Modeling NOx release from a single coal particle II. Formation of NO from char-nitrogen
✍ Scribed by S.P. Visona; B.R. Stanmore
- Publisher
- Elsevier Science
- Year
- 1996
- Tongue
- English
- Weight
- 812 KB
- Volume
- 106
- Category
- Article
- ISSN
- 0010-2180
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✦ Synopsis
Computational modeling has been carried out to study the formation of nitric oxide during the combustion of a single spherical char particle. Combustion conditions are representative of pulverized coal in the temperature range 1250 to 1750 K. The model is a generalized mechanistic model with nitric oxide or HCN being released directly from the char N. Homogenous gas-phase reactions of NO occur within the particle, as well as heterogenous NO reduction on the char's surface. Intrinsic rate kinetics are used to model the char combustion, while the NO reduction kinetics are chosen from the literature. The model was tested against experimental results for coal chars found in the literature and our own work with petroleum coke. Modeling suggests that two mechanisms are possible for the conversion of char N to NO at high temperatures: char N goes completely to NO and is subsequently reduced on the char's surface; or char N goes completely to HCN and is oxidized and reduced in the atmosphere external to the particle. Both approaches produce realistic results when applied to a laminar flow computational fluid flow/heat transfer model of a drop tube furnace. Our model describes NO formation at high temperatures and does not consider N20 reactions which are important at fluidized bed temperatures.