Use of Oscillatory Shear Rheometry and Thermogravimetric Analysis To Examine the Microstructural Changes during Coal Pyrolysis/Carbonization for the Prediction of IRSID Strength Indices

Steel, Karen M., Castro Diaz, Miguel, Duffy, John J. and Snape, Colin E. (2009) Use of Oscillatory Shear Rheometry and Thermogravimetric Analysis To Examine the Microstructural Changes during Coal Pyrolysis/Carbonization for the Prediction of IRSID Strength Indices. Energy & Fuels, 23 4: 2111-2117. doi:10.1021/ef800977q


Author Steel, Karen M.
Castro Diaz, Miguel
Duffy, John J.
Snape, Colin E.
Title Use of Oscillatory Shear Rheometry and Thermogravimetric Analysis To Examine the Microstructural Changes during Coal Pyrolysis/Carbonization for the Prediction of IRSID Strength Indices
Journal name Energy & Fuels   Check publisher's open access policy
ISSN 0887-0624
Publication date 2009-03-27
Sub-type Article (original research)
DOI 10.1021/ef800977q
Volume 23
Issue 4
Start page 2111
End page 2117
Total pages 7
Place of publication Washington, D.C.
Publisher American Chemical Society
Language eng
Subject 090405 Non-automotive Combustion and Fuel Engineering (incl. Alternative/Renewable Fuels)
0904 Chemical Engineering
Abstract During pyrolysis and carbonization of coal, the viscoelastic properties vary across a wide range, with complex viscosity (eta*) decreasing to as low as 100 Pa s before increasing to approximately 10(8) Pa s and phase angle (delta) varying from close to 90 degrees (Newtonian liquid) down to 0 degrees (Hookean solid). A new rheometry method has been developed that combines tests using 25 and 8 mm plates to enable measurements of the entire resolidification process. When combined with thermogravimetric analysis, the method has provided new insights into the mechanisms leading to high and low IRSID, I40 strength indices. Although coals with very different volatile matter contents have similar rates of volatile release above 475 degrees C, viscoelastic properties above this temperature are highly variable. From a study of 13 coals, all coals for which delta < 55 degrees at 475 degrees C had an I40 index < 44%, while all coals for which delta > 65 degrees at 475 degrees C had an I40 index > 44%. It is thought that, when delta < 55 degrees, the material is less able to deform and accommodate the loss of mass/volume, causing it to crack/fissure. However, when the delta > 65 degrees and stays high until higher temperatures, the material is able to contract as volatiles are released without fissuring, ultimately leading to a higher I40 index. A relationship between the final storage modulus (G') of the material and the I10 index was also found, whereby a low G' corresponded to a high I10 index. Greater understanding of the relationships between viscoclasticity and pore/fissure network development could enable more precise relationships to be developed, ultimately leading to improved methods for predicting coke quality and devising strategies to make high-quality coke from various sources.
Keyword lump coke
Q-Index Code C1
Q-Index Status Provisional Code

Document type: Journal Article
Sub-type: Article (original research)
Collection: Faculty of Engineering, Architecture and Information Technology Publications
 
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Created: Sat, 11 Jul 2009, 02:50:26 EST by Dr Karen Steel on behalf of School of Chemical Engineering