Are process-intensified extractive distillation always energetically more efficient?

Abstract

The thermally coupled, dividing wall column, and side-stream configurations are some of the energy-intensified techniques widely applied to the extractive distillation for improving the energy efficiency. Today, several heuristics are available for analysing the energy-saving efficiency of these intensified techniques for ideal distillation system but there is no heuristic available for analysing the complex distillations system. Therefore, it has not yet been established what variables affect the energy-savings and under what particular conditions the intensified processes for these complex distillation systems present energy-savings. In this work, we aim to provide insights and preliminary conclusions that open a field of study for a more detailed and in-depth analysis for future researches through three different case studies where their corresponding intensified configurations do not provide any energy-saving relative to the conventional extractive distillation (CED). Based on our preliminary analysis, we attributed this to the poor values of interconnecting flowrate or composition and high column internal vapour flowrate. Our results also revealed the possibility of extending several heuristics, previously developed for evaluating the energy-saving efficiency in ideal distillation system, for complex distillation. Lastly, several recommendations are given that were derived from our simulation results and the analyses we carried out on existing publications.