煤层自燃模拟实验

以柴家沟煤矿煤样为测试煤样,利用自主研发的煤层自燃实验系统,对煤层的自燃过程进行了模拟实验。根据实验测试数据,对煤温与供气量以及实验过程的各个指标气体情况进行了分析和研究,从而得出柴家沟煤矿煤层自燃的临界温度、瓦斯脱附温度等各个指标参数,其结果对预测和防治煤层自燃火灾具有指导意义。      

煤样自燃性升温程序实验研究

以铜川煤矿煤样为测试样品,利用自主研发的煤层自燃性升温的实验系统,对煤层的自燃过程进行实验模拟。根据实验测试数据对煤温与供气量以及实验过程的指标气体情况进行分析,得出煤层自燃性的临界温度、干裂温度等各个自燃特性。实验结果对煤矿分析和预测煤层自燃的过程具有指导意义。     

煤岩组分对预测自燃标志气体的影响

介绍了煤岩组分在低温氧化阶段产出的氧化分解气体浓度变化和低温氧化的难易程度，指出应用标志气体预测预报自燃发火时，煤岩组分的影响决不可忽视，煤矿应采用本矿有代表性的煤样做模拟实验，求得标志气体的浓度与煤温的相关值作为本矿预测预报临界值的依据。     

Q型主因子分析法在沁水盆地南部煤储层特征评价中的应用

为了定量表征沁水盆地南部山西组3#煤层和太原组15#煤层孔隙结构的差异性,采用压汞试验和Q型主因子分析的方法对煤储层孔隙结构特征进行了研究。结果表明:研究区煤储层孔隙度较小,孔隙类型以微孔及小孔占优,不同煤样所测得孔隙结构参数具有较大的差异;由样本总得分将煤储层划分为3种类型:Ⅰ类储层压汞曲线滞后环较大、孔隙连通性较好,Ⅲ类储层进退汞曲线几乎重合、半封闭型孔隙含量较高,Ⅱ类储层居中;通过分析对比,研究区主力产层3#煤层以Ⅱ类储层为主,15#煤层主要为Ⅲ类储层。     

基于模糊综合评判的煤自燃发火倾向性研究

自燃发火倾向性是煤自燃火灾的主要影响因素之一。通过对国内外煤自燃倾向性鉴定方法的分析, 指出了我国现行的煤自燃倾向性的不足之处。根据煤自燃机理的煤、氧复合理论,建立了依据煤在低温氧化过程中的吸氧率、放热强度和着火燃烧阶段的活化能作为鉴定煤自燃发火倾向性影响因素的模糊综合评判新方法。在此基础上,用热重分析方法测试了5种煤样在相同条件的指标参数,建立模糊综合评判模型,通过模糊运算得出评判5种煤样自燃发火倾向性的综合指标。验证表明,该方法有较强的实用性,其评判结果与5种煤样的实际自燃发火期趋势一致。      

高温高压条件下深部煤层气吸附行为

为了对深部煤层吸附特性进行分析,以鄂尔多斯盆地东部主要煤层为对象,展开 4 组不同温度条件下煤样的高压等 温吸附实验。从温度、压力、煤级等地质要素方面入手,研究较高温压条件下煤样的吸附特征。同时,通过对比分析各地 质因素对吸附行为的影响,比较深部煤层吸附行为与浅部煤层吸附行为的差异性。结果表明:深部煤层的吸附特性主要受 温度、压力的控制;高温条件下煤样对 CH4 的吸附量大大减少,且煤级、煤岩显微组分、灰分产率以及水分含量对吸附性 能的影响已明显小于浅部煤层,温度、压力成为控制吸附量的决定因素。在 100°C条件下,吸附量到达某一压力后随着压 力的增大煤样吸附量下降,分析认为由于在此温压下,随着压力的增加,吸附相与游离相气体的密度差逐渐减小,超临界 吸附已不再符合 Langmuir 等温吸附模型。     

