Modeling of Dual-Zone Structured Reactors for Natural Gas Steam Reforming

The performance of dual-zone structured catalytic reactors in natural gas steam reforming under typical commercial operating conditions is evaluated by means of detailed Computational Fluid Dynamics (CFD) simulations, including detailed reaction kinetics. A hybrid CFD model is developed, combining a porous medium type description of the reactor core zone and a detailed description of the reactor internals in the near-wall region. The porous medium model parameters are determined from specific pressure drop measurements in a wide mass flow rate range. Additional pressure drop measurements with the complete structure and with pellets serve for CFD model validation. The influence of the flow and catalyst distribution over the different reactor zones and the influence of the catalyst loading are then numerically studied. A comparison with a conventional packed bed reactor is made, and advantages of the dual-zone structured reactors with respect to pressure drop, heat transfer, and catalyst effectiveness are illustrated.