Hydrodynamic and Mass Transfer Properties in a Three Phase External Loop Airlift Compared with a Three Phase Internal Loop Airlift and a Slurry Bubble Column

K. Nakao, S. Suenaga, K. Furumoto, M. Yoshimoto and K. Fukunaga

Abstract
The effects of suspended solid particles on the hydrodynamic and mass transfer properties were experimentally studied in a wide range of the superficial gas velocity, solid particle property and liquid viscosity in an external loop airlift bubble column in comparison with those in an internal loop airlift bubble column as well as a normal bubble column. The circulating liquid velocities UL, gas holdups εG and volumetric gas liquid oxygen transfer coefficients kLa in the riser of the external loop airlift were found to be almost unaffected by the completely suspended solid particles. The above three properties obtained could be represented by our previous correlations for the gas-liquid two phase flow within an accuracy of ∓ 30 % for a practical reactor design and operation. The analogous results were obtained on the εG and kLa data in the three phase normal and internal loop airlift bubble columns, although a small amount of suspended solid particles was observed to cause a slight decrease in these values in contrast to a lower or negligible decrease in those of the three phase external loop airlift.

This work is licensed under a Creative Commons Attribution 4.0 International License

Keywords
External loop airlift, internal loop airlift, normal bubble column, three phase flow, suspended solid particles, circulating liquid velocity, gas holdup, volumetric oxygen transfer coefficient