矿井主通风机叶轮磨损失效的评价

矿井主通风机叶轮严重磨损威胁着矿井安全生产 ,研究主通风机叶轮磨损和正确地评价叶轮的磨损失效 ,对煤矿安全生产具有重大的现实意义。应用气—固两相流动理论分析了主通风机叶轮的磨损部位 ,结论与现场叶轮的实际磨损相吻合。提出了叶轮磨损过程的 3个阶段。利用材料磨损理论分析了主通风机叶轮磨损机理 ,得出了叶轮磨损是以气体动力学磨料的冲蚀磨损为主 ,低应力擦伤型磨料磨损、腐蚀磨损为辅的结论。依据国家标准 ,结合矿井主通风机工作特点 ,从安全角度提出了矿井主通风机叶轮磨损永久失效的判据 ,并给出了判定标准。     

煤体注水湿润半径预测的神经网络模型

合理的注水半径一直是煤体注水防尘技术中难以确定的参数。笔者基于对影响煤体注水半径因素的分析和神经网络理论的原理之上 ,设计网络模型为 3层 ,输入层为 7个节点 ,应用BP网络算法 ,建立了煤体注水湿润半径的预测模型 ,并对其参数进行了讨论。然后 ,用平顶山矿务局和水城矿务局 13个矿 19个回采工作面的统计资料对BP网络进行自适应学习 ,并取η =0 .9,α =0 .82 ,控制网络总误差E≤ 10 6。经过 2 12 34次迭代后 ,网络趋于稳定。用训练好的网络对平顶山矿务局的某矿的 3层煤的注水湿润半径进行预测 ,预测结果与实测值很接近。其误差分别为 0 .5 %,0 .6 %和 0 .7%。     

复采残采煤层小煤矿开采技术研究

平顶山市新华区为全国重点产煤县 (区 ) ,区内煤矿以乡镇小煤矿为主 ;小煤矿井田多位于平顶山煤业集团大型矿井浅部报废水平内 ,主要开采残留煤柱和采后剩余底部煤层。笔者根据新华区小煤矿生产的特点 ,总结、规范了复采残采煤层小煤矿井田开拓、采煤方法 ,重点研究了房柱式采煤法采准巷道布置和采煤工艺 ,特别是保持煤房稳定、提高采煤工作面安全生产的特殊支护问题 ;同时结合小煤矿生产中存在的主要问题 ,依据煤炭行业的法律、法规 ,提出了小煤矿采煤方法改进的技术措施。上述研究成果 ,对规范我国小煤矿的采煤方法、提高小煤矿的安全生产能力、推动小煤矿由数量型向质量效益型转化、发展地方经济都具有重要的现实意义。     

改进BP算法在煤与瓦斯突出预测中的应用

为了正确预测煤与瓦斯突出的趋势与危险性 ,基于反向BP神经网络 ,笔者提出了一种改进的BP网络模型 :为了加快BP网络的收敛速度 ,增强其跳出局部极小点的能力 ,采用了自适应变步长法和改进模拟退火法 (SA法 )相结合的方法。实际应用表明 ,该模型收敛速度快 ,准确性高 ,具有较高的可靠性和实用性 ,是一种十分有效的煤与瓦斯突出危险性预测方法。     

煤矸石山自然发火数学模型在红阳三矿新矸石山自燃防治中的应用

煤矿矸石山自燃现象普遍存在 ,对环境污染及危害极大 ,防治矸石山自燃是矿区环境修复的重点研究内容。笔者利用宏观的连续介质研究方法 ,以多孔介质流体动力学理论为指导 ,建立了煤矿矸石山自然发火数学模型 ,从数学上揭示了矸石山自燃的动态演变过程。通过分析矸石山内的渗流场明确了自然发火的影响因素及内在联系 ,针对红阳三矿新矸石山的自燃预防问题 ,提出了碾压、覆盖和边界注浆相结合的综合防治施工方案。该技术在红阳三矿新矸石山的现场应用表明 ,治理方案科学、经济、合理 ,实施效果良好。研究结果对预防矸石山自燃具有理论指导意义与实际应用价值。     

煤层底板采动导水破坏深度计算的神经网络方法

在综合分析影响煤层底板采动导水破坏深度因素的基础上 ,应用人工神经网络方法 ,建立了底板破坏深度的计算模型。该模型利用现场观测资料作为学习训练样本和测试样本 ,对模型的测算结果、理论计算值和实测值进行了对比分析。结果表明 :用神经网络方法计算底板破坏深度考虑的因素更加全面 ,结果更接近于实际。笔者研究的计算模型和测算方法 ,为承压水上安全采煤决策提供了科学依据。     

