Experimental study on microscopic action of different form moisture on coal spontaneous combustion
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摘要: 制备不同外在水分和原始赋存水分含量的煤体，通过模拟煤自燃升温氧化过程得到不同温度下的氧化煤样；利用原位傅里叶红外变换光谱仪测定不同氧化煤样中活性官能团的含量，研究形态水分对煤自燃过程微观官能团生成和转化的影响；利用氮吸附仪表征不同氧化煤样中比表面积大小，研究形态水分对煤自燃过程微观孔结构变化的影响；同时结合官能团与比表面积的变化规律，探讨形态水分对煤自燃过程的微观作用机制。形态水分对煤自燃过程的作用机制随着煤自燃状态发展而发生变化，表现出阶段性特征。外来水分含量和原始赋存水分都会促进酚、醇类羟基及含羧基类化合物的生成。外来水分和原始赋存水分的含量对煤自燃过程中微观比表面积、脂肪族C−H组分、含羟基化合物以及含羰基类化合物的生成和转化影响具有差异性；水分形态对微观比表面积和脂肪族C−H组分含量的变化影响具有差异性，而对含羟基化合物以及羧基化合物的生成和转化具有相似性。Abstract: Moisture is one of the important factors affecting coal spontaneous combustion. Coal with different moisture contents was prepared to obtain oxidized coal samples at different temperatures through temperature programming. In situ Fourier Transform Spectrometer was used to determine content of active functional groups in different oxidized coal samples, and to study influence of moisture form on formation and transformation of microscopic functional groups during coal spontaneous combustion. Nitrogen adsorber was used to study specific surface area of different oxidized coal samples and influence of form moisture on changes of micro-pore structure during coal spontaneous combustion. Combined with the change law of functional groups and specific surface area, microscopic action of different form moisture on coal spontaneous combustion process was discussed. The action regime of outside moisture varies with the development of coal spontaneous combustion. Different forms of moisture can promote formation of phenols, alcohols, hydroxyl groups, and carbonyl-containing compounds. Effects of moisture form and its content on change of micro-specific surface area, and on evolution of aliphatic C−H components, hydroxyl-containing compounds and carbonyl-containing compounds during spontaneous combustion of coal are different. While effect of moisture form and its content on formation and transformation of hydroxyl-containing compounds and carboxylic acid compounds are similar.
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Key words:
- coal spontaneous combustion /
- form moisture /
- microstructure /
- action mechanism
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图 1 程序升温氧化装置示意图
Figure 1 Schematic diagram of temperature-programmed oxidation device
1 : air; 2 : nitrogen; 3 : mass flowmeter; 4 : heating device;5 : preheating gas circuit; 6 : thermocouple in coal sample;7 : outlet pipeline; 8 : thermocouple in device; 9 : gas filter; 10 : air generator; 11 : hydrogen generator; 12 : GC;13 : computer; 14 : argon
图 2 原始赋存水分含量褐煤与外来水含量长焰煤在不同氧化温度下的红外光谱谱图
Figure 2 FT-IR spectra of candle coals with an initial inherent water content and lignite coal with external water content under different oxidation temperatures
(a) : XM 30 ℃; (b) : SD 30 ℃; (c) : XM 110 ℃; (d) : SD 110 ℃; (e) : XM 180 ℃; (f) : SD 180 ℃
图 3 不同含水煤体在煤自燃过程中羟基变化
(a): XM free hydroxyl; (b): SD free hydroxyl; (c): XM hydrogen bond association; (d): SD hydrogen bond association; (e): XM OH of alcohol-phenol; (f): SD OH of alcohol-phenol
Figure 3 Change trends of hydroxyl groups in coal samples with different water contents during the spontaneous combustion of coals
图 4 不同含水煤体在煤自燃过程中脂肪族C−H变化
Figure 4 Fatty-group C−H change trends of coals with different water contents during the spontaneous combustion of coals
(a) : XM methyl −CH3; (b) : SD methyl −CH3; (c) : XM methylene CH2; (d) : SD methylene CH2; (e) : XM methyne CH; (f) : SD HM methyne CH
图 5 不同含水煤体煤自燃过程中含C=O类化合物变化
Figure 5 Change trends of C=O compounds of coals with different water contents during the spontaneous combustion of coal
(a) : XM lipid compounds; (b) : SD lipid compounds; (c) : XM carboxylic acid compounds; (d) : SD carboxylic acid compounds; (e) : XM carbonyl compounds; (f) : SD carbonyl compounds
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