In the multicomponent distillation, the concentration profiles for the n-hexane/n-heptane/n-octane system and the methanol/2-propanol/water system are predicted by following three methods:
(1) assumption of constant number of overall vapor phase transfer units, [Nov]
(2) solution of Maxwell-Stefan equation based on linearized theory
(3) the general solution of Maxwell-Stefan equation
The experiments are performed in a 1 in. diameter Oldershaw column with 10 plates and 15 plates respectively, in order to compare the predicted concentration profiles with the measured concentration profiles. The predicted concentration profiles using the assumption of constant [Nov] are deviated from the measured concentration profiles for both systems. But the predicted concentration profiles using other two methods are in good agreement with the measured concentration profiles. And three methods are used to predict the required number of stages for a specified separation. In non-ideal system the predicted numbers of stages are different from each other. But in ideal system three methods predict almost same numbers of stages with each other.