机械类毕业设计外文翻译

机械类毕业设计外文翻译 Make coal system and explode with the strick precaution countermeasure of the coal storehouse with high temperature (Abstract) Since the coal plant of Zou County of summary went into operation , had often made coal system explodes and the coal powder storehouse powder is warm and high, happen powder storehouse explosion accident , lead to the fact the great equipment damaging and serious economic losses while being numerous. Through analysing and researching, find out and make powder system exploding , warm high reason of storehouse powder of powder, propose making the systematic operation technology of powder and improved measure of equipment. (Keyword) Coal-fired power plant Make coal system Explosion reason Prevent and transform The power plant ,? of Zou County of Shandong, ,. a project amount to 4 300 MW unit . Coal-fired steam dome stove of hotter natural circulation the middle the DG1000/170-1 type inferior critical pressure that the boiler produces for the eastern boiler factory . Each boiler dispose 4 warehouse make coal system , exhausted gas give powder , adopt DTM350/700 low-speed cylinder ball mill. Each boiler consists of 2 coal powder storehouses, the volume of each powder storehouse is 440 m3. Coal powder storehouse top set a type as spiral reversible type of GX-500 fail powder machine (entangle the dragon ), can guarantee 4 make powder system transport coal powder each other , in entangle dragon and coal powder equip with 4 suck tide in charge of at the storehouse. Since the boiler goes into operation , make powder system exploding many times and high situation of powder storehouse temperature, not only cause the equipment to be damaged threaten the personal and security which the power plant produce seriously seriously but also, still cause polluting to the production environment seriously. So far , make powder system examination accident formed to explode have 3 , obstacle up to dozens of more than 1..Warm and high danger that make powder system exploding and coal powder storehouse powder 1.1 Make the danger that powder system explodes It will cause the equipment to damage , generate electricity , reduce the economic benefits little to make powder system and explode, even cause the personal casualty accident. Such as will it be May 26 1992, 1 man , stove of No. , make powder system explode , is it is it supply water electronic pieces of cable , make powder system control the cable to fire to guide, forced to stop the stove , generate electricity 3,990,000kWh little. On for another example May 10 , 1993, the coal powder fritted, influenced the machine supplying powder to produce powder in second powder storehouse of stove No. 1. While dealing with the machine supplying powder for the 13th the powder, the coal powder suddenly squirted to deflagrate, burnt out partlying , heat accused of the cable, lead to the fact that stops the stove and protects movements and stops the stove promptly . Force electric wire netting draw way ration the power supply 6,720,000kWh , by 49 systematic cycle to the outside. 95 Hz is dropped to 49. 45 Hz, lacks power generating 1 4,400,000kWh. 3 No. stove is it transport course take place 2 coal powder storehouse explode , the last 1 ceiling , powder of storehouse raise , belt burn out one coal to try, one is on-the-spot constructors burn and cause death. 