Numerical determination of distillation boundaries for multicomponent homogeneous and heterogeneous azeotropic systems

Abstract

As it is very well known, especially when dealing with the planning and operation of distillation processes and equipment, it is essential to characterise the intrinsic limitations due to the VL equilibrium of the system under consideration. This paper addresses a new approach to directly and numerically calculate the distillation boundaries present in ternary and quaternary azeotropic systems, simply involving the concept that such boundaries are distillation trajectories passing through specific singular points. To generate the tested distillation trajectories, that after the optimization process will be the searched boundary, we use cubic splines and polynomial equations (although any other adequate equation could be used). The commercial software package Simulis Thermodynamics (ProSim) has been used to calculate the VLE using the available thermodynamic models such as NRTL and UNIFAQ.