Multi-scale membrane reactor (MR) modeling and simulation for the water gas shift reaction

Abstract

This work focuses on the multi-scale modeling of a high-pressure membrane reactor (MR) carrying out the water gas shift reaction (WGSR). The work assesses the MR’s effectiveness in transforming coal-derived syngas into two streams, one rich in hydrogen and the other rich in carbon dioxide. The model employs Reynolds Transport Theorem derived constitutive equations at the reactor and the catalyst pellet scales. Convection/conduction/reaction/diffusion phenomena are accounted for, using the Ergun, Chapman-Enskog, Stefan-Maxwell, and Dusty-Gas models, respectively. The model’s power and flexibility are demonstrated by carrying out numerical simulations for both the MR and packed-bed reactors (PBR) for various operating conditions and design parameters. It is shown that significant variation of the catalyst pellet effectiveness factor occurs along the reactors’ axial direction, and that catalyst pellets of the same diameter exhibit different effectiveness factors within the PBR and MR environments. The effect of the catalyst solid’s thermal conductivity on the temperature gradients within the catalytic pellet, and the effect of the sweeping gas’ pressure/temperature on the MR’s behavior are both quantified. Adiabatic and wall-isothermal operations are examined and are shown to exhibit significant differences from each other for both reactors.