Yu Ruirui, Dong Ziwen, Zhao Wanting, Zhu Peitao, Kong Song, Zhang Zhenya
School of Materials and Chemical Engineering/School of Safety Engineering, Ningbo University of Technology, Ningbo, 315211, Zhejiang, China.
Zhejiang Institute of Tianjin University, Tianjin University, NiBo, 315211, China.
Sci Rep. 2025 Jan 2;15(1):510. doi: 10.1038/s41598-024-84345-9.
To further elucidate the variations of secondary oxidation spontaneous combustion risk of lignite under different air flows and immersion time. Secondary oxidation experiments of short-term water-immersed coal and long-term water-immersed coal were conducted under four air flows. The results show that, the presence of a temperature inflection point during primary oxidation process, when coal temperature exceeds it, both the oxygen consumption rate and heat release intensity of long-term water-immersed coal are lower, furthermore, decrease in air flow leads to reduction in the temperature inflection point. The oxygen consumption rate and heat release intensity during the primary oxidation process exceed those observed during the subsequent secondary oxidation process. In the secondary oxidation process, long-term water-immersed coal exhibits higher rates of oxygen consumption and heat release intensity compared to short-term water-immersed coal. Additionally, the oxygen-consuming activation energy for oxygen consumption of long-term water-immersed coal is lower. The increase in air flow and water immersion time generally leads to the extreme value of the limit parameters, such as the local maximum of minimal thickness of residual coal and the lower limit oxygen fraction, the local minimum of the maximal air leakage intensity develops in the direction of increasing the risk of spontaneous combustion of coal in goaf.
为进一步阐明不同风流和浸水时间下褐煤二次氧化自燃危险性的变化规律，对短期浸水煤样和长期浸水煤样在四种风流条件下进行了二次氧化实验。结果表明，原煤氧化过程存在温度拐点，超过该拐点后，长期浸水煤样的耗氧速率和放热强度均降低，且风流减小导致温度拐点降低。原煤氧化过程中的耗氧速率和放热强度均高于后续二次氧化过程。二次氧化过程中，长期浸水煤样的耗氧速率和放热强度高于短期浸水煤样。此外，长期浸水煤样的耗氧活化能较低。风流和浸水时间增加一般导致极限参数的极值，如残余煤最小厚度局部最大值、下限氧浓度，最大漏风强度局部最小值，向着采空区煤炭自燃危险性增大的方向发展。
