Batch Rectification of a Binary Mixture at Total Reflux

composition in the still

0.7

number of theoretical stages

4

Binary batch rectification at total reflux obeys the relation

x

i

=

y

i-1

, where

x

i

is the composition of the liquid stream leaving stage

i

and

y

i-1

is the composition of the vapor stream entering stage

i

.

For an ideal binary mixture composed of benzene and toluene, this Demonstration (1) computes VLE (vapor-liquid equilibrium) data; (2) steps off stages using the bubble-point and dew-point curves (because operations are conducted at total reflux); and (3) shows the McCabe and Thiele construction for values of the number of stages and initial composition in the still, to be set by the user. Finally, the distillate composition is displayed in green.