基于指标气体法对水浸煤的氧化特性研究

Research on oxidation characteristics of aqueous coal based on index gas method

为研究水分对煤氧化特性的影响,通过煤自然发火试验确定能预报煤自燃的复合气体指标,然后采用程序升温试验测试不同含水率煤样氧化过程中复合气体指标的变化,研究在水分的影响下所产生复合气体指标的变化规律,同时探讨煤样的含水率对煤氧化特性的影响规律和作用机制。研究结果表明:煤自然发火温度与φ(CO)/φ(CH_(4))、φ(C_(2)H_(6))/φ(CO)、φ(CO)/φ(CO_(2))以及Graham指数有明显关系。含水率对煤氧化升温过程中的影响在不同温度呈现出不同的阶段特征:在30~120℃时,水分对煤氧反应既有催化作用,也有抑制作用,而抑制作用占主导地位,表现出抑制作用最好的含水率为20%;在120~140℃时,水分对煤氧化反应的抑制作用减少,且水分作为反应物参与到煤氧反应中进而表现出水分对煤氧化的促进作用,此时水分对煤氧反应以化学促进为主,促进效果最好的含水率为10%;在120~140℃时,则由于水分蒸发使得煤样的原有孔隙体积增大并且产生了新的微小孔隙,变得更有利于煤氧化反应的发生,进而表现出对反应的间接促进作用,促进效果最好的含水率为15%。最终确定在水分的影响下,可以较为准确预报煤自燃的复合气体指标为φ(CO)/φ(CH_(4))、φ(C_(2)H_(6))/φ(CO)和Graham指数。研究结果可丰富现场实际煤自燃的参数指标,增加高湿度煤层的开采安全性和自燃预测的准确性,有效地减少和预防煤自燃事故的发生。

To research the influence of moisture on the oxidation characteristics of coal,the coal spontaneous combustion experiment was carried out to determine the composite index gas that can predict the spontaneous combustion of coal,and then the temperature-programing experiments were carried out to test the changes of composite gas index during the oxidation process of coal samples with different moisture content,the change law of the composite gas index generated under the influence of moisture was researched,and the influence law and mechanism of coal sample moisture content on coal oxidation characteristics were discussed.The results of research show that the spontaneous combustion temperature of coal has an obvious relationship with CO/CH_(4),C_(2)H_(6)/CO,CO/CO_(2) and Graham index.The influence moisture content on the temperature rise process of coal oxidation presents different stage characteristics at different temperatures:at 30-120℃,moisture has both catalytic and inhibitory effects on the coal oxidation reaction,and the inhibitory effect is dominant,showing the moisture content with the best inhibitory effect is 20%;at 120-140℃,the inhibitory effect of moisture on coal oxidation reaction is reduced,and moisture participates in the coal oxidation reaction as a reactant,and then shows the promotion effect of moisture on coal oxidation.At this time,the moisture in the coal oxidation reaction is mainly chemically promoted,and the moisture content with the best promotion effect is 10%;at 120-140℃,the original pore volume of the coal sample increases due to the evaporation of water and new coal samples are produced.The tiny pores become more conducive to the occurrence of coal oxidation reaction,and then show an indirect pro motion effect on the reaction.The moisture content with the best promotion effect is 15%.It was finally determined that under the influence of moisture,the composite index gas that can more accurately predict the spontaneous combustion of coal are CO/CH_(4),C_(2)H_(6)/CO and Graham index.The research results can enrich the parameters of actual coal spontaneous combustion on site,increase the mining safety of high-humidity coal seams and the accuracy of spontaneous combustion prediction,and effectively reduce and prevent the occurrence of coal spontaneous combustion accidents.