Role of Initial Still Charge on Batch Distillation

Abstract

Batch distillation is widely used in chemical industries, but the role of initial still charge on batch distillation has not been well understood and is still the focus of debate among researchers. A constant molar holdup model for batch distillation was built in this work in order to study the role of initial still charge. The degree of separation difficulty q was used to correlate the design and operating parameters in batch distillation. And yield was selected as the criterion of evaluating the performance of batch distillation under different initial still charge. The simulation results show that an optimum initial charge occurs in batch distillation at q ≤ 0.6 for ideal mixtures. Moreover, the yield keeps constant if the column holdup and initial still charge increase and drop in the same scale with the other operating parameters being fixed. Experiments were made to check the optimum charge with an iso-propanol−n-propanol−n-butanol system, which agreed well with the simulation results. The investigations make it possible to achieve a profitable operation by choosing an optimal amount of charge.