Effect of oxygen concentration on low-temperature exothermic oxidation of pulverized coal

Low-temperature exothermic oxidation characteristics of pulverized sub-bituminous coal was investigated using differential scanning calorimetry system in atmospheres where the oxygen concentrations were 21, 17, 13, 9, and 5 vol. %, respectively. The results indicate that the heat flow gradually decreases after it reaches the maximum value. A decreased oxygen concentration had a delaying effect on the heat flow and derivative of heat flow curves. A low oxygen concentration has typical stage characteristics for inhibiting the exothermic oxidation of pulverized coal. The oxygen concentration has a significant influence on the kinetics characteristics and kinetics parameters. The apparent activation energy increased under different oxygen concentrations with an increase in the conversion rate. The apparent activation energy was less than that in the low oxygen concentration under a high oxygen concentration. When the oxygen concentration less than 9%, the activation energy increases significantly.