1.2 High danger that the coal powder storehouse powder is warm Boiler coal powder storehouses of Taiwan generally have powder a warm and high phenomenon, cause the following consequence : In order to prevent baking and losing the coal belt badly because the temperature of storehouse ceiling of the powder is too high , have to make the belt run and does not park in succession ; Powder storehouse is it keep outside flame to emit , burn out such equipment as the top belt ,etc. sometimes; 3 No. stove go into operation initial stage because being warm to influence normal running while being high , powder have to install one nitrogen fire extinguishing system additional, by often filling the nitrogen to maintain and run; Because the temperature of powder storehouse exceeds 400 degrees Centigrade sometimes, make the 2 The reason and precautionary measures that make powder system and explode 2.1 Reason analysis that make powder system and explode By the look of on-the-spot situation after numerous explosions , ignite piece mainly apt to accumulate coal or accumulate position of powder for a long time. The heat source ignited is mainly the machine for rubbing coal and arranged the hot air door of entry of the powder machine and did not take shape severely . The situation analysis that and explode according to the operation operating mode of making powder system, make the main reason why powder system explodes as follows. 2.1.1 iled with coal powder degree, the density of wind powder and coal-fired composition have something to do with It is often spontaneous combustion in earlier stage when the coal powder explodes . When the wind powder air current of certain density blows to spontaneous combustion to click, not merely aggravate spontaneous combustion, will also cause and burn , and the wind powder air current of touching the flame will emerge and explode at any time. Is it flow coal main factor that powder explode wind oxygen content , coal powder detailed degree , wind density and temperature , powder of mixture , powder of air current to cause. Because the coal powder is too high in density, oxygen is small in density; The coal powder is too low in density, lack the flammable thing . Only the density of the coal powder is 1. 2-2 Kg/m3 most easy to produce to explode. And the power plant of Zou County makes the density of systematic coal powder of powder in 0. 3-0. The change in 6 kg/m3 range, so the danger of exploding exists. Volatilize copies of Vdaf greater than 25% , caloric value high coal , the possibility of exploding is heavy generally, Zou County power plant is it use coal 525 kj/kg , Qy23 of caloric value , to design , volatilize copies of Vdaf42. 07%, is prone to one of the reasons to explode too. 2.1.2 The entry to the machine for rubbing coal accumulates coal spontaneous combustion Machine for rubbing coal office accumulate coal take place in entry 6 top mainly. On the pipeline of 5 m. Open 4 holes in a utensil here, powder tube , recycling are in charge of with going back separately, and 2 explosion doors are joined . From whom one side come over is hot wind and wind powder that come over not corresponding form vortex of, strike not glueing above turning on holing at inboard wall of pipeline from coal feeder coal not wet come down to fall( Artificial to can't remove to accumulate coal is warm to up to more than 300 degrees Centigrade from one wind that preheater come at the same time here in not operating. After making the systematic stoppage in transit of powder, because the entry air door of machine for rubbing coal is not tight, the hot wind leaking makes the temperature of entrance of machine for rubbing coal up to more than 100 degrees Centigrade, apt to accumulate entrance coal is it fire to guide , coal that burn enter machine for rubbing coal can cause explosion. 