Distillation as an art goes back to the Middle Ages at least, as evidenced by alchemical prints showing various early forms of equipment. Particularly prominent up to the present century were destructive distillation processes, and the distillation of wines and fermented mashes to yield brandies and other spirituous liquors. Until the appearance of treatises by Sorel and by Hausbrand, and indeed even to the present day, knowledge of the subject was almost entirely empirical and uncoordinated with basic scientific laws. Sorel treated the distillation of binary mixtures mathematically from the standpoint of heat and material balances, and thus laid the foundation for the science of distillation. Since then steady and progressive applications of mathematics, physics and chemistry have been made. Current lines of work include refinements of present methods of calculation for binary mixtures, for three-component and more complex mixtures, and for design of equipment. Peculiarly enough, although there is a very active interest in distillation, the great majority of the articles on the subject are theoretical in nature and do not represent new distillation data under commercial or semi-commercial conditions. In fact, no published data are available on semi-commercial bubble-tray columns to comprehensively show the effect of operating conditions, in particular, reflux ratio and point of introduction of feed. This work was undertaken to shed some light on these very important factors for bubble-cap columnsChemical Engineerin
