Hydrogen addition effects on high intensity distributed combustion

Distributed combustion provides significant improvements under high intensity conditions characteristic of gas turbine to provide uniform thermal field (improved pattern factor), ultra-low pollution, enhanced stability and higher efficiency. Mixing between fresh air/fuel stream with hot reactive species is critical to result in distributed reactions and spontaneous ignition. Hydrogen enrichment of fuel is examined with emphasis on combustion stability and emissions under swirling flow conditions. Results are presented on the role of hydrogen enrichment to methane (4-15% by mass, 25-58.5% by volume) on the combustion characteristics under fuel-lean conditions. CO emission was substantially reduced with hydrogen enrichment, with minimal effect on NO emission under premixed combustion. Hydrogen addition extended the lean operational limits of the combustor with stable combustion and no flame fluctuations or flashback. Results obtained on pollutants emission and flame marking via OH* chemiluminescence revealed near volume distributed high intensity combustion with ultra-low emission (<3PPM NO and <9PPM CO) and high performance at lower equivalence ratio. Hybrid numerical-experimental approach can provide more realistic prediction of NO emission from hydrogen enriched methane combustion. (C) 2012 Elsevier Ltd. All rights reserved.