老虎台矿泥浆环境煤的瓦斯解吸机制研究

为了研究老虎台矿泥浆环境煤的瓦斯解吸机制,探讨了泥浆钻孔取心过程煤的瓦斯解吸状态,按照煤心管内的煤的瓦斯压力与管壁泥浆压力大小关系得出瓦斯解吸的四个阶段,并系统研究了相应阶段煤的瓦斯解吸特征;在此基础上研究了影响老虎台矿泥浆环境煤的瓦斯解吸控制因素,从提钻速率、瓦斯压力和粒径等因子深入分析了对泥浆环境煤的瓦斯解吸的影响,得出提钻速率愈小,泥浆环境下瓦斯逸散量愈大;在相同瓦斯压力条件下,煤样瓦斯解吸Q-t曲线呈"S"形态,一定时间后,瓦斯解吸量将不再增加,且瓦斯逸散量与瓦斯压力具有同步增大的趋势;煤样粒径在增加的同时,煤样瓦斯解吸初速度呈现不断减小的趋势,且粒径达到某一数值后,曲线收敛,煤样瓦斯解吸初速度趋于稳定。最后对老虎台矿煤样,在泥浆压力6.00MPa,瓦斯压力2.00MPa,提钻速率0.2m/s条件下开展瓦斯解吸实验,得出煤层瓦斯解吸规律曲线呈"S"形态展布,经多项式拟合得出瓦斯解吸规律Q-t模型。研究结果为地勘时期煤的瓦斯解吸测试,分析瓦斯逸散提供指导。     

巨野矿区煤自燃特性及动力学研究

针对巨野矿区3号煤层自然发火严重的现状,选择巨野矿区3上和3下两煤层煤样,采用煤的物性参数测试、热重分析、傅里叶红外光谱测试等实验方法,进行巨野矿区3煤层的自燃特性及动力学参数实验研究。结果表明,巨野矿区煤属于Ⅱ类自燃煤,煤的孔隙主要以大孔和中孔为主;煤在失水失重与吸氧增重阶段的活化能分别为94.49~123.61 kJ/mol和231.50~241.08 kJ/mol;煤分子中含有大量的羟基、甲基、亚甲基等活性官能团,这些活性官能团是导致巨野矿区煤自燃的关键化学结构。      

液态水影响不同煤级煤吸附甲烷的差异及其机理

以IS100等温吸附解吸仪和MTS815型电液伺服岩石实验系统为主要实验平台,应用已建立的模拟储层条件下煤样注水和注水试样等温吸附实验方法,对3种不同煤级的煤储层样品开展了高压（8～20 MPa）注水和等温吸附实验,发现储层条件下煤层中的液态水（注水煤样）对不同煤级（0.46%<Ro,max<1.72%）煤吸附甲烷影响有差异,其含水量随煤级升高呈L型降低,而吸附量则线性增加。笔者认为液态水造成吸附差异的原因是煤体润湿性的差异,对于中低煤级的煤样来说,煤表面的物理化学性质起着控制作用,直接影响着煤体润湿性,吸附势和含水量的曲线都说明了这一点。     

