Air-stripping of isobutyl acetate in aqueous solution for measuring tray and point efficiencies in hydraulic air/water column mockups

The knowledge of the tray efficiency value is crucial for a correct design of tray columns [1]. In the last decades, several models have been developed for predicting the tray efficiency value, given the point efficiency. Validation of these models requires determining both tray and point efficiency experimentally.
The tray efficiencies are mostly determined by sampling the incoming and exiting streams of liquid and gas over the tray. On the contrary, experimentally determining point efficiencies is technically challenging and thus, their value is often derived from correlations or small-scale experiments (e.g. Oldershaw columns). Only few studies on the experimental determination of point efficiencies on large-scale distillation trays exist (e.g. [2], [3]). The physical systems used in these studies pose several technical restrictions and safety concerns. For these reasons, a setup designed ad hoc for point efficiency studies is mostly needed.
Recently Marchini et al. [4] proposed the stripping of isobutyl acetate from an aqueous solution using air as a physical system,which was proven to offer several advantages over the traditional ones and to be readily integrated into existing cold fluid air/water mockups without any major modification. The authors also showed how the tray-to-point efficiency ratio can be determined based on the liquid concentration distribution on the tray, accounting for liquid mixing phenomena in both the axial and transversal directions.
In this study, the tray and point efficiency values of an 800 mm dia. distillation sieve tray were determined at different gas and liquid flow rates by sampling the liquid at different deck locations for subsequent UV-spectroscopy, obtaining the liquid concentration distribution (Figure 1).