Liquid load point determination in a reactive distillation packing by X-ray tomography

In this paper, we report on the use of X-ray tomography to determine the liquid load point in 0.1 m diameter modular catalytic distillation packings Katapak-SP11 and Katapak-SP12. The liquid load point corresponds to the overall packed bed liquid load above which there is an increment in the liquid flowing outside the catalytic baskets and the catalytic baskets themselves are saturated with liquid. From tomographic images, we show that several factors affect the wetting and filling of catalytic baskets. The complex hybrid structure of catalytic packings influences the liquid distribution inside the elements. The liquid preferentially fills the external catalytic baskets because they receive the liquid not only from the packing element situated above but also from the wall wipers. Moreover, liquid hold-up inside a catalytic basket section depends significantly on the vertical position in the packing element and on the position of the packing in the column packed bed. The counter-current gas flow speeds up the process of liquid filling of the baskets, also for low liquid loads. The non-uniform distribution of liquid in catalytic basket which is observed experimentally makes the identification of a unique liquid load point not straightforward.