Mass transfer studies of external-loop airlifts and a bubble column
Article first published online: 17 JUN 2004
Copyright © 1989 American Institute of Chemical Engineers
Volume 35, Issue 3, pages 393–405, March 1989
How to Cite
Popovic, M. K. and Robinson, C. W. (1989), Mass transfer studies of external-loop airlifts and a bubble column. AIChE J., 35: 393–405. doi: 10.1002/aic.690350307
- Issue published online: 17 JUN 2004
- Article first published online: 17 JUN 2004
- Manuscript Revised: 14 OCT 1988
- Manuscript Received: 12 AUG 1987
Gas holdups (ϵGR) and liquid-phase volumetric oxygen transfer coefficients (kLaT) were measured for a bubble column (BC) and three different external-circulation-loop airlift (ECL-AL) fermentors of 50 to 60 L working volume, using viscous non-Newtonian aqueous solutions of various carboxymethylcelluloses. Some measurements also were done with a viscous Newtonian system (51.8 wt. % sucrose solution).
Discussed in this paper are correlations of ϵGR and kLaT with riser superficial gas velocity (0.02 ≦ UGR ≦ 0.26 m/s), the ratio of the downcomer and riser crosssectional areas (0[BC] ≦ Ad/Ar ≦ 0.444), and the effective viscosity of the liquid phase (0.02 ≦ ηeff ≦ 0.5 Pa · s), over the parameter ranges indicated. It is shown that both ϵGR and KLaT are highly dependent upon UGR and Ad/Ar. The effective viscosity has a significant effect on KLaT, but has only a relatively weak affect on ϵGR. The KLaT correlation developed for non-Newtonian systems was extended to include the results obtained for the viscous Newtonian system studied by incorporating the effects of liquid-phase molecular diffusivity, density, and interfacial tension as determined by Nakanoh and Yoshida (1980).