Incorporating Tangent Pinch Points into the Conceptual Modeling of Batch Distillations: Ternary Mixtures

KARINA ANDREA TORRES; JOSÉ ESPINOSA

INDUSTRIAL & ENGINEERING CHEMICAL RESEARCH

American Chemical Society

Lugar: Washington, DC; Año: 2008 vol. 48 p. 857 - 869

0888-5885

This contribution explores the influence of tangent pinch points on the performance of batch distillations of highly nonideal ternary mixtures and its incorporation into a conceptual modeling framework under the assumption of a rectifier with an infinite number of stages. The maximum feasible distillate composition on the line of preferred separation and its corresponding limiting reflux ratio are first determined with the aid of bifurcation analysis of reversible distillation profiles. Then, the dependence of feasible distillate mole fractions on reflux ratios above the limiting one is calculated by solving a nonlinear equation system, which incorporates the tangency condition. Results obtained from the conceptual model for instantaneous column performance are in excellent agreement with those calculated from rigorous simulation. Two highly nonideal ternary mixtures are studied.