2.1.3 Detailed powder separator office accumulate powder spontaneous combustion Detailed powder separator office accumulate powder spontaneous combustion take place square pipeline bottom gentlely on the piece in detailed powder separator entry mainly. Because this level section turn on have one square explosion door, make place this coherent to flow area increase, the velocity of flow of the wind powder air current drops, has increased the possibility of accumulating the powder. 2.1.4 Leak in the hot air door Through is it can know 4 No. third stove make powder main reason that system explode third powder machine short cut hot tight air door 1995 to analyse. Especially third powder machine hot-blast pitch can only imprison to 70%, so that a large amount of hot wind is it is it should make powder system 9 explosions in the half a year to cause to leak. 2.1.5 Accumulate powder spontaneous combustion in the recycling air door place Thinner coal powder in the exhausted air, easy to accumulate have person who arranges powder recycling air door office that export. Because this system is seldom used, the hot wind leaking from the hot air door of machine for rubbing coal while making the system stoppage in transit of powder, flowed into the powder arranging machine by recycling under the circumstances that the system is shouldered and pigeonholes, will cause this place to accumulate powder spontaneous combustion . The ones that burn are burnt one falls into the powder arranging machine or in the machine for rubbing coal, will cause the explosion . 2.2 Make the precautionary measures that powder system explodes 2.2.1 Prevent the entry to the machine for rubbing coal from accumulating the coal The entry to the machine for rubbing coal is 6. 5 m place accumulated the coal, glued under the circumstances that the air current is struck of wet coal. No matter make powder system in not running or while stopping transport , accumulate coal guide and fire probably. Go back powder is it is it is it fall coal in charge of entry to get to move upwards to in charge of (see 1 Fig.), mix powder and coal stage advance in advance, reduce the possibility of accumulating the coal. If add a mixing device in the pipeline above the entry of machine for rubbing coal (see Fig. 1), can make the powder , coal , wind get good mixing , can already be prevented in 6. 5 m office accumulate coal , can alleviate underpart hopper slope accumulate the coal , solve the problem that the steel ball falls into astringent air door of hot air door card while adding the steel ball even. 2.2.2 Carry on the transformation to the detailed powder separator Is it accumulate powder to detailed powder separator entry to place to cut , can adopt in the tunnel installing the water conservancy diversion board additional, increase some perturbation , raise the velocity of flow of this place , strengthening the air current will accumulate the eroding of powder to the underpart, solve . Meanwhile, after installing the water conservancy diversion board additional, because the wind powder air current is even , can also improve the efficiency of separating . 2.2.3 Improve the thick powder separator Original thick powder separator awl answer the shelf board of the powder below the body (shutter ), often pile up incidentals or coal powder, not only lead to the fact the wind powder air current to short out, is it answer to influence the powders, but also often spontaneous combustion causes the explosion. 3, 4 No. stove thick powder interior awl body of separator pour toper change ladder (bump into ) into after the type, have remove a hidden danger, has made experience. Change the thick powder separator of stove No. 1 , 2 for new-type SD-CB axial ?