Patent GB-670180-A (GB)
Title: Screening and filtering apparatus
IPC: D21D5/04
Filed: 1949-03-14
Abstract: 670,180. Screening liquids. COWAN, B., and CUNNINGHAM, A. March 14, 1949 [Nov 3, 1948], No. 6959/49. Class 46 [Also In an apparatus for screening and filtering suspensions of solids in liquids such as aqueous pulp suspensions used in the manufacture of paper and comprising an inclined or substantially horizontal screenin Groups II and XXX] ing element in a flow channel or vat, the screen is mounted on the side walls of the flow channel or vat by flexible supporting members arranged in shear between the said side walls and the sides of the screen, the said members forming continuous seals closing the gaps between the side walls and sides of the screen and a flexible seal is arranged between the lower end of the screen and the adjacent part of the flow passage or vat, or, in the case of the horizontal screen, between the ends of the screen and the adjacent walls of the vat. As shown, the screen frame and supporting walls comprise oppositely disposed channel members 9, 11, Fig. 2, in which are located seal holders 12, 13 which support between them, under compression, a series of flexible springy rubber or like blocks 14 fitted into channels formed in the holders 12, 13. These blocks under compression laterally are thus subjected to shear stress and butt together to prevent leakage therebetween and may take the form shown in Figs. 4, 5 and 6. Alternatively, the blocks may be replaced by a single continuous strip in compression and shear, of rubber or other material having the requisite flexibility. A seal 17, Fig. 1, is formed between the lower end of the screen frame and the bottom of the stock channel by a resilient sealing block 20 secured in a channelshaped holder 21 retained in the stock channel, the block 20 embedding a sealing rib 19 of circular section formed on the screen frame. Alternatively this end seal may be formed by a continuous rubber strip arched between the screen frame and stock channel or by a flat flexible lip on the frame received between a metal plate fastened to the bottom of the channel and a stationary rubber sealing strip. The screen is vibrated by a pair of unbalanced flywheels 44, Fig. 2, each wheel having a radially adjustable weight 46. The wheels are mounted on the screen frame and driven from an electric motor 43 by means of a belt 40, the frame being vibrated. when viewed as in Fig. 1, in a clockwise direction in a circular path so as to advance the tailings progressively toward the upper end for discharge into the trough 48. An adjustable counterweight 49, Fig. 1, is provided at the upper end of the screen to bring the complete screen frame assembly into balance on the shaft 35, Fig. 2, of the unbalanced wheels 44 at any preselected angle of the screen. One or more screen plates may be arranged in a vat in spaced parallel relation to the bottom of the vat which vat is provided with a feed trough at one end and with a tailings discharge outlet at the opposite end and with an outlet for the screened stock in the bottom of the vat. Damper means may be suspended from the upper end of an inclined screen and be immersed in stock in the channel or vat. The Specification as to inspection under Sect. 91 states that the invention may also be applied to the screening of any materials (see Group II). This subject-matter does not appear in the Specification as accepted.