CFD (Computational Fluid Dynamics) simulations of industrial furnaces have become an integral part of the design process in many thermal processing industries. CFD studies can provide detailed insight into the complex phenomena in industrial furnaces, including flow fields, combustion, heat transfer and pollutant formation, making them a powerful tool for design and optimization purposes. However, despite significant advances with regards to computing power in the last decades, the inherent complexity of combustion processes means that chemical models, based on simplifying assumptions, are required. These models are always a compromise between applicability and accuracy on the one hand, and the numerical effort involved on the other. Most combustion models found in today's commercially available CFD codes were developed for the combustion of a fuel (in the context of processing industries usually natural gas or, simplified, methane) with air. In recent years, however, the use of oxy-fuel combustion, i.e. the combustion of natural gas with pure oxygen, to obtain high process temperatures, has become more and more widespread in many thermal processing industries. This combustion technology offers significant advantages compared to traditional air-preheating such as increased heat transfer and potentially extremely low nitrogen oxide emissions. In the course of a German research project, GWI (Gas-und Warme-Institut Essen) in cooperation with its partners, investigated ways to improve the modelling of oxy-fuel combustion for the simulation of industrial furnaces with reasonable numerical cost.
