Comparison of bituminous coal apparent activation energy in different heating rates and oxygen concentrations based on thermo gravimetric analysis

Simultaneous thermal analysis (STA) experiments are carried on to study the relationship between the coal apparent activation energy and the heating rate as well as the oxygen concentration, respectively. Bituminous coal samples are analyzed using the simultaneous thermal analyzer. Experimental condition involves two aspects: different heating rates (2, 5, 10, 20 and 30 °C min−1) and different oxygen concentrations (5, 10, 15, 21 and 30%). A mixture of oxygen and nitrogen flows through the coal sample. Characteristic points at different temperatures are obtained; Coats–Redfern integral method is utilized to calculate the apparent activation energy in different experimental conditions. The results indicate that the variation of apparent activation energy in different heating rates follows the exponential function mathematically, which falls in order as the heating rate increases. The apparent activation energy of coal increases in order as the oxygen concentration increases, and the variation of apparent activation energy in different oxygen concentrations follows the logarithmic function mathematically.