Patent GB-362431-A (GB)
Title: Improvements in methods and apparatus for clarifying liquids
IPC: B01D21/06
Filed: 1930-09-01
Abstract: 362,431. Gravity-separation apparatus. GILCHRIST, W. A., 122, South Michigan Avenue, Chicago, U.S.A. Sept. 1, 1930, No. 26078. Convention date, Sept. 9, 1929. [Class 46.] Settling tanks are arranged so that the liquid passes upward through a layer of accumulated sediment while both liquid and sediment move towards their respective outlets in a substantially parallel direction. A tank 1, Fig. 1, is divided into compartments by trays 16 with pendent peripheral curtains 22 and central apertures which provide a vertical passage through which the liquid, which enters an upper feed-box 4 through a pipe 5, is supplied to the several compartments. The trays have pendent collars 27 on their inner edges, and the liquid enters the compartments below these collars and passes upward and outward in each compartment through a layer of sediment which has been allowed to accumulate up to a level indicated by the dotted line 49. The clear liquid leaves the compartments through inclined pipes 53, the upper ends of which are situated in a common discharge box 59 and are provided with nozzles 54 pivoted so that their outer ends can be raised or lowered to regulate the head under which the liquid is discharged. Sediment is continually pushed outward from the settling compartments by means of scrapers, attached to arms 34 fixed by bracket arms 29 to a central rotary shaft 32, and directed bv the curtains 22 down the outer peripheral passage to the lowest compartment 15. This compartment is closed from the central passage by a conical member 67 attached to the shaft 32. The liquid from the compartment 15 is discharged through a pipe 69 which has its inlet near the centre, and the sediment is pushed by scrapers 39 towards a discharge pocket 41. The lower edge of each collar 27 is disposed in a groove in a ring member 30 carried by the corresponding bracket arm 29, sediment collecting in the grooves to form liquid seals. The upper edge of each collar 27 is formed with vents 46 through which gas separating from the liquid in the compartment can escape. Modified apparatus is described in which the pipes 53 are replaced by a single vertical compartment inside of and adjacent to the wall of the tank 1 and having apertures opening into the upper part of each settling compartment. As shown in Fig. 4, the trays 16 have inclined vanes 114, 115, 116 which protrude into the central passage to different distances, so that heavy sediment, which tends to separate in the passage, will be distributed equally among the compartments. Fig. 3 shows apparatus in which the trays are inclined towards the centre. The liquid is supplied from a peripheral passage 72, the settled matter is pushed towards a central passage formed by collars 101, carried by the central shaft, and ring-shaped pipes 91 with upwardly directed inlet nipples 92 are provided for the discharge of the clear liquid. The liquid enters each compartment through the space between an annular collar 75 and an annular vane 74. The vanes for the lower compartments project further into the passage 72 than those for the higher compartments. Fig. 15 shows apparatus in which each tray has a central aperture smaller than that of the tray above so that equal distribution of the heavier sediment between the several compartments is assured. The scrapers attached to the arms 34 may be constructed as shown in Fig. 13. To each end of a scraper blade 35 is attached a chain formed of short links 139 with intermediate bars 138 having sharp scraping edges.