ó type striking type thick powder separator . Obstruction is by original 240*9. 8 Pa is dropped to 80*9. 8 Pa, exerting oneself can improve by 14% , the total electricity can drop to dawdle by 21% 2.2.4 Dispel and leak in the hot air door Make powder system is it is it open , park procedure to have to design , hot wind total door operate and adopt the electronic executive body. But has never used this procedure since going into operation , and this electronic air door is not tight, cause and leak out. Can repack the total door of hot wind of entry of machine for rubbing coal into (or increases ) a manual total door and leak out by reducing . Still natural cold air door after change to the hot wind pitch before the hot wind pitch position, make it in shouldering the pressing area, this not only can solve the problem that it causes the temperature of the entry to the machine for rubbing coal to be high to leak and enter the hot wind , can also solve hot wind in operating from cold air door leak the problem of polluting the environment naturally. 3 The reason the temperature of powder storehouse of coal is high and precautionary measures 3.1 The reason the temperature of powder storehouse of coal is high 3.1.1 Coal powder storehouse structure existing problem (1)Because original powder storehouse cliff side angle and interior awl body angle too little (powder storehouse horizontal storehouse design of wall inclination 71. 6?ã, the awl body angle is 65?ãin the bottom), make the storehouse wall and interior awl body apt to accumulate the powder (see Fig. 2), cause the temperature of powder storehouse to be high. (2)Powder storehouse top leave one high about 600mm when the installation all around, deep about 540 mm, invite the dead angle (see Fig. 2 ) of 45?ã, as the coal powder falls into the powder storehouse, thinner coal powder will be flown upward everywhere, fall and locate in this slowly, pile up for a long time. If go to the temperature in the storehouse high, accumulate the powder and know spontaneous combustion. (3) Equipped with 2 manhole doors horizontally on the storehouse top of the powder, among them the manhole door of north side can not be sealed tightly (see Fig. 2), it causes coal powder spontaneous combustion that the air leaks and enters the powder storehouse, the high-temperature gas builds up and bakes the storehouse ceiling of the powder to split. (4)Weld but the awl body in the coal powder storehouse underpart that becomes with 16 Mn stencil plate , divide the powder storehouse into 2 parts, every part cut 6 light storehouse dose apart into, every storehouse dose leave stencil plate awl body in welding into of 10 mm on thickness too. Because powder storehouse all underpart surface area , awl of body reach 100 m2 to be above, awl body surface take measure of keeping warm, in addition, give powder seal tightly, environment temperature low winter, lead to the fact powder storehouse awl body the surface forms and reveals and accumulates the powder. 3.1.2 The human factor influencing (1) Suck the tide valve and does not operate according to the regulation . Equipped with and sucked the tide and is in charge of in the top of powder storehouse of coal (see Fig. 3). According to the rules demand, the coal powder storehouse sucks the tide valve and must be opened when making powder system and operating, suck the tide valve and should be closed while making the systematic stoppage in transit of powder. But in running , make powder system to sucking the tide valve of the powder storehouse , should open