A novel method for the search and identification of feasible splits of extractive distillations in ternary mixtures

• We extend the method of infinitely sharp splits to extractive distillation columns.
• The method identifies feasible splits in ternary systems of any VLE topology.
• The method determines the limits for entrainer rates and reflux ratio.
• For given purity specifications, the number of trays is determined.

This article describes a novel general method for the search and identification of possible splits of extractive distillations in any ternary azeotropic mixture – the method of infinitely sharp splits. This method finds all feasible product compositions that can be obtained in an extractive column at infinite height and finite reflux. Limiting parameters of mode for the entrainer flow rate and the reflux ratio are determined fast and robustly from the local K-values (vapor–liquid distribution coefficients) of all three components along the sides of the concentration triangle. For the given product specifications the method additionally determines the required number of trays in all the column sections. Hence, both operating and investment costs can quickly be analyzed without cumbersome simulations. The method can be extended to multi-component mixtures.