Citation: | LIU Yao,WANG Fusheng,DONG Xuanmeng,et al. Study on the characteristics and microscopic mechanism of coal spontaneouscombustion based on programmed heating experiment[J]. Coal Science and Technology,2024,52(S1):94−106. DOI: 10.13199/j.cnki.cst.2023-0567 |
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.
[1] |
曹凯. 复杂环境条件下煤自燃火灾治理技术[J]. 煤矿安全,2020,51(9):85−88.
CAO Kai. Coal spontaneous combustion fire control technology under complex environmental conditions[J]. Safety in Coal Mines,2020,51(9):85−88.
|
[2] |
郭军,蔡国斌,金彦,等. 煤自燃火灾防治技术研究进展及趋势[J]. 煤矿安全,2020,51(11):180−184.
GUO Jun,CAI Guobin,JIN Yan,et al. Research progress and trend of coal spontaneous combustion fire prevention technology[J]. Safety in Coal Mines,2020,51(11):180−184.
|
[3] |
刘俊,李洪生,赵训,等. 土城矿采空区自燃“三带”宽度的划定[J]. 煤矿安全,2019,50(3):193−195.
LIU Jun,LI Hongsheng,ZHAO Xun,et al. Delineation of the width of the "three zones" of spontaneous combustion in the goaf of Tucheng Mine [J]. Safety in Coal Mines,2019,50 (3):193−195.
|
[4] |
王坤. 短臂大采高综放工作面注氮防灭火工艺[J]. 煤矿安全,2020,51(3):137−143.
WANG Kun. Nitrogen injection fire prevention and extinguishing technology in fully mechanized caving face with short arm and large mining height [J]. Safety in Coal Mines,2020,51 (3):137−143.
|
[5] |
张群,李玉福,姚海飞,等. 贫氧条件下煤自燃特性实验研究[J]. 煤矿开采,2016,21(6):96−100.
ZHANG Qun,LI Yufu,YAO Haifei,et al. Experimental study on spontaneous combustion characteristics of coal under oxygen deficient conditions[J]. Coal Mining Technology,2016,21(6):96−100.
|
[6] |
郝长胜,袁迎春,贾廷贵,等. 不同变质程度煤的化学结构红外光谱研究[J]. 煤矿安全,2022,53(11):15−22.
HAO Changsheng,YUAN Yingchun,JIA Tinggui,et al. Infrared spectroscopic study of the chemical structure of coal with different metamorphic degrees[J]. Safety in Coal Mines,2022,53(11):15−22.
|
[7] |
HONG D,LIU L,WANG C,et al. Construction of a coal char model and its combustion and gasification characteristics:molecular dynamic simulations based on ReaxFF[J]. Fuel,2021,300:120972. doi: 10.1016/j.fuel.2021.120972
|
[8] |
XIAO Yang,ZENG J F,LIU J W,et al. Reactive force field (ReaxFF) molecular dynamics investigation of bituminous coal combustion under oxygen-deficient conditions[J]. Fuel,2022,318:123583. doi: 10.1016/j.fuel.2022.123583
|
[9] |
QIU Y,ZHONG W,YU A. The molecular dynamics simulation of lignite combustion process in O2/CO2 atmosphere with ReaxFF force field[J]. Powder Technology,2022,410:117837. doi: 10.1016/j.powtec.2022.117837
|
[10] |
WANG C P,DENG Y,XIAO Y,et al. Gas-heat characteristics and oxidation kinetics of coal spontaneous combustion in heating and decaying processes[J]. Energy,2022,250:123810. doi: 10.1016/j.energy.2022.123810
|
[11] |
CASTRO-MARCANO F,RUSSO J M F,VAN DUIN A C T,et al. Pyrolysis of a large-scale molecular model for Illinois no. 6 coal using the ReaxFF reactive force field[J]. Journal of Analytical and Applied Pyrolysis,2014,109:79−89. doi: 10.1016/j.jaap.2014.07.011
|
[12] |
BHIO S,BANERJEE T,MOHANTY K. Molecular dynamic simulation of spontaneous combustion and pyrolysis of brown coal using ReaxFF[J]. Fuel,2014,136:326−333. doi: 10.1016/j.fuel.2014.07.058
|
[13] |
CASTRO-MARCANO F,KAMAT A M,RUSSO J M F,et al. Combustion of an Illinois No. 6 coal char simulated using an atomistic char representation and the ReaxFF reactive force field[J]. Combustion and Flame,2012,159(3):1272−1285. doi: 10.1016/j.combustflame.2011.10.022
|
[14] |
VAN DUIN A C T,DASGUPTA S,LORANT F,et al. ReaxFF:a reactive force field for hydrocarbons[J]. The Journal of Physical Chemistry A,2001,105(41):9396−9409. doi: 10.1021/jp004368u
|
[15] |
宋双林. 不同氧气体积分数下风化煤自燃特性研究[J]. 煤矿安全,2022,53(7):32−37.
SONG Shuanglin. Study on spontaneous combustion characteristics of weathered coal under variable oxygen volume fractions[J]. Safety in Coal Mines,2022,53(7):32−37.
|
[16] |
孙萌,王福生,王建涛,等. 2-羧乙基苯基次膦酸抑制煤自燃特性研究[J]. 矿业研究与开发,2021,41(4):76−80.
