Consider a quaternary mixture of components
with relative volatilities
. This mixture is subject to an equilibrium-limited chemical reaction
with reaction rate
, where the equilibrium constant
. This mixture is fed to a reactive distillation column with 16 plates. The feed stage location is stage number 10, the reactive stages are stages 6–14, and the feed composition is equimolar in
(i.e., the feed is composed of 50 mole %
and 50 mole %
). The feed, a saturated liquid, has a flow rate of 10 kmol/min. For simplicity, constant molal overflow (CMO) is assumed and heat effects are neglected.
The molar hold-up of the condenser and reboiler are set equal to 2000 and 5000 kmol, respectively. The hold-up in the reactive and nonreactive trays is chosen equal to 200 kmol. The reaction rate constant is equal to 5 and the Damköhler number defined by
is set to 100.
This Demonstration shows how one can select the distillate composition of component
using a simple proportional-integral controller. The distillate and bottom flow rates are equal because the reboil ratio,
, and the reflux ratio,
, are chosen so that
. In addition to the composition profile of the products (bottom and distillate) versus time, the Demonstration provides the reflux rate policy. The reflux rate is chosen so that it is at least equal to 0.2.