Steady State of an Extractive Distillation Column

Consider an extractive distillation column operating at atmospheric pressure. This column has 22 stages, a partial reboiler, and a total condenser. It is used to obtain anhydrous ethanol using ethylene glycol as an entrainer.

Pure entrainer at

80°C

is fed to the column at a flow rate equal to

100kmole/hr

and at stage two (counting from the top). The lower feed is composed of a mixture of ethanol and water (

55mole%

ethanol and

45mole%

water). The lower feed, a saturated liquid, is located at stage 12 (counting from the top) and has a flow rate equal to

10kmole/hr

.

The Demonstration solves the MESH equations (mass, equilibrium, summation, and heat) and displays the composition and temperature profiles for user-set values of the reflux ratio. The second degree of freedom is set by taking a distillate flow rate equal to

5kmole/hr

.

Finally, a comparison of the present calculation with Aspen-HYSYS shows excellent agreement.