The effect of N2/CO2 blend ratios on the pyrolysis and combustion behaviors of coal particles: Kinetic and thermodynamic analyses

The aim of this work is to investigate the impact of various CO2/N2 ratios on coal pyrolysis and combustion properties and to provide theoretical guidance for better preventing and controlling coal spontaneous combustion in the goaf. The dynamic pyrolysis and combustion characteristics of DX coal were analyzed by using a thermal gravimetric analyzer (TGA) in a constant oxygen atmosphere with different CO2/N2 blend ratios. The M & PRIME;alek method combining Coats-Redfern and Achar methods was used to determine the most probable mechanism functions. CO2 containing atmospheres increased characteristic temperatures, burnout rate, maximum mass loss rate and comprehensive combustion performance index compared to O2/N2 atmospheres. In stages I-III, a lower apparent activation energy was observed in O2/CO2 atmospheres. Apparent activation energy and enthalpy changes showed upward trends in the reaction stage (I & RARR;III & RARR;IV), whereas Gibbs free energy change and entropy change decreased. The dynamic pyrolysis and combustion of DX coal necessitated increased energy in environment with a CO2/N2 ratio of 4:6, revealing the optimal inhibitory effect on DX coal with this particular ratio.