Study on the volatility order of systems with two maximum azeotropes

In systems with two maximum azeotropes, different volatility orders can be obtained according to different isovolatility line. In this paper, the volatility orders of systems with two maximum azeotropes are identified according to the rigorous simulation of Aspen Plus, and are compared with that identified according to the isovolatility lines. The results show that, there are two distillation regions in systems with two maximum azeotropes and two isovolatility lines, the volatility order in them can be identified according to the isovolatility line lying in them. Based on this, the rule for identifying the volatility order is proposed. And, it is applied to two different cases, and the results shows that this rule is accurate, simple and can be applied convienently.