Stage inhibition characteristics of composite inhibitor in process of inhibiting coal spontaneous combustion
JIANG Feng, SUN Wenqian, LI Zhenbao, LIANG Rui, LI Lei, LIANG Qiuyue
为解决单一阻化剂阻化效果弱、作用时间短的缺陷,基于2种物质不同阶段的阻化特性,选用碳酸氢钠作为物理阻化成分,高效抗氧化剂茶多酚作为化学阻化成分,开展复配阻化剂优选的实验研究。采用TG-DSC和FTIR实验,结合氧化动力学分析方法及分峰拟合技术,分析了复合阻化剂对煤氧化过程特性参数和微观基团的影响,从宏观和微观层面验证了复合阻化剂对煤自燃抑制的高效阻化效果,揭示其微观阻化机理。结果表明:阻化煤样的6个特征温度较原煤提高,质量损失减少,低温氧化过程煤体吸热量增加,高温阶段煤体放热量减少,可燃指数及综合燃烧指数均明显降低,阻化煤样在氧化过程4个阶段的表〖JP2〗观活化能均得到提高,分析得到复合阻化剂的优选质量配比(碳酸氢钠∶〖JP〗茶多酚=3∶1)。通过定量分析原煤及阻化煤样的活性官能团在氧化过程中的变化规律,得出复合阻化剂的添加减少了煤中的活性基团(羟基、甲基以及亚甲基)以及煤氧复合反应中间产物(羧基、羰基)的含量,稳定的官能团醚键的含量增加。在煤低温氧化过程中,碳酸氢钠热分解生成CO2,通过表面CO2-O2竞争吸附效应,物理惰化抑制煤自燃;煤在高温氧化过程中,茶多酚内部羟基消耗煤体表面活泼基团并生成醚键,通过中断化学反应进程起到抑制煤自燃的作用。
In order to solve the defects of weak inhibitory effect and short action time of single inhibitor, sodium bicarbonate was selected as physical inhibitory component and high-efficiency antioxidant tea polyphenol as chemical inhibitor based on the resistance characteristics of the two substances at different stages, and carried out experimental research on the optimization of composite inhibitor.Using TG-DSC and FTIR experiments, combined with oxidative kinetic analysis methods and peak fitting technology, the effects of composite chemicals on the characteristic parameters and microscopic groups of coal oxidation process were analyzed.The high efficiency inhibition effect of composite inhibitor on coal spontaneous combustion was verified from macro and micro aspects, and its micro inhibition mechanism was revealed. The results show that the six characteristic temperatures of the inhibited coal samples are higher than that of the raw coal, the mass loss is reduced, the heat absorption of coal increases in the low temperature oxidation process, the heat release of the coal body decreasesat the high temperature stage, and the flammability index and comprehensive combustion index are significantly reduced. The apparent activation energy of coal samples in the four stages of the oxidation process is improved, and the optimal ratio of composite inhibitor is obtained by analysis (sodium bicarbonate: tea polyphenol=3∶1). By quantitatively analyzing the change law of the active functional groups of the raw coal and the inhibitory coal samples during the oxidation process, it is concluded that the addition of the composite inhibitor reduces the active groups (hydroxyl, methyl and methylene) in the coal and the coal-oxygen complex. The content of reaction intermediates (carboxyl group, carbonyl group) and the content of stable functional group ether bondsalso increase. In the process of coal oxidation at low temperature, sodium bicarbonate thermally decomposes to form CO2, which achieved physical inerting and inhibited coal spontaneous combustion through the competitive adsorption effect of CO2-O2 on the surface. In the process of coal combustion at high temperatures, hydroxyl groups in tea polyphenols consume active groups on the surface of coal and form ether bonds, which can inhibit the spontaneous combustion of coal by interrupting the chemical reaction process.
coal spontaneous combustion; composite inhibitor; oxidation characteristics; apparent activation energy; functional group; inhibition characteristics
主办单位:煤炭科学研究总院有限公司 中国煤炭学会学术期刊工作委员会