Experimental Study of Methane-Oxygen Flames Doped with Nitrogen Oxide or Ammonia. Comparison with Modeling

Abstract

NH, and NO have been added to low pressure. premixed laminar CH,-O, flames of different equivalence ratios. The profiles of concentrations of major radicals and stable species have been obtained, using a molecular beam sampling technique coupled with a mass spectrometer. Laser-induced fluorescence has been used to measure CH radicals. Absorption spectroscopy has been applied to OH radical and temperature measurements.The behaviours of NO and HCN are mainly discussed, and the whole experimental result compared to complete flame structure computations.Using a recent reaction mechanism described by Miller, we notice that pollutants NO and HCN are generally underestimated by computations. Another mechanism. proposed by Dian et al., for nitrogen oxidation has been tested. Sensitivity and reaction path analysis made it possible to identify the reactions which would require modifications, according to a review of recently published kinetic values, in order to get a better fit between the experimental profiles and the computed ones.

Combustion Chemistry of Nitrogen

“…The literature contains many flame studies which suggest that important aspects of hydrocarbon-nitrogen interactions remain to be discovered. Examples include the studies by Etzkorn et al (1992) and Williams and Fleming (1994) of NO-doped methane flames, of Garo et al (1992) on production of NO and HCN in flames, and the analysis of reburn chemistry by Staph and Leuckel (1996). Reinvestigation of the relevant reaction pathways using the Table 2.19 mechanism, together with an appropriate hydrocarbon oxidation mechanism, for the conditions studied by these authors would be a useful undertaking.…”

Chemical Effect of CH4 on NH3 Combustion in an O2/N2 Environment Via ReaxFF

“…Similarly, Rosier et al measured the concentration curves of CO and H 2 O under the same flame conditions using laser spectroscopy. Based on mass spectrometry, absorption spectroscopy, and laser-induced fluorescence techniques, Garo et al studied the ammonia-doped CH 4 /O 2 flames and obtained the spatial distribution curves of some major species and intermediates, including stable intermediates such as HCN and free radicals such as H, O, OH, and CH 3 . Besides, Williams and Fleming measured the relative concentration curves of CN, NH, NCO, and NO.…”