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_La 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_La. The diameter of the contactor was varied from 12.5 cm to 70 cm. The effect of the following variables on a and K_La 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_La cannot be predicted a priori, as system properties have a profound effect on a and k_La. 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.