Hydrogen addition effects on methane–air colorless distributed combustion flames

In this investigation the role of hydrogen addition in a reverse flow configuration, consisting of both non-premixed and premixed combustion modes, have been examined for the CDC flames. In the non-premixed configuration the air injection port is positioned at combustor exit end while the fuel injection port is positioned on the side so that the fuel is injected in cross-flow with respect to air injection. The thermal intensity of the flames investigated is 85 MW/m3 atm to simulate high thermal intensity gas turbine combustion conditions. The results are presented on the global flame signatures, exhaust emissions, and radical emissions using experiments and flowfield using numerical simulations. Ultra low NOx emissions are found for both the premixed and non-premixed combustion modes. Addition of hydrogen to methane fuel resulted in only a slight increase of NO emission, significant decrease of CO emission and extended the lean operational limit of the combustor.

► Demonstrated CDC flames at thermal intensity of 85 MW/m3 atm.
► Ultra low NO emissions for both non-premixed (∼4 ppm) and premixed (∼1 ppm) flow configurations.
► Addition of hydrogen to methane resulted in increase in NO and decrease in CO emissions in the non-premixed mode.
► Hydrogen addition extends the lean operational limit of CDC flames.