Plate Efficiencies in Rectification of Binary Mixtures

Abstract

In the design of commercial distilling columns, estimation of plate efficiency is a problem of considerable importance.
In order to solve this problem, the author defined the no. of stages (n') as Eq. (1), and the modified local efficiency (ELO) as plate efficiency at n'=1, and from these he derived a theoretical relation between them as Eq. (17).
As the relation -Eq. (3)- between local efficiency (EL) and NOG was obtained from WalterSherwood's study44) of NOG, it would be reasonable to correlate ELO directly with physical properties of binary mixtures in question.
Thus the author obtained an empirical equation for ELO as Eq. (25), by utilizing both his experimental data and those in literature.
To determine plate efficiency or X_n in practice, the author adopted the graphical solution as illustrated in Fig. (14), instead of employing Eq. (17) and a trial-and-error procedure.
As to the estimation of allowable vapor velocity in a bubble-cap plate column, the author developed Eq. (29), an empirical equation based on Peavy-Baker's data (35).
Of the correlation of the plate efficiency and allowable vapor velocity in plate columns, the observed values in literature and the calculated values by the present method showed fairly good agreements.