Consider a distillation column with 10 stages a partial reboiler and a total condenser The column is used to separate a nonideal equimolar mixture of ethanol and water Deviation from ideal behavior is taken into account using the Wilson model The feed a biphasic stream with a quality equal to enters at stage 8 with a rate equal to The reboil ratio is constant and equal to 15 Suppose that the column is subject to a step in the reflux ratio as follows and where is the percent increase or decrease in the reflux ratio This Demonstration performs a rigorous dynamic simulation including both material and energy balance equations of this column and plots the behavior of both the distillate and bottom compositions versus time Molar holdups of the reboiler condenser and plates are taken equal to and respectively