An intensified energy-saving architecture for side-stream extractive distillation of four-azeotrope mixtures considering economic, environmental and safety criteria simultaneously

Abstract

Side-stream extractive distillation is used in separating azeotropic mixtures due to its advantages in energy-saving. However, environmental and safety aspects should also be considered in most chemical industries. Thus, this work focuses on thermodynamic analysis, multi-objective optimization and multi-criteria decision making. The main contributions of this work are developing the intensified side-stream extractive distillation for complex ternary azeotropic mixture, obtaining the trade-offs between the economic, environmental and safety impacts of SSED processes and determining the best sustainable SSED process according to objective mathematical analysis. A systematic intensified architecture including conceptual design, multi-objective optimization and multi-criteria decision making is proposed. Firstly, three strategies of side-stream extractive distillation (i.e., SSED-1, SSED-2, and SSED-3) are proposed via the thermodynamic analysis including quaternary phase diagram. Subsequently, the three strategies are optimized via the multi-objective particle swarm algorithm simultaneously using total annual costs (TAC), CO2 emission and process route index (PRI) as objective functions. Finally, the optimal economic, environmental and safety performance of such a complex system is determined by the technique for order of preference by similarity to ideal solution method with entropy weighting information. The results indicate that the introduction of the side-stream for extractive distillation could decrease the exergy loss and increase the thermodynamic efficiency. The SSED-1 process shows that the best performance in economic, safety and environmental aspects, which reduce 19.21% of TAC, 5.24% of PRI and 16.80% of CO2 emission, respectively.