Thermochemical analysis of premixed ammonia/biogas flames in a model gas turbine swirl combustion system

This study examined the premixed NH3/biogas combustion at near stoichiometric using an experimentally validated numerical method. Raising the NH3 wt.% in NH3/CH4 combustion at phi = 0.8 brought up the average reaction temperature (T-avg) due to heat retention. Intensified by CO2 addition, T-avg in NH3/biogas increased by a factor of 1.2 compared to NH3/CH4. At phi = 1.1, higher NH3 and CO2 wt.% reduced T-avg. The local Damk & ouml;hler number (Da) was reduced marginally in the absence of CO2 as phi increased from 0.8 to 1.1. Conversely, local Da grew considerably in the presence of CO2 and was particularly sensitive to variations in the excess air ratio. Increased NH3 wt.% promoted NO emission, primarily via N + OH -> NO + H and H + HCNO -> CH2 + NO pathways. NH3/biogas produced more NO than NH3/CH4 from phi = 0.9 to 1.1, but as phi approached 1.1, NO is generally lowered. N2O is produced mainly by NH + NO -> N2O + H. Fuel-lean operation generally results in a higher N2O than fuel-rich operation. The NH3/biogas combustion at phi = 0.8 is a potential clean fuel solution in lowering NO emissions, as compared to NH3/CH4 combustion.