Energy-Efficient Extractive Distillation Process by Combining Preconcentration Column and Entrainer Recovery Column

An energy-efficient two-column process based on a conventional extractive column process is explored by combining a preconcentration column and entrainer recovery column, which provides potential energy savings and capital investment reduction. Two case studies are demonstrated to verify the above-mentioned energy and economic advantages: the separation of isopropyl alcohol-water using DMSO as the entrainer and the separation of acetonitrile-water using ethylene glycol as the entrainer. In both cases, based on the global economic optimization, a design with optimized operation conditions for the conventional and improved processes is developed. It is revealed that the new process offers energy savings of 13.7% and 16.3%, respectively, and a similar reduction in total annual costs as compared to those of the conventional process.