Side-stream extractive distillation process with intermediate reboiler and heat integration design: from green entrainer screening to energy-saving improvement

Green entrainer screening and heat integration techniques are significant two stages for the energy-saving extractive distillation design of azeotropic mixtures. In this study, the complex butanone/ethanol/water ternary system with four azeotropes is set as the case study to demonstrate the distillation design and improvement. Firstly, a green entrainer screening process is conducted from 1432 potential organic solvents through the quantum chemical calculations, thermodynamic diagram insights, and the Venn diagrams with multi-criteria decision-making (MCDM) method. Based on the identified optimal entrainer ethylene glycol (EG), a hybrid process intensification approach is further proposed by introducing the side-stream configuration, intermediate reboiler, and heat integration techniques into the conventional triple-column extractive distillation process. Encompassing with a total eight developed extractive distillation processes for the separation of butanone/ethanol/water, the multi-objective particle swarm optimization (MOPSO) algorithm is employed to determine the operational parameters with two objectives namely the total annual cost (TAC) and CO₂ emissions. The results indicate that the side-stream extractive distillation process with intermediate reboiler and heat integration (SSED-IR-HI) is superior to the others, which lead to an 8.23 % reduction in TAC, a 19.13 % reduction in CO₂ emissions, and an 8.67 % increase in thermodynamic efficiency, respectively when compared to the benchmark extractive distillation process.