Separation of a Reactive Quaternary Mixture in a Distillation Column
Consider a quaternary mixture of components , , , and with relative volatilities , , and . 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 such that the total number of plates is 17. The feed stage location is stage number 10, the reactive stages are from stage 6 to stage 14, and the feed composition is equimolar in and (i.e., the feed is composed of 50 mole % and 50 mole % ). The feed, a saturated liquid, has a flow rate of 100 kmol/hr. For simplicity, constant molal overflow (CMO) is assumed and heat effects are neglected.[more]
This Demonstration shows the liquid and vapor phase compositions versus plate number for components , , , and (in red, blue, green, and magenta, respectively) with the reactive zone shown in light blue, while the stripping and rectifying zones are indicated in light red and light green, respectively.
You can set the values of the Damköhler number, , and the reflux ratio, where is the liquid hold-up in a plate, is the reaction rate constant, and is the liquid flow rate in each section of the column.
When , one recovers the case where no reaction is taking place, shown in one of the snapshots, with no or components in the column.
If is very large, the simulation represents a situation close to reaction equilibrium (i.e., ).
One snapshot shows good conditions where almost pure and exit the column. Hence, this reactive distillation setup can achieve conversions near 100% in addition to the simplification of the operation scheme: no reactor followed by separation units and no recycling of unreacted and components.[less]
For more information, see
M. F. Doherty and M. F. Malone, Conceptual Design of Distillation Systems, New York: McGraw–Hill, 2001.