Investigation of the flame structure and nitrogen oxides formation in lean porous premixed combustion of natural gas/hydrogen blends

The effect of the natural gas to H2 ratio on the flame structure and NOx formation in lean premixed porous combustion was determined by combining Comsol and Premix codes. The thermal pathway was of secondary importance while the NNH, N2O and prompt pathways were the most important routes involved in NO formation. H2 enrichment resulted in the penetration of the combustion zone into the porous burner and in the decrease of the importance of the prompt pathway, which leads to the decrease of NO formation. The chemical effect of NO recirculation was also investigated.