OCR Text |
Show On the other hand, the influence of SR on UB was relatively small compared with that of the furnace exit 0, concentration on UB. Thus, the UB value was found to be greatly influenced by the 0, concentration in the whole furnace whereas NOx concentration was greatly influenced by the 0, concentration near the burner. Figure 12 shows the effects of particle size on NOx, BR and UB. Fine particles decreased more NOx and UB for every type of coal. This is due to the high temperature NOx reduction region characterizing the single-burner unit mentioned in the preceding section. . N ~ ~ 400r;::t:::==r--,----r---, I 0 Coal I eX.O;?=3% /0 ~Q'"~ ~y o al~UU~if O~~ __ ~ ____ ~ __ ~~ __ ~ 0.8 0.9 1.0 1.1 1.2 20r-~,----,,----~.~--~.~--~ · 100 15 '" ~L¢ ¢ -'-~. '- DR • 99 10 ~,~ 5- O~k--o · 98 • 97 o I . . I 0.8 0.9 1.0 1.1 1.2 Air Ratio aL Burner Zone. SR (-) F jg. 11 E ffeet. of "ir Hutio 11 t B unmr Zone 5. Conclusion ~ ex: c:c N ~ ~ 200 ~ :z _.-() -.~()-.( J....... _A~t) Qe~ O•~" ",' o.,~ 6 ______ () "'. ..... _ 9 ---0 ........ ....-. ---() ---. ...... _()_.- 10 80 90 200 Mesh Pass (wL%) Fig.12 Effect of Particle Size These are the findings obtained In the present study. (1) The influence of particle size distribution on NOx concen-tration depends on the a.ount of excess O2 • To obtain low NOx, low excess 0, requires fine particles but high excess O2 requires coarse particles. -8- |