共查询到20条相似文献，搜索用时 15 毫秒
1.
Control of gas emissions in underground coal mines 总被引：4，自引：0，他引：4
Klaus Noack 《International Journal of Coal Geology》1998,35(1-4)
A high level of knowledge is now available in the extremely relevant field of underground gas emissions from coal mines. However, there are still tasks seeking improved solutions, such as prediction of gas emissions, choice of the most suitable panel design, extension of predrainage systems, further optimization of postdrainage systems, options for the control of gas emissions during retreat mining operations, and prevention of gas outbursts. Research results on these most important topics are presented and critically evaluated. Methods to predict gas emissions for disturbed and undisturbed longwall faces are presented. Prediction of the worked seam gas emission and the gas emission from headings are also mentioned but not examined in detail. The ventilation requirements are derived from the prediction results and in combination with gas drainage the best distribution of available air currents is planned. The drainage of the gas from the worked coal seam, also referred to as predrainage, can be performed without application of suction only by over or underworking the seam. But in cases where this simple method is not applicable or not effective enough, inseam-boreholes are needed to which suction is applied for a relatively long time. The reason for this is the low permeability of deep coal seams in Europe. The main influences on the efficiency of the different degasing methods are explained. Conventional gas drainage employing cross measure boreholes is still capable of improvement, in terms of drilling and equipment as well as the geometrical borehole parameters and the operation of the overall system. Improved control of gas emissions at the return end of retreating faces can be achieved by installation of gas drainage systems based on drainage roadways or with long and large diameter boreholes. The back-return method can be operated safely only with great difficulty, if at all. Another method is lean-gas drainage from the goaf. The gas outburst situation in Germany is characterized by events predominantly in the form of ‘nonclassical' outbursts categorized as ‘sudden liberation of significant quantities of gas'. Recent research results in this field led to a classification of these phenomena into five categories, for which suitable early detection and prevention measures are mentioned. 相似文献
2.
Modeling and prediction of ventilation methane emissions of U.S. longwall mines using supervised artificial neural networks 总被引：1，自引：1，他引：0
C.
zgen Karacan 《International Journal of Coal Geology》2008,73(3-4):371-387
Methane emissions from a longwall ventilation system are an important indicator of how much methane a particular mine is producing and how much air should be provided to keep the methane levels under statutory limits. Knowing the amount of ventilation methane emission is also important for environmental considerations and for identifying opportunities to capture and utilize the methane for energy production.Prediction of methane emissions before mining is difficult since it depends on a number of geological, geographical, and operational factors. This study proposes a principle component analysis (PCA) and artificial neural network (ANN)-based approach to predict the ventilation methane emission rates of U.S. longwall mines.Ventilation emission data obtained from 63 longwall mines in 10 states for the years between 1985 and 2005 were combined with corresponding coalbed properties, geographical information, and longwall operation parameters. The compiled database resulted in 17 parameters that potentially impacted emissions. PCA was used to determine those variables that most influenced ventilation emissions and were considered for further predictive modeling using ANN. Different combinations of variables in the data set and network structures were used for network training and testing to achieve minimum mean square errors and high correlations between measurements and predictions. The resultant ANN model using nine main input variables was superior to multilinear and second-order non-linear models for predicting the new data. The ANN model predicted methane emissions with high accuracy. It is concluded that the model can be used as a predictive tool since it includes those factors that influence longwall ventilation emission rates. 相似文献
3.
目前,在波兰41对主要生产矿井中,有23对高瓦斯矿井进行了瓦斯抽放。2004年瓦斯平均抽放率为30%,平均利用率为39%。根据瓦斯地质条件、瓦斯涌出特点和采区通风方式,着重介绍了波兰煤矿强化煤层、围岩和采空区瓦斯抽放,提高矿井瓦斯抽放效率的工艺技术特点。在工作面的瓦斯排放中,注重开采、通风与瓦斯抽放一体化,通过优化抽放钻孔布置,取得钻孔瓦斯抽放的最佳效果,是波兰煤矿瓦斯治理的一项成功经验,成为煤矿持续安全高效生产的重要技术保障。 相似文献
4.
