Chemical Engineering Science, Vol.52, No.24, 4511-4524, 1997
Effect of wetting geometry on overall effectiveness factors in trickle beds
The effectiveness factors of partially wetted 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.