Dynamics and control of electrified pressure-swing distillation for separating a maximum-boiling azeotrope featuring small pressure-induced shift

Abstract

Pressure-swing distillation (PSD) is a typical thermal-driven technique for separating pressure-sensitive azeotropes. By implementing heat pump assisted distillation (HPAD) and self-heat recuperation technology (SHRT), the process can be modified as an electrical-driven one. Previous works have verified the overwhelming steady-state economic advantages of electrified PSDs over a conventional design. However, highly integrated electrified processes could jeopardize the dynamics and controllability. In light of potential dynamic control issues, a demonstrating case of a maximum-boiling acetone/chloroform azeotrope featuring a small pressure-induced shift was studied. Severe snowball effects were observed in these complicated electrified systems. To maintain process stability under throughput and composition disturbances, several robust control structures based on decentralized proportional-integral feedback controllers were developed. These control structures feature temperature controllers with no composition measurement. The results indicate that there is no conflict between the steady-state advantage and dynamic controllability. Therefore, considering the great advantages in economic and environmental aspects of electrified PSD, it is encouraged to extend process electrification measures to other distillation processes.