GAS HOLDUP AND AXIAL LIQUID DISPERSION IN THREE PHASE BUBBLE COLUMNS

Abstract

Axial liquid dispersion coefficient was studied in air-tap water systems (bubble columns) and air-tap water-PVC solid particles systems for different column diameters, 10, 15, and 30 cm, Each column had a gas distributor plate with perforated holes of 2 mm diameter. The superficial gas velocity was varied in the range of 0.87–7.54 cm/s. The overall gas holdup was measured experimentally by bed expansion technique and the liquid-phase axial dispersion coefficients were obtained by adjusting the experimental profiles of tracer concentration with the predictions of the model. The experimental results show the overall gas hold-up decreases with an increase in column diameter and solid concentration. The experimental results show that the one-dimensional axial dispersion coefficient, Dax, L, reveals strong scale dependence. Liquid phase axial dispersion coefficient increases with the diameter of the reactor and with solid concentration. Correlations have been used for the estimation of the overall gas holdup and the liquid phase dispersion coefficient in the gas-liquid-solid system bubble column.