Thermally Induced Structural Changes in Coal Combustion

It has been observed that certain char particles shrink when oxidized under kinetically limited conditions, instead of reacting at constant diameter, as expected. This study was perfonned to determine whether or not char from PSOC 1451 coal, prepared at different temperatures would also shrink during low temperature gasification. Coal chars, formed at l 200K and 1600K, were levitated in the electrodynamic balance and heated with a carbon dioxide laser. The 1200K char did shrink, while the 1600K char reacted at constant diameter, as expected under the kinetically limited conditions. Therefore, the time and temperature history of a char is an important factor in detennining how it might react during subsequent oxidation. •Author to whom correspondance should be addressed at the Chemical Industry Institute of Toxicology. P. 0. Box 12137. Research Triangle Park. NC 277('1).