TRANSPORT PHENOMENA IN BUBBLE COLUMN REACTORS .2. PRESSURE-DROP

The two-phase frictional pressure drop was measured in a 0.15 m internal diameter bubble column operated in a continuous co-current manner. The fractional gas hold-up was measured using the gamma-ray absorption technique and the pressure drop using modified differential manometry. The superficial gas and liquid velocities were varied in the ranges 0.127-0.451 m s-1 and 0.047-0.236 m s-1 respectively. The effects of liquid viscosity, non-Newtonian behaviour, and the presence of electrolyte were investigated. A coherent model was developed to predict the pressure drop in homogeneous (bubbly flow) and heterogeneous (churn-turbulent) regimes. For this purpose, knowledge of the liquid phase flow pattern was used. A comparison between model predictions and experimental observations is presented. On the basis of the pressure drop, a criterion was developed to predict the transition from the homogeneous to the heterogeneous regime. A favourable comparison is shown between model predictions and experimental observations.