GB1450260A - Traction-driven composite sludge raking mechanism for sedi mentation tanks - Google Patents

Abstract

1450260 Sewage settling tank DORR-OLIVER INC 24 Dec 1974 [28 Dec 1973] 55801/74 Heading BID A circular sewage settling tank comprises a central pier 12 on which is rotatably supported a cage 21 carrying the inner end of a radial arm 18 whose outer end is moved along peripheral track 13 by an electrically powered carriage (14), the outer annular area A1 of the tank floor being cleaned by scrapers 22 rigidly suspended from arm 18 while the inner annular area A2 is cleaned by a scraper arm 27, 28, which is hinged to cage 21, supported by guy wires 35 to the upper part of the cage and pulled round the tank by traction wires 36 leading to arm 18. The hinge connection of arm 27 to cage 21 enables pivoting about both vertical and horizontal axes so that the arm can overide large sludge masses. The tank has a peripheral weir for clear liquid (not shown) and a fixed bridge 15 carrying a conduit 17 delivering sewage to distributor 69, 70 rotating with cage 21 (Fig. 6). Conduit 17 opens into an upper annular vessel 70 from which sewage passes over weirs 84 and 85 and down two pipes 71, 72 whose lower ends are directed opposite ways around the inside of a sleeve 69 at different levels, to minimise turbulence. Fig. 9 (not shown) illustrates the spherical bearing supporting cage 21 for rotation on pier 12 and an electric slip ring connecting a cable (19) along bridge 15 with a cable (20) leading along arm 18 to power carriage (14). The tank floor has a central sump with sludge outlet P. Additional scraper arms such as 37, (38, 39) (Fig. 2, not shown) may be similarly arranged to arm 27 to clean the inner area A2 of the tank. In Fig. 3 arm 18, and equivalent arms (42a, 46, 47) are mounted above the liquid level, and outer area scrapers 22 are suspended by struts 26. In Figs. 4, 5 (not shown) the radial arm (86) is inclined and partly submerged, so that the outer scrapers can be mounted directly on the lower longitudinal girders of the arm, and traction wires for the inner scraper arm are connected to an upper girder of the radial arm.