提高中速磨煤机出口温度的可行性研究
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摘要
能源的短缺是制约人类社会发展的重大问题,我国目前积极推进节能降耗工程建设,落实节约资源基本国策。火电厂是耗煤大户,充分挖掘火电厂节能降耗潜力,对推动我国的节能事业、促进社会可持续发展有着重要的实际意义。锅炉排烟热损失是锅炉系统最大的热损失,降低排烟热损失可以充分利用煤炭资源,达到节能降耗的目的。本文立足于研究提高中速磨煤机出口温度的可行性,确定出燃烧实际煤种安全运行时能承受的最高磨煤机进口热空气温度,最大限度的利用空预器中烟气换热量,降低排烟热损失,提高锅炉运行经济性。
实际运行时规定了中速磨煤机最高出口温度,这是为了防止进口热空气温度过高而导致制粉系统运行安全性降低,这牺牲了系统经济性。从理论上说,不同的煤对应着不同的最高且安全的磨煤机进口温度,如何从实验室出发,找出实际煤种的最高承受温度,是本文要解决的问题。
利用TG-FTIR技术可以确定煤中可燃气体在不同气氛下的析出情况。一般中速磨煤机磨制挥发分较大的烟煤、次烟煤及褐煤,其主要析出可燃气体为CO,本文通过TG-FTIR分析N2、air气氛下CO的析出情况,确定CO开始析出温度,并将此温度认定为该煤种可承受的最高热空气温度,分析了CO开始析出温度与Vdaf的关系,并从机理上对CO析出情况进行阐述。
实验室确定出实际煤种的最高进口热空气温度,通过理论计算验证了温州电厂燃烧富动24时干燥出力满足磨煤机出口温度提高至95℃的工况,在温州电厂300MW机组上进行了提高中速磨煤机出口温度的现场试验,得出一系列锅炉参数随磨煤机出口温度变化的情况,试验期间制粉系统运行安全,磨煤机内部无CO析出,锅炉排烟温度下降7℃左右,锅炉热效率提高了0.37%,有较好的经济效益。
The lack of energy impedes advance of society, so far authority took action to carry out Energy conservation and cost reduction projects. Thermal power plant is the largest coal consumer in China, so it is highly significant to develop cost reduction projects.Exhaust gas loss (q2) is the biggest loss in boiler, so if we can decrease q2, coal can be used less.The paper deeply analysed the feasibility of increasing medium-speed pulverizer outlet temperature, then found the maximum pulverizer inlet hot air temperature when boiler run safely, then decreased q2 and raised thermal efficiency of boiler.
Generally, operation regulations set rules about pulverizer outlet temperature to assure system running safely; always it leads to energy waste. Theoretically, a coal corresponds to a safe and maximum pulverizer inlet hot air temperature, so this paper worked at how to get the optimum temperature.
TG-FTIR can make sure how CO Separated from coal.Generally medium-speed pulverizer can mill bituminous coal、subbituminous and brown coal,these coals contains a lot of O,therefore the flammable gas from coals always is CO,the paper analysed CO separation from coal under conditions of N2 or air by TG-FTIR,then defined CO first generated temperature.This temperature was defined to be the safe and maximum pulverizer inlet hot air temperature, and analysed the relationship between CO and Vdaf.
Field test of Improving medium-speed pulverizer outlet temperature began in 300WM wenzhou Thermal power plant, during test the Coal Preparation System ran safely,and there was no CO generated in pulverizer, and exhaust temperature decreased 7℃,and the thermal efficiency of boiler raised 0.37%.
