Experimental study on thermal decomposition and kinetic characteristics of coal in O2/CO2/N2 atmospheres with various CO2/N2 blend ratios

This study explores the inhibitory mechanisms of CO 2 /N 2 ratios and O 2 concentrations on coal oxidative pyrolysis to provide theoretical insights into the use of CO 2 -N 2 mixed inert gas in goaf fire prevention. Thermogravimetric analysis (TGA) was employed to investigate coal pyrolysis under varying coal metamorphism, heating rates, O 2 concentrations, and CO 2 /N 2 ratios. Results show that increasing the heating rate raises characteristic temperatures and enhances the oxidative pyrolysis in DX coal. The apparent activation energies of DX, TX, and YCW coals exhibit an initial increase followed by a decrease as conversion rates rise, peaking at 0.15 conversion. At a constant O 2 concentration, the apparent activation energy is highest when the CO 2 /N 2 ratio is 4:6, suggesting more energy is required and oxidation is more effectively inhibited. Conversely, increasing O 2 concentration leads to a linear decrease in the apparent activation energies, indicating enhanced coal oxidative pyrolysis.