Ammonia/syngas MILD combustion by a novel burner

Ammonia has received increasing attention as one of the most attractive energy carriers because of its carbon-free nature and the established reliable and economic infrastructure for its storage and distribution. However, the low burning velocity and nitrogen-containment of pure NH3 can cause some challenges for its combustion control such as flame instability and large NOx emissions. To overcome these issues, strategies of co-burning NH3 with highly reactive fuels such as CH4 or H-2 have been developed and applied. Syngas, which can be produced from biomass pyrolysis, is a promising alternative fuel in the transition from carbon-based fuels to carbon-free fuels. Therefore, comparing to co-firing NH3 with CH4, co-firing NH3 with syngas is a better environmentally friendly option to improve the NH3 combustion property. However, co-firing NH3 with syngas faces severer combustion instability, NOx emissions and NH3 leakage due to the low heating value of syngas. To the best of the authors' knowledge, the NH3/syngas combustion with low NOx emissions and zero NH3 leakage has not been achieved in a lab-scale combustor. In the present study, NH3/syngas MILD combustion was carried out in a novel burner developed in our previous work. In the novel burner, the high-temperature and diluted air produced by the lean premixed syngas combustion is the key to accomplish the MILD combustion of NH3. The impact of the temperature and O-2 mole fraction of the HTDA on the emissions of NO, NO2, N2O, NH3, and CO was experimentally investigated with varying equivalence ratios and NH3 flow rates. The chemical reactor network was employed to analyze the experimental observation from the chemical kinetic aspect. (c) 2023 The Combustion Institute. Published by Elsevier Inc. All rights reserved.

Automated summary

Ammonia has attracted attention as a carbon-free energy carrier with established infrastructure for storage and distribution. However, its low burning velocity and nitrogen content pose challenges for combustion control. Co-burning ammonia with reactive fuels like CH4 or H-2 has been developed as a strategy to overcome these issues. Syngas, produced from biomass pyrolysis, is a promising alternative fuel for transitioning to carbon-free fuels. Co-firing ammonia with syngas is a more environmentally friendly option compared to CH4, but it faces challenges of combustion instability, NOx emissions, and ammonia leakage. This study investigates NH3/syngas MILD combustion using a novel burner, analyzing the impact of temperature and O-2 mole fraction on emissions.