我国煤火灾害十分严重，其发展演化是放热和散热相互竞争的动态过程，氧浓度是影响其放热特性的重要因素。因此，探究煤氧化放热官能团在低氧浓度下的转变特征，为煤低氧浓度燃烧特性以及机制奠定基础。

本文针对华亭长焰煤低氧浓度下氧化放热过程中的热反应特性、阶段划分、官能团变化规律进行研究，利用证据信念函数模型、频率比模型、确定性系数模型分别计算了宏观放热特性与微观官能团之间的关联性。通过模型优选，得到氧化条件下的官能团对放热性影响程度排序，确定出各个阶段影响氧化放热的重点官能团及其变化规律，得到氧化放热官能团的低氧转变特征。主要研究成果如下：

从宏观上来看，煤样在不同氧浓度（0%、3%、5%、7%、10%、13%、17%、21%）条件下，从温度30~700℃的氧化过程可划分为初始失重、增重、受热分解、燃烧这四个阶段。且随着氧浓度的增大，干裂温度和燃点温度均呈现降低趋势，说明较高氧浓度会促进煤氧复合反应。实验过程中升温速率较大，初始失重阶段呈现吸热，而在增重、受热分解、燃烧阶段煤样则呈现放热。21%、17%、13%、10%、7%、5%氧浓度时在初始失重阶段吸热分别为3%氧浓度时的82.41%、84.74%、86.79%、93.83%、94.92%、98.95%；在增重阶段放热分别为3%氧浓度时的4.11、3.89、3.79、2.76、1.89、1.36倍；在受热分解阶段放热分别为3%氧浓度时的1.48、1.43、1.43、1.39、1.33、1.11倍；在燃烧阶段放热分别为3%氧浓度时的1.21、1.18、1.16、1.11、1.06、1.03倍。氧浓度的升高能够促进热量的释放，说明此时煤氧复合反应更加强烈。

从微观上来看，煤样氧化放热过程中影响显著的重点官能团为，初始失重阶段：亚甲基剪切、甲基对称变形、芳环-C=C-、羰基、醚键；增重阶段：甲基反对称变形、亚甲基剪切、甲基对称变形、芳环-C=C-、酸酐、羧基；受热分解阶段：甲基反对称伸缩、亚甲基反对称伸缩、亚甲基对称伸缩、甲基反对称变形、亚甲基剪切、甲基对称变形、芳环-C=C-、酸酐、羰基、醚键；燃烧阶段：分子间缔合氢键、甲基反对称伸缩、亚甲基反对称伸缩、亚甲基对称伸缩、芳烃-CH、酸酐、羧基、羰基、醚键。

针对重点官能团在不同氧浓度和阶段下的变化规律进行分析，得出初始失重阶段时，氧浓度对官能团影响较小，而在增重、受热分解、燃烧阶段氧浓度对官能团影响显著。增重阶段时，侧链顶端的醛基结合氧气形成羧基，羧基脱水生成酸酐；受热分解阶段时，甲基和亚甲基在氧气作用下生成醛基和羰基，醛基氧化生成羧基，芳烃-CH和芳环-C=C-在温度升高时，不饱和双键氧化断裂；燃烧阶段时，煤氧复合反应加剧，甲基、亚甲基、酸酐、羧基、羰基等发生燃烧反应产生大量的热量同时还释放出CO、CO₂、CH₄等气体产物。

The coal fire disaster in my country is very serious. Its development and evolution is a dynamic process in which heat release and heat dissipation compete with each other. Oxygen concentration is an important factor affecting its heat release characteristics. Therefore, the investigation of the transformation characteristics of coal oxidation exothermic functional groups at low oxygen concentration can lay the foundation for the study of coal combustion characteristics and mechanisms at low oxygen concentration.

