矿井火灾外文翻译.docx

英文原文mine fire1. introductionthe most feared of hazards in underground mines or other subsurface facilities are those of firseand explosions. like airplane crashes ,these do not occur often but, when they do ,have the potential of causing diaastrous loss of life and property as well as a temporary or permanent sterilization of mineral reserves. fuithermore,” near-misses” occur all to frequently .the incidence of min fires appears not to be declining despite greatly improved methods of mine environmental design and hazard control .this is a consequence of two matters .first the growing varity of material that are imported into modern mine workings, varying from resins and plastics to liquid fuels and hydraulic fluids. a second factor is the contions increase in the employment of mechanized procedurds, mang of the maching involving flammable liquids and materials that can produce toxic fumes when over-heated .the enormous loss of life due to mine fires and explosions during the eighteenth and nineteenth centuries preoccupied the minds of mining engineers and scientists of the time .through the 1980s ,mine fires reemerged as a topoc of prissing research need .the majority of deaths arising from mine fires and explosions are caused ,not by burning or blast effects ,but by the inhalation of toxic gases ,in particular ,carbon monoxide. there are two major differences between underground fires and those that occur in suiface strucrures. the firsr concerns the long distances, often seversl kilometers, that personnel might be required to travel in passageways that may be smoke-filed. secondly, the ventilation routes are bounded by the confines of the airways and workings, causing closely coupled interactions between the airflows and behaviour of the fire.it is difficult for anyone who has not had the experience, to comprehend the sensations of compete isolstionand disorientation involved in feeling ones way through a long smoke-files mine airway and to walk just a few steps ,even without the trauma of a highly polluted atmosphere .it is, therefore, a matter of ongoing importance that all personnel involved in the design and detection of subsurface fires ,as well as procedies of personnel warning systems ,escapeways , firefighing, toxic gases, training, fire drills and the vital need for prompt resporise to a fire emergency. these are some of the topic s that are discussed in this chapter.1.1 the fire triangle and the comcuetion processpeihaps the most basic precept in firefighter training is the fire triangle shown on figure 12.1. this illustrates that the combustion process which we term “fire” requires three comptnents: furs, heat and oxygen. remove any one of thest and the fire will be extinguished. the fuel may be solids, liquids or gases .the liquids and gases might be introduced into the mine environment at ambient temperature by natural or mining processes, or may be produced by heating solid materisls.whenever a solid or liquid is heated to a sufficiently high temperature ,it will produce a vapour that is capable of being ignited by a flame, spark or hot surface which has the required concentration and duiation of thermal energy. gasoline has a flashpoint of -45 degrees c while most commonly available solids require the application of a flame for them to reach flashpoint theignition temperature of any given substance is the lowest temperature at which sustsined combustion is initisted. flaming is the process of the vapours accompanied ,usually ,by the emission of heat and light .in the case of self-sustained burning ,that heat is sufficient to raise the temperarure of the newly exposed or surrounding areas of suiface to flashpoint. however, combustion cancontinue at a slower tate without flaming through the process we knows as smouldering. in this case ,the oxidation process continues on the suiface of the material and produces sufficient heat to be selfsustaining, but not enough to cause the emission of vapours in the quantity required for flaming combustion.the oxygen which