Gas holdup and volumetric liquid-phase mass transfer coefficient in bubble column with draught tube and with gas dispersion into annulus.

Abstract

The gas holdup e and the volumetric liquid-phase mass transfer coefficient kLa were studied experimentally in a bubble column with a draught tube and with gas dispersion into the tube. From experimental observation e increases with increasing gas velocity and frothing ability of liquid, while the other properties of the liquid and the column dimensions have a minor effect on e. kLa increases with gas velocity, column diameter, frothing ability of liquid and diffusivity of the dissolved gas, and decreases with increase in (Di/Do). Other dimensions of the column have a minor effect on kLa. Based on these observations, empirical equations for e and kLa are proposed which are applicable to columns with diameters of 0.1-0.3 m. At the same gas velocity, kLa in this column is larger than that in the bubble column and smaller than that in the column with a draught tube and with gas dispersion into the annulus for a liquid with frothing ability.