Absorption of oxygen in countercurrent multistage bubble columns—II: Aqueous solutions with high viscosity

Abstract

The mean relative gas hold up, ϵ g, and the volumetric mass transfer coefficients, k La , were measured by steady state method in the first stage of a multistage countercurrent column 20 cm in diameter. Perforated plate trays with different bore hole diameters and free cross sectional area were applied. The height of the stage was varied. Newtonian (glycerol) and pseudo plastic (CMC) solutions were used as media. In general with increasing superficial gas velocity, with decreasing bore hole diameter and free cross sectional area of the perforated platé trays as well as with decreasing concentration and viscosity k La increases. With increasing height of the bubbling layer k La diminishes except for glycerol, for which no or only slight influence of the bubble layer height prevails. This effect for CMC diminishes with the increase of their concentration. With increasing specific power input k La becomes larger. At constant power input the highest k La is attained with the smallest bore hole diameter of the trays for CMC solutions. For glycerol no such an effect was found.