Effect of Hydrogen Content on Pollutant Emissions and Combustion Characteristics of a Methane-Hydrogen Mixture Fueled Multi-Nozzles Array Model Combustor

As a green and clean energy, how to achieve stable, high-efficiency, and low-emission combustion of hydrogen-rich fuel is the development trend of heavy-duty gas turbine, which meets the goal of carbon emissions peaking and neutrality. The combustion characteristics of a multi-nozzles array model combustor with flame stabilization mechanism by flue gas recirculation induced by high-speed paralleled jet have been investigated. The effects of the length of chamber, premixed mode and hydrogen content on the combustion characteristics of the model combustor, including NOx/CO emissions, flame morphology, reaction zone distribution and dynamic pressure have been obtained. The experimental results show that for hydrogen enriched fuel with 20% Vol hydrogen content, the model combustor that the length of chamber is 400 mm has a significant intermediate-frequency oscillation of 270 Hz at an equivalent ratio of 0.644, while the model combustor that the length of chamber is 300 mm can achieve stable and low-emission combustion within a wide range of adiabatic flame temperatures from 1500 K to 2100 K. Compared to full premixed mode, the lean blowout (LBO) of the model combustor fueled CH4 in partial premixed mode is extended. NOx emissions are less than 10 ppm@15% O2 and CO emissions are less than 20 ppm@15% O2 in the adiabatic temperature range of 1600 K to 2000 K. The fuel distribution at the exit of the microscale nozzle in partial premixed mode lead to more thermal NOx and enhance the combustion stabilization. As the hydrogen content increased from 0% Vol to 40% Vol, the lean burnout (LBO) temperature of the model combustor is extended from 1600 K to 1400 K. NOx emissions are not sensitive to hydrogen content at the same adiabatic temperature. The reaction zone is more concentrated along the axial and radial directions increasing the hydrogen conten. The liftoff height of flame is only 1.6 Dn under the condition of 40% Vol hydrogen content. The frequency and maximum amplitude of dynamic pressure increase when the hydrogen content increased. The high-efficiency, stable and low-emission combustion in partially premixed mode has been achieved when the hydrogen content ranged from 0% Vol to 40% Vol