Gas Holdup and liquid Phase RTD Studies in Multistage Bubble Columns

Abstract

Installation of perforated sieve plates into a bubble column has the effect of introducing structure into an otherwise chaotic hydrodynamic behavior. In this study, we studied the effect of tray plates spacing and geometry on the overall gas holdup and liquid phase residence time distribution (RTD). The measurement carried out in bubble columns with diameter 10 cm and 20 cm with air-water system. Partition sieve plates with open areas of 15 and 30% and the tray spacing equal the column diameter (10, 20 cm) and twice the column diameters (20, 40 cm) were used in the studies. The overall gas holdup is measured experimentally by bed expansion technique and the liquid phase backmixing has been studied by measuring liquid phase RTD and analysed using one parameter dispersion model. The experimental results show that the increase in the tray spacing reduces the overall gas holdup and increase liquid phase dispersion. Also by comparing the liquid phase dispersion coefficient values with that in the conventional bubble column, it has been observed that there is reduction in the backmixing by 45-11% for tray spacing of 10 cm and 20 cm respectively in the 10 cm bubble column diameter. Correlations have been used for the estimation of the overall gas holdup and liquid phase dispersion coefficient in multistage bubble column.