No abstract

The steam reforming of methane is the main route for industrial production of hydrogen, used afterward for energy generation and production of chemicals. However, modeling of industrial methane reformers is not an easy task, due to the complex geometries of the employed catalyst pellets. The complex geometries are required to improve the contact between the gas phase and the solid catalyst. In this work a one-dimensional pseudohomogeneous model with axial mass and heat dispersion is used to model the tubular industrial reactors. The effect of the complex catalyst geometry of the pellets is considered with the help of empirical metamodels developed a priori for the effectiveness factors, based on CFD modeling of heat and mass balances inside pellets with different shapes and subject to distinct reactions conditions. It is shown that the proposed model can be successfully applied for simulation and design of industrial reformers, allowing for analysis of the effects introduced by distinct catalyst geometries on the performances of industrial operations.

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.