The potential for aligning industrial processes, such as steam-methane reforming for large-scale hydrogen production, with carbon capture and storage provides three unique vectors (hydrogen, carbon dioxide, and steam) for utilization in decarbonized gas turbine power generation, considering both new hydrogen-fired gas turbines and retrofit of existing industrial gas turbine fleet.  Therefore, a study has been undertaken to experimentally and numerically evaluate the use of carbon dioxide and steam as premixed fuel additive in hydrogen-air flames to aid in the development of lean premixed swirl burner technology for low NO~x~ operation.  Chemical kinetics modelling indicates that the use of carbon dioxide and steam in the premixed reactants reduces H~2~-air laminar flame speed and adiabatic flame temperature within the well-characterized range of preheated lean premixed methane-air flames, albeit in markedly different proportions; for example, nearly 70% vol carbon dioxide as a proportion of the fuel is required for a reduction in laminar flame speed to equivalent methane-air values, while approximately 30% vol carbon dioxide in the fuel is required for an equivalent reduction in adiabatic flame temperature, significantly impacted by the increased heat capacity of carbon dioxide.  The 2^nd^ generation high-pressure generic swirl burner, designed for use with lean premixed methane-air, is therefore utilized to experimentally investigate the influence of carbon dioxide and steam dilution on pressurized (25 kW/bar), preheated (573 K), lean premixed hydrogen-air flame stability using high-speed OH\* chemiluminescence and dynamic pressure sensing.  In addition, exhaust gas emissions, such as NO~x~, have been measured in comparison with equivalent thermal power conditions for methane-air flames, showing that low NO~x~ operation can be achieved.  Furthermore, pure lean premixed hydrogen-air flames are characterized for the first time in this burner, stabilized at low equivalence ratio (approximately 0.25) and increased Reynolds number (31000) at atmospheric pressure compared to the stable methane-air flame (equivalence ratio of 0.55 and Reynolds number of 17500, respectively).  The influences of extinction strain rate and Lewis number are suggested to characterize, both experimentally and numerically, the observed lean flame behavior, in particular as extinction strain rate has been shown to be non-monotonic with pressure for highly-reactive and diffuse fuels such as hydrogen.  


Experimental and Kinetic Evaluation of Pressurized Lean Premixed Hydrogen-Air Flame Stability With Carbon Dioxide and Steam Dilution

Division / Sponsor:
International Gas Turbine Institute (IGTI)

Paper Proceedings: https://asmedigitalcollection.asme.org/GT/GT2020/volume/84058

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