In this paper, the thermal reaction characteristics, stage division, and functional group change rules of Huating long-flame coal in the process of coal oxidation exothermic process under low oxygen concentration were explored. The correlation between macroscopic exothermic properties and microscopic functional groups was calculated using the evidential belief functions model, frequency ratio model and confirmatory factor model, respectively. Through model optimization, the degree of influence of functional groups on exothermicity under oxidation conditions was obtained, the key functional groups affecting oxidation exothermicity at each stage and their change laws were determined, and the low oxygen transition characteristics of oxidation exotherm functional groups were obtained. The main research results are as follows:

From a macroscopic point of view, the oxidation process of Huating long-flame coal under low oxygen concentration (0%, 3%, 5%, 7%, 10%, 13%, 17% and 21%) at temperatures from 30 to 700°C can be divided into four stages: initial weight loss, weight gain, thermal decomposition and combustion. And as the oxygen concentration increases, the cracking temperature and combustion point temperature both show a decreasing trend, which indicates that high oxygen concentration will promote the coal-oxygen composite reaction. During the experimental process, the heating rate was high, and the initial weight loss stage showed heat absorption, while the weight gain, thermal decomposition and combustion stages showed exothermic heat absorption. The heat absorption in the initial weight loss stage at 21%, 17%, 13%, 10%, 7% and 5% oxygen concentration is 82.41%, 84.74%, 86.79%, 93.83%, 94.92% and 98.95% of that at 3% oxygen concentration respectively. The heat release in the weight gain stage is 4.11, 3.89, 3.79, 2.76, 1.89 and 1.36 times that at 3% oxygen concentration respectively. The heat release in the thermal decomposition stage is 1.48, 1.43, 1.43, 1.39, 1.33 and 1.11 times that at 3% oxygen concentration. The heat release in the combustion stage is 1.21, 1.18, 1.16, 1.11, 1.06, 1.03 times that of 3% oxygen concentration. The increase in oxygen concentration promotes the release of heat, indicating that the coal-oxygen complex reaction is more intense at this time.

From a microscopic point of view, the key functional groups that have a significant influence on the exothermic process of coal oxidation are as follows, the initial weightless stage: methylene shearing, methyl symmetric deformation, aromatic ring -C=C-, carbonyl group, ether bond. Weight gain stage: methyl antisymmetric deformation, methylene shear, methyl symmetric deformation, aromatic ring -C=C-, anhydride, carboxyl group. Thermal decomposition stage: methyl antisymmetric expansion, methylene antisymmetric expansion, methylene symmetric expansion, methyl antisymmetric deformation, methylene shear, methyl symmetric deformation, aromatic ring -C=C-, anhydride, carbonyl, ether bond. Combustion stage: intermolecular association hydrogen bond, methyl antisymmetric expansion, methylene antisymmetric expansion, methylene symmetric expansion, aromatic -CH, anhydride, carboxyl, carbonyl, ether bond.

Based on the analysis of the changes of key functional groups in different oxygen concentrations and stages, it is concluded that oxygen concentration has little influence on functional groups in the initial weight loss stage, while oxygen concentration has significant influence on functional groups in the stages of weight gain, thermal decomposition and combustion. During the weight gain stage, the aldehyde group at the top of the side chain combines with oxygen to form a carboxyl group, and the carboxyl group is dehydrated to form an acid anhydride. In the thermal decomposition stage, the methyl and methylene groups form aldehyde groups and carbonyl groups under the action of oxygen, and the aldehyde groups are oxidized to form carboxyl group, aromatic hydrocarbon-CH and aromatic ring -C=C- are oxidized and broken by unsaturated double bonds when the temperature increases. During the combustion stage, the coal-oxygen composite reaction intensifies, and the combustion reaction of methyl, methylene, acid anhydride, carboxyl, carbonyl, etc., generates a large amount of heat, and also releases gaseous products such as CO, CO₂, and CH₄.

[1] 王俊峰. 煤地下自燃时覆岩中氡气运移规律及应用研究[D]. 太原理工大学, 2010.

[2] 邬剑明. 煤自燃火灾防治新技术及矿用新型密闭堵漏材料的研究与应用[D]. 太原理工大学, 2008.

