(43f) Quantifying the Point Efficiency of a Distillation Column Under Non-Total Reflux Mode of Operation

Important variables that affect the distillation tray efficiency have been explored in the past. Several models and correlations have been developed over the years to predict distillation tray efficiencies. However, the models are based on efficiency data obtained under total reflux conditions. However, the actual operation of a commercial distillation column is based on non-total reflux conditions. Therefore, the current efficiency models may not be truly representative of actual efficiencies observed in the field. There is a need to develop reliable efficiency models using data on both total reflux and non-total reflux conditions over a range of physical properties.

The purpose of this research is to collect reliable point efficiency data under non-total reflux conditions and develop or improve current efficiency models. Since the stripping factor plays an important role in determining efficiencies in non-total reflux mode, the effect of stripping factor on distillation efficiencies was systematically investigated over industrially relevant test systems covering a range of physical properties.

An Oldershaw column capable of operating in both total reflux and non-total reflux modes was used to measure point efficiency data over a range of conditions. Results indicate that the point efficiency increased as the concentration of light key in the feed increased. Further, higher efficiency was observed under atmospheric conditions compared to that in vacuum. An increase in point efficiency with the decrease in striping factor was also observed for both the operating conditions. Important findings from this ongoing study will be discussed.