Lean-non-premixed combustion for low-NOx emission gas turbines: emission characteristics

摘要

This paper describes the low-NO{sub}x emissions of a non-premixed, direct fuel injection double-swirler burner which is being developed for high-temperature combustors of methane-fueled gas turbines and supersonic aero engines. The burner hasconcentric, circular and annular air channels to which swirlers are fitted. The circular channel on the burner axis is converging into a throat and then diverging downstream. Fuel is injected by a multi-hole fuel nozzle in the inner air channel. Gaseousspecies were measured at the flame tube exit by using a gas-sampling rake, at atmospheric pressure, at inlet air temperatures of 650, 950, and 1,100 K. Emissions measurements were made for conventional swirl burners equipped with single axial swirlers ofdifferent hub sizes. The double-swirler burner achieved the lowest NO{sub}x emissions levels over the range of equivalence ratios tested while the conventional. large-hub swirler burner showed the highest NO{sub}x emissions levels the difference beinglarger at leaner conditions. The difference between the NO{sub}x emissions characteristics of these burners was discussed, based on the fuel-air mixing in the region near the burner exit under non-burning conditions. At 950 K inlet air and 1,800 K gastemperatures, emission indices of 0.5,1.1 and 2.2 g NO{sub}2/kg fuel were measured for the double-swirler burner, conventional small-hub and large-hub swirler burners, respectively.