forms the third side of the fire triangle is normally provided by the air. flammable liquids such as the oil of a flame safety lamp will cease to burn when the oxygen content of the air is reduced to some 16 percent .flaming combustion of all kinds is extinguished at oxygen concentrations below 2 percent .however ,some materials may contain sufficient inherent oxygen for slow combustion to continue at wven furthen reduces levels of atmospheric oxygen .coupled tith the low values of thermal conductivity of crushed material ,this can result in “hot spots ”lying dormant in abandoned ateas for long perods of time ,but capable of re-ignition if a renwwed air supple is admitted suesequently .1.2 classification of mine fires fires underground can be classified into two broad groups ,open and concealed fires.open fires occur in airways ,faces and other openings that form part of the active ventilation system of the mine and , hence, affedt the quality of the mine airflows quickly and directly .as the term might imply ,open fires are often accompanied by flaming combustion because of the concealed firesoccur in areas that are difficult or impossible to access such as caved or abandoned zones. these are usually, but not necessarily ,initiated as a result of spontaneous combustion and can occur in both coal and sulphide ore minerals as well as within any imported organic matter such as paper diacarded fabrics or timbering in abandoned areas. the degree to which concealed fires propagate and pollute the mine atmosphere depends upon the rate at which air lesks through the areas affected. the matter of spontaneous combustion is diancussed in further fetail in section 12.42. causes od ignitionsthe variety of proceduies, processed and materials used in modern mining provides mang opportunities for the ignition of flammable materials .however ,the most commonly reported causes of fires and ecplosions in mines are lisred in the following subsectiongs.2.1 mechanized equipmentmanchines intended for use underground should be designed to operste tith a high degree of safety in a harsh physical environment, and are subject to legal requirementsand conditiongs in most mining countries. it is no suiprise, therefore,thst the majority of fires attributable to machines arise out of :misuse lack of proper maintenance removal or bywpassing of safety features such as diagnostic devices, environment monitors or thermal trip switches andrunning unattended for long periods of time exhaust systems on diesel equipment should be fitted with scrubbers that nor only reduce airborne pollution ,but also provent the emission of incandescent particles. furthermore, hoses, transmission or brake fluids and a variety of components made from synthetic materials on modern diesels may be capable of producing toxic gased when ignited. allvehicles or other diesel equipment should be fitted with on-board fire extinguishers .it is particularly importsnt that equipment which contains significant quantities of oil, such as large transformers or air compressors, shoule be safeguarded by thermal trips, pressure relief valves, and other devices necessary for automatic cut-off in the even of any abnormal codition. such devices should be subjected to routine testing and maintenance. wherever possible non-mobile equipment soule be located within enclosures with fire-resistant roof,floor and walls, and which are ventilated to a retuin airway. again ,fireextinguishers and ,preferably,an automatic fire suppression system should be bvailable within the chanber. in coal mines, the surroundings in adjacent airways should routinely be coated with stonedust.2.2 electrical apparatusin assttion to the general comments on mechanized equipment made in the preceding suvsection,electrical gear can give rise to incendive hazards from aparking and overheating. awitchgear should be sited such that it is not affected by convergence or falls of roof .this is mosr liable to ovvur close to mneral winning arwas. fuithermore, start switches shoule be protected against