Hybrid Modeling of Methane Reformers. 1. A Metamodel for the Effectiveness Factor of a Catalyst Pellet with Complex Geometry

In this work, effectiveness factors for methane steam reforming reactions were obtained by solving mass and heat balance equations inside catalytic pellets for different reaction conditions and catalytic pellet geometries with the help of CFD (computational fluid dynamic) techniques. CFD computations were performed for real particle geometries and real kinetic rate expressions as described in the technical literature. A linear correlation was found between the effectiveness factor and the area/volume ratio, which characterizes the methane steam reforming as a diffusion-controlled process. The slopes of the straight lines depend of the external reaction conditions, thermal conductivity, and effective diffusivity. On the basis of the CFD results, empirical metamodels were built to represent effectiveness factors for methane steam reforming reactions at different reaction conditions. The metamodels can be easily inserted into a reactor model for simulation of the full industrial process.