Stripping and Rectifying Cascades for Isopropyl Acetate Chemistry
Consider an equimolar feed composed of acetic acid (AA) and isopropanol (IPA). These two components react in the liquid phase to form water and isopropyl acetate (IPOAc). This esterification reaction is: AA + IPA ⇌ O+IPOAC.[more]
This Demonstration plots the trajectory for the stripping and rectifying cascades so that the vapor fraction is always equal to 50% and the Damköhler number, , is identical in all flash vessels. One can conveniently introduce a new dimensionless parameter, , which is equal to a user-set value varying from zero (no reaction and ) to 1 (equilibrium case and ).
It is observed that a pinch point is obtained for large values of the number of flash vessels both for the stripping and rectifying cascades. These two pinch points are pure AA and a quaternary mixture for the stripping and rectifying cascades, respectively.
At very high Damköhler numbers and for a large number of flash vessels, one can verify that the equilibrium case is recovered (i.e., the reaction is almost instantaneous). The composition of the vapor stream that exits the rectifying cascade approaches that of the reactive azeotrope with transformed compositions equal to and , in agreement with values found by Maier and coworkers  (see last snapshot).
This Demonstration shows the set-up with values of the transformed compositions of the vapor stream that exits the rectifying cascade and the transformed compositions of the liquid stream that exits the stripping cascade.
Finally, data tables are provided that give the temperature and the transformed compositions of all vapor streams in the rectifying cascade and all liquid streams in the stripping cascade.
Liquid-phase transformed compositions are related to actual mole fractions by and . Analogous expressions are defined for the vapor-phase transformed compositions.[less]
 R. W. Maier, J. F. Brennecke, and M. Stadtherr, "Reliable Computation of Reactive Azeotropes," Computers and Chemical Engineering, 24(8), 2000 pp. 1851–1858.
For more information, see:
K. Sundmacher and A. Kienle, eds., Reactive Distillation, Status and Future Directions, Weinheim: Wiley-VCH, 2002.