On first applying suction to the bellows 58, the top plate 74 thereof is lowered against a spring 71 and with it the distributor until the arms 57, 60 abut the top 79 of a sleeve 78 as shown in Fig. 4. This results in separation of a seal 72, 73 between the filter chamber first having been scavenged and the vent pipes 59, 60 and also between a flange 68 of the lower portion 48 of the distributor and the filter casing and which provides a friction brake. Continued application of suction to the bellows 58 results in the bottom plate 75 and hence the sleeve 76 and stops 80 being raised and this effects rotation of the distributor to its next position ;  the pinion 82 being held by a pawl 85. On disconnecting the bellows 58 from the source of suction, the bottom plate 75 and sleeve 76 descend linearly and with them the stops 82 ; the pinion being free to be rotated by the engagement of the stops in the helical grooves.