基于活化能的煤自燃倾向性研究

对国内外主要煤自燃倾向性鉴定方法进行了分析和评价，指出了我国现行的煤自燃倾向性色谱吸氧鉴定法的不足之处，同时给出了煤自燃倾向性鉴定标准的基本原则．在煤自燃动力学基本方程基础上得到了煤绝热氧化方程，并设计了相应绝热氧化实验装置．通过理论和实验研宄，提出了能够反应煤自燃关键阶段，即低温氧化阶段动力学参数活化能E作为煤自燃倾向性鉴定指标，并测试了3个典型煤样的低温氧化活化能E．最后，通过现场煤自燃发火期与煤物理吸附氧量和低温氧化活化能E的对比，对该指标的实用性和科学性进行了检验．     

煤自燃倾向性的氧化动力学测定方法研究

通过煤自燃过程中的绝热氧化升温速率、耗氧量、交叉点温度的综合分析研究,指出以煤自燃某一阶段的单一特征参数无法体现煤自燃过程的整体特性,提出了煤自燃倾向性的氧化动力学测定方法.该方法在测试程序升温条件下煤样温度70℃时煤样罐出气口氧气浓度和之后的交叉点温度的基础上,得出煤自燃倾向性的氧化动力学综合判定指数,根据该指数的大小判定煤自燃倾向性的强弱.对不同煤种的综合判定指数与绝热氧化、30℃物理吸氧量对比分析,结果表明氧化动力学综合判定指数更能够反映煤自燃的难易程度.     

煤自燃逐步自活化反应理论

为了深入了解煤自燃发生发展过程，对煤自燃过程进行了绝热氧化模拟，获得了煤自燃过程升温曲线，得出煤自燃过程活化能随温度升高而逐渐上升的规律，同时对煤低温氧化过程微观结构变化规律进行了红外光谱测试．在充分研究煤自燃过程宏观特性和微观结构变化之间关系的基础上，提出了煤自燃逐步自活化反应机理：煤结构中不同官能团（活性结构）治化需要的温度与能量不一样，先被活化而发生氧化反应的官能团释放能量使其它需要更高活化温度和能量的官能团活化而进一步与氧发生反应释放更多能量，煤自燃过程是不同官能团依次分步浙进活化而与氧发生反应的自加速升温过程．     

综放工作面撤架期间预防采空区遗煤自燃措施探索

煤矿工作面末采撤架期间,由于操作时间长和采空区漏风量较大,因而采空区遗煤很容易发生自燃．鹤煤二矿3407综放工作面在末采撤架期间,通过工作面自燃监测、采空区埋管注浆、预设回撤通道减少回撤时间、阻化剂防灭火以及停采时设置多道密闭、翔闭采空区等措施,确保了工作面末采回撤的安全,同时也得到了较好的经济效益．     

易自燃煤层放顶煤开采工作面合理长度分析

以采空区自然发火危险为约束条件,用采空区场流方法(数值模拟)和自燃三带理论,结合实例,研究放顶煤开采工作面合理长度问题.得到工作面长度安全临界值与煤的最短自然发火期成正比关系.通过现场测定风量和采空区气体浓度分布,得到在当前工作面特定采空区流场环境下的自燃氧化带宽度和模型基础参数,数值模拟出不同工作面长度的采空区自燃氧化区宽度的变化关系;回归得到,在理论上,工作面长度与自燃氧化带宽度近似服从二次曲线关系.分析中给出了自燃安全判别量和自燃安全区间.     

综放面采空区遗煤自燃“三带”范围的预测

以峰峰矿区小屯矿14252综放面为研究对象,通过氧化热解实验测定煤样产生的气体成分;利用自制气体采样系统对采空区气体进行采集和分析,进而划分遗煤自燃"三带"范围。结果表明C2H2可作为该综放面煤炭自燃的预测指标,以C2H2浓度划分的采空区遗煤自燃"三带"范围为:散热带0~30m,自燃带30~127m,窒息带大于127m。     

乌达矿区煤自燃预测标志气体研究

为遴选预测煤自燃进程的标志气体,采集了乌达矿区6个具有代表性的煤样．在实验室开展煤升温氧化气体产物的测定实验,主要测试了煤样在升温氧化条件下各种气体组分的发生量．根据各种气体组分的发生量及最低检测温度,确定了乌达矿区煤自燃预测预报的标志气体,为该矿区煤自燃火灾的预测预报提供了实验依据,对矿区的安全生产具有较好的指导作用．     

煤表面对单氧分子的物理吸附机理

煤的氧化自燃是由煤表面对氧的吸附开始．应用量子化学密度泛函理论,研究了煤表面对氧分子的物理吸附机理和吸附过程．结果表明,煤表面与氧分子组成的吸附态中,煤表面苯环碳原子的电子向氧分子中的氧原子转移,导致氧原子的净电荷增加;单氧分子在苯环位置吸附时,其O-O键的伸缩振动频率向低波数位移;单氧分子在侧链位置吸附时,UC14-H16和UO24-UO25红外光谱的振动频率变小,分子之间的作用力减弱了分子的伸缩振动．氧与苯环吸附时的吸附能为30．94kJ／mol,与氨基基团吸附时的吸附能为71．81kJ／mol煤表面侧链吸附放出的热量大于与苯环吸附所放出的热量,侧链吸附对煤的氧化自燃的贡献大于苯环的吸附．     

