Distillation Theory

Ikari and Kubo [16] modeled a particular live steam pot distillation, and found encouraging agreement between theory and experiment regarding the evolution of alcoholic strength and congener abundance with distillation progress. In this chapter, the general idea proposed by Ikari and Kubo will be extended to model a number of different distillation scenarios: double pot distillation (Sect. 7.4); double pot distillation with internal reflux (Sect. 7.5); a single pot still with a passive (unheated) doubler (Sect. 7.6); a triple pot distillation (Sect. 7.7); a live-steam continuous beer column with continuous doubler (Sect. 7.8); and a hybrid pot-column distillation as found in some Scottish and many craft distilleries (Sect. 7.9). Each of the calculations starts with a wash (or beer) of equal strength, and all use the same Ikari and Kubo congener partitioning models. This permits a quantitative comparison of the energy demand of these different apparatus (Sect. 7.10), and a quantitative comparison of how distilling style affects congener removal during distillation (Sect. 7.11). This in turn permits a more qualitative, speculative, inference of the impact of distillation style on flavor. To lay some groundwork for these calculations, thermodynamic preliminaries are developed in Sects. 7.1 and 7.2. Section 7.3 describes how whisky evaporation can be reconciled with binary phase data, and in Sect. 7.12 the case is made that whisky pot distillation does not change the methanol:ethanol ratio. Methanol poisoning results from adulteration, not faulty whisky distillation.