Coalbed methane: From hazard to resource 总被引：4，自引：0，他引：4
Coalbed gas, which mainly consists of methane, has remained a major hazard affecting safety and productivity in underground coal mines for more than 100 years. Coalbed gas emissions have resulted in outbursts and explosions where ignited by open lights, smoking or improper use of black blasting powder, and machinery operations. Investigations of coal gas outbursts and explosions during the past century were aimed at predicting and preventing this mine hazard. During this time, gas emissions were diluted with ventilation by airways (e.g., tunnels, vertical and horizontal drillholes, shafts) and by drainage boreholes. The 1970's ‘energy crisis' led to studies of the feasibility of producing the gas for commercial use. Subsequent research on the origin, accumulation, distribution, availability, and recoverability has been pursued vigorously during the past two decades. Since the 1970's research investigations on the causes and effects of coal mine outbursts and gas emissions have led to major advances towards the recovery and development of coalbed methane for commercial use. Thus, coalbed methane as a mining hazard was harnessed as a conventional gas resource. 相似文献
5.
B. B. Beamish 《Geotechnical and Geological Engineering》1990,8(2):131-147
Summary Continuous gas monitoring has been performed in three development panels at No. 2 Mine, Collinsville, Queensland, Australia to assess seam gassiness at the mining face as an indication of outburst-proneness. The first panel monitored encountered two outbursts during mining of virgin conditions, and a third outburst occurred on the fringe of a gas-drained block, adjacent to a thrust fault. The second panel successfully mined through the thrust fault without outbursting and finally halted due to high gas emissions. The third panel mined through a gas-drained block of coal, where an overall substantial reduction in gas emission was observed.The results from all three panels have been analysed and compared to establish parameters for outburst-proneness assessment, based on a face cut-out cycle (FCC) CO2 emission. For FCC CO2 emissions less than 2.6 m3 t–1, no outbursting occurs, and normal mining proceeds. Up to 3.8 m3 t–1, low-medium outburst-prone conditions exist and mining takes place under controlled procedures. When values exceed 3.8 m3 t–1, high outburst-prone conditions exist and mining is halted. 相似文献
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Hydrogen from coal: Production and utilisation technologies 总被引：2，自引：0，他引：2
E. Shoko B. McLellan A.L. Dicks J.C. Diniz da Costa 《International Journal of Coal Geology》2006,65(3-4):213-222
Although coal may be viewed as a dirty fuel due to its high greenhouse emissions when combusted, a strong case can be made for coal to be a major world source of clean H2 energy. Apart from the fact that resources of coal will outlast oil and natural gas by centuries, there is a shift towards developing environmentally benign coal technologies, which can lead to high energy conversion efficiencies and low air pollution emissions as compared to conventional coal fired power generation plant. There are currently several world research and industrial development projects in the areas of Integrated Gasification Combined Cycles (IGCC) and Integrated Gasification Fuel Cell (IGFC) systems. In such systems, there is a need to integrate complex unit operations including gasifiers, gas separation and cleaning units, water gas shift reactors, turbines, heat exchangers, steam generators and fuel cells. IGFC systems tested in the USA, Europe and Japan employing gasifiers (Texaco, Lurgi and Eagle) and fuel cells have resulted in energy conversions at efficiency of 47.5% (HHV) which is much higher than the 30–35% efficiency of conventional coal fired power generation. Solid oxide fuel cells (SOFC) and molten carbonate fuel cells (MCFC) are the front runners in energy production from coal gases. These fuel cells can operate at high temperatures and are robust to gas poisoning impurities. IGCC and IGFC technologies are expensive and currently economically uncompetitive as compared to established and mature power generation technology. However, further efficiency and technology improvements coupled with world pressures on limitation of greenhouse gases and other gaseous pollutants could make IGCC/IGFC technically and economically viable for hydrogen production and utilisation in clean and environmentally benign energy systems. 相似文献
9.