简放工作面供风量与采空区遗煤自燃危险性研究

针对地方煤矿易自燃厚煤层简易放顶煤开采推进速度低的现实条件,本文在分析不同氧浓度条件下煤的耗氧速度、采空区煤氧化自燃三带及其与采空区漏风量关系基础上,研究了工作面供风量与漏风量及其采空区氧化带宽度的关系,研究结果为厚煤层简放开采工作面的合理供风量及防治煤炭自燃措施应用提供了技术依据.     

空气流量下易燃煤层采空区遗煤氧化升温特性研究

为研究空气流量对采空区遗煤自燃的影响,基于九宫格原理设计了易燃煤层采空区的漏风通道,借助自行搭建的实验平台进行了煤自燃氧化升温实验,分析煤样耗氧速率和放热强度随煤温变化的规律。结果表明:考虑煤样空隙率时,耗氧速率有3次较为明显的峰值,第一次峰值出现在48℃左右,第二次峰值出现在75℃左右,第三次峰值出现在105℃左右;不考虑煤样空隙率时,大空气流量下,耗氧速率的3次峰值均高于第一种方法计算出的耗氧速率,在小空气流量下,耗氧速率的峰值差别不大;80℃之后,实验煤样生成的热量开始占据主导地位,放热强度与温度呈指数变化。可根据实验结果调节矿井的漏风量,来防治井下采空区的遗煤自燃。     

基于热重实验的煤自燃临界氧体积分数分析

对同一种煤样在不同氧体积分数下进行热重实验,利用Matlab得出了该煤样的残留质量比率(TG),质量变化率(DTG),放热速率(DSC)和放热变化率(DDSC)的立体分布和等值线图,研究了不同条件下残留质量和放热速率的变化规律.结果显示,当氧体积分数大于10%时,该煤样在设定的温度内能完全反应和存在最大放热速率,但完全反应对应的温度随着氧体积分数的降低而升高;当氧体积分数小于10%时,尤其是氧体积分数趋向于0时,该煤样难以在设定的温度范围内完全反应,且残留质量随氧体积分数的降低加速上升,同时在实验温度段内放热速率波动不大.最后,对煤样产生不同残留质量的原因进行了分析,结合热重实验得出该煤自燃的临界氧体积分数为18%和8%,从而为采空区自燃"三带"划分提供指导.     

A new apparatus to establish the spontaneous combustion propensity of coals and coal-shales

Coal and coal-shale both tend to undergo spontaneous combustion under favourable atmospheric conditions. The Wits-Ehac index has been developed in South Africa since the late 1980's to test the spontaneous combustion liability of coal. However, in some cases, the Wits-Ehac index fails to produce tangible results when testing coal-shales. To overcome this problem, a new apparatus has been developed to test carbonaceous materials such as coal and coal-shale under chemical reactions with oxygen and an index has been obtained. This index is called the Wits-CT index. The equipment emulates the influence of oxygen adsorption on carbonaceous material for a period of 24 h without a heating system.The Wits-CT index uses the total carbon content of the sample and the temperature variations obtained from the samples during reaction with oxygen to predict the spontaneous combustion liability. Eighteen samples have been analyzed using both indices and the results are in-line. It was found that coals and coal-shales with higher values of the Wits-CT index are more liable to spontaneous combustion.Further research on different coal-shales is underway in order to establish an extensive database for coal and coal-shales, together with known incidences of self-heating.     

Spontaneous combustion of coals and coal-shales

Spontaneous combustion of coal is a well-known phenomena around the globe. Apart from the coal itself,burning coal-shales is becoming a problem in the South African coal mines. Serious incidents of spontaneous combustion have been reported as a result of self-heating of reactive coal-shales. The intrinsic properties and spontaneous combustion tests of 28 selected coal and coal-shale samples were conducted and a relationship between the two has been established. Intrinsic properties were obtained by using the proximate and ultimate analysis, and spontaneous combustion liability tests results were obtained by using the Wits-Ehac and Wits-CT indices. The experimental results show that intrinsic properties of these materials complement to the spontaneous combustion liability tests results. Comparative analyses of intrinsic properties and spontaneous combustion characteristics indicate similarities between the mechanism of coal oxidation and that of the oxidative processes undergone by coal-shales. For the tested samples, coal samples have a higher intrinsic spontaneous combustion reactivity rating than the coal-shales.Furthermore, an increase in carbon, moisture, hydrogen, volatile matter, nitrogen and a decrease in ash content indicate an increased proneness to self-heating. The concentration of pyrite found in the coal-shales accelerates self-heating. The event of spontaneous combustion can occur if coal-shales absorb sufficient oxygen when subjected to atmospheric conditions.     

