Using image analysis in the study of multiphase gas absorption

Abstract

For the air–water–calcium alginate beads system, the effect of the presence of solids on the mass transfer characteristics in a bubble column was experimentally studied. Volumetric liquid side mass transfer coefficient, k L a , specific interfacial area, a, and hence liquid side mass transfer coefficient, k L , were determined under different solid concentrations (0, 5, and 10 vol%), superficial gas velocities (up to 0.27 cm/s) and solid sizes (1.2 and 2.1 mm diameter). The bubble characteristics, namely the interfacial area, were obtained using an image analysis technique. This technique proved to be a suitable and practical method to characterize mass transfer phenomena in bubble columns for the range of operating conditions used. The solids affect negatively k L a , decreasing both a and k L , the effect being more pronounced for the smaller particles. For these particles the variation of k L a is due to the variation of its two components, while for larger particles k L a variation is due, essentially, to changes in k L as no significant differences in a were observed.