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Show Ansaldo Energia s.p.a. Full load N O x emissions of about 150 mg/Nm3 have been steadely achieved in gas firing whereas N O x levels of about 180 mg/Nm3 have been obtained in cofiring (~ 5 0 % oil firing in 9 burners) with process conditions far from optimised. CONCLUSIONS Reburning is a technology which has proven, through plant demonstration capable of providing compliance with very stringent regulatory emissions requests (less than 90 ppm N O x firing oil and gas). Designing a Reburn system requires a simultaneous control of many parameters like: flow rates, local stoichiometrics residence times etc.; it also requires the use of complex and reliable simulation tools. Although the system can be adapted fairly to any already installed hardware, it should be noted that the availability of reliable LNB's and of specifically designed OFA's and Reburn fuel injectors can greatly enhance the system performance. Design of O F A system is a subcase of a Reburn System design, as it implies the same concepts of mixing and residence time which are the basis of Reburn System. As shown in the cases previously presented Reburning always provides additional margins to OFA operation, specifically when very low emission limits are pursued. REFERENCES [1] R. De Santis et al. "Designing Low NOx Combustion Systems" IJPGC, 1995 Minneapolis, Minnesota, Oct. 9 * 11 [2] M. Sala et al. "Reburning Test in a 6MWth Furnace at Ansaldo CCA: Experimental Results and Analytical Predictions" C R O C U S Salsomaggiore 1994, Sept 20 + 23 [31 Antifora et al. "Scale up procedure from Pilot Plant Tests to Full Size Power Plant Results. Experimentation vs. Mathematical Modelling" 3rd Int. Conf. Comb. Tech. for a clean Environment - Lisbon 1995, July 3 + 6 [4] L. Lazzeri et al. "Further experience for Environmental improvement in fossil fuel Combustion" Am. Pow. Conf. Chicago 1998, April 14 H- 16 [5] A. Antifora et al. "Towards an effective reduction of emissions in boilers via combustion control" Power Gen Europe Milano 1998, June 9 + 11 [6] R. De Santis et al. "Latest Achievementsin oil and gas reburning" IJPGC Baltimore 1998, August 23 + 26 [7] G. De Michele et al. "Field Evaluation of Oil Reburning for NOx Emission Control in a 160 MWe Tangentially Oil Fired Boiler" EPRI Joint Symposium on Stationary Combustion N O x Control Bel Harbor - Florida 1993, M a y 24 + 27 [8] G. De Michele et al. "Development and Industrial Application of Oil Reburning for NOx Emission Control" Italian Technology Week, Chicago Dec. 1993 [9] G. De Michele et al. "Combustion Modifications for NOx Reduction " IJPGC A S M E , Minneapolis 1995, Oct. 9-11 [10] R De Santis et al. "Technologies and components for the control of emissions in oil fred boilers" Seminario ATICELCA Lucca (Italy) 1997, Oct. 16 [111 V. Cenci et. al. "ENEL and Ansaldo Experience in Designing, Installing and Operating Reburn Systems in large oil fred Boilers" U P G C 1997 A S M E EC Vol. 5 pgg. 661 - 669 |