Hierarchical design of extraction-distillation processes using short-cut apparatus models with piece-wise linearized thermodynamics

A hierarchical optimization approach for the conceptual design of extraction-distillation processes is presented. The approach includes the solvent selection and flowsheet synthesis using pinch-based short-cut apparatus models which take into account of the material balances and piece-wise linearized thermodynamics (MLT models) and is limited to ternary systems. MLT models enable fast and robust identification of feasible flowsheet-solvent combinations and optimization thereof. Performant solvents are found by assessing process stream tables. Promising solvent-flowsheet combinations are evaluated using flowsheet simulation with detailed models, whereby the MLT results are in good agreement with the results of the detailed models. The approach is presented along an example of the separation of acetic acid and water.