A new method of locating all pinch points in nonideal distillation systems, and its application to pinch point loci and distillation boundaries

A new method for automatically finding all of the pinch points in a user-specified composition space in nonideal distillations system at any reflux is presented. It does not rely on the solution of ODEs, and neither knowledge of the system topology, nor rigorous simulation is required. Moreover, the method can be applied to any column section, even those within complex configurations. The method works on the principle of a systematic search over an area to find where the conditions for a pinch point are satisfied; this includes nodes outside of the mass balance triangle, which, while physically impossible, do provide useful information. This principle is extended to reflux-parameterised pinch point loci and to finding distillation boundaries accurately. Nonidealities are modelled with the NRTL model, although any model can be used. Only ternary systems have been considered, but the method can extend to higher order systems.