[3] 武建军, 蒋卫国, 刘晓晨, 等. 地下煤火探测、监测与灭火技术研究进展[J]. 煤炭学报, 2009, 34(12): 1669-1674.

[4] 朱红青, 王海燕, 徐纪元, 等. 浅埋无烟煤发火原因分析[J]. 中国安全科学学报, 2013, 23(03): 45-50.

[5] 国家统计局. 中华人民共和国2021年国民经济和社会发展统计公报~([1])[N]. 人民日报,2022-03-01(010).DOI:10.28655/n.cnki.nrmrb.2022.002229.

[6]百科知识. 中国煤炭资源的分布和煤矿开采的地质条件[J/OL]. 百科知识, https://www.guayunfan.com/baike/190992.html, 2021-05-30.

[7]程爱国, 彭苏萍. 西部地区煤炭资源潜力综合评价与规划研究[C]. 西安科技学院学报论文集.西安:西安科技学院学报编辑部, 2000:7-13.

[8] Querol X, Izquierdo M, Monfort E, et al. Environmental characterization of burnt coal gangue banks at Yangquan, Shanxi Province, China[J]. International Journal of Coal Geology, 2008, 75(2): 93-104.

[9] Gedik E. Experimental investigation of the thermal performance of a two-phase closed thermosyphon at different operating conditions[J]. Energy and Buildings, 2016, 127: 1-34.

[10] 罗淑政. 煤火废弃地的生态恢复研究[D]. 新疆大学, 2009.

[11] 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]. 中国矿业大学, 2016.

[12] 徐精彩, 张辛亥, 文虎, 等. 煤氧复合过程及放热强度测算方法[J]. 中国矿业大学学报, 2000(03): 31-35.

[13] 文虎, 徐精彩, 葛岭梅, 等. 煤低温自燃发火的热效应及热平衡测算法[J]. 湘潭矿业学院学报, 2001(04): 1-4.

[14] 陈晓坤, 易欣, 邓军. 煤特征放热强度的实验研究[J]. 煤炭学报, 2005(05): 81-84.

[15] 张玉涛, 张园勃, 李亚清, 等. 低瓦斯气氛下煤氧化热效应和关键基团演变特性[J]. 中国矿业大学学报, 2021, 50(04): 776-783.

[16] 何瑾瑶, 单泽, 奚志林. 粒度对煤低温氧化特性的影响[J]. 煤炭技术, 2021, 40(07): 189-193.

[17] 刘春辉. 侏罗纪煤热反应模型构建及氧化历程研究[D]. 西安科技大学, 2021.

[18] 张嬿妮. 煤氧化自燃微观特征及其宏观表征研究[D]. 西安科技大学, 2012.

[19] 朱建芳, 许育铭, 郭文杰, 等. 煤自然发火过程中的放热特性实验研究[J]. 华北科技学院学报, 2016, 13(01): 1-8.

[20] 张玉龙. 基于宏观表现与微观特性的煤低温氧化机理及其应用研究[D]. 太原理工大学, 2014.

[21] Xu Y L, Wang D M, Wang L Y, et al. Experimental research on inhibition performances of the sand-suspended colloid for coal spontaneous combustion[J]. Safety Science, 2012, 50(4):822-827.

[22] Deng J, Xiao Y, Li Q, et al. Experimental studies of spontaneous combustion and anaerobic cooling of coal[J]. Fuel, 2015, 157: 261-269.

[23] Ibarra J, Muñoz E, Moliner R. FTIR study of the evolution of coal structure during the coalification process[J]. Organic Geochemistry, 1996, 24(6): 725-735.

[24] Painter P, Snyder R, Starsinic M, et al. Concerning the Application of FT-IR to the Study of Coal: A Critical Assessment of Band Assignments and the Application of Spectral Analysis Programs[J]. Applied Spectroscopy, 1981, 35: 475-485.

