Combinatorial energy intensification of a ternary distillation process

Abstract

Engineers seeking to improve performance and reduce the cost and environmental impact of distillation processes by energy intensification face a plethora of choices, including cyclic distillation, HiGee distillation, dividing-wall columns (DWCs), side-streams, column stacking, heat pumps, and others. Often multiple strategies can be combined in the same process. All of these methods have been shown to save energy and reduce cost separately, but alternatives are seldom compared and there is little guidance for selecting among the options. To address these deficiencies, in this work a combinatorial study of energy intensification strategies is conducted. For a given separation task (in this case the separation of methylcyclopentane, cyclohexane, and methylcyclohexane) and a set of intensification strategies, all feasible combinations are optimized and compared. The results show that all energy intensification strategies by themselves save money compared the base case. Without heat pumps, DWCs outperform stacked sequences and side-stream sequences, but the combination of stacking and side-streams performs better than the DWC. Heat pumps are found to reduce cost by themselves, but to increase cost when they are applied to DWCs or stacked sequences. A stacked side-stream sequence without a heat pump is found to perform the best overall.