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不同浓度氯盐抑制煤自燃特性研究与评价

Research and evaluation on the inhibition of coal spontaneous combustion characteristics by different concentrations of chloride salts

  • 摘要: 煤自燃灾害严重威胁矿井安全生产,喷洒阻化剂技术在矿井火灾治理中发挥了重要作用,其中氯盐是矿井煤自燃阻化防控中较为普遍使用的阻化剂。为研究不同浓度卤盐及氯化钠对煤自燃的阻化特性,并依据阻化性能指标评价优选阻化剂。采用程序升温-气相色谱及同步热分析试验分析了煤样在不同浓度卤盐及氯化钠作用下,煤自燃过程中不同温度阶段预测指标、特征温度、表观活化能等参数变化规律;结合氧化反应热动力学特性,探讨氯盐阻化剂的阻化机理;并采用熵权法评价优选阻化剂。研究结果表明:30%卤盐或20%氯化钠在煤自燃氧化30~80 ℃阶段的预测指标V(O2):V(CO+CO2)最高;在80~200 ℃阶段各阻化煤样首次产生CH4指标气体的温度点均有推迟,且产生量较原煤减少;只有40%卤盐在200~240 ℃阶段的预测指标V(CO2):V(CO)低于原煤;卤盐及氯化钠阻化煤样的着火点温度较原煤分别提高23~31 ℃和7~15 ℃;而且有效提高煤体的表观活化能,降低了煤自燃倾向性;卤盐或氯化钠在煤体表面吸收空气中水分形成具有隔绝氧气和吸热降温作用的液膜,并与煤分子发生化学反应,延缓煤氧复合反应进程;采用熵权法对各阻化指标进行赋权评价,30%卤盐或20%氯化钠的综合评价值高于其他浓度同类阻化剂。优选获得30%卤盐或20%氯化钠在同类型阻化剂中综合阻化性能最佳。

     

    Abstract: Coal spontaneous combustion disaster seriously threatens mine safety production. Spraying inhibitor technology plays an important role in mine fire control. Chlorine salt is a commonly used inhibitor in mine coal spontaneous combustion prevention and control. In order to study the inhibition characteristics of different concentrations of halogen salt and sodium chloride on coal spontaneous combustion, and to evaluate and optimize the inhibitor according to the inhibition performance index. The temperature programmed-gas chromatography and synchronous thermal analysis experiments were used to analyze the variation of parameters such as prediction index, characteristic temperature and apparent activation energy of different temperature stages in the process of coal spontaneous combustion under the action of different concentrations of halogen salt and sodium chloride. Combined with the thermodynamic characteristics of oxidation reaction, the inhibition mechanism of chloride inhibitor was discussed. The entropy weight method was used to evaluate and optimize the inhibitor. The results show that the prediction index V ( O2 ) : V ( CO + CO2 ) of 30% halogen salt or 20% sodium chloride in the 30~80 ℃ stage of coal spontaneous combustion oxidation is the highest. In the stage of 80~200 ℃, the temperature point of the first CH4 gas index produced by each coal sample is delayed, and the amount of CH4 gas produced is less than that of raw coal. Only the prediction index V ( CO2 ) : V ( CO ) of 40% halogen salt in 200~240 ℃ stage is lower than that of raw coal ; the ignition temperature of coal samples with halogen salt and sodium chloride is 23~31 ℃ and 7~15 ℃ higher than that of raw coal, respectively. Moreover, it effectively improves the apparent activation energy of coal and reduces the tendency of coal spontaneous combustion. Halogen salt or sodium chloride absorbs water in the air on the surface of coal to form a liquid film with the function of isolating oxygen and endothermic cooling, and reacts with coal molecules to delay the process of coal-oxygen composite reaction.The comprehensive evaluation value of 30% halogen salt or 20% sodium chloride is higher than that of other concentrations of similar inhibitors. The comprehensive inhibition performance of 30% halogen salt or 20% sodium chloride in the same type of inhibitor is the best.

     

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