[25] Petersen H, Rosenberg P, Nytoft H. Oxygen groups in coals and alginite-rich kerogen revisited[J]. International Journal of Coal Geology, 2008, 74: 93-113.

[26] Petersen H I. The petroleum generation potential and effective oil window of humic coals related to coal composition and age[J]. International Journal of Coal Geology, 2006, 67(4): 221-248.

[27] Petersen H I, Nytoft H P. Oil generation capacity of coals as a function of coal age and aliphatic structure[J]. Organic Geochemistry, 2006, 37(5): 558-583.

[28] Macphee J A, Charland J P, Giroux L. Application of TG–FTIR to the determination of organic oxygen and its speciation in the Argonne premium coal samples[J]. Fuel Processing Technology, 2006, 87(4): 335-341.

[29] Sonibare O O, Haeger T, Foley S F. Structural characterization of Nigerian coals by X-ray diffraction, Raman and FTIR spectroscopy[J]. Energy, 2010, 35(12): 5347-5353.

[30] Okolo G N, Neomagus H W J P, Everson R C, et al. Chemical–structural properties of South African bituminous coals: Insights from wide angle XRD–carbon fraction analysis, ATR–FTIR, solid state 13C NMR, and HRTEM techniques[J]. Fuel, 2015, 158: 779-792.

[31] Odeh A O. Oualitative and quantitative ATR-FTIR analysis and its application to coal char of different ranks[J]. Journal of Fuel Chemistry and Technology, 2015, 43(2): 129-137.

[32] Tian B, Qiao Y, Bai L, et al. Separation and structural characterization of groups from a high-volatile bituminous coal based on multiple techniques[J]. Fuel Processing Technology, 2017, 159: 386-395.

[33] 张嬿妮, 邓军, 杨华, 等. 不同变质程度煤微观结构特征的试验研究[J]. 安全与环境学报, 2014, 14(04): 67-71.

[34] 周剑林. 低阶煤含氧官能团的赋存状态及其脱除研究[D]. 中国矿业大学, 2014.

[35] 李霞, 曾凡桂, 王威, 等. 低中煤级煤结构演化的FTIR表征[J]. 煤炭学报, 2015, 40(12): 2900-2908.

[36] 鄢晓忠, 邱靖, 尹艳山, 等. 褐煤中官能团对其燃烧特性的影响[J]. 煤炭科学技术, 2016, 44(04): 169-174.

[37] 赵孟浩, 张守玉, 郑红俊, 等. 低阶煤中含氧官能团干燥前后的演变规律[J]. 煤炭学报, 2016, 41(02): 483-489.

[38] 张小兵, 王蔚, 张玉贵, 等. 构造煤微晶取向生长机制探讨[J]. 煤炭学报, 2016, 41(03): 712-718.

[39] 相建华, 曾凡桂, 梁虎珍, 等. 不同变质程度煤的碳结构特征及其演化机制[J]. 煤炭学报, 2016, 41(06): 1498-1506.

[40] 姬新强, 要惠芳, 李伟. 韩城矿区构造煤红外光谱特征研究[J]. 煤炭学报, 2016, 41(08): 2050-2056.

[41] Wu D, Zhang H, Hu G, et al. Fine characterization of the macromolecular structure of huainan coal using XRD, FTIR, 13C-CP/MAS NMR, SEM, and AFM techniques[J]. Molecules, 2020, 25: 2661.

[42] 辛海会, 王德明, 戚绪尧, 等. 褐煤表面官能团的分布特征及量子化学分析[J]. 北京科技大学学报, 2013, 35(02): 135-139.

[43] 屈丽娜. 煤自燃阶段特征及其临界点变化规律的研究[D]. 中国矿业大学, 2013.

[44] Deng J, Wang K, Zhang Y, et al. Study on the kinetics and reactivity at the ignition temperature of Jurassic coal in North Shaanxi[J]. Journal of Thermal Analysis and Calorimetry, 2014, 118(1): 417-423.

