In this work, a computational fluid dynamics analysis (CFD) employing the Eulerian two-fluid model was carried out with the aim to understand the distribution process and to determine the wetting efficiency of the primary tray distributor (perforated plate) of a trickle bed reactor (TBR) under several operating conditions. The overall inlet geometry was considered, and the small holes of the perforated plate were modeled by sinks (drains) and sources, employing CFD and experimental models to obtain the hole discharge flow coefficients. The influence of the ceramic-ball bed above the catalyst bed was considered by a suitable correlation to estimate liquid distribution inside it.Results showed that because of the scarce liquid sloshing above the tray, little difference on liquid flow rate through the tray holes was found. Due to the really low inlet mass flow rate of gas, it has negligible influence on liquid behavior, which drops through holes slowly without spraying. Thus, the ceramic-ball bed above the catalyst bed is exclusively wetted in a small area under the tray holes. Although the ceramic-ball bed improves liquid distribution, which guarantees a minimum liquid volume fraction at all places, significant differences on the liquid mass flow rate across the top of the catalyst bed were found. Additional causes of low efficiency in TBR like the well-known fouling vulnerability of perforated-plate trays and unevenness were analyzed. For the first, two simple modifications were proposed to improve tray performance: reducing the amount of gas chimneys to only one and adding additional drip points and replacing the tray holes by short risers in order to avoid plugging.
Liquid Distribution in Trickle-Bed Reactor
