Effects of the ease of separation index (ESI) and feed composition on the selection of distillation configuration

Abstract

Distillation process consumes the energy in chemical industry. To reduce the consumption, divided wall column (DWC) has been known to be suitable for multicomponent separation and be able to save both energy and capital cost compared to conventional distillation column. However, due to more operation parameters than traditional distillation design method, control and operation of the DWC are more complicated. In this paper, firstly, a conceptual design of a DWC system is proposed. The method based on shortcut methods of Fenske, Underwood, Gilliland and Kirbride, which can rapidly determine structural and operational parameters of the DWC. Secondly, to compare the energy of use between DWC and conventional column, three ternary mixtures are studied with different values of the ease of separation index (ESI) and feed compositions. The results show that the energy consumption of the DWC system is more efficient than the traditional distillation column but it is not always the best arrangement in the multicomponent separation process. The selecting depended on both ESI value and feed composition of a mixture. Based on the comparison, a distillation boundary of ternary diagram is drawn to make a proper choice for the best configuration.