实际运行时规定了中速磨煤机最高出口温度,这是为了防止进口热空气温度过高而导致制粉系统运行安全性降低,这牺牲了系统经济性。从理论上说,不同的煤对应着不同的最高且安全的磨煤机进口温度,如何从实验室出发,找出实际煤种的最高承受温度,是本文要解决的问题。
利用TG-FTIR技术可以确定煤中可燃气体在不同气氛下的析出情况。一般中速磨煤机磨制挥发分较大的烟煤、次烟煤及褐煤,其主要析出可燃气体为CO,本文通过TG-FTIR分析N2、air气氛下CO的析出情况,确定CO开始析出温度,并将此温度认定为该煤种可承受的最高热空气温度,分析了CO开始析出温度与Vdaf的关系,并从机理上对CO析出情况进行阐述。
实验室确定出实际煤种的最高进口热空气温度,通过理论计算验证了温州电厂燃烧富动24时干燥出力满足磨煤机出口温度提高至95℃的工况,在温州电厂300MW机组上进行了提高中速磨煤机出口温度的现场试验,得出一系列锅炉参数随磨煤机出口温度变化的情况,试验期间制粉系统运行安全,磨煤机内部无CO析出,锅炉排烟温度下降7℃左右,锅炉热效率提高了0.37%,有较好的经济效益。
The lack of energy impedes advance of society, so far authority took action to carry out Energy conservation and cost reduction projects. Thermal power plant is the largest coal consumer in China, so it is highly significant to develop cost reduction projects.Exhaust gas loss (q2) is the biggest loss in boiler, so if we can decrease q2, coal can be used less.The paper deeply analysed the feasibility of increasing medium-speed pulverizer outlet temperature, then found the maximum pulverizer inlet hot air temperature when boiler run safely, then decreased q2 and raised thermal efficiency of boiler.
Generally, operation regulations set rules about pulverizer outlet temperature to assure system running safely; always it leads to energy waste. Theoretically, a coal corresponds to a safe and maximum pulverizer inlet hot air temperature, so this paper worked at how to get the optimum temperature.
TG-FTIR can make sure how CO Separated from coal.Generally medium-speed pulverizer can mill bituminous coal、subbituminous and brown coal,these coals contains a lot of O,therefore the flammable gas from coals always is CO,the paper analysed CO separation from coal under conditions of N2 or air by TG-FTIR,then defined CO first generated temperature.This temperature was defined to be the safe and maximum pulverizer inlet hot air temperature, and analysed the relationship between CO and Vdaf.
Field test of Improving medium-speed pulverizer outlet temperature began in 300WM wenzhou Thermal power plant, during test the Coal Preparation System ran safely,and there was no CO generated in pulverizer, and exhaust temperature decreased 7℃,and the thermal efficiency of boiler raised 0.37%.
引文
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[2]中国统计年鉴[M].中国统计出版社,2009
[3]戴为,牛海峰,马洪顺.中速磨煤机[M].北京,机械工业出版社,1999
[4]Babcock & Wilcox.Steam/its generation and use [M].1992
[5]DL/T 5145-2002,电厂制粉系统设计计算技术规定[S].
[6]水利电力部华北电力设计院技术处译.国外大型磨煤机的应用[M].北京：水利电力出版社,1984,94-96.
[7]杨胜强。粉尘防止理论及技术[M].徐州：中国矿业大学出版社,2007,
[8]叶昌.水分对煤的燃烧及传热的影响[M].节能,2001(8)
[9]陈一平.灰份对无烟煤燃烧特性影响试验研究[J].湖南电力技术,1994(5)
[10]王俊琪,方梦祥等.热解半焦孔隙特性研究[J].热力发电,2008(7)
[11]程军,潘华引等.神华配煤孔隙分形对燃烧特性的影响[J].浙江大学学报：工学版,2009(5)
[12]薛永强,来蔚鹏等.粒度对煤粒燃烧和热解影响的理论分析[J].煤炭转化,2005(3)
[13]赵衡阳.气体和粉尘爆炸原理[M].北京,北京理工大学出版社,1995.
[14]张守中.爆炸基本原理[M].北京,国防工业出版社,1988.
