OCR Text |
Show Measurements of Particle Number Density and PSD CO) -E ..u.... (/) .! u -... ca -£l. c: -o -.c.a. c: Q) u c: o o 1 0 5 rr--__- -r-----,r---___. .... 4 1 0 3 1 0 2 1 0 1 1 0 o CDO~ tnCD.,... Cf)CDo) 000 .... II II II ......... 1 0 ~-1;';';';';";";~~;";";";';";~~~2~ 1 0 1 0 Particle Diameter (~m) Figure 17: Number Based Concentration vs Diameter for Test 1 CO') -E ..u... (/) .! u -... ca -£l. c: o --.c.a. c: Q) u c: o o 105-..-.._ ... -....- ... ~..- ... -....~ ....~ . ~.... ~ ...~ .... ~ ...r . ..~ ... ~ 4 1 0 ............ ~ .............. . \ . . \'\ \ :. \\ 1 03 ............. +~;\ .. . : \. '!,,---~ ! ', : : \. : : \. : 2 : , , : 1 0 .............. L ......... l..~ .... , ........ : ...... -t .; ,\ 1\ .. : \ : . 1 .. \ : ~ .. 1 ; ;' \ 1 0 .............. {.. ......... ·.··~··\ ·· 9 ·· . .. ·1. .· . ... -I : : \ . : : , \ : : ,. ; ; , \ : : , . 1 00 .............. 1 .............. 1 .......... i ..... .. ~ 0 1 2 10 10 10 10 Particle Diameter (~m) Figure 18: Number Based Concentration vs Diameter for Test 2 The number density (or number-based concentration) of the particles in the boiler was measured at three radial positions of 0.3, 0.7 and 0.9 m, at an axial distance of xID= 8.75 for Tests 1 and 2. The number-based particle concentrations measured in Tests 1 and 2 were characterized by high number densities in the small size classes (0.4-2 J,lm) followed by a logarithmic decrease to larger particle sizes (Figure 17). The measured particle number densities at the three locations along the width of the boiler were all very similar because of the intimate mixing of air and fuel (Figure 17). In contrast to Test 1, the measured particle concentrations for Test 2 at radial distances of 0.3, 0.7 and 0.9 m were distinctly different. This segregation of particles in Test 2 as depicted by Figure 18 was caused by the different flow field associated with this test (Type III). As a result of the lower Overall Swirl Number for Test 2, a larger percentage of the particles penetrated the IRZ. The main reason for this is that the intensity of the IRZ had decreased compared to Test I. This change in the percentage of particles which either penetrated or was entrained in the IRZ affected the time-temperature history of the particles and their number densities as depicted in Figure 18. Expressing the measured particle concentrations on a number basis does not always allow for an accurate description of the particle size distribution moments (Figures 17 and 18). Consequently, the measurements were also expressed on a mass basis (Figures 19 and 20). Reporting the particle concentrations on a mass basis eliminates the inherent bias of the instrument toward the finer diameters and provides a mass-based particle concentration which is more realistic (Figures 19 and 20). |