(113a) The Influence of Swirl and O2 Addition On Flame Stability, NO Formation, Carbon Burnout, and Flame Temperature In a High Oxygen Participation Pulverized Coal Burner

To be submitted to AIChE 2011 Annual Meeting, October 16-21,
2011, Minneapolis, MN

The Influence of Swirl and O₂ Addition on
Flame Stability, NO Formation, Carbon Burnout, and Flame Temperature in a High
Oxygen Participation Pulverized Coal Burner

Darrel Zeltner, Teri S. Draper, and Dale R. Tree

Brigham Young University

Chendhil Periasamy, Taekyu Kang, Yuan Xue, and Remi Tsiava

Air Liquide

Air Liquide has developed a high oxygen participation burner
for coal combustion. For successful operation of such burners for different
applications, selection of burner design variables and appropriate oxygen
injection schemes are important.  In order to provide insights into the use of
higher oxygen concentration for coal burners, NO emissions, coal burnout, flame
temperature, and flame emissivity were  measured on a 150 kW_th,
pipe-in-pipe version of the burner for three swirl ratios and varying primary
and secondary O₂ concentrations. Swirl was varied by a swirl plate
with angles of 0, 15 and 40 degrees. Oxygen concentration injected into the
center of the coal stream was varied from 4 to 50% and CO₂ was added
to the secondary stream in increments from 0 to 72%. With no swirl, the coal
flame was attached only when CO₂ concentrations in the secondary
stream was less than 24%. At 15 degree swirl angle, the flame was stable over a
broad range of operating conditions. NO was lowest with 96% of the O₂
in the secondary annulus. Burnout and NO increased with increasing CO₂
concentration in the secondary annulus. With 40 degree swirl angle, images
showed large regions of unburned coal being transported through the flame.
Flame temperature increased and emissivity decreased with increasing O₂
flow to the primary. Further, the data show an increase of O₂ to the
primary center tube increases NO without improving burnout.