Measurement of PAH and soot of diffusion flames in a triple port burner

In this study, we measured PAH and soot in a triple port burner. The coannular burner consists of three concentric tubes, where air flows in both inner (central) and outer tubes, and fuel flows in the annulus between these air tubes. Two diffusion flames are formed in the boundaries of fuel and air. To detect PAH and soot regions, the techniques of PAH–LIF (laser-induced fluorescence) and soot LII (laser-induced incandescence) were applied. The system of GC/MS was also used to obtain quantitative PAH concentration. Through a comparison of LIF signal and PAH concentrations measured by GC/MS, LIF signals correspond well to the major PAHs of benzene and naphthalene. When the longer excitation wavelength was used, the higher-class PAH was better reflected in LIF signals. For comparison, a diffusion flame in a co-axial burner (simply, double port burner) was examined by changing the fuel and air flow rates. In the triple port burner, the flame height is smaller than that of the double port burner, which could be caused by the promoted mixing of fuel and air. Since PAH which is a precursory substance of soot is decreased in the triple port burner, the total soot in flames is resultantly reduced.

► We examine PAH and soot emissions of diffusion flames at different flow conditions.
► To detect PAH and soot regions, the techniques of PAH-LIF and soot LII are applied.
► The system of GC/MS is also used to obtain quantitative PAH concentration.
► A triple port burner is used, where the fuel is supplied between two air flows.
► PAH and soot emissions are reduced by enhancing the mixing of fuel and air.