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Structures and stabilization of low calorific value gas turbulent partially premixed flames in a conical burner

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Author

Summary, in English

Experiments are carried out on partially premixed turbulent flames stabilized in a conical burner. The investigated gaseous fuels are methane, methane diluted with nitrogen, and Mixtures of CH4, CO, CO2, H-2 and N-2, Simulating typical products from gasification of biomass, and co-firing of gasification gas with methane. The fuel and air are partially premixed in concentric tubes. Flame stabilization behavior is investigated and significantly different stabilization characteristics are observed in flames with and without the cone. Planar laser induced fluorescence (LIF) imaging of a fuel-tracer species, acetone, and OH radicals is carried out to characterize the flame structures. Large eddy simulations of the conical flames are carried out to gain further understanding of the flame/flow interaction in the cone. The data show that the flames with the cone are more stable than those without the cone. Without the cone (i.e. jet burner) the critical jet velocities for blowoff and liftoff of biomass derived gases are higher than that for methane/nitrogen mixture with the same heating values, indicating the enhanced flame stabilization by hydrogen in the mixture. With the cone the stability of flames is not sensitive to the compositions of the fuels, owing to the different flame stabilization mechanism in the conical flames than that in the jet flames. From the PLIF images it is shown that in the conical burner, the flame is stabilized by the cone at nearly the same position for different fuels. From large eddy simulations, the flames are shown to be controlled by the recirculation flows inside cone, which depends on the cone angle, but less sensitive to the fuel compositions and flow speed. The flames tend to be hold in the recirculation zones even at very high flow speed. Flame blowoff occurs when significant local extinction in the main body of the flame appears at high turbulence intensities. (C) 2009 Elsevier Inc. All rights reserved.

Publishing year

2010

Language

English

Pages

412-419

Publication/Series

Experimental Thermal and Fluid Science

Volume

34

Issue

3

Document type

Conference paper

Publisher

Elsevier

Topic

  • Fluid Mechanics and Acoustics
  • Atom and Molecular Physics and Optics

Keywords

  • Local flame extinction
  • Flame stability
  • Conical burner
  • Low calorific gas flames
  • Partially premixed flames

Conference name

6th Miditerranean Combustion Symposium

Conference date

2009-06-07 - 2009-06-11

Conference place

Corsica, France

Status

Published

ISBN/ISSN/Other

  • ISSN: 0894-1777
  • ISSN: 1879-2286