采空区瓦斯涌出与自燃耦合基础研究

基于漏风渗流方程、多组分气体混溶-扩散方程和综合传热方程,建立采空区瓦斯和自燃耦合数学模型．通过现场实测获得基础数据,用G3程序（有限元数值方法）求解了在煤耗氧和瓦斯涌出共同环境下采空区瓦斯-氧浓度及温度的分布．结果表明,在单纯瓦斯涌出（无消耗氧）条件下,采空区氧被瓦斯稀释现象比较显著;采空区内高强度的瓦斯涌出能够使自燃氧化区域进一步缩小,削弱了煤的自燃氧化进程;自燃产生的热风压也能加剧工作面向采空区的漏风及对采空区内瓦斯的排放．耦合影响随工作面向采空区的漏风量的提高而相对降低．     

利用自燃模拟试验装置分析影响矸石自燃的因素

通过大试样量自燃倾向性实验(模拟试验)装置,对煤矸石中硫铁矿、含水量、孔隙率对煤矸石氧化升温的影响进行的实验研究,得到了其对矸石氧化升温的影响规律,为了解矸石自燃规律和寻找控制措施提供依据。     

A review of research on spontaneous combustion of coal

Coal oxidation at low temperatures is the heat source liable for the self-heating and spontaneous combustion of coal. This phenomenon has imposed severe problems in coal related industries. Attempts to understand this phenomenon by previous researchers have provided significant progress. It is wellknown that coal oxidation at low temperatures involves oxygen consumption and formation of gaseous and solid oxidation products. This process is majorly influenced by temperature, oxidation history of coal,coal properties, particle size distribution of the coal, etc. The current understanding of the phenomenon of self-heating and spontaneous combustion of coal is discussed along with the different experimental and numerical models established to predict self-heating characteristics of coal. This paper focuses on the global position of the study carried out by academics, research institutes and industries on spontaneous combustion of coal and coal mine fires. Within this framework, the generally used spontaneous combustion techniques to predict the spontaneous combustion liability of coal were evaluated. These techniques are well-known in their usage, but no specific method has become a standard to predict the spontaneous combustion liability. Further study is still needed to indicate a number of impending issues and to obtain a more complete understanding on the phenomenon.     

采空区自燃"三带"微循环理论及漏风流场数值模拟

为掌握采空区自燃"三带"分布及其自然发火规律,通过唐口煤矿2307工作面采空区自燃"三带"现场温度和气样观测,利用FLUENT软件对采空区漏风流场数值模拟.结果表明:采空区自燃是一个氧热微循环过程,当漏风供氧大于氧化耗氧、氧化生热大于漏风散热时,氧热微循环可持续进行,直至自燃;得出工作面不同风量下采空区自燃"三带"的区域.进风巷侧采空区可能自燃带范围在48.2～98.6 m,而回风巷侧采空区可能自燃带范围在24.3～98.6 m.经对比分析,得出最有利于采空区防灭火的最佳供风量为1 200～1 440 m~3/min,可满足防灭火的需要.     

煤巷高冒区松散煤体自然发火的数值模拟研究

巷道高冒区自燃火灾，不仅严重影响到采掘工作面的安全生产，而且威胁到矿工们的生命安全．通过对煤巷高冒区特点和影响煤炭自燃因素的分析，根据多孔介质流体动力学、传热和传质理论，建立了高冒区松散煤体自然发火过程三维数学模型．以旗山煤矿高冒区为例，用有限元法进行了数值求解，得到高冒区渗流速度场、温度场和氧浓度场的分布，在此基础上划分出最易自然发火的区域，分析了高冒区自然发火的机理．结果表明：高冒区松散煤体漏风强度随孔隙率的增大而增加；高冒区松散煤体的中部区域存在最易自然发火区，是现场防治高冒区自然发火的重点区域．现场试验数据验证了数值模拟结果的合理性．     

Prediction of oxygen concentration and temperature distribution in loose coal based on BP neural network

An effective method for preventing spontaneous combustion of coal stockpiles on the ground is to control the air-flow in loose coal. In order to determine and predict accurately oxygen concentrations and temperatures within coal stockpiles, it is vital to obtain information of self-heating conditions and tendencies of spontaneous coal combustion. For laboratory conditions, we de-signed our own experimental equipment composed of a control-heating system, a coal column and an oxygen concentration and temperature monitoring system, for simulation of spontaneous combustion of block coal (13-25 ram) covered with fine coal (0-3 mm). A BP artificial neural network (ANN) with 150 training samples was gradually established over the course of our experiment. Heating time, relative position of measuring points, the ratio of fine coal thickness, artificial density, voidage and activation energy were selected as input variables and oxygen concentration and temperature of coal column as output variables. Then our trained network was applied to predict the trend on the untried experimental data. The results show that the oxygen concentration in the coal column could be reduced below the minimum still able to induce spontaneous combustion of coal-6% by covering the coal pile with fine coal, which would meet the requirement to prevent spontaneous combustion of coal stockpiles. Based on the predic-tion of this ANN, the average errors of oxygen concentration and temperature were respectively 0.5% and 7 ~C, which meet actual tolerances. The implementation of the method would provide a practical guide in understanding the course of self-heating and spontaneous combustion of coal stockpiles.