Experimental Quantification of Point Efficiency of Sieve Trays at Elevated Viscosity under Non-Total Reflux Conditions

Most of the data used to develop efficiency models were obtained from distillation tests under total reflux conditions. However, commercial distillation columns are generally operated in a non-total reflux mode of operation. 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. As a part of the current study, an Oldershaw column capable of operating in non-total reflux was used to measure point efficiency data for two viscous test systems: tert-amyl-alcohol/isobutanol and cyclopentanol/cyclohexanol. Results showed that the point efficiency decreased with an increase in the stripping factor and a decrease in the concentration of the light component in the feed. The effect of reflux ratio, L/V, and slope of the equilibrium curve was also studied. Important findings will be discussed along with a comparison of the point efficiency data for cyclohexane/n-heptane and the test systems used in this study.