but not open , reserve to make powder system get to suck tide valve should shut off and shut off powder storehouse (entangle dragon ), according to regulation being in entangle dragon is it suck tide valve should shut off , but in running actually when operating to stop, often open the position too. (2)The angry device of lock is ineffective. The separator underpart of the thin powder has angry device of 2 locks, its function one is preventing leaking out, prevent the fire source from entering the powder storehouse after making powder system and exploding two times. Because some stove leave 1 lock angry device work , therefore apt to cause powder to be storehouse on fire only. (3)The powder plugboard has not been closed to entangle under the dragon. Entangle below of the dragon and having 4 to lay powder mouth, make powder system to link with 4 separately. Lay powder mouth install one manual plugboard in each (see 3 Fig.), only in entangle dragon go on at handing over the powder, the ones that need pollinating put the powder plugboard once to open. But in not running actually, every stove entangle to lay powder plugboard is it open to in often or half open the state dragon, entangle to lay powder plugboard all hold the position frequently dragon both ends (first , man make powder system ). Make powder storehouse is it is it press to shoulder to take shape too , entangle dragon planted agent seal unable to seal even. (4)Board question of the reversing shelf. Below each saw-dust separator which make the powder system , there is a manual reversing shelf board (see Fig. 3). Function its to is it get powder storehouse or entangle the dragon to switch over separately detailed powder coal powder that separator get off. Should make the shelf board close one side of powder storehouse when making powder system and stopping operating, in order to prevent the air from entering the powder storehouse. But in running actually, when making the system stoppage in transit of powder, this reversing shelf of boards are seldom cut and sealed to the powder storehouse side. (5)Management system. On the initial stage of going into operation, the lift is all operated personnel to manage, no matter the evening of daytime , operate personnel get boiler top is it suck tide valve and reversing board very much convenient shelf to operate, can put in place in time too. But lift incorporate into industrial corporation lift class manage , daytime , operate personnel use lift is it let lift a messenger operate to need after 1991, is it get office , 32 m of elevation , operate on foot to need evening , is it make powder system open after parking to cause, can't operate on the spot according to the regulation in time . System this change until 1997, put in place situation is it take a favorable turn obviously to have. Operation issued to revise among the rules , stipulate machine for rubbing coal open powder storehouse inhale the tide valve after starting only 1989, but has not stipulated that close and suck the tide valve after making the systematic stoppage in transit of powder ; Have only stipulated that cuts the reversing shelf board to the powder storehouse while making powder system to start, stipulate after making powder systematic stoppage in transit cutting to entangle the dragon reversing shelf board, seal the powder storehouse. (6)Question left over after the technological transformation. For save ignition of the boiler spend oil , install additional coal powder precombustor fire the device , increase 4 new machine supplying powder, short verse length that machine supplying powder connect with powder storehouse, change 900 mm from 200 mm to (meet 2 picture), but short verse that machine supplying powder extend keep warm ; Lock powder storehouse top unsuitable modes in Chinese operatic music angry device change awl type into after locking the angry device, the outside of the angry device of lock has not been kept warm either, so will increase the powder storehouse inboard wall to form and reveal . 