RADIAL NONUNIFORMITY OF VELOCITY AND VOIDAGE IN A BUBBLE COLUMN

The radial variation of gas hold-up has been measured in a 138 mm diameter column using a conductivity probe technique. The method has been validated by comparison with a manometric method and the results show very large voidages in the center of the column at gas rates above 40 mm/s. Liquid circulation velocities have also been measured, using a modified Pitot tube, and have been shown to be very large; with no net liquid flow through the column and gas rates of up to 170 mm/s, upward liquid velocities in the column center were up to 500 mm/s. The two sets of results have been correlated by means of a simple theory of liquid circulation.