Multi-Stage Batch Distillation: Example Problems
Try to solve these problems before watching the solutions in the screencasts.
Example Problem 1
50 mol of an ethanol-water mixture is loaded into a pot still and heated. When the first distillate is collected, the head temperature is 84ºC The still is run until the heat temperature is 89ºC What is the total amount of distillate collected? What is the composition of the distillate and waste products?
Example Problem 2
An ethanol water batch distillation unit consists of two total equilibrium stages. The unit is run with a constant reflux ratio of 3. When the instantaneous distillate composition is 60 mol% ethanol, there is 750 mol of liquid in the reboiler. How much liquid is left in the reboiler when the instantaneous distillate composition is 50 mol%?
Example Problem 3 (optional)
An ethanol water batch still consisting of 2 equilibrium stages is used to generate a constant composition distillate stream of 60 mol% ethanol. The still reboiler is initially charged with 80 mol of 30 mol% ethanol. The still is run until the composition in the reboiler is 9% ethanol. How much distillate is produced and what is the range of reflux ratios used?
