GB791516A - Method and apparatus for filtering liquids - Google Patents

Abstract

791,516. Filters. WHITE FILTER SALES CO. Sept. 20, 1954, No. 28622/56. Divided out of 791,515. Class 46. A method of filtering liquids comprises adding a loose fibrous material, such as finely-shredded paper, to the entire volume of liquid to be filtered, stirring to produce a uniform dilute slurry, filtering through a fine-mesh filter element and periodically removing the accumulated layer of fibrous filter material, together with the dirt trapped therein, from the surface of the element while both aides of it are substantially wholly immersed in the liquid by agitation of the liquid in the neighbourhood of the filter layer (e.g., by reciprocation of a reticulated member supported outside the fibrous layer), so that the fibrous layer is displaced from the filter element by local liquid turbulence. Each filter element 21 may comprise a bottom 25, having threaded engagement with one of a series of nipples 20, Fig. 3, on a manifold comprising a box 15 from the sides of which extend semi-circular tubes 16, 17 and elbows 18, a stiff perforated cylinder 27 around which is wrapped a sheet 30 of fine-mesh wire gauze, and a cylinder 31 of expanded metal loosely surrounding the gauze cylinder 30 and resting on lugs 32 extending outwardly from the periphery of the bottom 25. The cylinder 31 may be raised and lowered, to agitate a layer of paper fibres located between itself and the cylinder 30 and also to agitate the liquid in the vicinity of the layer, by a handle 33 when the top of the filter casing (not shown) is removed. Liquid, e.g., dirty dry-cleaning solvent, is run into a tank 10, Fig. 1, and a few sheets of waste paper are passed through a shredder 11. The mixture is stirred and pumped to a chamber 12 housing the manifold and filter elements, filtrate passing through a valve 37 into a storage reservoir 13. When the layer of fibres has to be removed from each filter element the level of liquid is lowered until the filter elements are just covered, whereupon the cover is removed and the handles 33 operated as above. Fibres may be removed from the bottom of the chamber 12 by opening a discharge valve 36 and a pet cock 19, the slurry being received in a felt bag or filter basket 38 and filtrate pumped therefrom at 40. Figs. 5 and 6 show the mechanism for feeding the paper to the shredder 11. The mechanism comprises a flattened horn 46, Fig. 5, leading to the space between a knurled driven roller 45, Fig. 6, and a spring-loaded idler roller 44 which may also be knurled. A second flattened horn 47 leads therefrom to the shredder.