A comprehensive study of non-premixed combustion of ammonia and its blends: Flame stability and emission reduction

Ammonia is an interesting carbon free energy carrier in a future energy system, particularly in the context of decentralised process heating. Ammonia combustion is challenging due to its lower laminar combustion velocity, higher required ignition energy, and lower calorific value, which impact flame propagation and efficiency center dot NH3 must be handled with care due to its narrower flammability limits and potential for N2O and NOX emissions. This paper presents laboratory and semi- industrial scale ammonia combustion experiments using both industrial burners and a lab-scale burner developed at GWI. The experiments examine combustion stability and NOX emissions for atmospheric, non-premixed and near-stoichiometric conditions as commonly encountered in industrial process heating. The results show that while NH3 combustion is stable under certain conditions, NOX emissions are influenced by ammonia content, flame shape, and combustion parameters. These can be mitigated through air staging and low excess oxygen.