The flame structure and combustion dynamics in micro-mixing combustion of hydrogen-rich syngas with air

Micro-mixing (MM) combustion technology demonstrates remarkable NOx reduction capability in gas turbines. As for hydrogen-rich syngas with typical heating value, the experimental studies are carried out at different equivalence ratio (φ) of 0.380, 0.403, 0.426, 0.450, 0.474 and 0.499 and different nozzle outlet mixture velocity (v) of 32, 43, 54,64 and 75 m/s. An in-depth discussions on flame structure, combustion dynamics, and pollutant emissions is conducted. The result shows that in the operation range, no flashback or combustion oscillation occurred in actual experiments of the combined MM nozzles. With the increase of φ or decrease of v, the overall OH signal intensity and the anchoring ability of the flames become stronger, the heat release rate and temperature distribution uniformity would be enhanced, the degree of flame fluctuation decreases. NO emission increases rapidly with the increase of φ, which is consistent with the generation characteristics of thermal type NO, but under test conditions, they are not higher than 15 μL/L at 15 %O₂. The increase of v is beneficial for reducing NO emission, attributed to the shortened residence time of gas.