Unified approach for synthesizing crystallization-based separation processes

A procedure for synthesizing crystallization-based separation processes is presented. In an evolutionary manner and without being restricted to a particular crystallization technique, flowsheet alternatives are generated to meet the separation objectives for a given system. This is achieved by recognizing the fact that four basic crystallization-related movements in composition space are sufficient to represent a variety of crystallization processes. Suitable movements are selected based on relevant features of the phase diagram to construct feasible flowsheets. The procedure consists of six steps. First, separation objectives are defined. Second, a separation core structure is generated. Third, the separation sequence and unit operations are selected, followed by adding other units to the structure for proper plant operations. Fifth, appropriate crystallizer type is selected. Finally, economic evaluation and feasibility checks are performed for the generated alternatives. Rules are provided to aid decision-making at each step. The procedure is illustrated with various examples including separation of amino acids, p- and m-cresols, chlorobenzoic acids, calcium carbonate and magnesium oxide from dolomite, and the production of salt.