Combustion Phenomena of High Temperature Air Combustion - High Temperature Air Combustion: From Energy Conservation to Pollution Reduction - page 153

3 shows a different flame shape. The coal is injected far from the central air, it
entrains a large amount of combustion products with 3% O 2 before the ignition. The
flame was lifted; the ignition stand off distance of the coal jet was ~50 cm from the
burner. The combustion mainly takes place in a lower O 2 % environment (fuel-rich
zone) resulting in a lower NO x fl ame. Figure 2.119 shows a sketch of the effects of
the separation between central air and coal injections on the mixing between fuel
and comburent.

Jet Angle
Ur(x)/Um(x) = 0.1

Jet Angle
Ur(x)/Um(x) = 0.1

FIGURE 2.119 Mixing in the three coal gun positions.

100

98

96

94

low velocity coal guns
high velocity coal guns

92

90

1 2 3

Configurations

FIGURE 2.120 Burnout in the three different configurations for high- and low-velocity coal
guns.

The burnout level was high in all three coal gun configurations. Figure 2.120
shows the burnout % for high- and low-velocity coal guns in the three configurations.
The burnout measurements show for both high- and low-velocity coal guns a
similar trend slightly decreasing from configuration 1 to configuration 2 and then