A. Saghafi 《Australian Journal of Earth Sciences》2014,61(3):453-462
A new site-specific (Tier 3) method has been developed to determine greenhouse gas emissions from open coal mining. The Tier 3 method presented here is based on extensive measurement of gas emissions from open-cut coal mines and the physics of gas desorption from coal. It was adopted by Australian National Greenhouse and Energy Reporting in 2009 and since 2012 formed the scientific basis for the Australian Government guidelines on calculating greenhouse gas emissions from open cut mines. The main strength of this method is its site-specific nature and accuracy, as well as its ability to be integrated with routine coal exploration programs. New concepts were produced for the model: a coal mine is regarded as a ‘gas reservoir,’ with coal seam gas being emitted from a ‘gas release zone’ that consists of sedimentary geological units (emission layers) above and below the base of the mine. The primary data required for the method are the in situ gas content and gas composition of the coal and carbonaceous rocks contained within the gas-release zone. These data are obtained through direct measurement of gas desorption from bore cores. To reduce gas drilling, a mine lease is compartmentalised into ‘gas zones’ of similar gas content and reservoir properties. The outputs of the method are emission density (the potential volume of gas emitted from mining site per unit area of the ground surface) and emission factor (the gas volume emitted per tonne of raw coal extracted). Owing to spatial variability and errors of measurement, the estimate of emissions is associated with uncertainty. A simple method of calculating uncertainty of emissions is presented in this work. 相似文献
10.
林南仓属于低瓦斯矿井,但存在高瓦斯区域。煤层和采空区是瓦斯的主要来源,尤以采空涌出量大,给煤矿生产和安全带来了极大隐患。通过在1129综采工作面风道施工高位瓦斯孔,把钻孔打到采空区一侧煤层顶板以上冒落裂隙带内,用钻孔进行瓦斯抽放,使采空内的瓦斯通过裂隙带沿钻孔抽出,有效降低综采工作面瓦斯浓度,保证综采工作面正常回采和安全生产。 相似文献
11.
C.
zgen Karacan 《International Journal of Coal Geology》2009,79(4):131-144
Gob gas ventholes (GGV) are used to control methane inflows into a longwall operation by capturing it within the overlying fractured strata before it enters the work environment. Thus, it is important to understand the effects of various factors, such as drilling parameters, location of borehole, applied vacuum by exhausters and mining/panel parameters in order to be able to evaluate the performance of GGVs and to predict their effectiveness in controlling methane emissions. However, a practical model for this purpose currently does not exist.In this paper, we analyzed the total gas flow rates and methane percentages from 10 GGVs located on three adjacent panels operated in Pittsburgh coalbed in Southwestern Pennsylvania section of Northern Appalachian basin. The ventholes were drilled from different surface elevations and were located at varying distances from the start-up ends of the panels and from the tailgate entries. Exhauster pressures, casing diameters, location of longwall face and mining rates and production data were also recorded. These data were incorporated into a multilayer-perceptron (MLP) type artificial neural network (ANN) to model venthole production. The results showed that the two-hidden layer model predicted total production and the methane content of the GGVs with more than 90% accuracy. The ANN model was further used to conduct sensitivity analyses about the mean of the input variables to determine the effect of each input variable on the predicted production performance of GGVs. 相似文献
12.