accidental operation glancing blows from falling debris or passing traffic. electrical sub-stations and battery charging chambers should be equipped with non-aqueous fire extinguishers .cables in airways should be hung in catenary fashion on cradles suspended from the roof. they should be located such that they will not be convergence or the yielding of roof supports nor be impccted by vehicles.the insulation and type of sheathing must be suitable for the edectrical load and rigours of the under groung environmeng .all such cables shoule be inspected routinely for evidence of physical damage .electrical failures should result in immediate isolation of the power by means of overload and earth leakage protective devices.in gassy mines ,all electrical motors and heavy urrent devices shoule be enclosed within flameproof casings so that any ignition of methane is contained within the equipment ,signaling or other light current apparatus should be certified as intrinsically safe,ieincapable of producing sparks of sufficient energy to ignite a methane: air mixture.during non-working shifts, the electrical power supplies to each area of the mine shoule be isolated at the appropriate highest level control centre or substation .precautions shoule be taken against power suiges caused by lightning strikes on surface power lines, transformers or substations. similarly, particular care shoule be taken against electrical leakage in the vicinity of explosives or fuel storage areas.2.3 conveyorsconveyor fires have been subjected to particular study because of the rapidity of fire propagation along the early rubber-based types of conveyor belting .modern conveyor belting for underground use must be subjected to fire propagation tests .three types of materials are used for mine conveyor belts, namely, styrene-butadiene rubber ,neoprene and polyvinyl chloride. composites of these materials are also employed. following ignition of the belt material and removal of the igniting source, the fire should preferably fail to propagate or , if it does, move at a slow rate. however, it should be noted that heated belt material may produce hazardous fumes.numerous tests have indicated that fire propagation rates along convey or belting are influenced by airspeed. at a relative velocity of 1.5 m/s between the belt surface and the nearby airstream, a phenomenon known as flash over attains its maximum effect this occurs when a flame front from the burning belt reaches forward over an unburned surface with an optimum angle and length such that the radiant effect on that surface reaches a maximum. this can cause flaming of the top layer of belting and a significant increase in flame propagation rate along the surface of the belt. deeper layer in the weave of the material may or may not be ignited .the effect appears to be most pronounced in sbr belting .flashover involves a serious hazard as belt surface propagation rates may reach some 10m/min .the spread of fire along mine conveyors is influenced strongly by the turbulence of the airflow. hence, tests of small samples of belting can give misleading results. large scale gallery tests are more reliable.conveyor fires are most likely to be initiated by friction .if the belt becomes stsked at any point along its length and the drive rollers continue to turn, then high temperatures this condition .such devices should be wired to isolate electrical power from the conveyor drive when an alarm confition is detected. similarly ,a seized idler or return roller can become red-hot from the friction of a belt moving over or around it .conveyors should be patrolled during operation in order to detect the development of faulty rollers. worn bearing will often be noisy and may also be detected by the smell of heated surfaces. a further frictional hazard can occur if the conveyor becomes misaligned to the extent that the belt rubs against surrounding surface such as the conveyor structure or airway sides.in all of these cases, a fire mayy be intiated when lubricants ,coal dust or flammable