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Show 16 tubes from the reburn zone indicated no observable decrease in tube wall thickness. Follow-up UT testing will continue for the next five years. Details of the performance of the reburning demonstration are summarized by Yagiela, et al. (1994). CELL-FIRED BOILER Another of the Clean Coal Technology Demonstration projects is the IIFull-Scale Demonstration of Low-NOx Cell Burner Retrofit" (DOE Contract DE-FC22-90PC90545). Dayton Power & Light (DP&L) agreed to be the host utility for the full-scale demonstration of the LNCB® burner, offering the use of its J. M. Stuart Station Unit NO.4. Unit No.4 is a 605-MWe universal pressure (UP) boiler originally equipped with 24, two-nozzle cell burners arranged in an opposed-wall configuration. B&W designed and sold 36 cell-fired boilers, representing 25,188 MWe. The LNCB® burner, shown in Figure 16, was developed as an economical, plug-in replacement for the cell burner. Staging is accomplished without requiring pressure part modifications for the installation of overfire air ports. The original two coal nozzles of the cell burner are replaced with a single coal injection nozzle and a special secondary air injection port (or dedicated overfire air port). The port with the fuel nozzle operates at a low stoichiometry, typically 0.6, with the balance of air entering through the adjacent port. The role of modeling throughout the development of the burner is described by Fiveland and Latham (1993). SDlaidminpge rA Dirr ive ----E!i~~~~~~~ Upper NOx Port LDuver Damper __ --<~,o Adjustment Distribution Cone Figure 16 Low NOx Cell Burner (LNC8®) Configuration |