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刘 垚,王福生,董轩萌,等. 基于程序升温试验的煤自燃特性及微观机理研究[J]. 煤炭科学技术,2024,52(S1):1−13. doi: 10.13199/j.cnki.cst.2023-0567
引用本文: 刘 垚,王福生,董轩萌,等. 基于程序升温试验的煤自燃特性及微观机理研究[J]. 煤炭科学技术,2024,52(S1):1−13. doi: 10.13199/j.cnki.cst.2023-0567
LIU Yao,WANG Fusheng,DONG Xuanmeng,et al. Study on the characteristics and microscopic mechanism of coal spontaneous combustion based on programmed heating experiment[J]. Coal Science and Technology,2024,52(S1):1−13. doi: 10.13199/j.cnki.cst.2023-0567
Citation: LIU Yao,WANG Fusheng,DONG Xuanmeng,et al. Study on the characteristics and microscopic mechanism of coal spontaneous combustion based on programmed heating experiment[J]. Coal Science and Technology,2024,52(S1):1−13. doi: 10.13199/j.cnki.cst.2023-0567

基于程序升温试验的煤自燃特性及微观机理研究

Study on the characteristics and microscopic mechanism of coal spontaneous combustion based on programmed heating experiment

  • 摘要: 针对煤在变氧条件下氧化自燃能力不同这一情况,选取褐煤、气煤、肥煤3种不同变质程度的煤作为试验样品开展了氧气体积分数为3%、5%、10%、14%、18%条件下的程序升温−气相色谱试验和基于ReaxFF力场的分子动力学模拟,根据CO、CO2等的生成规律和路径,探究不同变质程度煤在变氧条件下基团受氧气影响的变化特征。结果表明:煤受温度和氧气影响容易产生CO、CO2等指标气体,且指标气体CO、CO2呈指数上升趋势,煤的变质程度越低,在相同氧气体积分数条件下产生指标气体的温度就越低。模拟结果显示,变氧条件下煤与氧的反应可能是氧与煤受温度影响产生的活性中间体片段反应,而不是直接攻击煤的主体结构。煤在受温度影响后煤结构基团并不是直接发生改变,而是经历结构调整进行键的扭转、断裂和原子上的转变生成适合与氧气反应的活性中间体片段。变质程度越高的煤分子结构越稳定越不易受温度的影响产生活性中间体片段,通入氧气后氧与活性中间体反应的速度低于煤受温度影响产生活性中间体的速度,所以变氧条件下氧一般是与活性中间体反应生成水、CO等指标气体,而不是直接与煤主体结构反应。综合分析试验结果与模拟结果发现:褐煤在氧气体积分数处于3%、气煤在氧气体积分数处于10%~14%、肥煤在氧气体积分数处于14%~18%时,水和含氧气体的数量相较于其他阶段明显增加,说明在氧含量较低的区间内这3种不同变质程度的煤受氧气影响较大,加速了煤氧化反应进程,煤自燃倾向性高。

     

    Abstract: For the situation that coal is still capable of oxidative spontaneous combustion under different oxygen conditions, we choose three coals with different metamorphic degrees: lignite, gas coal and fatty coal, selected as experimental samples to carry out programmed temperature gas chromatography(TPGC) experiments and molecular dynamics simulations based on ReaxFF force fields at oxygen concentrations of 3%, 5%, 10%, 14% and 18%, to investigate the characteristics of changes in the oxygen influence of groups under oxygen-poor conditions in coals with different degrees of metamorphosis according to the production patterns and pathways of CO and CO2, etc. The results show that coal is easily affected by temperature and oxygen to produce indicator gases such as CO and CO2, and when the indicator gas tends to increase exponentially, the lower the degree of coal deterioration and the lower the temperature at which the indicator gas is produced at the same oxygen concentration. The simulations show that the reaction of coal with oxygen under oxygen-poor conditions is likely to be an active intermediate fragment reaction between oxygen and coal affected by temperature, rather than a direct attack on the main structure of the coal. The coal structural groups are not directly altered when the coal is subjected to temperature, but undergo structural adjustments for bond twisting, breaking and atomic transformations to produce reactive intermediate fragments suitable for reaction with oxygen. The higher the degree of metamorphosis, the more stable the molecular structure of the coal and the less likely it is to be affected by temperature to produce reactive intermediate fragments, and when oxygen is introduced, the rate of reaction of oxygen with the reactive intermediate is lower than the rate at which the coal is affected by temperature to produce the reactive intermediate, therefore, oxygen under depleted conditions is generally reacted with reactive intermediates to produce indicator gases such as water, CO, rather than with the main structure of the coal among them. A combination of experimental and simulation analysis reveals that the amount of water and oxygen containing gases increases significantly at 3%-5% oxygen concentration for lignite, 10%-14% oxygen concentration for gas coal and 14%-18% oxygen concentration for fat coal compared to the other stages, indicating that these three coals with different degrees of deterioration are more affected by oxygen in this oxygen-poor concentration range and accelerated the process of coal oxidation reaction.

     

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