Patent ID: 6464384
Filing Date: 2002-10-15
Classification: B01F,B01J,C12M

Abstract:
A system for circulating a liquid medium in a tank, said system comprising:a) a tank for holding said liquid medium; b) a draft tube positioned entirely within said tank and defining a generally cylindrical region within the draft tube and an annular region between the draft tube wall and the tank wall; c) a plurality of impellers disposed in said draft tube and rotatable about an axis which establish flow of said liquid medium in opposite directions in said cylindrical and annular regions; and d) a plurality of baffles positioned within said draft tube having a radial width extending from said draft tube toward said axis and extending axially between said impellers; wherein the ratio of the draft tube diameter to the tank diameter is within the range of about 0.3 to 0.8 and wherein said impellers are positioned from one another along said axis within a distance of about 0.6 to 1.4 impeller diameters and wherein the ratio of the radial width of said baffles to the diameter of said draft tube is at least 0.1.