The mixture of benzene, toluene and xylene isomers shown in Table Q$12$ is to be

separated into pure component products using a sequence of distillation columns. Three

sequences are proposed:

Sequence $1$: B $/$ T pX oX $-$ T $/$ pX oX $-$ pX $/$ oX $($direct sequence$)$

Sequence $2$: B T$/$pX oX $-$ B$/$T $-$ pX$/$ oX

Sequence $3$: B T pX$/$oX$-$BT $/$ pX$-$B$/$T $($indirect sequence$)$

Table Q$12$ Feed composition and condition.

Use the total vapour load and reboiler duty to compare the proposed sequences. Identify

the most promising sequence. Use Fenske equation