Hydrodynamics of countercurrent bubble column: Experiments and predictions

Abstract

Experiments were conducted to study the hydrodynamics of a countercurrent bubble column equipped with porous plate distributor. Four flow regimes – purely homogeneous bubbling regime, discrete bubbling regime, helical flow regime and churn-turbulent regime are identified based on the bubble swarm velocity plot. Regime maps are presented showing the effect of liquid velocity on transition gas velocity and gas holdup along all three transition boundaries. The liquid velocity advances the onset of discrete bubbling regime, helical flow regime and churn-turbulent regime. Gas holdup increases with an increase in gas and liquid velocities. A methodology for predicting the gas holdup for both the homogeneous and heterogeneous regimes and the transition gas velocity and holdup is developed by extending existing models for homogeneous and heterogeneous regime. Bubble diameter, the model parameter in homogeneous regime, decreases with an increase in liquid velocity. Apparent slip velocity between gas and liquid phase, the model parameter in heterogeneous regime, increases with both gas and liquid velocity. The method predicts the data of the present work and literature satisfactorily. The effect of gas and liquid velocities on the radial profile of liquid velocity and its properties are simulated using the validated model.