Reflux Policy for a Batch Distillation Operation with a Constant Distillate Composition

In order to achieve a constant distillate composition for a batch distillation operation, one has to continuously vary the reflux ratio. This Demonstration presents the reflux policy needed to achieve the user-specified constant distillate purity. The still is initially fed with a binary mixture for which a constant relative volatility () adequately describes the vapor-liquid equilibrium (VLE) data. The feed composition is 30% mole fraction light component. The still's composition varies with warped time, , as follows:
where is the warped time, is the initial still composition, and is the desired constant distillate composition.
VLE data is given by .
Finally, the reflux ratio is given by the following approximation:
This Demonstration plots the reflux ratio and the still composition as a function of warped time, . In addition, a parametric plot shows the behavior of the reflux ratio versus the still composition.
It is obvious that as the warped time increases, the still composition goes to zero (the light component in the still is depleted). Thus, in order to achieve constant distillate compositions, the reflux ratio has to be increased (up to excessively high values) and the cost of the batch distillation operation becomes very high.


  • [Snapshot]
  • [Snapshot]
  • [Snapshot]


For more information, see:
M. F. Doherty and M. F. Malone, Conceptual Design of Distillation Systems, New York: McGraw-Hill, 2001.
    • Share:

Embed Interactive Demonstration New!

Just copy and paste this snippet of JavaScript code into your website or blog to put the live Demonstration on your site. More details »

Files require Wolfram CDF Player or Mathematica.

Mathematica »
The #1 tool for creating Demonstrations
and anything technical.
Wolfram|Alpha »
Explore anything with the first
computational knowledge engine.
MathWorld »
The web's most extensive
mathematics resource.
Course Assistant Apps »
An app for every course—
right in the palm of your hand.
Wolfram Blog »
Read our views on math,
science, and technology.
Computable Document Format »
The format that makes Demonstrations
(and any information) easy to share and
interact with.
STEM Initiative »
Programs & resources for
educators, schools & students.
Computerbasedmath.org »
Join the initiative for modernizing
math education.
Step-by-Step Solutions »
Walk through homework problems one step at a time, with hints to help along the way.
Wolfram Problem Generator »
Unlimited random practice problems and answers with built-in step-by-step solutions. Practice online or make a printable study sheet.
Wolfram Language »
Knowledge-based programming for everyone.
Powered by Wolfram Mathematica © 2018 Wolfram Demonstrations Project & Contributors  |  Terms of Use  |  Privacy Policy  |  RSS Give us your feedback
Note: To run this Demonstration you need Mathematica 7+ or the free Mathematica Player 7EX
Download or upgrade to Mathematica Player 7EX
I already have Mathematica Player or Mathematica 7+