SUN Meng,WANG Fusheng,WANG Jiantao,et al. Analysis of CEPPA to suppress the spontaneous combustion characteristics of coal[J]. Mining Research and Development,2021,41(4):76−80.
|
[17] |
张伟,高蕾,崔小超,等. 采空区低氧环境中煤自燃特性及极限参数研究[J]. 煤,2023,32(1):5−9. doi: 10.3969/j.issn.1005-2798.2023.01.002
ZHANG Wei,GAO Lei,CUI Xiaochao,et al. Study on characteristics and limit parameters of coal spontaneous combustion in low oxygen environment in goaf[J]. Coal,2023,32(1):5−9. doi: 10.3969/j.issn.1005-2798.2023.01.002
|
[18] |
张小艳. 柠檬酸对煤自燃特性的影响研究[D]. 徐州:中国矿业大学,2019.
ZHANG Xiaoyan. Study on the effect of Citric Acid on spontaneous combustion characteristics of coal [D]. Xuzhou:China University of Mining and Technology,2019
|
[19] |
郭一铭,何启林. 煤层自燃发火指标气体的选择及预测预报应用[J]. 安徽理工大学学报(自然科学版),2019,39(3):60−65. doi: 10.3969/j.issn.1672-1098.2019.03.010
GUO Yiming,HE Qilin. Selection and application of forecasting of signal gases for coal seam spontaneous combustion[J]. Journal of Anhui University of Science and Technology (Natural Science),2019,39(3):60−65. doi: 10.3969/j.issn.1672-1098.2019.03.010
|
[20] |
LIANG Y,TIAN F,GUO B,et al. Experimental investigation on microstructure evolution and spontaneous combustion properties of aerobic heated coal[J]. Fuel,2021,306:121766. doi: 10.1016/j.fuel.2021.121766
|
[21] |
WENDER I. Catalytic synthesis of chemicals from coal[J]. Catalysis Reviews—Science and Engineering,1976,14(1):97−129. doi: 10.1080/03602457608073408
|
[22] |
TROMP P J J,MOULIJN J. Slow and rapid pyrolysis of coal[J]. New trends in Coal Science,1988:305−338.
|
[23] |
GIVEN P H. Structure of bituminous coals:evidence from distribution of hydrogen[J]. Nature,1959,184(4691):980−981. doi: 10.1038/184980a0
|
[24] |
GIBSON J. Constitution of coal and its relevance to coal conversion processes[J]. The Robens Coal Science Lecture,1977.
|
[25] |
HILL G B,LYON L B. A new chemical structure for coal[J]. Industrial & Engineering Chemistry,1962,54(6):36−41.
|
[26] |
张玉涛,杨杰,李亚清,等. 煤自燃特征温度与微观结构变化及关联性分析[J]. 煤炭科学技术,2023,51(4):80−87. doi: 10.13199/j.cnki.cst.2021-0907
ZHANG Yutao,YANG Jie,LI Yaqing,et al. Correlation analysis between characteristic temperature and microstructure of coal spontaneous combustion[J]. Coal Science and Technology,2023,51(4):80−87. doi: 10.13199/j.cnki.cst.2021-0907
|
[27] |
李哲. 不同煤阶煤大分子建模及竞争吸附模拟[D]. 北京:中国地质大学(北京),2021.
LI Zhe. Macromolecular modeling and competitive adsorption simulation of different coal ranks [D]. Beijing:China University of Geosciences (Beijing),2021.
|
[28] |
相建华,曾凡桂,梁虎珍,等. 兖州煤大分子结构模型构建及其分子模拟[J]. 燃料化学学报,2011,39(7):481−488.
XIANG Jianhua,ZENG Fangui,LIANG Huzhen,et al. Construction of macromolecular structure model and molecular simulation of Yanzhou coal[J]. Journal of Fuel Chemistry,2011,39(7):481−488.
|
[29] |
辛海会. 煤火贫氧燃烧阶段特性演变的分子反应动力学机理[D]. 徐州:中国矿业大学,2016.
XIN Haihui. Molecular reaction kinetics mechanism for the evolution of characteristics of coal fire during oxygen deficient combustion phase [D]. Xuzhou:China University of Mining and Technology,2016.
|
[30] |
ZHENG M,LI X,LIU J,et al. Initial chemical reaction simulation of coal pyrolysis via ReaxFF molecular dynamics[J]. Energy & Fuels,2013,27(6):2942−2951.
|
[31] |
ZHANG Y,SHU P,DENG J,et al. Analysis of oxidation pathways for characteristic groups in coal spontaneous combustion[J]. Energy,2022,254:124211. doi: 10.1016/j.energy.2022.124211
|
[32] |
王德明,辛海会,戚绪尧,等. 煤自燃中的各种基元反应及相互关系:煤氧化动力学理论及应用[J]. 煤炭学报,2014,39(8):1667−1674.
WANG Deming,XIN Haihui,QI Xuyao,et al. Various elementary reactions and interrelationships in coal spontaneous combustion:theory and application of coal oxidation kinetics[J]. Journal of China Coal Society,2014,39(8):1667−1674.
|