甲烷是最主要的非二氧化碳温室气体,受到越来越多的重视。煤炭甲烷是我国最主要的甲烷排放源类型,我国也是世界煤炭甲烷排放量最大的国家,煤炭甲烷的有效排放管控与高效开发利用兼具温室气体减排、能源气体开发利用和灾害气体防治三重意义。基于系统调研和研究工作积累,概述了煤炭甲烷排放管控背景,总结了全球与代表性国家煤炭甲烷排放及其管控现状,阐释了我国煤炭甲烷开发利用与排放管控历程及发展趋势,讨论和前瞻了我国煤炭甲烷减排路径与减排潜力。已有研究工作表明:我国煤炭甲烷排放主要来自煤炭地下开采风排瓦斯,且较长时期内仍是我国煤炭甲烷的主要来源;随着我国关闭矿井增多,由此产生的关闭矿井甲烷排放量呈增长趋势,是我国煤炭甲烷不容忽视的来源。随着碳中和目标的提出,温室气体减排的政策导向逐渐成为我国煤炭甲烷排放管控的重点,明确了煤炭甲烷减排方向。我国煤炭甲烷排放管控形成了以煤层气勘探开发利用、煤矿瓦斯抽采利用、关闭/废弃矿井瓦斯抽采利用、乏风瓦斯利用等全浓度利用,煤炭采前、采中和采后全周期利用为特征的关键技术路径。我国煤炭甲烷排放管控面临巨大压力和严峻挑战,诸多政策、机制、技术问题亟待破解。突破复杂地质条件适配性煤层... 相似文献
13.
Methane exchange between coal-bearing basins and the atmosphere: the Ruhr Basin and the Lower Rhine Embayment, Germany 总被引：1，自引：0，他引：1
Thomas Thielemann Andreas Lücke Gerhard H. Schleser Ralf Littke 《Organic Geochemistry》2000,31(12):121
A precise knowledge of methane exchange processes is required to fully understand the recent rise of atmospheric methane concentration. Three of these processes take place at the lithosphere/atmosphere boundary: bacterial consumption of methane and emission of bacterial or thermogenic methane. This study was initiated to quantify these processes on a regional scale in the Ruhr Basin and the Lower Rhine Embayment. Since these areas are subject to bituminous coal and lignite mining, natural and anthropogenically-induced methane exchange processes could be studied. The methane emission and consumption rates and their carbon isotope signal were measured at the lithosphere/atmosphere boundary using flux chambers. On most of the soils studied, methane consumption by bacteria was identified. Thermogenic methane was released only at some of the natural faults examined. In active and abandoned bituminous coal mining areas methane emissions were restricted to small areas, where high emission rates were measured. The carbon isotope composition of methane at natural faults and in mining subsidence troughs was typical of thermogenic methane (−45 to −32 ‰ δ13C). Methane exchange balancing revealed that natural methane emissions from these two basins represent no source of atmospheric importance. However, methane release by upcast mining shafts dominates the methane exchange processes and is by about two orders of magnitude greater than methane consumption by bacterial oxidation in the soils. 相似文献
14.
Around the globe underground hard coal mining leads to a release of methane into the atmosphere. About 7% of the global annual methane emissions originate from coal mining. In the year 2002, 16 countries used coal gas to generate heat and electricity. In many cases, the exact size of coalbed methane reservoirs is not identified. The possibility of a long-term gas production and its profitability at single sites are unknown. To clarify these points, the processes of gas generation as well as the gas-in-place volume have to be determined. Both issues are tackled here for the Ruhr basin. Within this basin, coal gas samples were taken at 13 gas production sites, spread over three samplings within 14 months. There were virtually no changes in the concentrations of gas components at single sites within this period. The isotope composition of methane (δ13C-methane: −40.0 to −57.3‰ vs. PDB) revealed that the produced methane is a mixture of gases of thermogenic and microbial origin. The microbial contribution of methane seems to be more pronounced at sites of active and especially abandoned coal mining than at unmined places. Ethane and propane are of thermogenic origin, with ethane's isotopic composition tending to heavier values (richer in 13C) with time. This time-dependent phenomenon is interpreted as being caused by desorption. In addition, living methanogenic archaea were detected in mine water samples from depths down to 1200 m. 相似文献
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C.
