Volumetric mass transfer coefficients in an internal loop airlift reactor with low‐density particles

The influence of organic additives (propanol, benzoic acid, isoamyl alcohol and carboxymethylcellulose) on the volumetric mass transfer coefficient, k_La, in an internal loop airlift reactor with low‐density particles (nylon‐6 and polystyrene) was investigated. The k_La values increased with increase in superficial gas velocity, U_sg, and decreased with increase in solid loading. A draft tube to reactor diameter ratio, D_R/D, of 0.4 gave maximum k_La values. The addition of benzoic acid and propanol increased the k_La values owing to their coalescence inhibiting characteristics. The addition of isoamyl alcohol decreased k_La, owing to the formation of rigid bubbles and recirculation of small bubbles having a low oxygen content. The k_La values decreased with increase in the concentration of the non‐Newtonian fluid carboxymethylcellulose (CMC). The proposed correlations predicted the experimental data well. Copyright © 2006 Society of Chemical Industry