Minimum energy consumption in multicomponent distillation.: 1.: Vmin diagram for a two-product column

The V-min diagram is introduced to effectively visualize how the minimum energy consumption is related to the feed-component distribution for all possible operating points in a two-product distillation column with a multicomponent feed. The classical Underwood equations are used to derive analytical expressions for the ideal case with constant relative volatility and constant molar flows. However, the diagram can also be used for nonideal mixtures. The V-min diagram is very insightful for assessing multicomponent separation in a single column and is even more powerful for complex column arrangements, such as Petlyuk columns (parts 2 and 3 of this series of papers).