姚橋煤礦1.2Mta新井設(shè)計含5張CAD圖-采礦工程.zip
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英文原文
Coal fires
A coal fire is the underground smouldering of a coal seam or coal mine. They are emerging as a global threat with significant economic, social and ecological impacts.
?Coal seam fires ? ? ?? Prevention ? ? ?? Extinction ?
Coal seam fires may be categorized into near surface fires in outcropping seams that are supported by oxygen from direct contact to the atmosphere and mine fires supported by oxygen from the artificial mine ventilation.
Spontaneous coal fires
The final reason for all fires is the chemical reaction of the hydrocarbon molecules of the fuel with oxygen of the air. This exothermal reaction can take place at any temperature. The reaction velocity however is strongly temperature dependent and increases with temperature nearly exponential. If the fuel is broken up in small particles or porous, oxygen has access everywhere and the entire volume may act as a heat source.
The situation is not critical if the heat energy transported to the surface by either conduction or convection and finally lost to the environment is larger than the heat produced by the reaction. If the heat produced by the reaction however is over longer time larger than the heat loss to the environment the system will turn to be critical. Temperatures will rise continuously, the reaction will accelerate and finally the fuel will start burning spontaneously.
Two factors will finally be responsible: The surrounding temperature and the volume of fuel involved:
· If the surrounding temperatures are higher the oxidation processes will run faster and thus the heat production is higher within the fuel volume.
· If the fuel volume is larger the heat produced inside can hardly flow to the surface and into the environment, the fuel is more likely to start burning. In addition material broken up in small part or porous material usually has a low heat conduction coefficient and may act like thermal isolators.
The most important parameter characterizing self ignition is the self ignition temperature. This is not a material constant, but dependent on volume and shape, more specific on the relation of volume and surface. Self ignition temperatures decrease strongly with volume. Furthermore this temperature is dependent on many fuel material parameters as caloric value, heat conduction coefficient, particle size. In case of coal it depends further more on the coal type and rank; for hard coal its generally higher the for brown coal or lignite.
If the fuel volume is sufficient spontaneous ignition may happen at room temperatures or at temperature at the yearly average temperature. The time needed for the fire to develop may be month or even years.
Brown coal or lignite may start burning at 40 °C to 60 °C whereas anthracite will start (under the same conditions!) at 140 °C. The smouldering will usually start several decimeters below the surface in a depth where the permeability of the coal allows the access of enough air but the air flow is slow enough to not extract the produced heat by convection. Due to the low heat conductance coefficient of coal heat extraction by conduction alone is not sufficient.
Factors influencing spontaneous induction are beside others:
???? Air circulation
???? Climate (arid, semiarid)
???? Coal quality coal type (carbon content, gas content, ash content, rank)
???? Particle size (small particles have larger surface/volume relation)
???? Geological geomorphologic settings
???? Mining influence (Openings, fractures, subsidence)
???? Hydro geological settings (moisture content)
Spontaneous ignition needs time. How much depends on many factors, as temperature, volume, particle size. Finally the time to ignition is another parameter to describe the addiction of coal to burn. For larger volumes the temperature needed is smaller but the time needed larger. Normally it will take months before coal will start smouldering.
If coal seams outcrop to the surface, air has access for long times, at those location seams will start to burn spontaneous and continue burning for decades. Globally at least 20 to 30 million tons are burned by those fires. The coal being made inaccessible for further mining is about the times more.
Heat producing reactions
There are two know heat producing adsorption reactions:
Physisorption of oxygen. This takes place at temperatures up to 50 °C and delivers 42kJ/mol.
Chemisorptions of oxygen. This produces several chemical compounds after overcome the activation energy of the coal surface. From carbon-, hydrogen- and oxygen atoms peroxides are formed and about 100 kJ/mol of heat energy is produced. The newly built molecules may oxidize further and produce heat with increasing temperatures and finally exhaust as carbon dioxide, carbon monoxide and water (vapor).
The most important reactions are:
??? C und O2 form CO2 (394 kJ/mol)
??? 2C und O2 form 2CO (170 kJ/mol)
Coal seam fires not spontaneously ignited
Nearly all coal seam fire started spontaneously. In some case however external ignition is possible. Finally we may not see if a certain fire started spontaneous or not. This is in any case true for fires in deep mines, but also for fires close to the surface as long as mining is involved. Possible sources for ignition are electrical machinery, bad maintained bearings as well as handling of explosives or wrong application of welding or beveling.
