Combustion utilization of ammonia off-gas and reaction analysis of NH3/H2/N2 flame

Experiments and numerical calculations were performed to clarify the combustion characteristics of premixed flames for NH3/H2/N2 (i.e., NH3 off-gas during the cracking), which changes NH3 ratio in the fuel at equivalent ratio of 1.1. The flame length of NH3/H2/N2 premixed flame becomes longer as NH3 ratio in the fuel increases, and NH3/H2/N2 flame height is longer than that of the same ratio of NH3/H2. The NOx emission of NH3/H2/N2 premixed flame decreases compared with that of NH3/H2 premixed flame. The decrease in laminar burning velocity due to N2 in off-gas and the decrease in NOx emission due to the decrease in gas temperature of NH3/H2/N2 flame were obserbed. Most of the NOx produced from NH3/H2/N2 is fuel-NOx originating from NH3. The amount of NOx emission was confirmed by separating the thermal NOx and fuel NOx in the calculation.