Search

Liquid carbon dioxide has an excellent ability of endothermic cooling and inhibition on coal fire, which was an effective coal spontaneous combustion prevention technology. To analyze the oxidation characteristics and variation of apparent activation energies, a carboniferous–permian coal sample was investigated in O2/N2 and O2/CO2 atmospheres by the coal spontaneous combustion oxidation and the Fourier transform infrared spectroscopy experiments. The results indicated that with temperature, carbon monoxide (CO) concentration and oxygen (O2) consumption rate increased. While O2 concentration decreased, CO concentration and oxygen consumption rate reduced. At the same O2 concentration, the oxygen consumption rate and CO concentration on the O2/CO2 atmospheres were less than on the O2/N2 atmospheres. Therefore, O2 concentration reduced, or added CO2 significantly inhibited coal oxidation. As the temperature elevated, the apparent activation energy gradually increased. Furthermore, the apparent activation energy increased when the oxygen concentration reduced in the physical–chemical adsorption stage and the slow oxidation stage. In the rapid oxidation stage, the apparent activation energy lessened with increase in oxygen concentration. Through correlation analysis, the key functional groups in the physical–chemical adsorption stage were hydroxyl, C–O, –COO–, and aliphatic hydrocarbons. During the slow oxidation, the key functional groups were –COO– and aliphatic hydrocarbons. The key functional groups in the rapid oxidation stage were hydroxyl and C–O. [ABSTRACT FROM AUTHOR]

A thermal analysis experiment was conducted in O 2 /N 2 /CO 2 and O 2 /N 2 atmospheres (O 2 concentrations were 21, 14, 8, and CO 2 concentrations were 0, 39, 46, 52) to investigate the thermal behavior of coal oxidation and combustion. Results demonstrated that an elevated CO 2 concentration or decreased O 2 concentration had a delaying effect on the thermogravimetric analysis and differential scanning calorimetry (DSC) curves; moreover, the characteristic temperatures were substantially augmented. When the O 2 concentration was 21 vol%, the total heat released by coals A (highly volatile bituminous coal) and B (anthracite coal) decreased by 5.8% and 4.1%, respectively, after CO 2 addition. The comprehensive combustion performance index was also lowered. The DSC curve can be divided into two exothermic peaks, and the ratio of the peak 1 to peak 2 areas decreased with the addition of CO 2, which indicated that CO 2 inhibited the oxidation of the active functional groups of coal structures. Apparent activation energy in O 2 /CO 2 /N 2 was less than that in O 2 /N 2 ., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)