Zhao Wanting, Dong Ziwen, Wu Xian, Kong Song, Yang Yue, Zhang Zhenya, Yin Feifei, Sun Chuanwen
School of Safety Engineering, Ningbo University of Technology, Ningbo, Zhejiang 315211, China.
School of Safety Science and Engineering, Liaoning Technical University, Fuxin, Liaoning 123000, China.
ACS Omega. 2024 Nov 6;9(46):46224-46236. doi: 10.1021/acsomega.4c06945. eCollection 2024 Nov 19.
Primary and secondary low-temperature oxidation experiments were conducted on lignite immersed in water for short (50 days) and long (200 days) periods under three different oxygen concentrations (8, 18, and 21%), which provided a theoretical basis for the identification and risk judgment of a spontaneous combustion zone in goaf. The results indicate that in both the short-term water-immersed coal (STWIC) and long-term water-immersed coal (LTWIC), the apparent activation energy (Ea) for the three stages of secondary oxidation is lower than that for primary oxidation under 18% oxygen concentration, suggesting a greater risk of spontaneous combustion. The STWIC and LTWIC that have experienced a primary oxidation in the goaf are more prone to secondary oxidation spontaneous combustion when the oxygen concentration is 8 and 18%, while the risk of secondary oxidation spontaneous combustion is lower than that of primary oxidation at 21%. During the experimentation, a temperature inflection point was observed, which decreased with an increase in the oxygen concentration conditions. Beyond this temperature inflection point, the oxygen consumption rate and heat release intensity during the primary oxidation of STWIC surpassed those during secondary oxidation. Moreover, the generation rates of CO and CO during the secondary low-temperature oxidation process of LTWIC were lower than those of STWIC.
在三种不同氧气浓度（8%、18%和21%）下，对短期（50天）和长期（200天）浸泡在水中的褐煤进行了一次和二次低温氧化实验，为采空区自燃带的识别和风险判断提供了理论依据。结果表明，在18%氧气浓度下，短期水浸煤（STWIC）和长期水浸煤（LTWIC）二次氧化三个阶段的表观活化能（Ea）均低于一次氧化，表明自燃风险更大。采空区经历过一次氧化的STWIC和LTWIC，在氧气浓度为8%和18%时更易发生二次氧化自燃，而在21%时二次氧化自燃风险低于一次氧化。实验过程中观察到一个温度拐点，该拐点随氧气浓度条件的增加而降低。超过该温度拐点后，STWIC一次氧化过程中的氧气消耗率和放热强度超过二次氧化。此外，LTWIC二次低温氧化过程中CO和CO的生成速率低于STWIC。
