The relative importance of radicals on the N2O and NO formation and destruction paths in a quartz CFBC

In a laboratory-scale circulating fluidized bed combustor (CFBC), which mai nly consists of quartz-glass, the relative importance of the radicals, gene rated by the combustion process, on the N2O and NO formation and destructio n paths are studied. The CFBC unit is electrically heated and operating con ditions can be nearly independently changed over a wide ranger e.g., the be d temperature was varied between 700 and 900 degrees C. The radicals' impor tance on the destruction reactions of N2O has been investigated under CFBC conditions by a recently developed iodine-addition technique to suppress th e radical concentrations. Additionally, CO, CH4, and H2O have been added to study their influence and to change the pool of radicals. Time-resolved co ncentration changes at the top of the riser have been measured by using a h igh performance FT-IR spectrometer in combination with a low-volume, long-p ath gas cell. The FT-IR analysis is focused on the carbon containing specie s, viz., CO2, CO, CH4, and other hydrocarbons, as well as on the nitrogen-c ontaining species, viz., NO, NO2, N2O, and HCN. In the continuous combustio n rests, petroleum coke has been burned in the CFBC. Concentration profiles and concentration changes at the top of the riser have been measured, Iodi ne has been added and the bed temperature and the initial fuel particle siz e ape varied. With the knowledge of the N2O destruction reactions, the rela tive importance of the radicals on N2O and NO formation reactions has been identified and is discussed.