Effectiveness factors of n-th order reactions for incomplete wetting particles in trickle-bed reactors

Abstract

In trickle-bed reactors the catalyst particles may not be completely covered by liquid. Under this condition the boundary conditions on the outer surface are not uniform. A model which accounts for this incomplete wetting for an n-th order reaction is solved by the orthogonal collocation method and the global spline collocation method in this study. Both methods use much less computational time to obtain the same accuracy of effectiveness factor as compared with the finite difference method proposed in the literature. The allocation of interior collocation points does not seem to be critical for evaluation of the effectiveness factor, hence the orthogonal collocation method is recommended. In order to reduce the computational effort, a simple weighting-factor model which avoids complicated numerical calculations is also proposed in this study. Through the calculation it is observed that this approximate model can give quite satisfactory solutions except at low values of the Thiele modulus for liquid-limiting reactions.