Simple Method for Determining the Location of Distillation Region Boundaries in Quaternary Systems

For ternary systems, the use of residue curve maps as a representation of the phase behavior has greatly facilitated process synthesis. Especially important is the knowledge of distillation boundaries, which cannot be crossed by simple distillation. Here, an attempt is made to extend these procedures to quaternary systems by presenting a method to calculate the exact location of distillation region boundaries, i.e., the surfaces separating different distillation regions in composition space. The procedure is illustrated with a few examples.