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

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 (kL0) and the gas-phase mass transfer coefficient (kG) were determined. In dimensionless form, the correlations are given by ShL=0.01613 ReG0.664ReL0.426ScL0.5 ShG=0.00031 ReG1.05ReL0.207ScG0.5 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 ShG 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 ShL and ShG both depend on ReG and ReL 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 kG. A decrease in kG of up to 15% was seen at solid concentrations ranging from 0 to 30 wt%, though the observed effect could not be correlated.

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