Surface aeration impellers

Abstract

The invention is an improved surface aeration impeller for use in a liquid filled tank which particularly increases the surface turbulence and the entrainment of gas into the liquid surface. The impeller is an axial flow impeller and may be either a pitched blade turbine (PBT) or have airfoil shaped blades. In either case, the impeller has a portion which extends radially along an edge thereof which projects above the surface of the liquid being mixed in a vertical direction. The blades of the impeller are modified to include a top horizontal plate to lower the spray height of the liquid and an optional endcap, both of which can enhance and increase the standard aeration efficiency. Preferably, the impeller is rotated in an up-pumping direction and propels the liquid being aerated in a radially upward and outward direction. A sufficient upward surge of liquid is produced so that the liquid is observed to splash back onto the surface a plurality of times in the course of operation of the impeller. Such multiple splashing action enhances the contact between the air and the liquid itself to improve the oxygen transfer efficiency of the aeration impeller.

Dependencies are inferred from the claim text.