不同含水性无烟煤CO2吸附行为及其对地质封存的启示

深部煤层CO₂地质封存是助力“碳达峰碳中和”战略的重要途径,煤层含水性对以CO₂吸附封存为主的深部煤层CO₂地质封存能力影响显著。以无烟煤为例,开展了45℃下干燥、平衡水、饱和水煤样高压CO₂等温吸附实验,校正了饱和水煤样过剩吸附曲线,利用改进的D-R吸附模型拟合得到三者吸附能力与吸附热,对比了不同含水条件下CO₂绝对吸附曲线,阐释了饱和水增强无烟煤吸附能力的微观作用机理。结果表明:(1)干燥、平衡水、饱和水煤样CO₂吸附能力分别为56.72、45.19和48.36 cm3/g,吸附热分别为29.42、26.23和27.24 kJ/mol。(2) CO₂密度小于0.16 g/cm3(6.48 MPa)时,无烟煤CO₂绝对吸附量大小顺序为干燥煤样、饱和水煤样和平衡水煤样,而CO₂进入超临界状态后,顺序变为饱和水煤样、干燥煤样和平衡水煤样。(3)水分子优先占据高能吸附位是平衡水煤样吸附能力减弱的主要原因,而煤?水体系与CO₂相互作用强于CO₂与H₂O竞争吸附下的煤?CO₂相互作用是饱和水煤样在CO₂超临界阶段吸附能力高于干燥煤样的根本原因。(4)吸附封存是煤层CO₂地质封存的主要形式,深部煤储层条件下,煤层饱和水对超临界CO₂增储作用更为明显,高压注水是提高深部煤层CO₂地质封存潜力,改善煤储层渗透性的有效手段。      

论煤地质学与碳中和

煤基碳排放构成了中国碳排放总量中最重要的部分,做好煤基碳减排和煤炭高效洁净低碳化利用是实现“碳中和”国家目标的重要途径,碳中和背景下的煤地质学发展值得关注。系统评述与碳中和相关的煤地质学研究领域,分析煤地质学在碳中和研究与工程实践中的作用和应用前景,探讨碳中和背景下煤地质学的重要发展方向。取得以下认识:推进清洁煤地质研究、服务煤的高效洁净化燃烧,勘探开发煤系天然气低碳燃料、优化一次能源结构和化石能源结构,开展煤化工资源勘查与开发地质保障研究、推动煤炭的低碳能源转化和新型煤化工产业发展,深化瓦斯地质研究、提高煤矿瓦斯（井下）抽采率、控制煤矿瓦斯的大气排放和泄漏,研究煤层甲烷天然逸散和煤层自燃排放、控制煤层露头的天然排放,发展煤层CO₂地质封存与煤层气强化开发（CO₂-ECBM）技术、推动碳捕获、利用与封存（CCUS）技术发展及其在火力电厂烟气碳减排中的商业化应用,研究煤炭勘查企业的碳足迹、实现企业净零排放,是与煤地质学紧密相关的碳减排技术路径;其中煤层甲烷与煤系气高效勘探开发、深部煤层CO₂-ECBM、煤层露头气体逸散与自燃发火控制、洁净煤地质与煤炭精细勘查是碳中和背景下煤地质学优先发展的重要领域。      

易自燃煤层综放工作面采空区自然发火防治数值模拟

本文针对古山矿065-2大倾角易自燃综放工作面上部有小煤窑火区和上分层火区、且自然发火期仅为15d、工作面火灾防治极其困难的问题,采用在采空区埋设束管、取样化验采空区气体成分的方法,得出采空区气体浓度场分布,划分工作面采空区的自燃＂三带＂,计算出工作面日最小推进度为2.54m。运用Comsol软件,通过对采空区氧浓度进行数值模拟,并与实测采空区氧浓度进行对比验证,结果证明基于Comsol模拟采空区氧浓度分布是可行的,为易自燃煤层综放工作面采空区自然发火防治提供了可靠的理论指导。     

