CFD simulation of complex flow pattern reactors

Syngas is one of the most important base chemicals. It is usually synthesised through steam methane reforming. This process traditionally uses a packed bed reactor but structured reactors have emerged in recent years as part of the will to intensify the process The MIDREX NG™ process uses such a reactor to produce syngas. This modified version of the ZoneFlow™ structured reactor presents an intricate geometry. The modelling of a reaction mechanism in this kind of structure is complex and requires the use of computational fluid dynamics. A wide array of phenomena must be described when modelling a chemical reactor. One of these is of the utmost importance in high temperature processes like SMR: radiation. Radiative heat transfer, although intuitively understood by most of us due to its presence in every day life, is a complex heat transfer mechanism. This arises from a number factors and is the reason why, when considering radiation in high temperature reactors simulations, a radiation model must be used to somewhat simplify the problem and allow it to be solved. In this thesis, after presenting an overview of radiative heat transfer, we proceed to the study of the Discrete Ordinate radiation model in the MIDREX® reactor. Firstly, the DO model is validated for an inert feed using temperature measurements of a pilot scale reactor. It is then transposed to a commercial scale reactor model with simplified SMR kinetics where it is compared to the Rosseland radiation model. Finally, the DO model is used on a pilot scale reactor model with complete SMR kinetics, and the results are compared to temperature and molar fraction measurements.