SIMULTANEOUS DETERMINATION OF VAPOUR- AND LIQUID-SIDE VOLUMETRIC MASS TRANSFER COEFFICIENTS IN DISTILLATION COLUMN

摘要

The method for the determination of k_La and k_Va in distillation column consists in a fitting of the concentration profile along the column obtained by the integration of a differential model to the experimental one.Preliminary test of the method is presented using concentration profile measured in the binary distillation of the ethanol-water system at total reflux on metal Pall Ring 25 mm.The distillation is modelled as a simultaneous heat and mass transfer process and the mathematical model includes mass and energy balances and the heat and mass transfer equations.By using the Maxwell-Stefan flux expressions the convective transport contributions have been considered in the transfer equations.Vapour and liquid phases are supposed to be at their saturated temperatures along the column.Concentration and temperature dependent physical parameters and the liquid phase thermodynamic non-idealities have been taken into account.The distillation mass transfer coefficients in the liquid and vapour phases obtained by the fitting procedure are compared with those calculated from absorption data using Onda's,Billet's and Linek's correlations.The distillation heat transfer coefficients calculated from the model assuming saturated temperatures in both phases are compared with those calculated from the Chilton-Colburn and penetration model analogy.