3.2 Precautionary measures of the coal powder storehouse with high temperature 3.2.1 Improve the coal powder storehouse structure and keep warm (1)Because 3,, 4 No. stove powder storehouse adopt stencil plate structure, outside keep result warm to be bad, lead to the fact powder storehouse inboard wall marries and reveals and accumulates the powder, the temperature of powder storehouse often rises. Although changed all the external warm - keeping of powder storehouse in 1989, the powder storehouse inboard wall was the structure of the stencil plate , form the problem of revealing still without solving completely, watered a storey of concrete on the powder storehouse inboard wall later. Because ceiling is it is it leak out to split to cook, in 1993 overhaul lieutenant general 3 No. stove first powder storehouse roof beam and ceiling all change. Have all changed stove second setting a roof beam in place and ceiling of powder storehouse 4 3 in overhauling May of 1997. For prevent stone volume expansion under calcification under high temperature , make outside concrete bloated to shed. Adopt refractory cement matching, and change the aggregate from stone to the burnt gem. (2)Because the angle of cliff side and interior awl body angle are too small in the original powder storehouse. Utilized stove No. 1 to overhaul time in 1997, carried on the transformation to first , second coal powder storehouse. Storehouse inboard wall play rough hole in powder, water one fire-resistant concrete , make two wall angle by former 71. 6?ã turns into 77?ã. Add and weld a storey of stencil plates on the original interior awl body , make the awl body angle in the bottom change 70?ãfrom original 65?ã to (see Fig. 2), in order to dispel and accumulate the powd (3)The dead angle left at the time of installation all around on the storehouse top of the powder, have already watered with the concrete, make it and flat to be neat in the cliff side, accumulate powder to click after eliminating this. (4)Original detailed powder powder design for reversing type shelf board between in charge ofing under the storehouse from separator to powder, not tight, apt to leak out , powder. Lay 4 stove powder reversing shelf board is it insert modes in Chinese operatic music floodgate board door to change into even more all already (meet picture 3), have solved the problem of leaking out. (5)Entangle dragon change into chain type it fails to be unable to use after the powder machine , for reduce powder storehouse leak out originally, water and close in with the concrete entangling dragon all powder mouthing already now. Enter hole door cover flat , apt to leak out while being out of shape , already enter hole door apron switch over to a renovating type originally, adopt the stainless steel board and silicic acid aluminium felt to keep warm. Changing into the hole door position, it is vertical to fix up and change into by the horizontal axis, the powder storehouse inboard wall on the both sides of axis of the explosion door is fixed up. 3.2.2 It is in charge of the thorough fare and explosion door to improve the tide of sucking (1)The powder storehouse of raw coal sucks the tide and is in charge of exporting meeting with the coal powder pipeline in entries of thick powder separator , because system is it pigeonhole light to shoulder, easy to stop up coal powder that deposit. For improve defeat its press , now already suck tide is it is it is it receive person who arranges powder entry at the pipeline to change from thick powder separator entry pipeline to export to in charge of, the export is shouldered and pressed by 3. 