The Dependence of the Feasible Separation Region on Feed Quality and Column Equipment

Abstract

For zeotropic mixtures with C- or U-shaped distillation lines, the feasible separation region is bound by two elements: a product composition multitude and a generalized distillation limit. The generalized distillation limit demarcates the sloppy splits (i.e., separations in which the composition of at least one product lies inside the composition space) from regions not accessible by distillation and depends on the thermodynamic state of the feed (a mixture of vapor and liquid in equilibrium or saturated vapor/liquid) and column equipment (total/partial condenser and total/partial reboiler). Mathematical relationships for determining the generalized distillation limit are presented, as well as examples of feasible separation regions for different feed quality and column equipment.