A semi-empirical model is proposed to investigate the performance of packed columns equipped with structured packing at high pressures. The mass transfer efficiency is determined in terms of height equivalent to theoretcial plate (HETP) for empirical data of an iC4/nC4 mixture at elevated pressures. Some unexpected phenomena cause predictive models of mass transfer to be inaccurate at high pressures. The effects of the gas phase backmixing and the liquid maldistribution on the gas phase mass transfer coefficient and the effective interfacial area have been investigated in this study. The modified model is developed on the basis of the Delft model to predict the mass transfer behavior of structured packing at high pressures. The proposed model is validated by the empirical data and good agreement is observed between the empirical data and the results of the modified model. The error of HETP calculation by the modified model is less than the other models especially at moderate and high pressures. At low pressures, predicted values of different models are almost the same and they show minor errors. The difference between predicted HETP by various models increases by pressure rising. Moreover, the effect of liquid load on mass transfer in packed columns is investigated. The proposed model can predict the effect of liquid load on mass transfer performance. Proper efficiency has been obtained by the modified model for iC4/nC4 separation process in structured packed column at high pressures.

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