Energy-Saving Strategies for Waste Heat Recovery in an Extractive Pressure-Swing Distillation Process of a Chloroform/Ethanol/Water Ternary Azeotropic Mixture

By conventional distillation methods, it is difficult to achieve effective separation of complex mixtures, and special distillation processes are usually required, but these generally have the problem of high energy consumption. Three process schemes, namely, pressure-swing distillation (PSD), extractive distillation (ED), and extractive pressure-swing distillation (EPSD), were compared for the separation of the chloroform–ethanol–water ternary azeotropic system. After multiobjective optimization analysis, EPSD was determined as the optimal basic process. It is found that traditional heat integration has limited energy-saving effects, while vapor recompression technology increases electricity and equipment costs. Therefore, considering the observation that the top section of the high-temperature column exhibits a lower temperature than the bottom section of the low-temperature column, an intermediate heat exchange-assisted heat integration process (IHE-HI1-EPSD) was developed. Further in-depth analysis of sensible heat utilization revealed that the bottom streams of the high- and low-temperature columns can also implement heat exchange, leading to the development of the optimal-performance IHE-HI2-EPSD process. By the establishment of a comprehensive evaluation system, the process was systematically evaluated from three dimensions: economy, energy consumption, and environmental impact. Comparative analysis revealed that the IHE-HI2-EPSD process can reduce the total annual cost (TAC) by 22.44% and reduce energy consumption and gas emissions by 48.49%. This process has demonstrated significant advantages in energy conservation, providing a new sustainable technical solution for the energy-saving separation of azeotropic systems.