Staged Combustion Characteristics of Microgas Turbine Fired by Hydrogen–Ammonia Blended Fuel

Abstract

Three‐dimensional numerical simulations were performed to investigate the effects of the hydrogen blending ratio in the hydrogen–ammonia blended fueland the primary‐zone equivalence ratio, on combustion characteristics and gas composition in a 50 kW micro gas turbine combustor. The results indicate that increasing the primary‐zone equivalence ratio extends the recirculation zone and reduces the flow velocity in the combustor flow field, which is detrimental to effective mixing and complete combustion of the blended fuel. Meanwhile, increment in both the hydrogen blending ratio and the primary‐zone equivalence ratio leads to higher global and peak temperatures, thereby promoting thermal NO x formation. Under the operating condition with a hydrogen blending ratio of Y  = 0.5, when the primary‐zone equivalence ratio increases from 1.0 to 1.6, NO emissions decrease from 693 to 603 ppm when normalized to an oxygen concentration of 15%. However, the overall NO emissions still far exceed the national limit of 25 ppm, indicating that postcombustion treatment such as selective catalytic reduction (SCR) is required. The distribution of OH radicals closely overlaps with the NO formation region, highlighting their critical role in NO generation.