Mass transfer effects near the distributor of three-phase fluidized beds

An analysis is performed on the validity of the axial dispersion model (ADM) to quantify mass transfer and mixing in three-phase fluidized beds of different particle sizes. The magnified mass transfer effects observed near the distributor invalidate the ADM as a realistic model for three-phase fluid beds. A two-zone model (T-ZM) based on the present experimental findings has proven to account far more satisfactorily for these effects. Regardless of the model considered, volumetric mass transfer coefficients (K /SUB L/ a) increase with the gas (V /SUB g/ ) and liquid (V /SUB I/ ) superficial velocities. Bubble columns and dilute three-phase fluidized beds of 0.5-cm particles exhibit higher mass transfer rates than three-phase fluidized beds of 0.1- and 0.3-cm particles under the same flow rates.