Application of the partially thermally coupled distillation flowsheets for the extractive distillation of ternary azeotropic mixtures

An application is considered of the extractive distillation flowsheets with partially thermally coupled columns for the separation of ternary azeotropic mixtures with the different type of vapor-liquid equilibrium diagrams. The feasible extractive distillation flowsheets with such columns are identified for all types of the ternary azeotropic mixture vapor-liquid equilibrium diagrams. The manifold of flowsheets is the search space to identify the optimal arrangement for the separation of the individual mixture. An applicability analysis of all possible extractive distillation flowsheets for all types of vapor-liquid equilibrium diagram decreases the number of feasible configurations for the selection of the optimal extractive distillation sequence for the mixture with unique vapor-liquid equilibrium diagram separation. For example, in the case of benzene-cyclohexane-toluene mixture distillation with N-methylpyrrolidone as an entrainer, only 10 extractive distillation flowsheets instead of 22 potential ones must be analyzed, calculated and optimized for the identification of the best extractive distillation arrangement.