The relative importance of radicals on the N{sub 2}O and NO formation and destruction paths in a quartz CFBC
- Vienna Univ. of Technology (Austria)
In a laboratory-scale circulating fluidized bed combustor (CFBC) the relative importance of the radicals, generated by the combustion process, on the N{sub 2}O and NO formation and destruction paths are studied. The CFBC unit is electrically heated and operating conditions can be nearly independently changed in a wide range. The radicals` importance on the destruction reactions of N{sub 2}O has been investigated under CFBC conditions by a recently developed iodine-addition technique to suppress the radical concentrations. Additionally, CO, CH{sub 4}, and H{sub 2}O have been added to study their influence and to change the pool of radicals. Time-resolved concentration changes at the top of the riser have been measured by using a high performance FT-IR spectrometer. The FT-IR analysis is focused on the following species viz. CO{sub 2}, CO, CH{sub 4}, other hydrocarbons, NO, NO{sub 2}, N{sub 2}O, and HCN. These tests revealed the importance of radicals for N{sub 2}O destruction when CO or CH{sub 4} is added. Thermal decomposition was found to be of minor importance. The inhibiting effects of the sand particles are due to radical quenching. In the continuous combustion tests petroleum coke has been burned in the CFBC. Concentration profiles and concentration changes at the top of the riser have been measured. The combustion of the finer fuel particles led to substantial higher NO emissions by keeping the net conversion to NO and N{sub 2}O formation. Addition of CH{sub 4} decreased the NO and N{sub 2}O levels confirming that it is a promising technique for simultaneous reduction of NO and N{sub 2}O. Iodine addition tests indicate that radicals play also an important role in the NO and N{sub 2}O formation chemistry.
- OSTI ID:
- 357893
- Report Number(s):
- CONF-9705116--; ISBN 0-7918-1557-9
- Country of Publication:
- United States
- Language:
- English
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