Dividing Wall Columns (DWC) provide a new approach to age-old distillation techniques (Dejanovic et al., 2010 and Kiss 2009). These columns have become popular lately owing to the energy and capital benefits that they provide. DWCs, with their versatility and flexible operation, are found in both retrofit and grassroots applications for reformate splitters, naphtha splitters, among others.
DWCs work on the principle of removing thermodynamic design flaws in traditional distillation columns (Yildirim et al., 2011). These limitations are encountered in both two-column separation sequences as well as side-cut columns. This paper highlights these inherent design flaws in side-cut columns and illustrates how middle DWC technology helps to eliminate them.
Two examples of revamping naphtha splitter columns with DWC technology are presented. In one case, a DWC column produces better product specifications than the original design. In the other case, a two-column sequence is replaced by a single DWC column for the same product quality. This results in freeing up the second column for use in another service. In both cases, a DWC helps to achieve a better side-cut product. The product specifications of the top and middle cuts are somewhat flexible. Both columns are operational in one of the largest refineries in South East Asia.