Combustion characteristics of selected whole coals and macerals

A thermogravimetric analysis of the combustion of a Brazilian mineral coal

“…For the primary combustion step it follows that (8) where w r is the residual weight of the sample as primary combustion is finished, and k 1 is the reaction rate coefficient for the primary combustion step. For the secondary combustion step it follows that (9) where w f is the residual weight of the sample as secondary combustion is finished, and k 2 is the reaction rate coefficient for the secondary combustion step.…”

“…Figure 5 presents DTG curves obtained by time derivation of the TG curves from Figure 4. Two main reactive events take place which are identified as primary and secondary combustion 8 . Those events are well characterized through the observed changes of behavior of the DTG curves from ignition, which happened around 470 o C for all the heating rates.…”

“…Yong et al 7 included a third class named hetero-homogeneous, accounting for the simultaneous ignition of volatile matter and solid surfaces. Crelling et al 8 considered two main reactive events taking place during coal combustion, named primary and secondary combustion. The first takes account of the combined devolatilization and simultaneous fixed carbon combustion, while the second takes account of the following fixed carbon combustion alone.…”

Analysis on the Governing Reactions in Coal Oxidation at Temperatures up to 400°C

“…The TG curve obtained under aerial atmosphere was analyzed using the parameters defined by Crelling et al [5], with three characteristic temperatures found below 400˚C. Given the fluctuation of the derivative TG (DTG) data at temperatures between 120˚C and 170˚C, the parameter T 1 falls between 130.1˚C and 168.0˚C, whereas the parameters T 2 and T 3 are evaluated at 238.4˚C and 276.2˚C, respectively.…”

“…Crelling and coworkers [5] monitored the temperature-dependent mass change of a series of coals oxidized in the aerial atmosphere, and then suggested several temperature parameters to describe the profile of the TG curves collected. The parameters below 400˚C include "temperature of initial chemisorptions" T 1 , "temperature of maximum rate of chemisorptions" T 2 , and "temperature of combustion onset" T 3 .…”