0 kPa rises to 7. 0 kPa. But the coal powder storehouse is defeated by to press too big, leaking out will increase instead, the situation after stove No. 1 changes is seen, because is it press heavy to shoulder, 2nd lock angry device , saw-dust separator ,etc. to is it increase obviously to leak out place. You had better install additional 1 shoulder form of keeping , adjust coal powder storehouse is it pigeonhole to shoulder , maintain 300 Pa to be about, can't be greater than 500 Pa. 2)The original diaphragm type explosion door , has not opened when the numerous powder storehouse explodes , in addition the iron sheet of explosion door is often corroded and leaked out, it is difficult to play the function of the explosion door . Have already all entered the hole door to replace with the type of gravity (reprint ) now, has adopted aluminium board structure and yellow sand to seal, the result is good. 3.2.3 Strengthen management for operation Control the good machine for rubbing coal and export temperature, the too big coal powder enters the powder storehouse to prevent including the moisture. Lower the powder location regularly, prevent the coal powder from retaining in the storehouse for a long time. It avoid it fail at powder it powder will be accumulated,especially can't stove parked temporarily,must powder storehouse not sealed, prevent spontaneous combustion. Revise and perfect the rules of on-the-spot operation. 制煤系统爆炸与煤仓高温的防范对策 〔摘 要〕 邹县发电厂自投产以来，经常发生制煤系统爆炸和煤粉仓粉温高，还发生粉仓爆炸事故，多次造成重大设备损坏和严重经济损失。通过分析研究，找出制煤系统爆炸、粉仓粉温高的原因，提出制粉系统运行技术和设备改进的措施。 〔关键词〕 燃煤电厂 制煤系统 爆炸原因 预防及改造 山东邹县发电厂?、?期工程共4台300 MW机组。锅炉均为东方锅炉厂生产的DG1000/170-1型亚临界压力中间再热自然循环燃煤汽包炉。每台锅炉配置4套仓储式制煤系统，乏气送粉，均采用DTM350/700低速滚筒式球磨机。每台 3锅炉设有2个煤粉仓，每个粉仓的容积为440 m。煤粉仓上部设一台型号为GX-500的螺旋可逆式输粉机(绞龙)，可保证4套制粉系统相互输送煤粉，在绞龙和煤粉仓上装有4根吸潮管。 自锅炉投产以来，制粉系统多次发生爆炸和粉仓温度高等情况，既造成设备严重损坏，又严重威胁人身及电厂生产的安全，还对生产环境造成严重污染。至今，因制粉系统爆炸构成的考核事故就有3次，障碍达几十次之多。 1 制粉系统爆炸及煤粉仓粉温高的危害 1.1 制粉系统爆炸的危害 制粉系统爆炸会引起设备损坏、少发电、降低经济效益，甚至造成人身伤亡事故。 如1992年5月26日，1号炉丁制粉系统爆炸，引燃给水电动门电缆、制粉系统控制电缆，被迫停炉，少发电399万kWh。 再如1993年5月10日，1号炉乙粉仓内煤粉烧结，影响给粉机出粉。在给粉间处理13号给粉机时，煤粉突然喷出爆燃，烧坏部分热控电缆，导致紧急停炉保护动作停炉。迫使电网对外拉路限电672万kWh， 系统周波由49.95 Hz降至49.45 Hz，少发电1 440万kWh。3号炉试运过程中发生2次煤粉仓爆炸，后1次将煤粉仓的顶棚掀起、11号皮带烧坏，一名现场施工人员烧伤致死。 1.2 煤粉仓粉温高的危害 4台锅炉煤粉仓普遍存在粉温高的现象，造成以下后果:为了防止因粉仓顶棚温度太高而烤坏输煤皮带，只好使皮带连续运行不停车;有时粉仓冒正压向外喷火，烧坏上部皮带等设备;3号炉投产初期因粉温高影响正常运行，只好加装一套氮气灭火系统，靠经常充氮维持运行;由于粉仓温度有时超过400?，使粉仓顶棚预制件烧坏，大面积脱皮，局部塌陷，顶部4架钢筋砼梁均有烧坏现象。 2 制粉系统爆炸原因及防范措施 2.1 制粉系统爆炸原因分析 从多次爆炸后的现场情况看，引爆点主要在容易长期积煤或积粉的位置。引爆的热源主要是磨煤机与排粉机入口热风门不严形成的。根据制粉系统的运行工况和爆炸情况分析，制粉系统爆炸的主要原因如下。 2.1.1 与煤粉细度、风粉浓度及燃煤成份有关 煤粉爆炸的前期往往是自燃。一定浓度的风粉气流吹向自燃点时，不仅加剧自燃，还会引起燃烧，而接触到明火的风粉气流随时会产生爆炸。造成流动煤粉爆炸的主要因素是风粉气流中的含氧量、煤粉细度、风粉混合物的浓度和温度。 煤粉愈细，爆炸的危险性就愈大。粗煤粉爆炸的可能性就小些，当煤粉粒度大于0.1 mm时几乎不会爆炸。当煤粉浓度大于3,4 kg(煤粉)/m3(空气)或小于0.32,0.47 kg(煤粉)/m3(空气)时不易引起爆炸。 因为煤粉浓度太高，氧浓度小;煤粉浓度太低，缺少可燃物。只有煤粉浓度为1.2,2 kg/m3时最易产生爆炸。而邹县电厂制粉系统煤粉浓度在0.3,0.6 kg/m3范围内变动，因此存在爆炸的危险。 一般挥发份Vdaf大于25%，发热量高的煤，爆炸的可能性就大，邹县电厂设计燃用煤发热量Qy23 525 kj/kg，挥发份Vdaf42.07%，也是容易产生爆炸的原因之一。 2.1.2 磨煤机入口积煤自燃 磨煤机处积煤主要发生在入口上部6.5 m的管道上。在此处开有4个孔洞，分别与回粉管、再循环管，和2个防爆门连接。从一侧过来的热风与对应过来的风粉形成涡流，从给煤机落下来的湿煤就被冲击粘在开孔上方管道的内壁上(见图1)。在运行中人工无法清除此处的积煤，同时从预热器来的一次风温达300?以上。在制粉系统停运后，由于磨煤机入口风门不严，漏过的热风使磨煤机入口 处温度达100?以上，容易将入口处积煤引燃，燃烧的煤进入磨煤机就会引起爆炸。 2.1.3 细粉分离器处积粉自燃 细粉分离器处积粉自燃主要发生在细粉分离器入口方形管道下部的较平缓段上。