OXYGEN MASS-TRANSFER IN AIR-AGITATED PACHUCA TANKS .2. MATHEMATICAL-MODELING OF MASS-TRANSFER COEFFICIENTS

A volume-averaged, volumetric gas-liquid mass-transfer coefficient, K- av', has been used to characterize oxygen mass transfer in full-centre -column Pachuca tanks. k(av)', was determined using the axial dispersi on model. The resulting model used only tank geometry and air flow rat e as inputs for the prediction of K-av', in industrial-scale Pachuca t anks. Predictions by the model show clearly that 'local' mass-transfer coefficients, measured at one or two locations, may not represent gas -liquid mass transfer in industrial tanks adequately, for which purpos e it is necessary to obtain an estimate of k(av)'.