Effects of non-uniform weeping distributions on tray and point efficiencies

Abstract

Weeping is known to significantly reduce tray and point efficiencies in distillation tray columns. When designing distillation columns, conservative rules of thumb are applied to account for the effect of weeping on separation efficiency, while assuming uniform weeping distribution. However, experimental studies and CFD simulations generally reveal non-uniform weeping. The current study addresses this discrepancy, providing an experimental approach for simultaneously determining tray and point efficiencies at weeping conditions. The proposed approach is able to account for a non-uniform weeping distribution. This work evaluates the effect of several non-homogeneous weeping distribution patterns on tray and point efficiencies. In particular, state-of-the-art non-uniform weeping distributions, which have low spatial resolution, have been compared with arbitrarily assumed high resolution weeping distributions. A comparison with uniform weeping distribution is also provided. The results illustrate that assuming uniform weeping distribution leads to significant under- or overestimation of the tray and point efficiencies, depending on the real weeping distribution. In addition, high resolution weeping data can massively improve the quantification of separation efficiencies, allowing to confidently operate distillation columns at weeping conditions.

Keywords

• Distillation trays
• Weeping
• Tray efficiency
• Point efficiency
• Isobutyl acetate stripping