A Dispersion/Coalescence Model in a Turbulent Bed Contactor

A theoretical dispersion/coalescence model (DCM) is developed for mass transfer in a three-phase fluidized bed contactor, known as a Turbulent Bed Contactor (TBC), based on experimental data reported by the authors in a previous paper. The DCM is developed for the fluidized bed itself isolated from the gas entrance region, referred to herein as the lower column; the model is also adapted to the lower column, acting as a spray column, in which significant mass transfer takes place. The model is based on a balanced condition between the break-up of liquid drops at certain sites in the system and coalescence of droplets at others. Interactions among drops and bed solids are quantified in terms of a collision cross-section in analogy with the kinetic theory of gases. The DCM for the bed predicts the experimental result that K g a passes through a maximum with increasing superficial gas velocity, and also confirms the superiority of the lower column over the fluidized bed at high gas velocities. Both results are novel findings; and, the DCM, as a theoretical model, represents a unique contribution to the existing TBC literature.