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Show Low-NO Cell Burner Results x The coal analyses suggest that the same coal variation is enough to expect differences for NO" emissions for the two furnaces. Adiabatic flame temperature was higher for both CFPF coals (4166°/3769°F versus 4266°/3745°F, CFPF/LWS for Ohio No.6 and lower Kittanning, respectively). The results showed baseline NO" emissions were about 20% lower for the LWS (800 versus 1000 ppm at full load, 3% stack 02)' The effect of flame zone heat transfer and thus flame temperature may be more important in explaining these baseline differences. The low-NO burner results showed similar NO levels however, as shown in Figure 7. This coal ind"e pendence was seen for the same-s"c ale lower Kittanning and Ohio No.6 results. Others have noted that air-staged burners show this trend. This result is important in that the demonstration site baseline NO could be lower (or higher) than the pilot- It scale data, but we can anticipate similar low-NOll burner performance. The values of the main combustion-related parameters of concern, including FEGT, slagging, flame length, and unburned carbon, were about the same for both test furnaces. Corrosion information via ~S levels was measured in the L WS and will be further investigated in the demonstration project which will include both laboratory and field measurements. Unfortunately, the measured LWS FEGT data could not be used. Numerical modeling done for the project did predict slightly cooler FEGTs compared to the CFPF (1691°- 1720°F versus 2150o-2208°F). CFPF predictions were close to those measured. Measured FEGT increase for the low-NO" burners was less than 50°F. Slagging panel data at both sites showed no increase in slagging severity with the low-NO" burners. Flame length increase was minimized by using a coal impeller and making burner adjustments which sacrificed only part of the NO" reduction gains. These results are shown in Table 6. Unburned carbon was also found to be acceptable for both furnaces at baseline conditions with essentially no significant increase due to the low-NO burners. " Subtle differences in burner operation existed for optimum settings at the two scales. For example, vane angle and secondary air splits were slightly different. The optimum vane angle and air split are of secondary importance, since the NOll reduction results are close (55% versus 650/0) and field adjustments can be made. These results show one of the powers of pilot-scale work - trends can be identified and absolute data for scale up is not needed. Another example relates to initial testing problems in the CFPF. The coal impellers in the standard cell burners could not be adjusted to prevent pancaking of the flame (see Figure 1 for impeller details). The outer rings of the impellers were removed resulting in short flames typical of cell burners. The NO" levels and trends observed during the rest of the baseline testing looked very much like typical full-scale data (for example, 1000 ppmV NO). Cyclone Reburning Description An engineering feasibility study was followed by an extensive 6-million Btulhr pilotscale test project. Gas, oil, and coal were evaluated as reburning fuels. As previously noted, the results of those projects have been reported elsewhere. Pilot-scale studies were also performed as part of the Clean Coal Demonstration project. This pilot-scale work and subse- 7 |
