Combustion studies by thermogravimetric analysis: 2. Char oxidation

Abstract

The non-isothermal oxidation of coal chars was investigated by conventional thermogravimetric analysis (t.g.a.) over the temperature range 450–650 °C. For chars, produced by flame pyrolysis of pulverized low rank bituminous coals, three different components i.e. vitrinite-char, inertinite-char and soot, can be distinguished from one another by characteristic reactivity differences. Quantitative use of these differences has detected maceral segregation between different sized char fractions, and has demonstrated that vitrinitechar burns faster than inertinite-char, when oxidized by another combustion technique at 1050–1250 °C. Characteristic temperatures obtained from t.g.a. burning profiles of chars correlate well with their oxidation rates measured at these higher temperatures. However, the latter rates cannot be reliably determined by simple extrapolation of Arrhenius plots of the t.g.a. data.