Single-Stage Batch Distillation: Summary
Key points from this module:
- Batch distillation is a transient process in which the compositions in the still and the distillate change with time.
- The Rayleigh equation relates the amount remaining in the still to mole fractions of the more-volatile component (MVC) in the still and the distillate.
- Because the distillate and still compositions change with time, the Rayleigh equation is usually solved numerically.
For batch distillation of a binary mixture:
- The distillate concentration of the more-volatile component decreases with time if the system does not have an azeotrope.
- For a minimum boiling point azeotrope, the distillate composition will move away from the azeotrope composition.
- For a maximum boiling point azeotrope, the distillate composition will approach the azeotrope composition.
- Temperature increases with time during distillation for all binary systems.
From studying this module, you should now be able to:
- Understand how the mole fraction of distillate changes with time in a batch distillation.
- Be able to represent a batch distillation of a binary mixture on an x-y diagram.
- Know how to solve the Rayleigh equation for batch distillation.
Prepared by John L. Falconer, Department of Chemical and Biological Engineering, University of Colorado Boulder