| OCR Text |
Show and CO emission were also noted for each condition. Overall, the burner fired in a typical fashion to what has been seen in commercial operation and previously on the pilot-scale facility. During the overfrre air tests, the burner was operated at stoichiometries of 1.20 to 0.7 with no effect on the stability of the flame. The unburned carbon remained below 5% in all cases. After completion of the benchmark testing with the DRB-XCL ® burner, testing with the advanced lowNOx burner (ALNB#l) was initiated. Testing began with the burner in a previously tested configuration3 to test the repeatability and to benchmark the burner with the illinois #6 coal. Emission values were found to be similar to those previously obtained. Minor variations to the air distribution, excess air, and coal delivery were tested while in the original configuration. All variations showed similar trends as those obtained during previous testing. A number of hardware changes, including various flame stabilizer rings (FSR) and air distribution cones (ADC), were tested. Again, similar variations to the air distribution, excess air, and coal delivery were tested for each hardware configuration. Operating conditions, including air and coal flows, FLAMEVIEWTM temperature mappings, and stack emissions, were recorded for each test series. Fly ash samples and furnace exit gas temperatures were obtained for a number of cases. All variations were compared to one another and the optimum hardware and settings were determined. After the optimum hardware (ADC, FSR) and operating settings for the advanced 10w-NOx burner were determined, further hardware modifications to the air flow distribution and coal delivery system were made (ALNB#2). These changes were found to be very promising. NOx emissions of the advanced lowNOx burner (ALNB#2) were found to be at an approximately 10-15% reduced value compared to the DRB-XCL ® burner benchmark values. The unburned carbon and CO emissions were found to be similar with both burners, while the burner pressure drop increased only slightly with the ALNB#2. Based on the frrst two series of pilot-scale testing and the results obtained from numerical modeling of various hardware and operating configurations, further improvements were made to the advanced lowNO x burner. Staged (STAGED ALNB#3) and unstaged (UNSTAGED ALNB#3) versions of the modified advanced 10w-NOx burner were fabricated. Again, a series of minor hardware changes (FSR, ADC) were tested. Another series of tests was performed with the pilot-scale DRB-XCL ® and the ALNB#2 developed during the second series of testing, for baseline comparisons. A 10-15% reduction in NOx emissions was again noted for the ALNB#2 over the DRB-XCL ®. Preliminary results indicate that the UNSTAGED ALNB#3 has a 20-25% reduction in NOx emissions in comparison to the DRB-XCL ®. Again, the CO emissions were similar, while the burner pressure drop increased only slightly. Analyses are still being performed to determine the unburned carbon levels in 15 |