In many reported cases leaving back coal in mining application or accumulation of coal dust was the final reason for a fire. Consequent acceptance of mining regulation may avoid most of those fires.
Mine fire may interact with methane explosions or coal dust explosions in mines. Near surface coal fires may interact with forest fires. This was reported from the USA and especially from Sumatra, Indonesia.
Global coal seam fires ?
Coal fires are reported from coal mining districts all over the world. The most important are the following:
India
Besides the areas of Ranigani and Singareni coal seam fires rage in Jharia (North West India). In an area of about 700 km2 about 160 fires are burning. As a consequence of the fires hang slides, sink holes and subsidence is reported. As this area is densely populated pollution is severe.
Coal mining supports the development of fires it give air better access. On the other hand coal fires imitate the mining and may even stop it. It is estimated that in India 70% of the fires are due to mining.
USA
Many coal mining areas in the USA suffer from spontaneous coal seam fires. The Federal Office of Surface Mining (OSM) provides a data base (AMLIS) that lists 150 fire zones (1999). Those are not only in Kentucky, Pennsylvania and West Virginia in the east of the Appalachian-coal district, but also in?Colorado and the Rocky Mountains.
In Pennsylvania 45 fire zones are reported. The most known is Centralia Mine, in the anthracite- coal area of Columbia County. This fire burn since 1962 and develop below the city. There was some effort to extinguishing the fires but finally the city was lost.
In Colorado some spontaneous coal fires are due to annual changes in the water table. Those changes may rise water temperatures by 30 °C, and thus start the self ignition process.
In Powder River Basin in Wyoming und Montana about 800 billion tons of lignite is known. Already the Lewis-und-Clark-Expedition (1804 to 1806) reported on coal fires in that region. Here we have also coal fires from geological times. They are three million years old and shaped the landscape to a certain extend. An area of 4.ooo km2 is covered with clinker or scoria, part of the laying in the c. Well known and spectacular is the outlook from the scoria point on an extended area of fire red clinker.
Germany
In Planitz near Zwickau a coal seam burned from 1476 and was finally not extinguished before 1860. Ernst August Geitner started in 1479 a green house with tropical plants above the known Planitz fire zone and was possible the first in using energy from coal fires commercially. In Dudweiler (Saar) 1668 a coal seam started to burn and developed to a tourist attraction named 'Burning Mountain', even visited and described by Goethe. Equally known is the so called 'Smelling Wall' at the east slopes of 'Hohe Meissner', where after closing the lignite mining some seams started burning centuries ago and exhaust gases escaped to the surface causing the 'smell'. The hard rock mining was accompanied all time by coal- mainly mine fires. Reported are about two fires per year on average. As the coal mining concentrated in Germany on the Ruhr- and Saar Area, fire prevention technologies were developed in those areas. Today most of the coal fires here are due to unwanted ventilation in abandoned parts of the mines. Those measures were principally successful and heavy mine fires with loss of human life did not occur.
After closing the last deep lignite mines in Hirschberg close to Grossalmerode in Hessen in 2003, lignite is mined in Germany in open pits only, in the Rheinische Revier, in the?Mitteldeutschen Revier and in the?Lausitzer Revier. In the last years no coal fires were reported from these areas as complex strategies of prevention are successful.
Rest of Europe and Russia
Reported coal fires in those areas are decreasing parallel to the decrease of mining activity in general. Some burning is reported from Poland, Czech Republic and Ukraine. In Ukraine 2.000 million tons are laying on dumps and 74 fire zones are reported. This is mainly in the basins of Kuzbass, Petschora and Donezk.
In Kosovo (Serbia) and Bosnia-Herzegovina coal seams are burning close to open pit or deep mining.
Africa?
The big coal mining districts of Africa are in the south of the continent, in South Africa, Zimbabwe, Botswana, Mozambique and Zambia. Coal fires are reported from all that regions.
Australia
Five kilometers north of the city of Wingen in New South Wales (NSW) the Burning Mountain is a tourist place since thousands of years. Actually the fire is 30m below surface and advances about 1m per year. Overall it moved about 6 kilometers. Many more fire zones are reported in Australia.?
China
China is the larges coal producer (and consumer) world wide: It produces about 1.8 billion tons in 2006. As a result coal fires are a severe problem in China. It is estimated that 10-20 million tons are directly burned by coal seam fires and 100-200 million tons of coal are lost for the mining industry. The fire zones are located in a belt covering the entire north of China. More than 100 burning areas are known divided in several burning zones each. Concentrations are in the provinces (autonomous regions) Xinjiang, Inner Mongolia and Ningxia. Besides the loss of energy resources those fires cause air and water pollution and emit enormous amounts of green house gases (carbon dioxide and methane). This mainly causes the international interest in those fires. China is the only country in the world starting and performing enormous activities for extinction. Several fires are already extinguished. New methods are developed within a Sino-German Research Initiative.?
