Energy saving and capital cost evaluation in distillation column sequences with a divided wall column

The divided wall column (DWC) to separate three components in a single distillation tower is receiving increasing interest in industrial applications due to the potentiality in energy and capital cost savings. In this work, the DWC configurations for the separation of a four components mixture was considered, and 5 different composition cases were analyzed. After selecting the best simple column (SC) sequence, the hybrid structures obtained by considering a configuration with a DWC replacing the first or the last two SCs of the sequence are considered. To simulate the DWCs a short-cut code was used to get the input data necessary to initialize the rigorous simulations. The results obtained for the hybrid structures were compared with the performance of the best SC sequence from which are derived to evaluate energy and capital cost savings. The Petlyuk and the DWC structures were considered independently in the capital cost evaluation to select the most convenient configuration. A significant energy reduction was achieved with DWC structures, while the saving in capital costs is lower than the 30% value reported in most of the specialized literature. (C) 2009 The Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.