1527895 Aerating liquids UNION CARBIDE CORP 16 Oct 1975 [17 Oct 1974] 42413/75 Heading B1C [Also in Division G3] In a method of and apparatus for contacting a gas with a liquid, e.g. oxygen-rich gas with BOD liquor, and in which rotary surface aeration means 12, Fig. 2, are positioned in an enclosed treatment chamber 25 to which the liquid and gas are fed, the power consumption of the aeration means 12 is sensed by sensing means 89, a control signal generated and transmitted, 23, 24 and gas flow control means 6 adjusted in dependence thereon in order to adjust the gas pressure in the chamber and thereby the liquid level so as to maintain the power consumption at a predetermined optimum value and the liquid level at the design value. The rotary aerator may comprise four radially-extending, forwardly-angled blades mounted on a vertical shaft (Fig. 1 not shown) or alternatively a horizontally mounted brush-type aerator 39, Fig. 3, which extends through successive aeration chambers 40, 41, 42. In another embodiment (Fig. 5, not shown) the vertically arranged shafts of radial blade type aerators extend down into the liquid and carry mixing propellers at their lower ends. Controls (see Division G3) may be provided for controlling the oxygen concentration of the liquid undergoing treatment and the oxygen concentration of the spent gas.
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