中文譯文
煤炭火災(zāi)
煤炭火災(zāi)是指煤層或煤礦的煤炭在地下燜燃的現(xiàn)象。它是一種對經(jīng)濟(jì)、社會和生態(tài)有重大影響的全球性威脅。
煤層火災(zāi) 防火 滅火
煤層火災(zāi)可以分為兩種，一種是在地表巖層裂隙中發(fā)生的由大氣直接提供氧氣的近地表火災(zāi)，另一種是在礦井中發(fā)生的由人工通風(fēng)提供氧氣的井下火災(zāi)。
煤的自然發(fā)火
一切火災(zāi)發(fā)生的決定性因素是燃料中的碳?xì)浠衔锓肿雍涂諝庵械难鯕獍l(fā)生化學(xué)反應(yīng)。這種放熱反應(yīng)可以發(fā)生在任何溫度條件下。然而反應(yīng)的速度又與溫度非常相關(guān)，增長速度隨溫度的變化呈近似指數(shù)的關(guān)系。如果燃料被分解為很小的微粒，那么氧氣就能和它全面接觸，并且整個容積空間就可能成為一個熱源。
如果通過傳導(dǎo)或?qū)α鱾鬟f到表面并且最終損失在外界環(huán)境中的熱能比由輻射產(chǎn)生的熱能更多，那么這種條件不是臨界的。如果由長時間的輻射產(chǎn)生的熱量比損失在外界環(huán)境中的熱量要多，那么系統(tǒng)將變成臨界的。這時溫度將持續(xù)上升，反應(yīng)將加速，燃料最終將開始自發(fā)燃燒起來。
這里有兩個決定性的因素：周圍環(huán)境的溫度和所含燃料的體積。
· 如果周圍環(huán)境的溫度很高，那么氧化的進(jìn)程就非常的快，因此燃料內(nèi)部產(chǎn)生的熱量會非常多。
· 如果燃料的體積非常大，內(nèi)部產(chǎn)生的熱量很難傳遞到表面進(jìn)入到環(huán)境中去，那么燃料更可能會開始燃燒。另外如果物質(zhì)分解成細(xì)小多孔的狀態(tài)，那么通常會有低的熱傳導(dǎo)系數(shù)，就會變得像絕熱體一樣。
描述自燃最重要的參數(shù)就是自燃點。這并不是一個由物質(zhì)材料決定的常量，而是由體積形狀尤其是體積和表面之間的關(guān)系決定的。自燃點溫度隨著燃料體積的增大而降低。此外這個溫度還由燃料物質(zhì)的具體參數(shù)決定，如熱值、熱傳導(dǎo)系數(shù)、燃料微粒的大小等。對于煤炭來說，自燃點更取決于煤的類型和等級；如無煙煤的自燃點溫度通常要高于褐煤的。
如果燃料量充足，自然發(fā)火可能會發(fā)生在室溫或常年平均溫度情況下。從開始到著火的時間可能是幾個月甚至是幾年。
褐煤可以在40°C或60°C就開始燃燒，而在同樣條件下的無煙煤則在140°C的條件下才能燃燒。燜燃通常會發(fā)生在離地表幾公寸的地下，那里的煤的滲透性允許充足的空氣進(jìn)入煤體，但是空氣的流動速度非常的慢以至于不能夠把產(chǎn)生的熱量以對流的方式放散出來。由于煤的低的熱傳導(dǎo)系數(shù)，僅僅通過對流方式放散的熱量是非常少的。
影響自然發(fā)火的因素如下：
空氣循環(huán)；
氣候（干旱，半干旱的氣候）；
煤的質(zhì)量和煤的類型（含碳量、含瓦斯量、含灰量、煤的等級）；
粒子的大?。ㄎ⒘Ｓ懈蟮谋缺砻娣e）；
地質(zhì)因素；
采礦的影響（開礦、地層結(jié)構(gòu)破壞、地表沉陷）；
水文地質(zhì)因素（含水量）；
自然發(fā)火需要一定的時間。時間的長短取決于很多因素，例如溫度、空間、粒子大小等。所以發(fā)火時間是描述煤自燃的另一個參數(shù)。對于巨大的空間來說，發(fā)生自燃所需要的溫度是比較低的，但需要的時間是很長的。通常煤要發(fā)生燜燃需要幾個月的時間。
如果煤層露出到地面，并且與空氣接觸了很長時間，那么這種情況下的煤層會發(fā)生自燃，并且能持續(xù)數(shù)十年之久。世界上至少有兩千萬到三千萬噸的煤炭是被這種火災(zāi)燃燒掉的。多次的火災(zāi)將使煤炭資源不能進(jìn)行可持續(xù)開采。
