Bubble size and radial gas hold‐up distributions in a slurry bubble column using ultrafast electron beam X‐ray tomography

Abstract

Gas hold‐up and bubble size distribution in a slurry bubble column (SBC) were measured using the advanced noninvasive ultrafast electron beam X‐ray tomography technique. Experiments have been performed in a cylindrical column ( D T = 0.07 m) with air and water as the gas and liquid phase and spherical glass particles ( d P = 100 μm) as solids. The effects of solid concentration (0 ≤ C s ≤ 0.36) and superficial gas velocity (0.02 ≤ U G ≤ 0.05 m/s) on the flow structure, radial gas hold‐up profile and approximate bubble size distribution at different column heights in a SBC were studied. Bubble coalescence regime was observed with addition of solid particles; however, at higher solid concentrations, larger bubble slugs were found to break‐up. The approximate bubble size distribution and radial gas hold‐up was found to be dependent on U G and C s . The average bubble diameter calculated from the approximate bubble size distribution was increasing with increase of U G . The average gas hold‐up was calculated as a function of U G and agrees satisfactorily with previously published findings. The average gas hold‐up was also predicted as a function of C s and agrees well for low C s and disagrees for high C s with findings of previous literature. © 2012 American Institute of Chemical Engineers AIChE J, 59: 1709–1722, 2013