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Show EXPERIMENTAL STUDY OF THE EFFECT OF AIR PREHEAT UP TO 1200°F O N N O x EMISSIONS* Rita C. Bojko Mark J. Khinkis Richard T. Waibel Institute Of Gas Technology Energy Development Center 4201 West 36th Street Chicago, Illinois 60632 and William D. Boyd Southern California Gas Company 810 South Flower Street Los Angeles, California 90017 ABSTRACT The purpose of this study was to evaluate the environmental trade-offs associated with the use of high-temperature combustion air preheat and various N O control methods. The overall objective of this study was to evaluate the effect of excess air and flue gas recirculation on thermal NO emissions when burning natural gas using combustion air preheat from 650° to 1200°F. Tests were performed in IGT's pilot-scale Furnace No. 1, which was equipped with a hot air baffle burner and set up to fire a total heat input of 3 X 10 Btu/hr. The total heat input included the sensible heat of the preheated combustion air. The load on the furnace was adjusted to maintain a 2300°F flue temperature. Four different air preheat temperatures, up to seven different air/fuel ratios, and three levels of flue-gas recirculation were tested. The rates of recirculation tested were 0%, 5%, 10%, and 20%. The preheat temperatures tested were 650°, 800°, 1000°, and 1200°F. The air/fuel ratio was varied in 5% increments from ^ 0 % to 4 0 % excess air. The data from this study show the substantial growth of N O formation with air preheat temperature and effectiveness of both reduced excess air and flue-gas recirculation for reducing N O emissions, especially at high air preheat temperature. The data show the peaking of N O formation between 6% and 7 % excess oxygen in the flue. •This program was sponsored by the Southern California Gas Company. 4-1 |