Ren Lifeng, Li Qingwei, Deng Jun, Ma Li, Xiao Yang, Zhai Xiaowei, Hao Jianchi
Xi'an University of Science and Technology, 58, Yanta Mid. Road, Xi'an 710054, Shaanxi, PR China.
Post-doctoral Research Center of Mining Engineering, Xi'an University of Science and Technology, 58, Yanta Mid. Road, Xi'an 710054, Shaanxi, PR China.
ACS Omega. 2021 Sep 27;6(40):26170-26179. doi: 10.1021/acsomega.1c03160. eCollection 2021 Oct 12.
Spontaneous combustion of pulverized coal has become a safety topic and has been extensively researched. This study using differential scanning calorimetry investigated the exothermic characteristics and spontaneous combustion risk of three metamorphic pulverized coal samples during oxidative combustion, for oxygen concentrations of 21, 19, 17, 15, 13, 11, 9, 7, and 5 vol %. Results indicated that decreased oxygen concentrations reduced exothermic intensity and substantially increased ignition temperatures. The oxidative thermal release observed during the combustion stage was conspicuously higher than during the low-temperature oxidation stage. Thermal release during low-temperature oxidation was low during low oxygen concentrations; however, when the oxygen concentration was less than 13.0 vol.%, it had a considerable influence on exothermic combustion. When the oxygen level was lowered from 21.0 to 5.0 vol %, spontaneous combustion risk indexes lessened from 2.07 (sample A), 1.85 (sample B), and 0.81 [J/(mg min °C)] (sample C) to 1.08 (sample A), 1.13 (sample B), and 0.40 [J/(mg min °C)] (sample C), respectively. Both apparent activation energy and spontaneous combustion risk indexes of the samples decreased saliently as oxygen concentration decreased. Thus, reducing oxygen concentration would be an effective method of inhibiting or possibly even preventing the spontaneous combustion of pulverized coal.
煤粉自燃已成为一个安全课题并得到了广泛研究。本研究采用差示扫描量热法，研究了三种变质煤粉样品在氧化燃烧过程中，氧气浓度分别为21、19、17、15、13、11、9、7和5体积%时的放热特性和自燃风险。结果表明，氧气浓度降低会降低放热强度并显著提高着火温度。燃烧阶段观察到的氧化热释放明显高于低温氧化阶段。在低氧浓度下，低温氧化过程中的热释放较低；然而，当氧气浓度低于13.0体积%时，它对放热燃烧有相当大的影响。当氧气水平从21.0体积%降至5.0体积%时，自燃风险指数分别从2.07（样品A）、1.85（样品B）和0.81[焦/(毫克·分钟·摄氏度)]（样品C）降至1.08（样品A）、1.13（样品B）和0.40[焦/(毫克·分钟·摄氏度)]（样品C）。随着氧气浓度降低，样品的表观活化能和自燃风险指数均显著降低。因此，降低氧气浓度将是抑制甚至可能防止煤粉自燃的有效方法。
