Synthesis of drowning-out crystallization-based separations

A method is presented to synthesize drowning-out crystallization-based separation schemes for binary mixtures. The method tracks how the composition of each process stream changes from unit to unit on a phase diagram by assuming that the system is at equilibrium. Features of phase behavior favorable to drowning-out processes are identified. Two types of systems are highlighted. In the first, the drowning-out agent causes the solute to become sparingly soluble. Several process alternatives to separate the feed into pure components are proposed. Dominant costs of each configuration are identified. In the second, the solute is extracted into a phase rich with respect to the drowning-out agent. The extraction can be performed in a decanter countercurrent extractor, or fractional countercurrent extractor. Guidelines are given to select ail extractor type and to choose between crystallizer-extractor and extractor-crystallizer equipment trains.