(145c) Quantifying the Effect of Stripping Factor on Tray Column Efficiency Under Non-Total Reflux Conditions

Optimal design of distillation columns requires reliable estimates of column efficiencies. Several models and correlations have been developed over the years to predict column efficiencies. However, these models may not be truly representative of actual efficiencies observed in the plant as most experimental data used to develop these models were obtained from distillation tests under total reflux conditions. Since commercial scale distillation columns operate under non-total reflux, there is a need to obtain accurate experimental data on efficiencies under non-total reflux conditions. These data will be helpful in developing reliable efficiency models using data on both total reflux and non-total reflux conditions.

In this study, a modified Oldershaw column was installed and commissioned that is capable of operating under total as well as non-total reflux modes of operation. Furthermore, the Oldershaw column was validated with cyclohexane/n-heptane test system. Additional test systems were carefully selected to ensure that large VLE errors are avoided. The test systems also provided a wide variation in physical properties for the measurement of distillation column efficiencies. The effect of stripping factor on distillation column efficiency was studied by systematically varying the stripping factor for several test systems. The point efficiencies of the column under non-total reflux were compared with the results of our previous study under total reflux conditions. This paper will discuss important findings from the study.