NONWETTING FLOW OF A LIQUID THROUGH A PACKED-BED WITH GAS CROSS-FLOW

In this study, the effect of a cross-flow gas field on the percolating flow of a non-wetting liquid through a packed bed was investigated. E xperiments were conducted to measure the liquid shift, due to the cros s-flow of air, for the flow of aqueous barium chloride solutions and m ercury percolating through beds of polyethylene and expanded polystyre ne particles. An X-ray technique was used to visualize the liquid flow pattern through the packed bed. The liquid percolates through a packe d bed as a series of rivulets and droplets which are continuously brea king up and coalescing. A mathematical model to predict the direction of the liquid rivulet/droplet flow under the influence of a gas flow f ield was developed. The model treats the liquid as a discrete phase an d includes the effects of gravity, gas drag, and inertial and viscous bed resistance. The effective droplet/rivulet size is an important mod el parameter, and the model postulates that the droplet/rivulet size i s a function of both the effective capillary size of the bed and the l iquid flow rate. A simplified population balance analysis for droplet coalescence is used to predict the effect of liquid flow rate on dropl et/rivulet size. The model predictions are consistent with the experim ents.