Azeotropic batch distillation : new problems and some solutions
Résumé
Two methods of separating a complex quaternary industrial mixture of methanol, cyclohexane, ethanol and water using batch distillation are presented. The first method is an extractive batch distillation and the second method is a cyclic operation. Both methods are based on a thermodynamic analysis of the system (which contains four binary azeotropes and a ternary azeotrope, three of which are heterogeneous) and predictions of the product sequences. The effectiveness of these predictions is demonstrated by comparison with detailed simulations. It is found that quantities of products are important in the separation scheme as well as their relative sequence. The column hold-up seems to directly influence the period during which a given product may be obtained at the distillate. Therefore both thermodynamic and dynamic aspects must be considered in the design of optimal operations.