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Show 9 o Although the swirl generator was maintained in both cases at the highest setting, due to the variation in the burner throat diameter, and hence angular momentum of the combustion air, the swirl degree* values (s) for the two flames were somewhat different (S • 1.8 for Flame 1, S - 2.7 for Flame 2). 4.2 The Experimental Results - Measurements of Temperatures, In-Flame, Radiation, Velocity and Gaseous/Solids Specie's" Concentrations, and of Radiative Heat Flux from the Flame to the Furnace Vails The temperature distributions along the axes of the two coal-water slurry flames are shown in Figure 7. The effect of heat extraction is evident: the gas temperatures in Flame 1 (with less heat extraction) are higher than those of Flame 2 with the difference between the two flames becoming more pronounced towards the tail end. The gas temperature in Flame 1 peaks at a value of "'1450 C and decays to a combustion chamber exit value of * 1350 C. The values for Flame 2 at these positions are "' 1400 C and "1050 C respectively. Temperature profiles of coal-oil mixture and No. 6 fuel oil flames are included in Figure 7 for comparison. The relevant input conditions of these two flames are given in Table 5. The temperature rise in the case of COM and oil flames in close proximity of the burner is much steeper (despite the lower degree of combustion air swirl) than in the coal-water slurry flames. The difference is attributable to the cooling effect of the water contained in the fuel, which must be initially vaporized before combustion can commence. Axial distributions of radiative heat flux incident on the furnace wall are plotted in Figure 8 for the two coal-water slurry flames. Since the data were obtained with the same fuel type, relatively little difference in the emissivities of these two flames can be expected. The variation in their radiative heat flux distributions, therefore, is mainly attributable to differences in flame temperature. It is interesting to compare the radiative heat flux distributions of these flames with those of other fuel types. Also shown in Figure 8 are radiation profiles for two COM flames and one obtained with oil. (See Table 5 for flame input conditions). Examination of these profiles confirms the dominating influence of gas temperature on the flame radiative heat flux. Analysis of the data suggests that input variables which affect flame temperature such as air preheat and heat extraction have a stronger bearing on flame radiation than differences in emissivity, over this range of fuel types. * The swirl number, S~^ is a dimensionless number characterizing the degree of rotation of the combustion air and is represented in the following manner: S - G /G R where G • axial flux of angular momentum G^ • axial flux of linear momentum R • radius of burner air exit port (at point of narrowest cross-sectional area) |