Optimal design of heat pump assisted thermally coupled distillation sequences

Abstract

This work presents a comprehensive methodology for the optimal design of heat pump-assisted, thermally coupled distillation sequences, aiming to support the electrification and decarbonization of energy-intensive industrial processes. A rigorous simulation-based optimization approach is developed, coupling Aspen HYSYS with MATLAB through a client–server architecture. Optimization is carried out using a customized Particle Swarm Optimization algorithm. The methodology simultaneously considers optimal column sequencing, thermal coupling, direct and indirect heat integration (via vapor recompression and bottom flashing cycles), process intensification strategies such as Divided Wall Columns, and heat recovery techniques inspired by Self-Heat Recuperation Technology. The model is applied to several case studies involving the separation of zeotropic quaternary mixtures. Results indicate that the electrification of distillation sequences can be usually achieved with minimal or no economic penalties while reducing reliance on fossil-based utilities. But even in cases in which the full de-fossilization has an important penalty cost, the optimal solution usually includes heat pumps (partial electrification) with significant economic and environmental benefits compared with the actual configurations without heat pumps.