Stability and emission characteristics of ammonia-air flames in a lean-lean fuel staging tangential injection combustor

The present work suggests the stability and emission characteristics of an ammonia-air tubular flame in a fuel staging tangential injection combustor. Owing to the development of a large inner recirculation zone induced by a high swirling motion, the ammonia tubular flame exhibited wide operational flexibility at an ambient temperature condition. With ammonia fuel staging, we confirmed that the Thermal DeNOx process significantly mitigates NO emissions when the exit temperature of the primary region is close to the threshold for active NO reduction. In this study, fuel multi-stage technology was used for pure ammonia-air combustion, and the result effectively challenges the existing paradigm of the NO reduction strategy: Rich-Quench-Lean staging configuration. Thus, our results demonstrate the potential use of ammonia as a fuel in a dry low-NOx system.