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Show Measurements of Particle Number Density and PSD (Cont.) -4 1 0 -5 1 0 C") - -6 E 1 0 (,) ...... -0) ·7 C 1 0 .2 EEE U)o~ &t)U) ..... Mu)o) 000 II II II ... .a...s.. 1 0- 8 c CI) c(0,) 1 0 .g 0 ......... ·10 . • I . -- I I I 1 0 ·11 1 0 Particle Diameter (Jlm) Figure 19: Mass Based Concentration vs Diameter for Test 1 - C") E (,) ...... -0) C 0 ;: ..a..s.. C CI) (,) C 0 0 -4 1 0 -5 1 0 -6 1 0 ·7 1 0 -8 1 0 U)O~ &t)U) ..... -9 MU)O) 1 0 000 --- II II II ·10 ... ...... 1 0 ·11 1 0 ~=~~~~=,I;;.2~ 1 0 Particle Diameter (Jlm) Figure 20: Mass Based Concentration vs Diameter for Test 2 The final conclusion from the comparison of Figures 17-20 is that the PSD of the micronized coal measured in situ, is dependent on the flow field. The PSDs of the coal measured in the boiler for Type II flow were relatively close to each other. On the other hand, for Type ill flow, the measured PSDs showed distinct segregation trends (Figures 18 and 20). The segregation of particles in Test 2 as depicted by Figures 18 and 20, provides evidence that PSD can have an effect on NOx formation. It has been suggested that the formation and destruction mechanisms of nitrogen species may be affected by the PSD of the coal (Abbas, Costen, Lockwood, & Romo-Millares, 1993; Clark Midkiff & Altenkirch, 1986; Maier, Spliethoff, Fingerle, & Hein, 1993). More specifically, it has been found that both small (25 Jlm) and large (121 Jlm) particle size segregation can result in low NOx emissions (Abbas, et aI., 1993; Clark Midkiff & Altenkirch, 1986; Maier, et aI., 1993). Figures 18 and 20 provide evidence for the segregation of PSD associated with a low NOx flame. However, it is difficult to establish the exact impact of PSD on NOx emissions from the current investigation. The only conclusion that can be drawn is that the measured PSDs reflect the different flow fields. Summary and Conclusions For Test 1, with the higher Overall Swirl Number (2.1), the me~sured values ,of gas temperature at xlD=3.75 were in the range of 1,400-1,600 K, wIth small radIal gradients, while the corresponding measurements for Test 2 indica~ed val~es in the range of 1,200-1,650 K with large radial gradients. Measured gas velocIty proftles for the two tests indicated that the rate of decay of the velocity in the x-direction was higher for Test 1 than for Test 2. The measured gas velocity profiles for the two tests were drastically different. Finally, the measured values of particle speed for the two tests verified the above trends and provided insight into the behavior of the particles under two different |