debres reach their ignition points .it follows that dust or spollage should not be allowed to accumulate round and ,particularly, underneath conveyors. a clean conveyor road is more likely to be a safe one.2.4 other frictional ignitionsthe main cause of methance ignitions on the working faces of coal mines is frictional sparking at the pick points of coal winning machinery .this occurs particularly when the machine cuts through sandstone or pyretic material. two approaches have been taken to reduce this hazard .one is to ensure that there is sufficient ventilation around the cutting drum to provide rapid dilution of the methane as soon as it is emitted .it is ,of course ,important that the overall airflow at the working face is adequate to prevent methane layeringand that the layout of the system minimizes flushes of methane from woeked-out areas. a number of decices have been employed to enhanence air movement aross the pick points of shearers and continuous miners. unfortunately, these may exacerbate the dust problem unless combined with a wet scrubber.the second approach to the incendive streak of aparks that sometimes trails behind a cutter pick is to quench it with water. this technique combines the suppression of both dust and methane ignitions .it is achieved by pick face flushing and ,even more efficiently ,by yet assested cutting .rope haulage systems have been the cause of some mine fires .care should be taken that all pulleys and return wheels are routinely serviced and lubricated .ropes should not be allowed to rub against solid surfaces such as the roof ,sides or floor of airways and, particularly, timber supports. if haulage ropes must pass through holes in stoppings then again ,the ropes should not contact the sides of the orifices. fluid couplings and enclosed gearings or direct drives are preferred to mechanical clutched,belts or v-drives for the transmissions of mining machinery. however, where the latter are employed then, again, regular inspections and maintenance are required to ensure their continued safe operation. similarly, mechanical braking systems should be well looked after.中文译文矿井火灾1 引言煤矿井下或其他地面最严重的 危险是具有着火，爆炸危险的设备.这些不经常发生，但是这些可能造成惨重的 生命和财产以不暂时或永久的 矿产储量的 损失。而且小事故太频繁。煤矿火灾事件没有下降，尽管在煤矿环境设计和危险控制方面有了较大的改进。这些导致了两个问题，第一个是各种新型材料进入现代煤矿，各种个样从树脂和塑料到液体燃料和液压液。另一个因素是不断增加的机械化程度，许多机械包含着易燃的液体和物质，当过热时能产生有毒烟雾。在十八世纪和十九世纪期间，煤矿火灾和爆炸导致了巨大的生产损失，人们关谈于那个世纪的工程师和科学家。尽管在二十世纪80年代煤矿仍是一个迫切需要解决的课题。煤矿火灾和爆炸中大部分人之死不是由燃烧和爆炸导致的，而是吸入毒气，特别是一氧化碳。井下和地面建筑产生的火灾有两个不同点。第一点是距离长，常常有几千米，那里的人可能通过充满烟雾的巷道。第二点是通风路线受风巷和工作面边界的限制，风流和火的习性，两者密切的相互作用。这些对于没有经验的人是困难的，包括完全隔离的感觉和迷失的方向时凭感觉通过长长的充满烟雾零可见度的风巷。在没有照明的回风巷关闭矿灯不行是一个很好的训练，即使没有严重污染空气的损失。所以，一个正在进行的重要事情是地下开采设计和施工全部人员应该有关于预防和发现井下火灾的知识，以及人员预警系统，逃亡路线，灭火（消防）方案，有毒气体，培训，消防训练和对于火灾紧急事件迅速反应是至关重要的。在这个章节有些讨论。1.1 火三角和燃烧过程在消防队员进行训练或火灾燃烧方面最基本的原理就是如图所示的火三角。这个图阐述了我们所说的燃烧过程所需要的三要素：燃烧，热量，和氧气。去除这其中任一个要素，都可能火熄灭。燃烧可以是固体，液体，或气体。进入矿井的液体和气体可能是由自燃或采矿过程产生的，或也可能是由加热固体物质而产生的。无论何时当一种固体或液体被加热到一定高的温度，既所谓的闪点的时候，就会产生水蒸气，这种蒸汽能够被火焰，火花，或是有集中，持久热能的高温表面点燃。汽油在45度以下时被点燃，但大多数普通固体需要达到闪点才能燃烧。任何一种物质的点燃温度就是它维持燃烧的最低温度。燃烧是蒸汽迅速氧化并伴随着光和热的释放的过程。在自燃中，其热量若足够升高暴露面或表面附近范围内的温度至闪点。然而，这种燃烧能维持在较低的速率进行，而正个过程没有火焰，我们称之为阴燃。在这种情况下，氧化过程在物体表面持续进行并产生足够的热量来维持自身的燃烧，但并不能产生明火燃烧所需要的蒸汽量。火三角的第三条边氧气通常是由空气来提供的。当风流中的氧含量减少到16%时，可燃烧液体，诸如汽油外面的火焰灯就会停止燃烧。各种明火燃烧在氧浓度为1012%时就会停止燃烧，而阴燃通常在氧浓度低于2%时才停止。然而，一些富含氧的物质在甚至更低的空气含氧浓度下还可以进行缓慢燃烧。具有粉碎的，低热导率的两个特性的物质，在废弃的区域能将这种高温保存较长一段时间，但是当有新鲜风流共给时，它就会重新燃烧。1.2 矿井火灾的分类矿井火灾被分为两种，外因和内因火灾。外因火灾发生在工作面和其他被开采的区域，这些巷道形成良好的通风系统，因此，能够迅速直接影响矿井空气的质量。正像术语所暗示的那样，这些明火伴随着有焰燃烧是因为氧气充足，并有利于消防队员直接灭火。相反，内因火灾发生在难以进入或不可能接近的地方，比如冒落区或采空区。它经常发生，但不是必然的，作为自燃火灾的结果，起因，它能发生在废弃地区的煤或含有硫化物的矿石中，以及外来的有机物如，纸，丢弃的织物例如含油的麻棉纱或采空区的木材。内因火灾传播和污染矿井空气的程度应取决于通过影响区域的泄漏气的速度。2火灾的原因在现代采矿业中，由于使用不同的步骤工艺过程和材料，使这些可燃物质有利于燃烧。然而，矿井中的火灾和爆炸的原因最常见的报道在以下的内容中列出。2.1机械设备用于井下恶劣环境当中的设备应当被设计成在操作上有较高的安全性，并且应符合大多数采矿业国家的法律要求。因此，不可否认，绝大部分的火灾都是由机械产生的（绝大部分的火灾应当归于机械的出现）误操作缺乏正常的维修一些安全装置如环境监控器，诊断装置，过热保护没有使用或没安装。长时间运行无人看管内燃机设备的排气系统应该安装过滤器，这样不仅能减少空气污染，而且能防止发光，发热，颗粒排放。而且，在现代内燃机上的一些软器和其他启动件，制动件由多种材料复合的复合材料，在燃烧时会产生有毒气体，所有的内燃机装置都应装上车载灭火器。这是很重要的，包含有大量油液的设备如变压器，空压机等就应该被一些热熔断器，安全阀门和其它必要装置来保护，以防万一发生反常情况。这