
455Burner Design
less than 5% of the total oxygen ow, is used around the
central fuel jet to anchor the fuel jet and provides excellent
ame stability. As a result, the burner can operate at very
high FGR ratios and at a lower ame temperature than a
typical low NO
x
air burner using FGR.
Figure 18.16 shows the effects of oxygen-enriched
combustion on NO
x
emissions for two commercial air
burners (Bloom and Kinemax) and two commercial
oxy/fuel burners (Oxytherm and Praxair “A”) in a test
furnace.
15
Oxygen enrichment of combustion air in
the air burners increased the ame temperature and
resulted in sharp increases of NO
x
emissions. As the
oxy