OCR Text |
Show The furnace stack temperature was varied between 1800° F at low air injection rates and 1300° F at higher air injection rates. All data were corrected to 30/0 oxygen. Figure 6 accents the NOx emission results for the two loads and two configurations tested. All four curves show an increase in NOx concentration with increasing furnace content. With the rear exhaust configuration, the increase reaches a peak and then drops off. This is particularly evident at the medium load. With the middle exhaust configuration, the NOx emissions follow a consistent increase and do not peak. Changes in burner load have a small effect with the middle stack configuration, with the effect increasing at higher oxygen levels. With the rear exhaust configuration, however, changes in load have a pronounced effect at lower oxygen levels, and practically no effect at higher oxygen levels. N o tf. (") ci 0:: o 2- > 0:: C ~ Q. Q. , o:o...a- ~ / -7 ~ ----_. ~ / k2 ." ~ ~ ~ / V / / ~ ,// V /~ / 1/ V; / <" V o 2 4 6 8 10 12 14 18 16 -+ Medium Load - Middle Stack FURNACE OXYGEN CONTENT - % BY VOLUME -&- High Load - Middle Stack -e- Medium Load - Rear Stack +- High Load - Rear Stack Figure 6. NOx Emissions vs. Furnace Oxygen Content and Exhaust Configuration. Figure 7 shows the CO emission results for the two loads and configurations tested. Here the burner load had a minimal effect on CO emissions. The middle exhaust configuration resulted in higher CO emissions than the rear exhaust configuration. The steep increase in CO emissions with increasing furnace oxygen content seems anomalous, and is probably a function of the decreasing gas temperature at the higher air injection rates. |