The measurement of coal porosity with different gases

Sorption processes can be used to study different characteristics of coal properties, such as gas content (coalbed methane potential of a deposit), gas diffusion, porosity, internal surface area, etc. Coal microstructure (porosity system) is relevant for gas flow behaviour in coal and, consequently, directly influences gas recovery from the coalbed.This paper addresses the determination of coal porosity (namely micro- and macroporosity) in relation to the molecular size of different gases. Experiments entailed a sorption process, which includes the direct method of determining the “void volume” of samples using different gases (helium, nitrogen, carbon dioxide, and methane). Because gas behaviour depends on pressure and temperature conditions, it is critical, in each case, to know the gas characteristics, especially the compressibility factor.The experimental conditions of the sorption process were as follows: temperature in the bath 35 °C; sample with moisture equal to or greater than the moisture-holding capacity (MHC), particle size of sample less than 212 μm, and mass ca. 100 g.The present investigation was designed to confirm that when performing measurements of the coal void volume with helium and nitrogen, there are only small and insignificant changes in the volume determinations. Inducing great shrinkage and swelling effects in the coal molecular structure, carbon dioxide leads to “abnormal” negative values in coal void volume calculations, since the rate of sorbed and free gas is very high. In fact, when in contact with the coal structure, carbon dioxide is so strongly retained that the sorbed gas volume is much higher than the free gas volume. However, shrinkage and swelling effects in coal structure induced by carbon dioxide are fully reversible. Methane also induces shrinkage and swelling when in contact with coal molecular structure, but these effects, although smaller than those induced by carbon dioxide, are irreversible and increase the coal volume.     

Fine coal covering for preventing spontaneous combustion of coal pile

In order to investigate the effect of fine coal covering around the bottom of coal stockpile on spontaneous combustion prevention, a two-dimensional math model was established to numerically simulate the fine coal covering coal pile and a coal pile temperature-rising experimental system was setup to study the two-dimensional heat and mass transfer characteristics of air diffusion in the horizontal direction and air heat convection in the vertical direction inside coal stockpiles covered by different thicknesses of fine coal. The results showed that (1) the fine coal located at the bottom of the coal pile can effectively inhibit air convection and diffusion, cut off oxygen replenishment, and prevent the temperature rise inside coal pile, and (2) thicker fine coal has more obvious effect. Finally, the field experiments on the fine coal covering coal piles for preventing self-ignition of coal pile were carried out successfully. The results showed that the uncovered or exposed coal piles self-ignited rapidly within a very short period (18 days), while the coal pile covered with 1 m fine coal lasted for 123 days with a maximum coal temperature of only 59.9 °C. The characteristics of temperature distribution and diffusion inside coal stockpile were studied, and the high-temperature region was found in the region 1.3 m high and 2–3 m deep in the coal pile. The effects of environment temperature and precipitation on self-ignition of coal pile were also analyzed in field experiment. The experimental results proved that the fine coal covering technology can effectively prevent the spontaneous combustion of coal stockpiles.     

河南平煤四矿煤矸石山自燃爆炸成因及防治分析

2005年5月15日、16日,平煤集团四矿矸石山先后发生两次自燃爆炸灾害,8人遇难,122人受伤,造成生命财产的重大损失。论文首先介绍了平煤集团四矿煤矸石的物质组成,分析其致灾原因:高含硫煤矸石的存在是引起煤矸石山自燃的决定因素;煤矸石的堆积方式以及有效的粒径组成在一定程度上决定了煤矸石的透气性,是引起煤矸石山自燃的促进条件;突发降雨是本次灾害的主要导火索。在燃料含量一定,清除比较困难,燃烧已开始并还在不断堆积矸石的情况下,降温和隔氧显得尤为重要。针对本矸石山的实际情况,提出了采用注浆法为主,辅以高温区域表面喷射浆液、挖掘沟槽、表面覆盖等灭火方法;对今后避免矸石山自燃进行了展望。     

Geochemical study of products associated with spontaneous oxidation of coal in the Cerro Pelado Formation,Venezuela

