OCR Text |
Show At 3 0 % load combustion with O 2=2.4%, the maximum temperature at the measuring point A was 1105 °C at position 60 m m away from the furnace wall. The maximum temperature at measuring points C and D were 1002 °C and 890 °C, respectively. This means the maximum temperature became lower by about 200 °C than the case of the rated combustion. In the case of O 2=6.2%, the maximum temperature at the measuring point A was 1010 °C (close to the flame stability limit of O 2=6.5%). At this time, the flame length became longer. In gas/air mixture combustion, w e could observe rapid decrease of temperature when the combustion condition becomes at high excess air. 1500 " 1000 tf 500 o SAMPLING A (135* OOtfflM OF KU2LQ * SAMPLING C • SAMPLING O TEST CONDITIONS RATEO FIRING 0,-3.7X NOx-43pom(atO,-0% CORRECTED CO-OODO C0.-9.94X 0 (HALL) 100 200 01 STANCE FROM HALL (nun) 300 /FURNACE^ \CENTER ; FIGURE 5. DISTRIBUTION OF TEMPERATURE IN FURNACE AT RATCD LOAD 1500 •w 1000 500 / • - Vf $x2>-^**~K : 03- . • O SAMPLING A (IST DOMfUM OF M3Z2LO A SAMPLING C • SAMPLING 0 *"**• e o - »-8» ' ' -^t----o- ' 0,-2. AX - • 0^6.2X 1 0 (HALL) 100 200 OISTANCE FROM HALL (mm) 300 fFURNACEA \CENTER I FIGURE 6. DISTRIBUTION OF TEMPERATURE IN FURNACE ON DIFFERENT Oi % AT 30 % LOAD 2) NOx distribution (Figures 7, 8) Figure 7 shows N O x distribution in the furnace at rated load. When w e measured N O x distribution at the the position near the point A at rated load with O 2=3.7%, it was higher near the furnace wall, like the case of temperature distribution, and it became lower as it got close to the center. At the measuring points C and D in the downstream side, N O x value increased. The N O x value at the measuring point D was as high as 38-40 ppm which was very close to the value, 43 ppm measured in the flue. Fig.8 shows N O x distribution in the furnace at 3 0 % load. The N O x distribution at the points A, C and D were almost the same at 3 0 % load with O 2=6.2%. The N O x value measured at the point D exceeded that of the point A by only 2-5 ppm. This may be because the maximum temperature in the furnace was as low as 1 000 °C. These data show the combustion temperature has large influence for the N Ox |