Improvements in or relating to sedimentation or settling tanks

摘要

690,631. Gravity-separation apparatus. FILTRATORS, Ltd., and AITKEN, I.M.E. Oct. 19, 1951 [July 19, 1950], No. 18024/50. Class 46 In a settling tank in which the liquid flows upwards through a chamber of upwardly-increasing cross-sectional area the chamber is divided by one or more vertical or nearly vertical partitions into two or more sections between or amongst which the upward flow is distributed in sucn manner that a predetermined proportion of the total flow through the tank takes place through each section irrespective of the rate of flow of liquid through the tank. Liquid to be treated is delivered preferably tangentially into the upper end of a downwardly-expanding delivery passage F, Fig. 1, and flows radially outwardly beneath a ring-beam G between supporting pillars H. Some rises in an annular upwardly-expanding section Q within a circular wall J, Fig. 2, the supernatant liquid flowing through notches E1 into radial collecting channels E which convey it to a peripheral trough D. The remaining liquid rises in the remaining section R between the wall J and the outwardlysloping wall B of the tank, the supernatant liquid flowing through further notches E1 in the walls of the channels E and also through notches D3 in the inner wall D 2 of the trough D. The maximum value of one of the horizontal dimensions at any location in each of the sections Q and R is preferably not greater than three-quarters of the average vertical height of the respective section to prevent eddying. Preferably also the distribution and dimensions of the notches E' and D3 in relation to the sections Q and R are such that the upward velocity of the flow of liquid at approximately equivalent levels is the same in both sections. Sludge collecting in sumps L is drawn off by static head through pipes M, Fig. 4, each discharging by a spout M3 into a trough N communicating at circumferential intervals with a trough O at ground level. The rate of discharge of sludge from the spouts M3 may be varied by adjustment of a screw extension M2 in a socket M4. The pipes M and M2 are easily accessible for cleaning by a flexible rod. In an alternative arrangement a comparatively straight upper end portion of the sludge pipe may be connected to the rigid position by a knuckle joint. All the upper portions may be interconnected by a series of wire or rod links so arranged that when moved circumferentially the series of links causes simultaneous movement of all the upper portions to adjust the level of sludge discharge.