Abstract
Residence time distributions of gas phase in bubble columns were obtained by excluding end effects from observed responses to pulse inputs of tracer, using Fourier transforms. Based on the behavior of the residence time distributions, a gas-phase mixing model was proposed in which bubble swarm was assumed to be composed of two bubble groups, one in the core (or central) region and the other in the annular (or peripheral) region of the column. As a result, it was found that about 80% of all the bubbles are rising in the core region and that gas-phase mixing is more intensive in the core region than in the annular region. Axial dispersion coefficients in each bubble group were correlated empirically.
