This Demonstration presents the flash distillation cascade, which gives a benzene-rich vapor stream and a toluene-rich liquid stream. The compositions of these two streams are given in blue and red, respectively.

Temperature is decreased in the rectifying cascade in order to produce the benzene-rich stream and increased in the stripping cascade so that a benzene-lean stream is obtained. The gradual temperature changes are adjusted so that the vapor fraction in the feed of any flash vessel is 50%.

The simulations show in particular that almost pure benzene and pure toluene can be obtained if you use a large enough number of flash distillation vessels.

The VLE diagram selection shows the temperature changes as blue and red arrows as well as the location of the vapor streams in the rectifying cascade (shown as cyan dots). Finally, the liquid streams in the stripping cascade are shown using magenta dots.