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Show Parameter Changed Decreasing Main Burner Excess Air 20% to 5% Changing Upper FGR Elevation to Reburn Elevation Decreasing Total FGR by 3.2% by Eliminating Upper Furnace FGR Decreasing Rebum FGR by 2.5% by Increasing Upper Furnace FGR Increasing Total FGR by 3% by Increasing Upper Furnace FGR Decreasing Total Rebum Fuel by 8% with Main Burner Excess Air @ 5% Table 1: Furnace Thermal Performance Sensitivity Analyses As a result of the thermal performance sensitivity study, an optimized reburn operating case was identified. Table 2 illustrates the baseline as found, preliminary, and optimized reburn case parameters. As shown in Table 2, with the optimized preliminary reburn design conditions, the predicted furnace exit gas temperature was 18 °F lower than predicted current baseline as found during operation. Also, the furnace total waterwall heat absorption was essentially equal at 625 x 106 Btu/hr. Performance Variables Reburn Fuel Ratio Total Excess Air Burner Zone Excess Air Total FGR Rebum FGR Upper Furnace FGR Furnace Exit Gas Temperature % % % °/ %/o % op Furnace Heat Absorption x 106 Btu/hr Baseline as Found N.A. 20 20 18 N.A. 13.2 1967 626 Preliminary Reburn Case 20 20 20 18 10 3.2 2028 606 Optimum Reburn Case 12 20 5 21 7.5 8.7 1949 625 Table 2: Furnace Thermal Performance Summary Preliminary Reburn System Design The selection by the U.S. team of a preliminary reburn system design was based on the previously described reburn system design criteria, mass flow balance/stoichiometric calculations, physical flow modeling, boiler thermal performance analysis, a physical 9 Furnace Exit Gas Temperature (°F) Lowered 20 Raised 13 Raised 29 Lowered 10 Lowered 20 Lowered 21 Furnace Waterwall Absorption (106 Btu/hr) Raised 6 Lowered 8 Raised 2 Raised 6 Lowered 2 Raised 9 |