Ammonia/methane dual-fuel injection and Co-firing strategy in a swirl flame combustor for pollutant emissions control

Abstract

The co-firing of ammonia with hydrocarbon fuel is a promising way to reduce the emissions of carbon dioxides. However, conventional way of co-firing under premixed lean swirl flame results in high NOx pollutant emissions, thus requiring an innovative mitigation strategy to solve the CO2-NOx conundrum. In the present study, the combustion characteristics and emissions performance of a partially-mix ammonia-methane dual flames are examined and compared with fully premixed swirl flame. Flame imaging shows a distinctive luminous central jet flame surrounded by compact swirl flame for the dual flame, as opposed to the lean bluish single-stage premixed flame. The flow field of the dual flames shows the absence of the typical recirculation flow of premixed flame, yet stabilisation of the flame is barely affected. The dual-flame shows reduced NO and CO emissions by at least a factor of 2 compared with the fully premixed flame. Low emissions of NO and CO can be attained for NH3–CH4 dual-fuel flames at φ ∼0.65. The reduced NO emission via the dual-fuel injection technique can lead to improved economics for the subsequent flue gas treatment to meet the emission regulation targets.