STAGE-BY-STAGE ALGORITHM FOR SIMULATION OF LIQUID PHASE EXTRACTION CASCADES APPLYING THE EQUILIBRIUM MODEL

It is shown a stage-by-stage solution method for the group of mass balances, equilibrium relationships, sum of compositions and enthalpy equations (MESH equations) that represents the equilibrium model for a countercurrent multistage liquid-liquid extraction arrangement. The theoretical foundation is in thermodynamics: liquid-liquid equilibrium, isothermal flash, and adiabatic flash. The algorithm exceeds the scope of graphics and isothermal methods used in the study of extraction processes, which is applicable to very common typical situations: heat transfer by stage, adiabatic stages, and different temperatures in feed and solvent streams. The algorithm is illustrated in three examples, the first two in isothermal operation with three components (water, acetic acid and butyl acetate) and ten stages, and a third one more elaborated involving heat transfer with four components (water, acetic acid, butanol, butyl acetate) and fifteen stages.