Although MINLP-models have proven to be a powerful tool for the design and rigorous simulation of distillation sequences their application is mostly restricted to the separation of ideal or at least zeotropic mixtures. The implementation of a detailed thermodynamic description of vapour-liquid equilibrium using the Wilson approach, developed at the department of chemical engineering, TU Muenchen, makes it possible to deal with highly nonideal or even azeotropic mixtures. This contribution presents a design of complex column configurations for the separation of ternary azeotropic mixtures using a rigorous MINLP model that requires no preliminary shortcut calculations. The model can be applied either to the retrofit design of complex processes including a fixed total number of stages by only minimizing the energy demand or to the design of new processes by minimizing both the operating and capital costs.