Novel heat pump assisted distillation configurations for energy and economic savings and their application on propylene/propane and I-butane/N-butane separation systems

Abstract

Various configurations of vapor recompression heat pumps were previously proposed for enhancing its thermodynamic and/or economic performance. The outcomes of prior publications were documented using fundamentally distinct separation systems, making it challenging for process engineers to decisively determine the optimal processing options for a particular separation task. This difficulty arises from the variations in thermophysical properties exhibited by the materials involved. Despite limited research on bottom flashing heat pumps, they offer advantages over vapor recompression such as lower operating pressure and temperature in process sections. This can result in cost savings and safer operation. In this paper, novel configurations of bottom flashing are proposed, based on the ideas and schemes, previously proposed for vapor recompression. The novel processing systems were proposed and applied on propylene/propane and i-butane/n-butane separation processes as samples of close-boiling distillation systems. This study showed that the bottom flashing systems showed greater economic performances compared to vapor recompression for i-butane/n-butane separation. total annual costs savings of 19.0% was obtained, using the novel configuration of heat recuperated bottom flashing configuration on isobutane/n-butane separation. Also, annualized costs of the systems based on bottom flashing were 10.9%, 4.2% and 7.3% lower than their equivalent vapor recompression processes.