Comparison of different heat integration pressure swing distillation processes for separating isobutanol and p-xylene azeotrope

Chemical process intensification has attracted extensive interest of scholars. Distillation, as a high energy consumption industry, is in urgent need of energy saving and CO₂ emissions reduction by means of process intensification. In this paper, isobutanol and p-xylene azeotrope was separated by pressure swing distillation (PSD). Combined with process integration method, four heat integration PSD processes including partial heat integration PSD (PHI-PSD), enhanced partial heat integration PSD (EPHI-PSD), full heat integration PSD (FHI-PSD), and enhanced full heat integration PSD (EFHI-PSD) were designed and optimized through sequential iterative procedure. The total annual cost (TAC), CO₂ emissions, and thermodynamic efficiency were calculated and compared. By comparing relevant data, it is found that EPHI-PSD process has obvious advantages in terms of economic, thermodynamic efficiency, and environmental benefits. Specifically, comparing with the basic PSD process, thermodynamic efficiency of EPHI-PSD process is improved by 97.8% while TAC and CO₂ emissions are decreased by 37.0% and 50.1%, respectively.