由熱產(chǎn)生的一系列反應(yīng)
有兩種已知的由熱產(chǎn)生的吸附反應(yīng)：
氧的物理吸附。這種反應(yīng)發(fā)生在高達(dá)50°C的溫度條件下，并且能放出42kJ/mol的熱量。
氧的化學(xué)吸附。這種反應(yīng)在克服煤的表面活化能之后產(chǎn)生許多化合物，形成碳原子、氫原子和氧原子的過氧化合物，并且能夠放出大約100 kJ/mol的熱量。這些新形成的分子將進(jìn)一步的氧化，伴隨著溫度的升高產(chǎn)生更多的熱量，最終形成二氧化碳、一氧化碳和水蒸氣等產(chǎn)物。
主要的反應(yīng)如下：
(394kJ/mol)
（170kJ/mol）
非自然發(fā)火的煤層火災(zāi)
幾乎所有的煤層著火都是自發(fā)的。然而在一些情況下外部點燃也是有可能的。最終我們可能不能確定一場煤層火災(zāi)是自發(fā)的還是非自發(fā)的。這種情況不僅對深層礦井中的火災(zāi)來說是真實存在的，而且對于采礦中接近地表的火災(zāi)也是一樣的?？赡芤l(fā)火災(zāi)的點火源有機械電火花，軸承的摩擦，還有爆破操作或是焊接過程中的誤操作等。
在許多已報告的事故中，采礦過程中遺留的煤炭或者是煤塵的聚集物是火災(zāi)的決定性因素。相應(yīng)的遵從采礦規(guī)章制度就可以避免大多數(shù)這種火災(zāi)。此外礦井火災(zāi)也可能與礦井瓦斯爆炸、煤塵爆炸結(jié)合在一塊發(fā)生。近地表的煤炭火災(zāi)可能會和森林火災(zāi)一塊發(fā)生。這就是來自美國，特別是蘇門答臘、印尼等國的報告中提到的。
全球性的煤層火災(zāi)
據(jù)報道，煤炭火災(zāi)發(fā)在世界各地的礦井區(qū)域都有發(fā)生。一些最重要的地方如下：
印度
除了Ranigani 和Singareni地區(qū)外，煤層火災(zāi)遍布Jharia地區(qū)（印度的西北部）。在約700平方公里的區(qū)域范圍內(nèi)大概就有160處燃燒著的煤層。因此經(jīng)常有關(guān)于火災(zāi)蔓延、沉陷和下落的坑洞的報道。在這個人口稠密地區(qū)，這種現(xiàn)象是非常嚴(yán)重的。
煤礦開采使得空氣更容易接觸煤層因而促進(jìn)了火災(zāi)的發(fā)展。另一方面，煤炭火災(zāi)伴隨著煤炭的開采并甚至阻止采礦的進(jìn)行。據(jù)估計在印度有70%的煤層火災(zāi)是由于礦井開采引起的。
美國
在美國許多采礦地區(qū)也遭受著煤層自然發(fā)火引起的火災(zāi)。聯(lián)邦露天采礦辦公室(OSM)提供了一個數(shù)據(jù)庫(AMLIS)，上面列出了150個防火區(qū)域(1999)。這些防火區(qū)域不僅分布在肯塔基州，賓夕法尼亞州和西維吉尼亞州在東部的阿巴拉契亞礦區(qū)，而且還分布在科羅拉多州和洛磯山脈地區(qū)。
據(jù)報道，賓夕法尼亞州有45處防火區(qū)域。最著名的就是位于哥倫比亞郡無煙煤區(qū)域的Centralia煤礦。那里的火災(zāi)從1962年就開始燃燒，一直發(fā)展到了城市的下方。也曾經(jīng)采取了一些滅火措施，但最終還是沒能保住這座城市。
在科羅拉多州許多煤炭的自燃是由于每年地下水位的變化引起的。那些變化可能使水溫上升30°C，從而引發(fā)煤炭的自燃。
在懷俄明州和蒙大拿州的帕沃德河流域，已探明有8000億噸的褐煤儲量。Lewis-and-Clark探險隊(1804—1806)就曾經(jīng)報告過那個區(qū)域發(fā)生有煤炭火災(zāi)。這里我們也遭受著從地質(zhì)構(gòu)造時期就開始的煤炭火災(zāi)。這些火災(zāi)已有300萬年之久，并由此形成了一定范圍的景觀。4平方公里的區(qū)域覆蓋著燃燒過的礦渣，部分已經(jīng)冷卻了。最著名的壯觀的景象就是從紅色熔渣延伸區(qū)域的礦渣頂點處看到的景色。
