Improved Parametric Study of an Ethanol–Water Distillation Column with Direct Vapour Recompression Heat Pump

Vapour Recompression is an energy efficient technology that improves the thermodynamic efficiency of distillation processes, by compressing the overhead vapour from the top of the column, for use as heat source to the reboiler. High efficiency values obtained from models and simulations of this integrated unit differ significantly from efficiency values in real life process systems. However, studies show that certain fluid properties and flow conditions defined by Nusselt, Reynolds and Prandtl Numbers, are important for better estimation of realistic efficiency value from process models. In this work, an ethanol-water distillation system with heat pump is used as a case study and the unit was modeled by calculated design specifications. Analytical equations and empirical correlations for heat loss from the column , compressor duty, pressure energy losses and heat transfer across the reboiler-condenser ,was employed to provide practical efficiency value of the heat recuperation unit. The significance of this work is the provision of more accurate and realistic models of distillation-vapour recompression unit when compared with some other parametric study works on vapour recompression –distillation units..