Experimental Research on Combustion, Pyrolysis Characteristics, and Kinetics of Three Different Coal Samples in China

Coal thermal and kinetic parameters are important for the design of combustion reactors and risk assessment. Two methods were employed to investigate such key parameters of lignite, bituminous, and anthracite coal samples from China. With thermogravimetry (TG) and differential scanning calorimetry (DSC) methods, two distinct transitional stages were found in all coal samples combustion, but reaction intervals shifted to higher temperatures from lignite to anthracite and varied between 317 and 665 °C depending on the sample nature. Compared to the other two coal types, the pyrolysis of anthracite was less sensitive to increasing temperature, and its combustion process occurred at a much higher temperature. The results indicated that anthracite is difficult to ignite but has a considerable heat of reaction of 22.6 kJ/kg if ignited, which is close to that of bituminous. The basket heating method was used to obtain the kinetic data. Sample activation energies varied in the ranges of 38-51 kJ/mol from TG analysis and 49-67 kJ/mol from basket heating tests. Both results were comparable and consistent with the reference data. Due to its higher activation energy, anthracite poses a lower risk of thermal runaway than other coal types. This conclusion was validated by performing a minimum ignition temperature determination of a dust layer (MITL). In contrast, lignite and bituminous should be handled with greater safety precautions in coal-related process industries. The data presented will be used for hazard analysis and for designing more efficient combustion reactors in power plants. The data collected led to an extension of the current data for coal dust, as found in the literature.