Comparison of Several Startup Models for Binary and Ternary Batch Distillation with Holdups

Abstract

In batch distillation processes, the startup operation is one of die important operations which affect the overall separation performance. There are different startup models which were utilized when analyzing batch distillation operation. In this research, four different models (Models A, B, C, and D) representing the dynamic behavior of startup operation for binary and ternary batch distillation have been simulated and investigated. The effect of operation and design parameters such as the tray and reflux drum holdups, amount of feed, product specification, number of trays, and relative volatility on startup time were studied and analyzed for all the above models. Linear correlations governing the startup time were obtained in terms of the holdups of trays and reflux drum. These correlations could be used to determine startup time for different combinations of these holdups. The effect of the startup time on the overall separation performance was also analyzed. For most of the cases, it was found that startup time and the composition profile through the column at the end of startup for simple Model A and complicated Models Cand D are quite the same. The overall separation performance is a function of the startup time and the column's profile. Thus, the simulation result means that simple Model A is sufficient in representing the startup operation of batch distillation.