Synthesizing distillation processes requires the identification of feasible separations. For this purpose, an algorithm for determining feasible separation regions for a ternary system is proposed in this paper. An analysis of feasible separation regions revealed that these regions are the union of two product composition sets. One of these sets is bounded by a generalized distillation limit and a product composition multitude. Conversely, the border of the second set is determined by the feed distillation line and a product composition multitude. These two product composition sets either overlap or one set includes the other. Each of these sets can be separately determined by implementing the same algorithm with appropriate limiting curves. The algorithm accounts for the type of column internal (trays or packing), type of condenser and reboiler, and feed quality. Applying the algorithm to a benzene-cyclohexane-acetone mixture can help realize a novel promising distillation system.