Conceptual Design and Simulation-Based Optimization of Indirect Extractive Distillation Processes Considering Preconcentration for Separating Ternary Azeotropic Systems

It is a challenge to separate ternary azeotropic systems containing a large amount of one component since the vaporization of the high-content component means huge energy consumption. Incorporating preconcentration into extractive distillation processes can result in energy conservation. Toward this end, this work develops improved indirect extractive distillation with integrated distillation column (IIED-IDC) processes as well as one conventional indirect extractive distillation (CIED) process and three conventional indirect extractive distillation with preconcentration (CIED-PRE) processes for separating such azeotropes. The innovative characteristics of the proposed IIED-IDC schemes are that the preconcentration function is integrated with alternative functions (solvent recovery/extractive distillation functions) in the IDC. Three cases about the separation of methanol/acetonitrile/benzene multiazeotropic systems are used to prove the effectiveness of the presented processes. The simulation-based optimization results display that the IIED-IDC processes can achieve an average 33.63%/13.27% lower economic costs and 37.12%/14.81% lower energy costs than the CIED and CIED-PRE configurations.