The generalized cascade model must be used in order to compute stripping and rectifying profiles for the reactive cascade in the case of the following nonequimolar equilibrium-limited chemical reaction:
For the stripping cascade:
For the rectifying cascade, one has to use:
is the average molecular weight, the mass fraction of the feed that is vaporized is
is the Damköhler number, which is the ratio of the residence time relative to the reaction time. Short reaction times and long residence times result in large Damköhler numbers;
indicates that no reaction is occurring and
means that the reaction rate is fast and that the system will rapidly approach chemical equilibrium.
The molecular weights of species
for this hypothetical ternary chemical system are 86.18, 100.21 and 186.39 g/mol, respectively.
The relative volatilities have the values:
The vapor mole fractions are determined by
is the volatility of species
The equilibrium-limited chemical reaction taking place between species
with equilibrium constant
A feed with the following composition is assumed: 40%
, and 20%
Reference: M. F. Doherty and M. F. Malone, Conceptual Design of Distillation Systems
, New York: McGraw-Hill, 2001.