A new approach for determining tray and point efficiencies via revamping of hydraulic air/water column mockups

Tray and point efficiencies are the key parameters for characterizing the performance of a distillation tray.
The tray efficiencies are experimentally determined mostly by sampling the incoming and exiting streams of liquid and gas over the tray. Contrarily, the point efficiency determination is technically challenging and thus, it is derived mainly from correlations or small-scale experiments. Only few studies on the experimental determination of point efficiencies on large-scale distillation trays exist. However, the traditional physical systems pose several technical restrictions and safety concerns that often prevent their integration with the available air/water column mockups.
In this study, the stripping of isobutyl acetate from an aqueous solution using air is proposed as a physical system. It offers several advantages over the traditional ones (in terms of adaptability to different gas and liquid flow rates, safety and minimum revamping requirements), and is proved suitable for being readily integrated into existing cold fluid air/water mockups without any major modification.
The liquid concentration distribution on an 800 mm dia. distillation sieve tray was investigated by sampling the liquid at different deck locations for subsequent UV-spectroscopy. The concentration distribution was used to obtain the point efficiency values accounting for both axial and transverse liquid mixing on the tray. The concentration distributions, tray and point efficiency values obtained for different weir loads showed good agreement with the predictions given by the correlations and models used in the literature. The proposed approach can also account for the effect of weeping on the tray efficiency.
Potential future application of the proposed approach can address the investigation and design of novel tray concepts (e.g. with liquid flow conditioners), the development and validation of point and tray efficiency models as well as the validation of CFD simulations.