Introduction

Distillation remains the powerhouse of separation processes in the chemical industry, yet its high energy demand presents economic and environmental challenges, especially when dealing with azeotropic mixtures. This study explores process intensification strategies—namely thermal coupling and heat pump techniques—to enhance energy efficiency in pressure swing distillation (PSD) of THF/water and acetone/chloroform azeotropes.

Methods

Four configurations were evaluated: conventional PSD (CPSD), partial heat-integrated PSD (PHIPSD), full heat-integrated PSD (FHIPSD), and heat pump-assisted PSD (HPAPSD). Process design followed a structured four-step approach based on total annual cost (TAC), total energy consumption (TEC), CO₂ emissions, and second law efficiency. PHIPSD and FHIPSD utilized heat recovery between high-pressure and low-pressure columns, reducing steam and cooling utility demands. HPAPSD incorporated vapour recompression.

Results

In the tetrahydrofuran/water system, TAC, TEC, and CO₂ emissions were reduced by up to 50%, 60%, and 83%, respectively, with thermodynamic efficiency reaching 24%. For acetone/chloroform, reductions of up to 71% in TAC, 87% in CO₂ emissions, and efficiencies of 18% were observed. While HPAPSD involved higher capital investment due to compressor systems, it achieved the greatest energy savings and environmental benefits, significantly reducing CO₂ emissions and exergy loss. Thermodynamic efficiency confirmed the HPAPSD's superior performance across both azeotropic systems.

Conclusions

This study illustrates the potential of electrically driven, integrated distillation schemes in minimizing operational costs and environmental emissions. Findings show the need for the broader application of HPAPSD in azeotropic separations, aligning with global sustainability goals and the transition toward renewable energy sources.