zgen Karacan 《International Journal of Coal Geology》2007,72(3-4):221-239
In longwall development mining of coal seams, planning, optimizing and providing adequate ventilation are very important steps to eliminate the accumulation of explosive methane–air mixtures in the working environment. Mine operators usually try to supply maximum ventilation air based on the capacity of the system and the predicted need underground. This approach is neither economical nor safer as ventilation capacity may decrease in time depending on various mining and coalbed parameters. Thus, it is important to develop better engineered approaches to optimize mine ventilation effectiveness and, therefore, to ensure a safer work environment.This study presents an approach using coalbed methane reservoir modeling and an artificial neural network (ANN) design for prediction and optimization of methane inflows and ventilation air requirements to maintain methane concentrations below statutory limits. A coalbed reservoir model of a three-entry development section, which is typical of Pittsburgh Coalbed mines in the Southwestern Pennsylvania section of Northern Appalachian Basin, was developed taking into account the presence and absence of shielding boreholes around the entries against methane inflow. In the model, grids were dynamically controlled to simulate the advance of mining for parametric simulations.Development and application of artificial neural networks as an optimization tool for ventilation requirements are introduced. Model predictions are used to develop, train, and test artificial neural networks to optimize ventilation requirements. The sensitivity and applications of proposed networks for predicting simulator data are presented and discussed. Results show that reservoir simulations and integrated ANN models can be practical and powerful tools for predicting methane emissions and optimization of ventilation air requirements. 相似文献
17.
Geological and geotechnical aspects of underground coal mining methods within Australia 总被引：1，自引：1，他引：0
B. Scott P. G. Ranjtih S. K. Choi Manoj Khandelwal 《Environmental Earth Sciences》2010,60(5):1007-1019
About one quarter of the coal produced in Australia is by underground mining methods. The most commonly used underground coal
mining methods in Australia are longwall, and room and pillar. This paper provides a detailed review of the two methods, including
their advantages and disadvantages, the major geotechnical and operational issues, and the factors that need to be considered
regarding their choice, including the varying geological and geotechnical conditions suited to a particular method. Factors
and issues such as capital cost, productivity, recovery, versatility and mine safety associated with the two methods are discussed
and compared. The major advantages of the longwall mining method include its suitability for mining at greater depth, higher
recovery, and higher production rate compared to room and pillar. The main disadvantages of the room and pillar method are
the higher risks of roof and pillar collapse, higher capital costs incurred as well as lower recovery rate. 相似文献
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以潞安矿区备煤矿3煤层瓦斯含量为依据,运用瓦斯赋存构造逐级控制理论研究了矿区瓦斯赋存特征。,分析认为,矿区瓦斯浅部含量低,深部含量高,各矿瓦斯涌出由东向西呈现逐渐增加的趋势;以两大断褶带为界限,将矿区划分为北部（I）、中部（Ⅱ）和南部（Ⅲ）三个瓦斯地质单元：I区井田总体处于拉张体制下形成,使得井田内部分瓦斯得到释放;Ⅱ区东部近东西向断裂处于拉张体制,使得瓦斯大量逸散,至西部构造变形微弱,近南北向的褶曲和逆断裂有利于瓦斯保存,成为高瓦斯区;Ⅲ区构造复杂,尤其在深部,褶曲构造受后期构造运动影响较小,煤层瓦斯富集．瓦斯压力较大。 相似文献
20.
以煤矿钻孔煤样瓦斯数据及井下实测瓦斯含量为依据,分析了乌东矿区构造对瓦斯赋存的控制作用,认为区内以七道湾背斜、八道湾向斜和F2逆冲断层为主要构造形迹,并控制了煤层的赋存状态和瓦斯分布规律;八道湾向斜南翼地层倾角陡近乎直立,地层局部倒转,有利于瓦斯逸散,而北翼煤层倾角缓,且受到矿区南部碗窑沟逆冲断层（F2）挤压作用,断面形成瓦斯的＂隔挡＂面,阻断了瓦斯的逸散通道,造成向斜北翼瓦斯含量高于南翼;瓦斯含量与煤层埋深呈正相关关系。随着各矿向下延深开采,瓦斯涌出量将会逐渐加大。因此,掌握矿区的瓦斯地质规律,对其安全生产具有指导意义。 相似文献