Shortcut Methods for the Design of Heteroazeotropic Distillation of Multicomponent Mixtures

Shortcut methods are valuable tools in the early stages of chemical process design, where numerous flowsheet alternatives need to be evaluated to determine the most energy-efficient, feasible flowsheet. Various shortcut methods based on tray-to-tray calculation and pinch point analysis for the inspection of feasibility and the determination of the minimum energy demand (MED) for homogeneous nonideal distillation have been published in the literature. Recently, Kraemer et al. presented the feed pinch method (FPM) for heterogeneous azeotropic mixtures of any number of components. While the FPM returns an accurate representation of the MED, it still requires tray-to-tray calculations for one column section and it can only be applied to separations with a feed pinch, i.e. usually direct or indirect splits. In this work, we propose the feed angle method (FAM) which resolves both of these issues as it does not rely on numerous tray-to-tray calculations and can be applied to any kind of sharp split. The FAM is illustrated by ternary and quaternary heteroazeotropic separations with direct, indirect and intermediate splits.