Selecting entrainers for azeotropic distillation

A number of experts share their views on the selection of entrainers for azeotropic distillation. An entrainer facilitates the separation of an azeotropic mixture by selectively altering the relative volatilities of the components involved, effectively breaking the azeotrope. Entrainer selection is a critical step in the synthesis and conceptual design of azeotropic distillation processes, as the choice of an entrainer determines the separation sequence and the overall economics of the process. Entrainers are selected based on prior experience with the same or a similar process. Another methodology for determining entrainer feasibility utilizes residue curve map (RCM) technology. A RCM is a geometric representation of the vapor-liquid equilibrium (VLE) phase behavior of multicomponent mixtures, highlighting those properties that directly impact distillation. It also represents a collection of residue curves, or trajectories of liquid-phase compositions as they change with time.