Research on Self-Ignition Characteristics and Prediction Indices of Pulverized Low-Rank Coal Under Different Oxygen Concentrations

Self-ignition frequently takes place during transportation, storage, and application of low-rank coal dust, which may engender severe hazard issues. Grasping the self-ignition features of pulverized coal with a low maturity degree and effects of the thermostatic environment is indispensable for forestalling fires and explosions. Both minimum ignition temperature (MIT) and ignition delay time (t(i)) are beneficial for estimating the self-ignition difficulty of accumulated pulverized coal. Accordingly, this study explored both pulverized coal samples of low rank and tested them by a hot oven device under various limited oxygen concentration (X-O2) conditions ( <= 21 vol%). The results revealed that the MIT of the Yanzhou (YZ) sample was higher than that of the Zhangjiamao (ZJM) sample under the same X-O2 condition. Furthermore, an increase in ambient temperature markedly curtailed the The MITs were all increased by roughly 50 degrees C for the two samples when the X-O2 decreased from 21 to 5 vol%. The CO and C(2)H(4 )production, along with oxygen consumption rates, increased first and then tended to be stable with the extension of reaction time. The analysis result of the gas ratio suggested that the CO/CO2 and C2H4/C2H6 ratios could be considered as secondary indices for the prevention and control of pulverized coal self-ignition. Furthermore, with the decrease in the X-O2, both the apparent activation energies and pre-exponential factors of the two samples all showed a stage increase propensity. The reaction rates of the two samples decreased dramatically when the X-O2 decreased from 21 to 5 vol%. These results suggested that reducing X-O2, is an effective means for the prevention of pulverized coal self-ignition.

Automated summary

Self-ignition of low-rank coal dust during transportation, storage, and application is a common problem that can lead to severe hazards. Understanding the self-ignition characteristics and the effect of thermal conditions is crucial for preventing fires and explosions. Minimum ignition temperature and ignition delay time are useful parameters for estimating the self-ignition difficulty of accumulated coal dust.