[15]赫茨贝格M,凯什多勒KL.粉尘爆炸知识介绍[J].防爆电机1994(2)：33-40
[16]何朝远.瓦斯煤尘共存条件下爆炸危险性的研究[J].煤矿安全,1996(12)：5-7
[17]Cashdollar K L. Coal dust explosibility [J]. Journal of Loss Prevention in the Process Industry,1996,9(1):65-76
[18]邱莉莉,张忠孝,姚向东等.煤粉颗粒群与甲烷混合着火研究[J].锅炉技术,2004,5(5)：36-40
[19]张景林.气体、粉尘爆炸灾害及其安全技术[J].中国安全科学学报,2002,12(5)：9-14
[20]John E. Going, Kris Chatrathi, Kenneth L. Cashdollar. Flammability limit measurements for dusts in 20L and 1m3 vessels [J]. Journal of Loss Prevention in the Process Industries,2000,13:209-219
[21]Ju Wen-Jun, Ritsu Dobashi, Toshisuke Hirano. Dependence of flammability limits of a combustible particle cloud on particle diameter distribution [J]. Journal of Loss Prevention in the Process Industries,1998,11:177-185
[22]何宏达译.爆炸过程和防护措施[M].北京：化学工业出版社,1985.
[23]郑波,胡栋.铝粉激波点火的实验研究[J].爆炸与冲击1997,17(2)：174-180
[24]Lunn G. A., Nicol A. M., Collins P. D. et al. Effects of vent ducts on the reduced pressuresfrom explosions in dust collectors [J]. Journal of Loss Prevention in the Process Industries,1998,11:109-121
[25]Michael J.Sapko, Eric S.Weiss, Kenneth L.Cashdollar etal. Experimental mine and laboratory dust explosion research at NIOSH [J].Journal of Loss Prevention in the Process Industries,2000,13:229-242
[26]Gummer J., Lunn G. A. Ignitions of explosive dust clouds by smouldering and flaming agglomerates [J]. Journal of Loss Prevention in the Process Industries, 2003,16:27-32
[27]Markus Roser, Albrecht Vogl, Siegfried Radandt et al. Investigations of flame frontpropagation between interconnected process vessels:Development of a new flame frontpropagation time prediction model [J]. Journal of Loss Prevention in the Process Industries,1999,12:421-436
[28]Eckhoff R. K. Minimum ignition energy (MIE) a basic ignition sensitivity parameterin design of intrinsically safe electrical apparatus for explosive dust clouds [J]. Journal ofLoss Prevention in the Process Industries,2002, 15:305-310.
[29]Masaharu Nifuku, lbei Matsuda, Hei ji Enomoto. Recent development of standardization of testing methods for dust explosion in Japan [J]. Journal of Loss Prevention in the Process Industries,2000,13:243-251
[30]Gummer J, Lunn G.A. Ignitions of explosive dust clouds by smouldering and flaming agglomerates[J]. Journal of Loss Prevention in the Process Industries,2003,16:27-32
[31]Conde Lazaro E., Garc J. Torrent. Experimental:research on explosibility at high initial pressures of combustible dusts [J]. Journal of Loss Prevention in the Process Industries,2000,13:221-228.
[32]钟圣俊,邓煦帆.有机粉尘爆炸的数值模拟[J].中国粉体技术,2000,6(3)239-243
[33]理查德·西威克.粉尘爆炸技术的最新发展[J].中国安全科学学报,1995,5(3)：11-20
[34]R.K.耳克霍夫.工业生产粉尘爆炸预防和缓解—近期研究与发展综述[J].中国安全科学学报,1995,5(3)：5-10
[35]浦以康,贾复,胡俊.等容燃烧条件下粉尘等效燃烧速度的确定[J].燃烧科学与技术,2002,8(2)：2-5
[36]任守宏,林萍,董永福.建筑设备工程专业常见的爆炸及其预防措施[J].内蒙古科技与经济,2000,1：48-49
[37]范宝春,丁大玉,溥以康等.球型密闭容器中铝粉爆炸机理的研究[J].爆炸与冲击,1994,14(2)：148-155
[38]陈网桦,述忠,毅亭等.铝粉及黑索金粉尘爆炸的特性研究[J].含能材料,2003,11(2)：91-93
[39]詹世平.容器内粉尘爆炸的泄放计算[J].化学工业与工程技术,1999,20(1)：1-8
[40]刘庆明,白春华.铝粉粉尘云和戊烷云雾燃烧诱导爆炸研究[J].北京理工大学学报,1999,19(5)：567-568
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