Improved design of an extractive distillation system with an intermediate-boiling solvent

This paper explores a design proposed in the literature for separating methanol and toluene using the intermediate-boiling solvent triethylamine. The indirect sequence is shown to be more energy efficient. More importantly the solvent flowrate given in the published paper is shown to be much larger than required. Designs with greatly reduced solvent recycle flowrates reduce energy requirements by 50%.