Liquid-phase backmixing in bubble columns, structured by introduction of partition plates

Abstract

Installation of perforated sieve plates into a bubble column has the effect of introducing structure into an otherwise chaotic hydrodynamic behaviour. In this study, we focus on the reduction of backmixing of the liquid phase in compartmentalised bubble columns. Liquid-phase residence time distribution (RTD) measurements were carried out in bubble columns with diameters D_T=0.10, 0.15 and 0.38 m with air-water system operating at superficial gas velocities of U_G = 0.05-0.04m/s. Partition sieve plates with open areas of 18.6 and 30.7% were used in the studies. The measured data on RTD were interpreted in terms of an axial dispersion model extended to allow for liquid interchange between compartments. The interchange velocity was found to be strongly dependent on the free area of the plates but practically independent of the column diameter.