Several processes are available for the important operation of dehydrating ethanol/water mixtures to concentrations above the azeotrope (90 mol %). Heterogeneous azeotropic distillation has been studied using several entrainers: benzene, cyclohexane, isooctane, ethylene glycol, etc. A pioneering paper by Ryan and Doherty [Ryan, P. J.; Doherty, M. F. Design optimization of ternary heterogeneous azeotropic distillation sequences. AIChE J. 1989, 35, 1592-1601.] explored several alternative process configurations and concluded that the three-column flowsheet with a preconcentrai or (beer still), an azeotropic column, and a recovery column was the economic optimum. They used approximate ternary diagram methods. It appears that they arbitrarily assumed a beer still distillate composition with an ethanol concentration of about 88 mol %, which is quite close to the azeotropic composition of 90 mol %. Energy consumption in the beer still increases as its distillate composition gets closer to the azeotrope. On the other hand, energy consumption in the azeotropic-recovery column section of the process decreases as the feed to this section becomes richer in ethanol. It appears that this fundamental trade-off has not been studied in the literature. This paper examines quantitatively, using rigorous simulations, how this design parameter affects the energy and capital investment of the entire system. The focus is the distillate composition trade-off. The example used is the heterogeneous azeotropic distillation process, but the same issue applies in any of the other methods (such as extractive distillation) in which a preconcentrator column is used.