Liquid backmixing in bubble columns and the axial dispersion coefficient

Abstract

Abstract Liquid backmixing in bubble columns is commonly described using the 1‐D axial dispersion model, wherein all the contributing mechanisms leading to liquid macromixing are lumped into a single axial dispersion coefficient. No relationship has been reported that allows the quantification of various fluid‐dynamic contributions to the axial dispersion coefficient in bubble columns. In this study, a Taylor‐type analysis was performed to arrive at an expression for the axial dispersion coefficient in terms of the two dominant fluid‐dynamic factors, convective recirculation and eddy diffusion. Experimental measurements of the relevant fluid‐dynamic parameters are used to study the effects of operating conditions on the axial dispersion coefficient and its contributing factors.