The aim of this research work is a geochemical, mineralogical, and textural characterization of spontaneously smouldered coal-derived products in northwestern Venezuela (Cerro Pelado Formation, some 10 km from Pedregal city). Several solid samples were collected from this formation, six of unweathering coal, an other six of resulting unmelted rocks forming on a surface coal bed, and the last four of mineralizations found accumulating around gas vents. The fresh coal and the unmelted material were analysed by scanning electron microscopy, X-ray diffraction, and proximate techniques. Products such as magnetite and chabazite-K were identified in the alteration rocks. Likewise, both materials were also studied in order to determine the mobilization of 17 elements into the environment; such elements were analysed through inductively coupled plasma atomic emission spectroscopy on extracts obtained by a sequential extraction method: each sample was firstly extracted with MilliQ water and then the resultant residue was washed. This and the subsequently resulting residues are extracted according to the mentioned procedure by using, respectively, ammonium acetate, chlorhydric acid, peroxide and chlorhydric acid, nitric acid and fluorhydric acid, and nitric acid. The studied elements are classified as highly mobile (Na, Ni, ...), nearly immobile (Ti, P) and partially mobile (Mg, Fe, K, ...). In regards to mineralizations around fumaroles associated with smoldering coal seams, Fourier-transform infrared spectroscopy and X-ray diffraction analyses have revealed the presence of salammoniac, mascagnite and other solid combustion compounds formed by reaction of gas emitted from coal oxidation, in addition to previously non-reported sulfur-rich by-products associated with gas fissures, particularly ammonium thiosulfate, a phase first obtained only synthetically in the laboratory. Another objective of the research was to collect and analyse gases escaping from surficial vents. Relatively high concentrations of several aromatic compounds were detected in the gas collected at the studied coal outcrop, as well as aliphatic hydrocarbons including ethane, propane, butanes, among others. High contents of carbon monoxide, methane and carbon dioxide were also measured for gas samples.     

CO and CO2 emissions from spontaneous heating of coal under different ventilation rates

Carbon monoxide (CO) and carbon dioxide (CO₂) emissions during a spontaneous heating event in a coal mine are important gases to monitor for detecting the spontaneous heating at an early stage. However, in underground coal mines, the CO and CO₂ concentrations and their related fire ratios may be affected by mine ventilation. In this study, CO and CO₂ emissions from spontaneous heating of a U.S. coal sample were evaluated in an isothermal oven under different airflow ventilation rates ranging from 100 to 500 cm³/min. Laboratory experiments were conducted at oven temperatures of 70, 90, and 100 °C. The temperature at the center of the coal sample was continually monitored, while the CO, CO₂, and oxygen (O₂) concentrations of the exit gas were continually measured. The results indicate that CO was generated immediately after the airflow passed through the coal, while CO₂ was generated in a late phase. The amounts of CO generated under different airflow rates were approximately the same at the initial temperature of 70 °C, while the amounts of CO generated increased significantly as the airflow rates and initial temperatures increased. The ratio of CO/CO₂ was found to be independent of airflow rate and initial temperature, approaching a constant value of 0.2 quickly if there was no thermal runaway. The value tended to decrease when a thermal runaway took place. The CO/O₂ deficiency ratio was dependent on both airflow rates and the initial temperature. The experimental results are in qualitative agreement with some large-scale test and field monitoring results.     

苏鲁豫皖四省毗邻地区天然焦特征及燃烧特性

碳达峰碳中和背景下提高资源利用效率尤为重要,然而天然焦长久以来并未得到应有的重视。我国天然焦资源丰富,在苏鲁豫皖四省毗邻地区的煤矿开采中经常发现由于岩浆岩侵入,煤层受到烘烤而变质为天然焦的现象。广泛采集苏鲁豫皖四省毗邻地区天然焦样品,在描述天然焦宏观及显微特征的基础上,对天然焦开展工业分析、地球化学特征、自燃倾向性和焦尘爆炸性等方面的测试与分析,采用美国TA2100热分析仪测试典型样品的燃烧特性。结果表明:天然焦的宏观物理特性、显微组分特性与煤具有明显的差异性;总体上各项分析指标与无烟煤没有明显的界线,天然焦与同地的残留煤相比,其挥发分产率降低、C/H比大幅提高;天然焦变质程度达到或高于无烟煤阶段,不易自燃、焦尘无爆炸性。燃烧特性测试结果表明山东菏泽赵楼天然焦样品具有较强的反应活性,并根据天然焦的特性探讨了利用方向,认为其在制作型煤、合成氨、碳材料、生产水泥以及CO₂地质封存等方面具有利用价值或潜力。