Investigation of the plenum configuration effect on the maldistribution of liquid and gas phases in upflow packed bed reactors using Gamma-ray densitometry (GRD)

Abstract

The objective of this study was to investigate the effect of five plenum designs on the distribution of the flowing phases in the plenum itself and within the packed catalysts’ bed of the reactor. The line-averaged gas and liquid holdups were measured in the plenum at nine radial positions ($r/R=0,\pm 0.225,\pm 0.45,\pm 0.675,\pm 0.9$), and under two superficial inlet gas velocities ($0.07$ and $0.17m/s$) using the inhouse developed, non-invasive gamma-ray densitometry (GRD). With the same measurement conditions, the line-averaged dynamic liquid holdups were estimated in the packed catalysts’ bed at two axial levels $(Z/D=0.1,1.56).$ The results show that, with a plenum design containing four or five deflectors, an enhanced distribution uniformity of the liquid and gas phases can be obtained in the plenum and in the fully developed region of the packed catalysts’ bed. With these two plenum designs, the increase of the superficial inlet gas velocity was found to significantly increase the chaotic flow of the gas and liquid in the regions where the flow is not fully developed. However, it did not affect the level of the liquid in the plenum, indicating the applicability of these plenum designs for several U-PBR applications requiring high gas holdups.