德國
Zwickau州附近的Planitz地區(qū)的一個煤層從1476年就開始燃燒，并最終于1860年熄滅。Ernst August Geitner于1479年在Planitz火災(zāi)區(qū)域的上方建立了一個溫室，用于養(yǎng)殖熱帶植物，使得在商業(yè)領(lǐng)域首次利用煤炭火災(zāi)能源成為了可能。1668年在Dudweiler (Saar)的一個煤層發(fā)生火災(zāi)，這個地方由此演變?yōu)槁糜蝿俚兀⒚麨椤叭紵纳矫}”，甚至歌德也曾去旅游過，并用自己的詩進(jìn)行了描述。與其同樣著名的是位于“Hohe Meissner”東部斜坡的被人稱為“散發(fā)著氣味的墻”的地方，幾個世紀(jì)前那里的褐煤開采完后一些煤層就開始燃燒，溢出到地表的廢氣就引起了那種怪味。以煤為主的礦井的火災(zāi)幾乎總是伴隨著堅硬的巖石的開采。據(jù)報道平均每年大約有兩起火災(zāi)發(fā)生。德國的采礦業(yè)主要集中在魯爾和薩爾河地區(qū)，那些地方的防火技術(shù)非常發(fā)達(dá)?，F(xiàn)在煤礦火災(zāi)主要是由于采空區(qū)漏風(fēng)引起的。在那里采取的一些治理措施是非常成功的，造成重大人員傷亡的大型煤礦火災(zāi)已經(jīng)不在發(fā)生了。
2003年隨著艾森市Grossalmerode附近的Hirschberg地區(qū)的最后一個深層褐煤礦井的關(guān)閉，目前德國的褐煤只進(jìn)行露天開采，主要分布在Rheinische河、Mitteldeutschen河和Lausitzer河流域。去年由于綜合的防火策略的成功應(yīng)用，這些地區(qū)沒有發(fā)生火災(zāi)。
歐洲其他地區(qū)和俄羅斯
隨著總體上的采礦活動的減少，這些地區(qū)的煤炭火災(zāi)也在減少。但也有一些來自波蘭、捷克和烏克蘭的關(guān)于煤炭火災(zāi)的報道。在烏克蘭有兩百萬噸煤正堆積在煤場，并報道有74處防火區(qū)域。這些主要分布在Kuzbass、Petschora和 Donezk的盆地區(qū)域。
在科索沃（塞爾維亞）和波斯尼亞黑山共和國，一些煤層火災(zāi)燃燒已經(jīng)接近露天礦區(qū)和深部開采礦區(qū)。
非洲
非洲最大的煤礦開采區(qū)是在非洲的南大陸，主要是南非、津巴布韋、博茨瓦納、莫桑比克和贊比亞等國。關(guān)于煤礦的火災(zāi)報道都是來自這些地區(qū)。
中國
中國是世界上最大的煤炭生產(chǎn)國和消費國：僅2006年就生產(chǎn)了18億噸。因此煤炭火災(zāi)在中國是一個非常嚴(yán)重的問題。據(jù)估計由于煤層火災(zāi)直接燒掉的煤有1～2千萬噸，由煤炭工業(yè)損失掉的煤有1～2億噸?；馂?zāi)區(qū)域主要分布在覆蓋整個中國北方的一條區(qū)域帶。在許多分離燃燒的地帶中，每一個就有上百個燃燒區(qū)。主要集中在自治區(qū)、內(nèi)蒙古和寧夏地區(qū)。這些火災(zāi)除了引起了能源的浪費，還引起了空氣和水的污染，并且還釋放出了大量溫室氣體（二氧化碳和甲烷）。這引起了國際社會對這些火災(zāi)的關(guān)注。中國是世界上僅有的開展煤礦滅火領(lǐng)域研究的國家。有許多火災(zāi)已經(jīng)被撲滅了。由中德合作的研究機構(gòu)研究出了一系列的滅火方法。
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