Extractive Dividing Wall Column for Separating Azeotropic Systems: A Review

Extractive distillation (ED) can be combined with divided wall column (DWC) schemes to separate azeotropic mixtures within one column shell. Traditional extractive divided wall columns (EDWCs) have the dividing wall placed at the top of the column, eliminating the common rectifying section. This review covers the design schemes, entrainer selection process, simulation design methods, and control schemes for EDWCs. There is an emphasis on the 33 azeotropic systems that have been separated using EDWCs. Successful case studies and ongoing research challenges are highlighted in the review. As with switching from conventional distillation schemes to a DWC, the motivation to use EDWCs over ED is economic savings and environmental benefits.