Low NOx combustion of pulverized coal using the radially stratified flame core burner

Conference · Tue Dec 31 04:00:00 EST 1996

OSTI ID:504662

Barta, L E; Lewis, P F; Beer, J M ^[1]

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1. Massachusetts Inst. of Tech., Cambridge, MA (United States)

Results are presented of a theoretical-experimental study aimed at determining the characteristics of pulverizing coal flames produced with the Low NOx Radially Stratified Flame Core (RSFC) Burner. Following earlier studies with this burner in which very low pollutant emissions were attained with natural gas and heavy fuel oil, the present investigation turned to the combustion of pulverized coal. In particular, the fulfillment of the conditions required for staged combustion, i.e., maintenance of a fuel-rich flame core at high temperature and for an extended period of time by the stratification of the flow, have been investigated. The criterion for radial stratification of the flow was theoretically developed from the equations of motion, by balancing the rate of generation of turbulence and the rate of turbulence damping; the latter being due to the combination of steep radial density gradients and swirling flow. A parametric combustion study carried out by burning a high volatile bituminous coal at a thermal input of 1.5 MW has shown that by setting a ratio {alpha}/{beta} = 0.76 at the burner, a stratified flame was created, and the NOx emission was reduced from an uncontrolled range of 700--900 ppm to 217 ppm. Further reduction to 70 ppm was achieved by external air staging. For this latter condition, however, the RSFC burner was operated to produce a well stirred, high temperature, fuel-rich flame with overfire air injected at some distance downstream of the burner. Both flame types were highly stable with 99.5% and 99.3% carbon conversion, respectively.

• OSTI ID: 504662
• Report Number(s): CONF-960954--
• Country of Publication: United States
• Language: English

Related Subjects

01 COAL, LIGNITE, AND PEAT
AIR POLLUTION ABATEMENT
BITUMINOUS COAL
BURNERS
COMBUSTION KINETICS
MATHEMATICAL MODELS
NITROGEN OXIDES
PERFORMANCE
PULVERIZED FUELS
STAGED COMBUSTION