18 research outputs found
Influence of the NO Concentration and the Presence of Oxygen in the Acetylene Soot Reaction with NO
Reactions of Nitrogen and Oxygen Surface Groups in Nanoporous Carbons under Inert and Reducing Atmospheres
Vito Flaker@Boj za (2012): Direktno socialno delo, (OranĹžna zbirka). Ljubljana: ZaloĹžba /*cf. 372 str. ISBN 978-961-257-047-7
The
yields of NO from combustion of bituminous coal, lignite, and
biomass chars were investigated in O<sub>2</sub>/N<sub>2</sub> and
O<sub>2</sub>/CO<sub>2</sub> atmospheres. The experiments were performed
in a laboratory-scale fixed-bed reactor in the temperature range of
850â1150 °C. To minimize thermal deactivation during char
preparation, the chars were generated by in situ pyrolysis at the
reaction temperature. The NO yield clearly decreased and the CO yield
increased when the atmosphere was altered from O<sub>2</sub>/N<sub>2</sub> to O<sub>2</sub>/CO<sub>2</sub> at 850 °C, but only
small differences in NO and CO yields were observed between the two
atmospheres at 1050â1150 °C. To examine how CO influences
the NO yield, the effect of CO on NO reduction over char as well as
NO reduction by CO over ash was investigated in the fixed-bed reactor.
Furthermore, the influence of CO on the homogeneous oxidation of HCN,
possibly a product of the char-N oxidation, was evaluated using a
detailed chemical kinetic model. The results indicate that CO influences
the NO yield from char combustion through two paths at 850 °C:
(1) CO accelerates NO reduction over char and (2) CO accelerates HCN
oxidation, increasing the possibility of NO reduction over char. Both
effects were more pronounced at 850 °C than at 1050â1150
°C. The present work indicates that the effect of CO<sub>2</sub> on NO formation in oxy-fuel combustion in fluidized beds can partly
be attributed to heterogeneous reactions, whereas for high-temperature
pulverized fuel combustion, CO<sub>2</sub> mainly affects the volatile
chemistry