Activation energy distribution of thermal annealing of a bituminous coal

Feng, B., Jensen, A., Bhatia, S. and Dam-Johansen, K. (2003) Activation energy distribution of thermal annealing of a bituminous coal. Energy & Fuels, 17 2: 399-404.


Author Feng, B.
Jensen, A.
Bhatia, S.
Dam-Johansen, K.
Title Activation energy distribution of thermal annealing of a bituminous coal
Journal name Energy & Fuels   Check publisher's open access policy
ISSN 0887-0624
Publication date 2003
Sub-type Article (original research)
DOI 10.1021/ef020108v
Volume 17
Issue 2
Start page 399
End page 404
Total pages 6
Place of publication Washington, DC.
Publisher American Chemical Society
Collection year 2003
Language eng
Subject C1
290699 Chemical Engineering not elsewhere classified
660103 Coal-other purposes
Abstract A bituminous coal was pyrolyzed in a nitrogen stream in an entrained flow reactor at various temperatures from 700 to 1475 degreesC. Char samples were collected at different positions along the reactor. Each collected sample was oxidized nonisothermally in a TGA for reactivity determination. The reactivity of the coal char was found to decrease rapidly with residence time until 0.5 s, after which it decreased only slightly. On the bases of the reactivity data at various temperatures, a new approach was utilized to obtaining the true activation energy distribution function for thermal annealing without the assumption of any distribution function form or a constant preexponential factor. It appears that the true activation energy distribution function consists of two separate parts corresponding to different temperature ranges, suggesting different mechanisms in different temperature ranges. Partially burnt coal chars were also collected along the reactor when the coal was oxidized in air at various temperatures from 700 to 1475 degreesC. The collected samples were analyzed for the residual carbon content and the specific reaction rate was estimated. The characteristic time of thermal deactivation was compared with that of oxidation under realistic conditions. The characteristic times were found to be close to each other, indicating the importance of thermal deactivation during combustion of the coal studied.
Keyword Energy & Fuels
Combustion
Reactivity
Char
Temperature
Oxygen
Carbon
Model
Q-Index Code C1

 
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