Ternary Batch Rectification
Ternary Batch Rectification
Consider a ternary mixture composed of 30 mole% benzene, 30 mole% toluene, and 40 mole% -xylene. This mixture, which obeys Raoult's law, is fed to the still of a batch distillation rectifier operating at . Here, the batch rectification begins with total reflux to obtain a steady state, and the distillate is withdrawn after that point. Stages and condenser holdups are assumed constant, equal to 1 and 7.5, respectively.
p
P=101.325kPa
Based on the CMO (constant molal overflow) assumption, this Demonstration shows plots of the composition (curves in blue, yellow, and green for benzene, toluene, and -xylene, respectively) and the temperature of the distillate versus time, for a boil-up rate of . You can set the values of the reflux ratio and the number of stages . The separation is perfect when and are large (see Snapshots 1 and 2). It is clear that one can collect a high-purity cut every time the distillate temperature reaches one of the plateaus (as in Snapshot 2). On the other hand, for low values of the reflux ratio and number of plateaus, the separation is sloppy (see Snapshots 3 and 4).
p
V=15
R
N
R
N