GB642439A - Improvements in or relating to tray-type clarifiers - Google Patents

Abstract

642,439. Gravity-separation apparatus. STEVENS, A. H. (Graver Tank & Mfg. Co., Inc.). Dec. 9, 1947, No. 32443. [Class 46] A tray clarifier includes trays made from plate material having progressively - increasing slope from the horizontal plane and being peripherally supported and so spaced that the clarification zones between them are wider than they are deep. Scrapers having lower edges corresponding with the shape of the trays are also provided. As shown in Fig. 1, each tray comprises a frustospherical or ellipsoidal part 16, having a radius of curvature approximately equal to its peripheral diameter, and a depending skirt 17, joined by a knuckle portion 18 having a radius of curvature of about 1 per cent of that of the part 16. The trays are spaced vertically to provide narrow slots 23 and from the tank wall 11 to provide an annular channel 22. Angle-section scrapers 28, conforming to the tray curvature, are provided. Liquid to be clarified enters by a pipe 30, a fixed cylinder 39 surrounding a rotatable shaft 24 and then passes through a cylinder 38 attached to the shaft 24 into a flocculating compartment 20 from which scum is removed through an outlet 34 by a freely-swinging skimmer blade 35 attached to a rotating arm 36. The liquid then passes via channel 22 and slots 23 into clarification compartment 21. while solids deposit finally in a mud-conditioning chamber 42. A relatively small unflanged mud-conditioning tray 40 may be provided. The end closures 12, 13 of the tank 10 have a shape similar to that of the tray-heads 16. In the modification of Fig. 2, which may be operated under pressure, a separate compartment 55 is provided, above the main tank 50, from which scum is withdrawn through a pipe 62, and from which the liquid flows through slots 59 down the inside of a rotatable tube 52, which takes the place of the shaft 24. The liquid is expelled through slots 60 into a flocculating chamber 42. in which it is stirred by fingers 66 attached to a mudconditioning tray 40 and scrapers 28B rotating with the tube 52 under a fixed scraper 68. The movement of the liquid is thereafter upward. For relatively large internal tank pressures, the knuckle radius of the closures 12, 13, 57, 58 should be about 3 per cerit of the main radius of curvature. Specifications 500,896, 635,285, and U.S.A. Specification 2,336,659, are referred to.