PREDICTION OF THE VOLUMETRIC MASS-TRANSFER COEFFICIENT IN PNEUMATIC CONTACTORS

Semi-theoretical expressions are developed for the prediction of the volumetric mass transfer coefficient (K//La//D)//T, in pneumatic contactors, using the correlation of P. H. Calderbank and M. Moo-Young for the mass transfer coefficient and the local isotropic turbulence theory for predicting bubble diameter. A direct proportionality of (K//La//D)//T to the gas hold-up is predicted, with an exponent of 1. 2 on epsilon //G, while, in terms of physical parameters, (K//La//D)//T is predicted to be proportional to the 0. 8 power of the superficial gas velocity for both bubble column and airlift contactors, and proportional to (1 plus A//d/A//r)** minus **2 for airlift contactors, where A//d/A//r is the downcomer-to-riser cross-sectional area ratio. Experimental results obtained in bubble column and airlift contactors (external-loop and concentric-tube) of pilot-plant scale (ca. 50L liquid capacity), with water and 0. 15 kmol m** minus **3 NaCl solution as liquid media, were used to test the proposed expressions.