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Show o o E Q. a. O 1000 ° Q A Before Rebum Modification 26S MWe •, A Rebum Tett 12% Reburn Fuel 300 M W e 02 After Economizer (%) Figure 15: Ladyzhin Unit 4 Emissions Performance operating at increased economizer outlet 0 2 levels. At 4.5 percent 02, N O x was 660 p p m prior to reburn retrofit and approximately 280 p p m with reburn in service, for a 58 percent N O x reduction with a C O concentration of 83 ppm. Additionally, testing thus far has indicated that mean carbon in flyash from the boiler prior to reburn retrofit averaged 1-2 percent. After the retrofit, with the reburn system in service, the mean carbon in flyash level has risen slightly to the 2-3 percent range. The increase in carbon-in- flyash is within the Ladyzhin plant's acceptable range. It should be noted that the performance of subsequent reburn systems on similar units would likely be enhanced by providing for an adjustable nozzle yaw and tilt capability6. The existing Ladyzhin system has fixed injection angle reburn fuel/FGR and burnout air nozzle assemblies. The fixed geometry hardware at Ladyzhin was mechanically simple to design and install. A B B C-E's experience, both in the physical flow modeling of the Ladyzhin boiler, as well as on operating U.S. utility boilers, is that nozzles with vertically adjustable tilt and horizontally adjustable yaw can be effectively used to change and optimize fuel/air mixing. Externally adjustable nozzles provide a "fine tuning" capability for the system; this "tuning" has been effective in minimizing C O and carbon in flyash, and would analogously be useful for this purpose if integrated into subsequent reburn system installations. In summary, the Ladyzhin reburn system has thus far met the emissions and thermal performance expectations of the U.S., Russian, and Ukrainian team members. Additional testing is planned for the future, and system operating performance will be monitored over the long term with the unit on normal load dispatch. The reburn system o o E OL D. X o BUU 600 - 400 - 200 - 0 - 17 |