GB454598A - Improvements in continuous automatic centrifugal separating machines - Google Patents

Abstract

454,598. Centrifugal machines. AMERICAN CENTRIFUGAL CORPORATION, 70, Pine Street, New York, U.S.A. April 5, 1935, No. 10628. Convention date, April 12, 1934. [Class 23] A centrifugal machine for the treatment of sewage sludge is mounted on a vertical axis with low and high speed motors arranged above and below the basket for cleaning and purging speeds respectively; means are also provided for cleaning dry material from the basket while the basket is rotated at a low cleaning speed. The basket 5 is enclosed by the section 3 of the casing and this is bolted to the top of the basic section 1 which forms an annular sedimentation and settling tank 6 for the liquid discharged from the basket. The inner wall 7, Fig. 1, of the tank has a flange 10 forming with the outer wall 8 an annular mouth to the tank 6. A central shell 13 encases and supports the high-speed motor 14, bearings 18, 19 being arranged in the neck of the shell which is connected to the inner tank wall 7 by braces 23. The central shaft 20 carries the basket 5, the bottom plate 48 of which has openings 52 for the discharge of sludge. The annular top plate 49 of the basket is of stepped formation as shown in Fig. 7 and has a number of inverted conical openings 56 which are staggered circumferentially so that the flow from one does not interfere with another. The openings 56 increase in diameter as one progresses from the periphery of the seepage plate 49 to the centre, and a screen 57 is arranged below the plate. This screen has groups of perforations at the seepage openings 56, the groups near the centre having a larger number than the groups near the periphery. The edges 49<a> of successive steps of the plate 49 are inclined upward and outward to facilitate discharge from the openings. The material is supplied through the feed pipe 61 arranged in the top section 4 of the casing and divided into two branches 64 which have flanges 65 for connection to pipe sections 67 in the casing part 2. These sections have dependent nozzle sections 68, Fig. 1, which enter the basket and have flattened widened nozzles 69 for the discharge of the material into the basket. A hopper 70 with a valve 72 is associated with the feed pipe 61 and is used for the supply of sludge treating material. The liquid from the basket 5 passes through the screen 57 and seepage plate 49, inside the casing part 3 to the tank 6 from which the clearer part is drawn through the pipes 33, 30. The sludge deposited in the basket is removed by hollow scrapers 75 with serrated edges 78, Fig. 2 ; the scrapers are secured to spindles 74, the upper ends of which have operating arms 79 provided with pins 80 connected with blocks 81 sliding in openings in a bar 83, Fig. 4. One end of the bar is connected to a worm 86 which engages in a threaded sleeve 87 geared to an auxiliary motor 91. The operation of this motor causes the bar 83 to slide longitudinally and so bring the scrapers 75 into or out of engagement with the deposited sludge. Nuts 95 can be adjusted to limit the movement of the scrapers to prevent them from engaging the basket wall. Clutches 38, 40 connect the motors 14, 41 respectively to the basket shaft 20. During separation and treatment of the material the basket is driven by the high speed motor 14, while the motor 41 is idle. When the treatment is completed, the motor 14 is disconnected, the motor 41 is started, and the brake 42 is applied to reduce the speed of the basket shaft. The basket is thus rotated at a low speed, while the scrapers 75 are operated by the motor 91 to release the deposited sludge for discharge through the apertures 52 and the space 12. By removing the bolts which normally connect sections 4, 2, 3 of the casing, the sections 4, 2 and all the mechanism supported therefrom, including the basket with its feeding and discharging means, can be lifted clear of the other sections. Specifications 453,651, 453,652, and 454,597 are referred to.