Gas hold-up and axial mixing in the fluid phase of bubble columns

Abstract

Gas hold-up and liquid phase axial dispersion coefficient have been measured in water filled bubble columns of 5·08, 14·0 and 29·0 cm dia. as a function of the superficial gas velocity. From the gas hold-up measurements the following relationship between the relative velocity between gas and liquid, v r , the superficial gas velocity, v g,0 , and the rise velocity of a single bubble, v s , can be established. ▪ The axial dispersion in the 14 and 29 cm column can be characterized by a nearly constant Péclet number based on the column diameter, D, and the relative gas velocity. ▪ for superficial gas velocities between 10 and 45 cm/sec. One series of experiments with ionic solutions (140g NaCl per litre of water) was performed; Although higher gas hold-ups and lower relative gas velocities were measured, the axial dispersion coefficient could again be characterized by ▪ in the same range of superficial gas velocities. In the 5·08 cm column slug flow was observed.