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Show COAL-WATER SLURRY FIRING Figure 8 shows the ratio of the UV channels (OH/CH) and the IR channels (IR/ref), plotted agains~ the distance from the burner for CWS firing at 2- percent excess oxygen. Due to greater luminosity of the flame, as compared to the one in gas-firing, the effect of the watercooled windows on ratio of UV signals is not as prominent. The response to the OH radical emission in the UV and C02 radical emission in the IR at three excess oxygen levels is shown in Figures 9 and 10, respectively. As expected, in the UV range, the SFA response is largest at 2 percent excess oxygen and diminishes as the amount of the excess air is increased. In the IR range, the SFA response shows significant variation in the signal strengths at the water-cooled window. Thus, both the UV and IR channels have adequate sensitivity and dynamic range. o ~ 5 C1 - ANALYZER MOVING AWAY FROM THE BURNER 't"- o C2 - ANALYZER MOVING TOWARO THE BURNER IR/REF C1 METERS FROM BURNER FACE Fig. 8 - Coal-Water Slurry at 2 Percent Excess Oxygen Check for Self-Consistency 4.5 ,.-~----r---r---r--'----'-----r---r---r--.----'--....,....-~~ 4.0 3.5 3.0 2.5 > 2.0 1.5 1.0 0.5 SPECTRAL FLAME VOLTAGE OAT A MIT TESTS-COAL SLURRY OH SIGNAL ~J~2-~-~~--L-~-0~.6-2-~-0~.72--L-0-.8L2-~-0.L92-~~1.02 METERS FROM BURNER FACE Fig. 9 - Plot of OH Species Versus Distance from the Burner for Three Excess Oxygen Levels <J) ~ o > 4.0 r-~--r--'-----.---.-------r---r---r--""---'----'--r-~---, 1.5 1.0 0.5 ~.32 SPECTRAL FLAME VOLTAGE DATA MIT TESTS - COAL SLURRY CO, SIGNAL 0.42 0.52 0.62 • 0.72 METERS FROM BURNER FACE 0.82 0.92 1.02 Fig. 10 - Plot of CO2 Species Versus Distance from the Burner for Three Excess Oxygen Levels 226 CONCLUSIONS AND FUTURE PLANS The tests carried out in the MIT-CRF have demonstrated the potential of the SFA for monitoring the effect of changes in air-fuel ratio. Specific results obtained from the test program are: • The SFA receives an adequate signal in the UV and IR range to discriminate the four channels. • The SFA output varies with the change in the air-fuel ratio and the luminosity of the flame. The SFA technology has shown the potential of being a major advance in boiler combustion control and burner balancing. Further tests are presently planned in the MIT-CRF to optimize the selection of spectral wavelengths. Tests will also be carried out at the 100,000 lb per hour steam capacity industrial boiler installed at the Polaroid facility in Waltham, Massachusetts. The SFA will be installed on the boiler front at an existing observation port. The sight angle of the SFA will be such that spectral signals are obtained in as much of the axial length of the flame as possible. The tests at the Polaroid facility will be carried out with No. 6 oil firing. In order to determine the combustion conditions during the test program, measurements will be made in the flue gases at the back-end of the boiler to determine CO and 02 levels. These data will be correlated with the signals recorded by the SFA. The firing rate will be changed to operate the boiler at full-load, 75 percent full-load, and 40 percent full-load steam generating capacity. At these load conditions structured tests will be carried out by varying the air-fuel ratio and optimizing the boiler operating parameters. |