[45] Cao W, Cao W, Peng Y, et al. Experimental study on the combustion sensitivity parameters and pre-combusted changes in functional groups of lignite coal dust[J]. Powder Technology, 2015, 283: 512-518.

[46] 王凤, 李光跃, 李莹莹, 等. 煤化学结构模型研究进展及应用[J]. 洁净煤技术, 2016, 22(01): 26-32.

[47] Zhang Y, Wang J, Xue S, et al. Kinetic study on changes in methyl and methylene groups during low-temperature oxidation of coal via in-situ FTIR[J]. International Journal of Coal Geology, 2016, 154-155: 155-164.

[48] Zhou C, Zhang Y, Wang J, et al. Study on the relationship between microscopic functional group and coal mass changes during low-temperature oxidation of coal[J]. International Journal of Coal Geology, 2017, 171: 212-222.

[49] 周福宝, 邵和, 李金海, 等. 低O2含量条件下煤自燃产物生成规律的实验研究[J]. 中国矿业大学学报, 2010, 39(06): 808-812.

[50] 金永飞, 李海涛, 岳宁芳, 等. 变氧浓度环境下煤自然发火气体预报指标优选[J]. 煤矿安全, 2014, 45(11): 27-30.

[51] 许凯航. 氧浓度对淮南煤自燃特性的影响实验研究[D]. 西安科技大学, 2018.

[52] 曹凯, 王德明. 贫氧条件煤自燃产热特性试验研究[J]. 中国安全科学学报, 2015, 25(10): 127-132.

[53] 王海燕, 李凯, 高鹏. 氧浓度对煤绝热氧化过程特征的影响[J]. 中国安全科学学报, 2013, 23(06): 58-62.

[54] 李玉谦, 乔珽, 王文强, 等. 不同氧浓度下煤氧化动力学参数的试验研究[J]. 煤矿安全, 2015, 46(07): 44-47.

[55] 金永飞, 郭军, 文虎, 等. 煤自燃高温贫氧氧化燃烧特性参数的实验研究[J]. 煤炭学报, 2015, 40(03): 596-602.

[56] 王凯, 翟小伟, 王炜罡, 等. 氧浓度与风量对煤热物性参数影响的实验研究[J]. 西安科技大学学报, 2018, 38(01): 31-36.

[57] 张辛亥, 张天赐, 王玥, 等. 不同氧浓度和温度下侏罗纪煤氧化动力学参数规律[J]. 西安科技大学学报, 2019, 39(04): 564-570.

[58] 李青蔚, 任立峰, 任帅京. 煤低温贫氧氧化放热特性研究[J]. 煤矿安全, 2020, 51(11): 34-38.

[59] 陈龙, 张嬿妮. 氧浓度对煤低温氧化热效应影响规律研究[J]. 中国安全生产科学技术, 2020, 16(06): 49-54.

[60] Xu T, Shen X-T, Chen J-Y, et al. Distribution of the functional groups in various coals with different spontaneous propensity[J]. International Journal of Coal Preparation and Utilization, 2020, 40(6): 349-358.

[61] Pradhan B, Abokharima M H, Jebur M N, et al. Land subsidence susceptibility mapping at Kinta Valley (Malaysia) using the evidential belief function model in GIS[J]. Natural Hazards, 2014, 73(2): 1019-1042.

[62] Pourghasemi H R, Kerle N. Random forests and evidential belief function-based landslide susceptibility assessment in Western Mazandaran Province, Iran[J]. Environmental Earth Sciences, 2016, 75(3): 185.

[63] 李增华, 林柏泉, 张兰君, 等. 氢气的生成及对瓦斯爆炸的影响[J]. 中国矿业大学学报, 2008(02): 147-151.

[64] 谢克昌. 煤的结构与反应性[M]. 北京: 科学出版社, 2002.

[65] Zhu H, Huo Y, Wang W, et al. Quantum chemical calculation of reaction characteristics of hydroxyl at different positions during coal spontaneous combustion[J]. Process Safety and Environmental Protection, 2021, 148: 624-635.