Mass transfer in wetted-wall columns: Correlations at high Reynolds numbers

Abstract

The rate of gas- and liquid-phase mass transport in a pilot-scale wetted-wall column with an inner diameter of 3.26 cm and a length of 5 m was investigated. Empirical correlations for the physical liquid-phase mass transfer coefficient ( k L 0) and the gas-phase mass transfer coefficient ( k G ) were determined. In dimensionless form, the correlations are given by Sh L=0.01613 Re G 0.664Re L 0.426Sc L 0.5 Sh G=0.00031 Re G 1.05Re L 0.207Sc G 0.5 and are valid at gas-phase Reynolds numbers from 7500 to 18,300 and liquid-phase Reynolds numbers from 4000 to 12,000, conditions of industrial relevance. To our knowledge, no correlations for Sh G have been reported in the literature which are valid at such high Reynolds numbers. The wetted-wall column was equipped with six intermediate measuring positions for gas and two for liquid samples, giving rise to a high accuracy of the obtained correlations. Our data showed that Sh L and Sh G both depend on Re G and Re L due to changes in the interfacial area at the high Reynolds numbers employed. The presence of inert particles in the liquid-phase may influence the rate of mass transport, and experimental work was initiated to study the effect on k G . A decrease in k G of up to 15% was seen at solid concentrations ranging from 0 to 30 wt%, though the observed effect could not be correlated.