p

choose feed composition

flash calculation

pressure in mmHg

760

temperature in °C

120

Consider a ternary mixture of benzene, toluene, and

p

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

P

y

i



sat

P

i

x

i

, where

sat

P

i

is the vapor pressure of component

i

given by Antoine's equation,

P

is the total pressure, and

x

i

and

y

i

are the liquid and vapor phase mole fraction of component

i

. 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

P

(expressed in mmHg) and

T

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

ϕ

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

T

bubble

<T<

T

dew

will the feed be a two-phase mixture such that

0<ϕ<1

.