Design and eco-efficiency analysis of sustainable extractive distillation process combining preconcentration and solvent recovery functions for separating the tetrahydrofuran/ethanol/water ternary multi-azeotropic mixture

It is of great significance to design a sustainable extractive distillation separation configuration that can implement efficient separation of the ternary multi-azeotropic mixtures with a large single component content and propose a feasible and accuracy sustainable evaluation method. This is because the extractive distillation separation scheme with preconcentration should be designed for the particularity of such ternary multi-azeotropic azeotropes. To fill this gap, the paper designs a novel and sustainable three-column extractive distillation process containing one integrated distillation column (TCED-IDC) with both preconcentration and solvent recovery functions and two extractive distillation columns taking the separation of the tetrahydrofuran/ethanol/water ternary multi-azeotropic mixtures containing large amounts of water as an example. Simultaneously, economic optimization of the TCED-IDC process as well as the conventional three-column extractive distillation (TCED) process and the four-column extractive distillation (FCED) process is implemented to determine economically optimal design parameters via minimizing the total annual costs (TAC) using genetic algorithm. Following that, environmental and thermodynamic evaluations are comprehensively conducted to prove the advantages of the TCED-IDC process. The TCED-IDC separation schemes achieves 79.05%/8.47% reduction in CO2 emissions and 71.92%/9.57% economic cost savings compared to the TCED and the FCED schemes, and the corresponding thermodynamic efficiency is 7.87%. Moreover, an extended Eco-efficiency Comparison Index (ECI) method is proposed to perform the eco-efficiency analysis covering economic, environmental, and thermodynamic aspects for the three extractive distillation separation processes proposed. The analysis results demonstrate that the integration of preconcentration and solvent recovery functions improve the eco-efficiency compared to the other two separation schemes, and the corresponding ECI reaches 91.57% and achieves 1.42% points increase compared to the FCED scheme.