Flow pattern of cocurrent gas-liquid downflow in packed beds

Flow patterns observed for cocurrent air-water downflow in beds packed with glass spheres of 3 different sizes (0.12-0.43 cm) were classified into four regimes, i. e. gas continuous flow, transient flow, pulsation flow and dispersed bubble flow. A novel flow regime map was prepared in terms of a volumetric fraction of gas flow rate and a modified Froude number, in which the sum of superficial velocities of gas and liquid is employed as a characteristic velocity and the particle diameter as a characteristic length. In this flow regime map, the regions where each flow pattern appeared were distinguished by simple and plain curves, irrespective of particle diameter. Static pressure gradient was also correlated with the flow regime map coordinates. The static pressure gradient chart as well as the flow regime map can be used to estimate the flow pattern and the static pressure gradient from the operating conditions alone. © 2015, Society of Chemical Engineers, Japan. All rights reserved.