CO2 storage capacity estimation: Methodology and gaps

Implementation of CO₂ capture and geological storage (CCGS) technology at the scale needed to achieve a significant and meaningful reduction in CO₂ emissions requires knowledge of the available CO₂ storage capacity. CO₂ storage capacity assessments may be conducted at various scales—in decreasing order of size and increasing order of resolution: country, basin, regional, local and site-specific. Estimation of the CO₂ storage capacity in depleted oil and gas reservoirs is straightforward and is based on recoverable reserves, reservoir properties and in situ CO₂ characteristics. In the case of CO₂-EOR, the CO₂ storage capacity can be roughly evaluated on the basis of worldwide field experience or more accurately through numerical simulations. Determination of the theoretical CO₂ storage capacity in coal beds is based on coal thickness and CO₂ adsorption isotherms, and recovery and completion factors. Evaluation of the CO₂ storage capacity in deep saline aquifers is very complex because four trapping mechanisms that act at different rates are involved and, at times, all mechanisms may be operating simultaneously. The level of detail and resolution required in the data make reliable and accurate estimation of CO₂ storage capacity in deep saline aquifers practical only at the local and site-specific scales. This paper follows a previous one on issues and development of standards for CO₂ storage capacity estimation, and provides a clear set of definitions and methodologies for the assessment of CO₂ storage capacity in geological media. Notwithstanding the defined methodologies suggested for estimating CO₂ storage capacity, major challenges lie ahead because of lack of data, particularly for coal beds and deep saline aquifers, lack of knowledge about the coefficients that reduce storage capacity from theoretical to effective and to practical, and lack of knowledge about the interplay between various trapping mechanisms at work in deep saline aquifers.     

Kinetics characteristics of coal low-temperature oxidation in oxygen-depleted air

The longwall gob (mined-out) area is one of the main places that are prone to coal spontaneous combustion and most of the residual coal in it is in oxygen-depleted air as it is a semi-enclosed space. A DSC (Differential scanning calorimetry) test system was designed to accurately test the heat generation of coal oxidation in different oxygen concentration atmosphere, based on which the kinetics parameters (activation energy and pre-exponential factor) of coal low-temperature oxidation in oxygen-depleted air were solved out. The results show that the kinetics parameters present obvious stage features and the lower the oxygen concentration is, the smaller is the difference of the kinetics parameters that in different oxidation stages. When the oxygen concentration is lower than 5% and 3% for jet coal and meagre coal respectively, the kinetics parameters of slow oxidation start to be greater than that of rapid oxidation. Both in the slow oxidation and rapid oxidation stage, with the decrease of oxygen concentration, kinetics parameters present significant decline on the whole while in different oxygen concentration range, the decline rate is different. It's concluded that when assessing the residual coal's self-heating risk, we need to use the corresponding kinetics parameters of coal oxidation in the oxygen concentration of the location where the residual coal is and the safety factor will be greater to only use the kinetics parameters of coal oxidation in slow oxidation stage. This study is of great significance for the assessment and control of the self-heating risk of coal that in different oxygen concentration atmospheres of the longwall gob areas.     

Serious BTEX pollution in rural area of the North China Plain during winter season

Atmospheric BTEX compounds(benzene, toluene, ethylbenzene and xylenes) in a rural site of the North China Plain(NCP) were preliminarily investigated in winter, and the outdoor concentrations(25.8–236.0 μg/m3) were found to be much higher than those reported in urban regions. The pollution of BTEX inside a farmer's house was even more serious, with combined concentrations of 254.5–1552.9 μg/m3. Based on the ratio of benzene to toluene(1.17 ± 0.34) measured, the serious BTEX pollution in the rural site was mainly ascribed to domestic coal combustion for heating during the winter season. With the enhancement of farmers' incomes in recent years, coal consumption by farmers in the NCP is rapidly increasing to keep their houses warm, and hence the serious air pollution in rural areas of the NCP during winter, including BTEX, should be paid great attention.     

Study on acceleration and suppression properties of coal gangue with different void fractions on gas explosion propagation

Gas explosion is one of the main disasters in coal mining. Plenty of coal gangue are generally distributed in the disaster areas in gob. Experiments were carried out to explore the propagation law of the gas explosion distributed by coal gangue. The variation characteristics of the overpressure, pressure rise rate, and flame shape with void fractions were analyzed. The results showed that the effect of the coal gangue on the explosion intensity changed from suppression to acceleration with the increase of void fraction, the flame front upstream blockage area changed from laminar state to turbulent divergent state, and a reverse flame was formed. When the void fraction of the coal gangue was 0.50–0.65, the maximum overpressure downstream of the blocked area were positively correlated with the void fraction and the critical suppression range was between 0.50 and 0.55. When the void fraction was lower than 0.50, the flame was quenched in the coal gangue, neither the flame nor the pressure could pass through the blocked area. It is helpful to guide the improvement of coal recovery process to avoid the expansion of the explosion impact in coalmine gob.