Effect of wetting geometry on overall effectiveness factors in trickle beds

Abstract

The effectiveness factors of partially wetteb slab, cylindric shell, cubic and cylindric catalyst pellets in trickle-bed reactors are numerically computed at different wetting geometries for the generalized catalytic reaction A + B → P 1, where A is a gaseous component and B is a nonvolatile liquid component. Three different cases have been studied: (a) the gaseous component is limiting, (b) the main reaction is accompanied by a homogeneous side reaction A + C → P 2 where C is nonvolatile, and (c) both, the gaseous and the nonvolatile liquid component B are limiting. The reaction rates are described by a power law or a Langmuir-Hindshelwood model. Results show that in case (a) the effect of wetting geometry on overall effectiveness factors is insignificant if cylindric catalyst pellets are used and less than 10% for cubic catalyst pellets. However, the wetting geometry can cause more then 40% difference in case (b) for cubic catalyst particles and more than 50% difference in case (c), depending on Thile's modulus and reaction order. The numerical solutions based on one- and two-dimensional diffusion equations are compared with Tan's and Beaudry's approximations.