Modelling NOx-formation for application in a biomass combustion furnace

To optimize the design for biomass combustion furnaces for NOx-emission reduction, numerical models can be used. In these models, the Eddy Dissipation Concept and the PDF-flamelet approach can be applied to describe the interaction between the chemistry and the turbulence. As a first step in comparing these models for a grate furnace, they are tested for a flame from the literature (Sandia Flame D). In the calculations, only the kinetics for methane combustion without N-chemistry are used. The N-chemistry will be added in later stage. The predictions of the models agree qualitatively well with the measurements. Some deviations that are observed are related to the settings of the boundary conditions for the fuel inlet stream. Quantitatively, the two models are quite close, but deviatesignificantly from the measurements. The boundary conditions have to be improved to draw definitive conclusions.