Consider a ternary mixture of benzene, toluene, and

-xylene (BTX). For this ideal system, vapor-liquid equilibrium data can be computed using Raoult's law,

, where

is the vapor pressure of component

given by Antoine's equation,

is the total pressure, and

and

are the liquid and vapor phase mole fraction of component

. You can select a feed composition by dragging the locator in the ternary triangular diagram (i.e. inside the light blue region) and you can vary the values of

(expressed in mmHg) and

(expressed in °C). This Demonstration computes the vapor fraction

of the feed and the composition of the liquid and vapor streams leaving the isothermal flash drum. Only when

will the feed be a two-phase mixture such that

.