Mass transfer in mechanically agitated gas—liquid contactors

Abstract

The theory of absorption with pseudo mth order irreversible reaction was used to obtain effective interfacial area, a, in mechanically agitated vessels. The liquid-side mass transfer coefficient, k L a was found by using the theory of absorption with slow chemical reaction. Eleven different systems were used to obtain a and four different systems were used to obtain k L a. The diameter of the contactor was varied from 12.5 cm to 70 cm. The effect of the following variables on a and K L a was investigated: speed, type and diameter of the agitator; tank diameter, height of the agitator and height of the clear liquid from the base of the contactor; ionic strength, nature of ions, viscosity and surface tension of the liquid. It appears that values of a and k L a cannot be predicted a priori, as system properties have a profound effect on a and k L a. However, experiments can be done in a small agitated contactor (say, 20 cm dia. contactor) and scale-up can be done on the basis of equal tip speed divided by the square root of the contactor diameter, possibly with a fair degree of confidence.