因为此水平段正上方开有一个方形防爆门，因而使该处的通流面积增大，风粉气流的流速下降，增加了积粉的可能性。 2.1.4 热风门内漏 通过分析可知，1995年4号炉丙制粉系统发生爆炸的主要原因就是丙排粉机近路热风门不严。特别是丙排粉机热风调门只能关至70%，以致大量的热风内漏造成该制粉系统半年内9次爆炸。 2.1.5 再循环风门处积粉自燃 乏气中较细的煤粉，容易积存在排粉机出口的再循环风门处。由于此系统不常使用，在制粉系统停运时，从磨煤机热风门漏过的热风，在系统负压下经再循环流向排粉机，会引起该处积粉自燃。燃烧的焦块掉入排粉机或磨煤机内，就会引起爆炸。 2.2 制粉系统爆炸的防范措施 2.2.1 防止磨煤机入口积煤 磨煤机入口6.5 m处积煤，主要是湿煤在气流冲击下粘上去的。不论制粉系统在运行中还是在停运时，都有可能将积煤引燃。如果将回粉管向上移到落煤管入口(见图1)，将粉与煤的预混阶段提前，就减少了积煤的可能性。如果在磨煤机入口上方的管道内加一个混合器(见图1)，可使粉、煤、风得到良好的混合，既可防止在6.5 m处积煤，又能缓解下部料斗斜坡积煤，还解决了添加钢球时钢球掉入热风门卡涩风门的问题。 2.2.2 对细粉分离器进行改造 对细粉分离器入口切向处积粉，可通过在风道内加装导流板，增加局部扰动，提高该处的流速，增强气流对下部积粉的冲刷，予以解决。同时，在加装导流板后，因风粉气流均匀，还可提高分离效率。 2.2.3 改进粗粉分离器 原粗粉分离器内锥体下方回粉档板(百叶窗)，经常堆积杂物或煤粉，不但造 成风粉气流短路，影响回粉，也经常自燃引起爆炸。把3、4号炉粗粉分离器的内锥体由倒锥形改为阶梯(撞击)式之后，消除了隐患，取得了经验。 将1、2号炉的粗粉分离器，更换为新型的SD-CB轴向?型撞击式粗粉分离器。阻力由原来的240×9.8 Pa降至80×9.8 Pa，出力可提高14%，总电耗可下降21%。 通过对4台锅炉粗粉分离器的改造，不但解决了内部积粉问题，还提高了锅炉的效率。 2.2.4 消除热风门内漏 制粉系统设计有启、停程序，热风总门操作采用电动执行机构。但自投产以来从未使用过该程序，且此电动风门不严，造成漏风。可以将磨煤机入口热风总门改装成(或增加)一只手动总门以减少漏风。还可将自然冷风门位置从热风调门前改至热风调门后，使其处于负压区，这不但可以解决漏入热风造成磨煤机入口温度高的问题，还可以解决运行中热风从自然冷风门外漏污染环境问题。 3 煤粉仓温度高的原因及防范措施 3.1 煤粉仓温度高的原因 3.1.1 煤粉仓结构存在问题 (1) 由于原粉仓内壁面角度和内锥体角度太小(粉仓横向仓壁倾角为71.6?，底部内锥体角度为65?)，使仓壁及内锥体易积粉(见图2)，造成粉仓温度高。 (2) 粉仓顶部四周因安装时留下一段高约600mm，深约540 mm，约45?的死角(见图2)，当煤粉落入粉仓内，比较细的煤粉会到处飞扬，慢慢落在该处，长时间堆积。遇上仓内温度高时，积粉便会自燃。 图2 横向粉仓改造示意图 (3) 在粉仓顶部横向装有2个人孔门，其中北侧人孔门封闭不严(见图2)，空气漏进粉仓引起煤粉自燃，高温气体聚积将粉仓顶棚烤裂。 (4) 用16 Mn钢板焊接而成的煤粉仓下部内锥体，将粉仓分成2部分，每1部分又分割成6个小的仓格，每1仓格同样采用厚度为10 mm的钢板焊接成内锥体。由于粉仓下部所有内锥体的表面积达100 m2以上，而锥体外表面又没有采取保温措施，再加上给粉间封闭不严，冬季环境温度低，造成粉仓内锥体内表面结露积粉。 3.1.2 人为因素影响 (1) 吸潮阀不按规定操作。在煤粉仓上部装有吸潮管(见图3)。按规程要求，制粉系统运行时煤粉仓吸潮阀必须开启，制粉系统停运时吸潮阀应关闭。但在实行运行中，制粉系统到粉仓的吸潮阀，应开启而没有开启，备用制粉系统到粉仓(绞龙)的吸潮阀应关闭而未关闭，按规定在绞龙停止运行时吸潮阀应关闭，但在实际运行中，也经常在开启位置。 (2) 锁气器失去作用。细粉分离器下部有2道锁气器，它的作用一是防止漏风，二是在制粉系统爆炸后防止火源进入粉仓。由于有的炉只剩1道锁气器起作用，因而易引起粉仓起火。 (3) 绞龙下粉插板未关闭。在绞龙的下方设有4个下粉口，分别与4个制粉系统联接。在每个下粉口安装一只手动插板(见图3)，只有在绞龙进行送粉时，需要授粉的下粉口插板才打开。但在实际运行中，各炉绞龙的下粉插板经常处于开启或半开启状态，特别是绞龙两端(甲、丁制粉系统)的下粉插板经常在全开位置。因此也就使粉仓形不成负压，绞龙内应封闭也无法封闭。 (4) 换向档板问题。在每台制粉系统的木屑分离器下方，设有一只手动换向档板(见图3)。其作用是把细粉分离器下来的煤粉分别切换到粉仓或绞龙。当制粉系统停止运行时应使档板关闭粉仓一侧，以防止空气进入粉仓。但在实际运行中，当制粉系统停运时，此换向档板很少切向粉仓侧进行封闭。 (5) 管理制度 档案管理制度下载食品安全管理制度下载三类维修管理制度下载财务管理制度免费下载安全设施管理制度下载 方面。在投产初期，电梯都由运行人员自己管理，不论白天晚上，运行人员到锅炉上部操作吸潮阀及换向档板都很方便，也能及时到位。但在1991年以后电梯划归实业公司电梯班管理，白天，运行人员使用电梯需找电梯班来人操作，晚上则需步行到标高32 m处操作，所以就造成制粉系统启停后，不能及时按规定进行就地操作。直到1997年这一 制度 关于办公室下班关闭电源制度矿山事故隐患举报和奖励制度制度下载人事管理制度doc盘点制度下载 才改变，到位情况有了明显好转。 图3 粉仓上部布置图 1989年修改颁发的运行规程中，只规定了磨煤机启动后开启粉仓吸潮阀，但没有规定在制粉系统停运后关闭吸潮阀;只规定了在制粉系统启动时将换向档板切向粉仓，但未规定在制粉系统停运后将换向档板切向绞龙，封闭粉仓。 (6) 技改后遗留的问题。为了节省锅炉点火用油，加装了煤粉预燃室点火装置，增加4台新给粉机，将给粉机与粉仓连接的短节长度，由200 mm改为900 mm(见图2)，但给粉机加长的短节未进行保温;在将粉仓上部不适合的板式锁气器改 为锥式锁气器后，锁气器的外部也未进行保温，所以会增加粉仓内壁结露。 3.2 煤粉仓温度高的防范措施 3.2.1 改进煤粉仓结构和保温 (1) 因为3、4号炉粉仓采用钢板结构，外部保温效果差，造成粉仓内壁结露积粉，粉仓温度经常升高。虽于1989年把粉仓外部的保温全部进行了更换，但因粉仓内壁为钢板结构，结露问题仍没有彻底解决，后来就在粉仓内壁浇灌一层砼。 由于顶棚烧裂漏风，在1993年大修中将3号炉甲粉仓梁及顶棚全部更换。在1997年5月份大修中又将3号炉乙粉仓4架梁及顶棚全部进行了更换。为了防止在高温下石子钙化后体积膨胀，将外部砼胀掉。采用耐火水泥配比，并将骨料由石子改为焦宝石。 (2) 由于原粉仓内壁面角度和内锥体角度太小。1997年利用1号炉大修时间，对甲、乙煤粉仓进行了改造。在粉仓内壁打出麻坑，浇上一层耐火砼，使两壁角度由原71.6?变为77?。又在原内锥体上加焊一层钢板，使底部内锥体角度由原65?改为70?(见图2)，以消除积粉。 (3) 粉仓顶部四周安装时留下的死角，已用砼浇灌，使其与壁面平齐，根除了此积粉点。 (4) 原细粉分离器至粉仓下粉管之间设计为换向式档板，不严密，易漏风、粉。已将4台炉的下粉换向档板全部更换成插板式闸板门(见图3)，解决了漏风问题。 (5) 因原绞龙改为链式输粉机后一直无法使用，为了减少粉仓漏风，现已将绞龙所有下粉口用砼浇灌封堵。原入孔门盖子为平板式，容易变形漏风，已将入孔门盖板改为翻盖式，采用不锈钢板外加硅酸铝毡保温。改变入孔门位置，由横向轴线布置改为纵向，在防爆门轴线两侧的粉仓内壁布置。 3.2.2 改进吸潮管通路及防爆门 (1) 原煤粉仓吸潮管出口与粗粉分离器入口的煤粉管道相接，因系统负压小，易被沉积的煤粉堵塞。为了提高其负压，现已将吸潮管出口从粗粉分离器入口管道改接到排粉机入口管道上，出口负压由3.0 kPa提高到7.0 kPa。但是煤粉仓内负压过大，漏风反而会增加，从1号炉改后的情况看，因负压大，第2道锁气器、木屑分离器等处的漏风明显增加。最好加装1只负压表，调整煤粉仓负压，维持在300 Pa左右，不得大于500 Pa。 (2) 原膜片式防爆门，在多次粉仓爆炸时均未打开，加之防爆门铁皮经常腐蚀漏风，难以起到防爆门的作用。现已全部用重力(翻版)式入孔门代替，采用铝板结构和黄砂密封，效果良好。 3.2.3 加强运行管理 控制好磨煤机出口温度，防止含水分过大的煤粉进入粉仓。定期降粉位，防止煤粉长时间在仓内存留。避免输粉机内积粉，特别是临时停炉，一定要密封粉仓，防止自燃。修订和完善现场运行规程。