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Show quent scale up efforts as well as some comparisons with full-scale baseline results will be addressed here. Some comparisons of coal reburning results for both pilot-scale programs will also be made. The B&W pilot-scale facility modified for cyclone firing as shown in Figure 5 was used for both pilot-scale projects. The coal reburners constructed in the fust (EPRI/GRI cosponsored) work were used. Figure 6 illustrates the relative sizes of the pilot- and full-scale facilities. Parameters for NO. . prediction in a cyclone (like HNSC for PC firing) have not ,- been developed, but results shown in Table 2 indicate excellent pilot-scale reproduction of typical cyclone boiler combustion and emissions perfonnance. Gas residence times are duplicated between main, rebum, and overfire air zones, but gas velocities are considerably lower. Cyclone furnace coal grind was scaled as previously discussed, while reburner coal grind was set to match full-scale. Coal analyses for the pilot-scale programs are shown in Tables 7 and 8. Coal used in the second (demonstration) project matches that being used at the WP&L station. Some testing was also done with a higher-sulfur Illinois coal to provide a larger database for future technology evaluation. Effect of reburn coal grind size was also investigated as part of the clean coal project. Cyclone Reburning Results Greater than 50% NO .. reduction with no extraordinary operational problems associated with furnace exit gas temperature, deposition/fouling, or combustibles were previously reported for the first pilot-scale project. Figure 8 shows some preliminary pilot-scale data from the Clean Coal Demonstration Project compared to the earlier pilot-scale study. Medium- grind reburning coal was used. Similar NO .. reductions can be seen. Preliminary baseline results from the WP&L field testing show NO .. levels about 300/0 lower than the nominal 1000 ppmV measured in the pilot-scale tests. The analyses for the coals used are somewhat different (on a dry basis, 43.69% volatile matter, 51.350/0 fixed carbon for the pilot-scale tests versus 40.97% volatile matter, 53.07% fixed carbon for the WP&L tests), so this and cyclone and main furnace differences between pilot-scale and full-scale must account for the NO. . level differences. Some combustion occurs in the main furnace, and the SBS target box geometry and heat transfer differ from the baffle and slag-screen tubes in the WP&L boiler. Since NO .. measured near the SBS cyclone furnace throat was the same as at the stack, cyclone furnace differences and coal properties may dominate. In any case, these pilot-scale limitations are not defeating. At the demonstration site, more coal may be switched to reburn fuel to obtain 50% NO,. reduction as is implied by Figure 8. Effects on electrostatic precipitor performance, FEGT, and combustibles may limit this increase. This illustrates the site-specific considerations for retrofitting the technology. It also illustrates the useful screening and trend data obtainable from pilot-scale testing. Absolute values for scale up aren't needed, especially since modeling work and correlations can provide further design input. 8 |