This study reports on the lean stability limits and exhaust emissions of ammonia-methane-air swirl flames with varied ammonia fuel fractions. A reduced-scale burner was manufactured, inspired by Ansaldo’s micro gas turbine AE-T100 burner, and it was installed inside a high-pressure combustion duct to operate at 4.5 bar. This pressure corresponds to that found at full-load in the actual micro gas turbine’s combustion chamber. The lean stability limits were measured by igniting the flame at an equivalence ratio of ϕ = 0.85 and then progressively decreasing the equivalence ratio until lean blowout. Emissions of CO2, NO, and N2O were recorded for different equivalence ratios and ammonia fractions. Rich flames at an equivalence ratio of ϕ = 1.20 were also considered. Results show that the equivalence ratio at lean blowout increases when the ammonia fraction increases and that all the ammonia fractions tested lead to flames more prone to lean blowout than the pure methane reference flame. The CO2 emissions are monotonically reduced by increasing the ammonia fraction, both for lean and rich flames. The NO emissions exceed many regulations limit regardless of the ammonia fraction for all lean equivalence ratios. N2O emissions are almost negligible, except for very lean equivalence ratios where the N2O mole fraction in the exhaust reaches unacceptably high values. Only rich ammonia-methane-air flames show good NO and N2O performance. Therefore, FTIR analysis was carried out to quantify the amount of the unburnt NH3 in the exhaust for these flames. Results show that unburnt NH3 concentration is invariant, around 200 ppmv, between 0.70 ≤ XNH3 ≤ 0.95. Data reported in this study provide insights for future work on combustors and after-treatment systems towards zero-emissions micro gas turbines.
|Original language||English (US)|
|Title of host publication||Volume 3A: Combustion, Fuels, and Emissions|
|Publisher||American Society of Mechanical Engineers|
|State||Published - Oct 28 2022|
Bibliographical noteKAUST Repository Item: Exported on 2022-10-31
Acknowledgements: The present work is supported by Saudi Aramco Research and Development Center under research agreement number RGC/3/3837-01-01 and by the clean combustion research center at King Abdullah University of Science and Technology (KAUST).