Effects of addition NH3 and N2 dilution on combustion and the emission characteristics of syngas

This study investigates the potential advantages of co-combustion of ammonia with syngas, particularly in terms of combustion characteristics and pollutant emission levels. Given the inherently low combustion velocity and high ignition energy of pure ammonia, blending it with syngas could yield beneficial outcomes. Experiments involving the addition of NH₃ and N₂ dilution were conducted in a constant volume combustion chamber at T = 298 K and P = 0.1 Mpa, with numerical simulations performed using CHEMKIN. The experimental data reveal that NH3 addition reduces the laminar flame speed, thereby promoting a more stable flame propagation. Concurrently, a reduction in the concentration of H/OH radicals is observed. Notably, when the NH₃ proportion reaches 20 %-30 %, the molar fraction of NO peaks, and in the overall pathway, the contribution from the NH₃-NH₂-NH-N-N₂ reaction is enhanced. Additionally, N₂ dilution is found to lower the laminar flame speed and mitigate flame instability. This dilution also results in a reduced maximum NO molar fraction, effectively curbing NO_x emissions without a significant alteration in the reaction mechanism. These findings are instrumental in enhancing the combustion efficiency of ammonia/syngas mixtures and mitigating pollutant emissions.