Temperature-Programmed Oxidation Experiments on Typical Bituminous Coal Under Inert Conditions

In this study, an experimental investigation was presented on the oxidation behaviors of bituminous coal for different inert gases (N₂ and CO₂) at different concentrations (oxygen concentration indexes 21%, 18.4%, 15.8%, and 13.1%) using a temperature-programmed experimental device. The purpose of this research was to examine the oxidation patterns of bituminous coal under different inert conditions. The results showed that: (1) the oxidative heating of the coal underwent two stages: an initial slow heating stage and a fast heating stage. The injection of both inert gases would result in a delay in the crossing point temperature (CPT) of the coal, but the injection of N₂ resulted in greater delays in the CPT of the coal; (2) the injection of both N₂ and CO₂ inhibited the concentrations of CO and alkane/olefin gases produced from the oxidative heating of the coal, with CO₂ displaying higher inhibition efficiencies than that of N₂; (3) Under a non-inerting environment, the C₂H₄ and C₂H₆ generation temperatures were 110 °C and 100 °C. Under an inerting environment, when N₂ was injected, the higher the N₂ concentration, the higher the initial C₂H₄ and C₂H₆ generation temperatures; when CO₂ was injected, the higher the CO₂ concentration, the lower the initial C₂H₄ and C₂H₆ generation temperatures; and (4) under a non-inerting environment, the C₃H₈ generation temperature was 90 °C; and when an inert gas was injected, there was a hysteresis in the C₃H₈ generation temperature for all concentrations. The above research results can be used to predict the spontaneous combustion of residual coal in an inert environment and prevent fires.