Kinetics modeling of NOx emissions characteristics of a NH3/H2 fueled gas turbine combustor

The two major challenges for ammonia combustion in gas turbines are its high NOx emission and low burning velocity. Recently, while H-2 doping has been proved as an effective means of improving the NH3 burning velocity, there is a knowledge gap on the emissions characteristics of NH3/H-2 fuel mixture in gas turbine conditions. This paper presents a kinetics modeling study on the NO(x )emission characteristics of a staged rich-lean combustor cofiring NH3/H-2 mixture. A chemical reaction network was set up to model the staged combustor. Emission characteristics were obtained at various operating parameters, including equivalence ratio, residence time, and H-2 doping ratio. The rich-burn stage equivalence ratio was found to be the primary factor influencing NO(x )emissions. The key to reduce NOx emissions is to balance the NO production and the unburnt NH3 in the rich-burn stage. Extending the residence time of its post-flame zone and increasing H-2 secondary impact. NO reaction pathway analyses showed that NO is formed mainly through the HNO pathway in the flame zone of the rich-burn stage, while NHi decomposition in the post-flame zone plays a key role in NO reduction. Depending on the NHi concentration, different mechanisms dominate NO reduction in the post-flame zone. (C) 2020 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.

Automated summary

This paper conducted a kinetics modeling study on the NO(x) emission characteristics of a staged rich-lean combustor cofiring NH3/H-2 mixture, revealing that the equivalence ratio in the rich-burn stage is a key factor influencing NOx emissions. Balancing NO production and unburnt NH3 in the rich-burn stage is crucial for reducing NOx emissions.