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第3期 刘柏谦等：大颗粒煤流化床燃烧的微观过程 .301. 400 明微孔和小孔的数量占绝大多数，与燃烧时间有关； 大孔数量不随燃烧过程而增加， ★1=10s 300 0-1=80s (③)煤颗粒的比表面积随燃烧时间的增加呈现 明显的上升趋势，与孔隙结构的变化基本相符合， 参考文献 100 [1]Cen K F,Ni M J.Luo Z Y,et al.Theory,Design and Opera- tion of Circulating Fluidized Bed Boilers.Beijing:China Electric 200 40060080010001200 Power Press.1998:207 孔隙面积/像素 (岑可法，倪明江，骆仲泱，等.循环流化床锅炉理论设计与运 行，北京：中国电力出版社，1998：270) 图4燃烧时间为10s和80s时孔隙分布对比 [2]Adanez J.de Diego L F.Gayan P,et al.A model for predication Fig4 Pore distribution comparison between 10s and 80s combus- of carbon combustion efficiency in circulating fluidized bed com- tion time bustor.Fel,1995,74(7):1049 [3]Arena U.Chiroe R.Amore M D.et al.Some issues in modeling 3氮吸附法测量煤颗粒的比表面积 bubbling and circulating fluidized bed coal combustors.Po der Technol,1995,82(3):301 为验证图像处理的可靠性，利用气体吸附方法 [4]KnoebigT,Luecke K.Werther J.Mixing and reaction in the 测量相同条件下煤颗粒比表面积变化，见图5 circulating fluidized bed,a three dimensional combustor model. 140 Chem Eng Sci.1999.54:2151 [5]Winter F.Prah M E.Hofbauer H.Temperature in a fuel particle 120 burning in a fluidized bed:the effect of drying,devolatilization >100 and char combustion.Combust Flame,1997,108:302 0 [6]Marban G.Pis J J.Fuertes A B.Charactering fuels for atmo- 80 spheric fluidized bed combustion.Combust Flame.1995,103; 60 41 40 [7]Zhou HS,Flamant G.Gauthier D.DEM-LES simulation of coal 20 combustion in a bubbling fluidized bed lI:Coal combustion at a 日4 particle level.Chem Eng Sci.2004.59:4205 50 100150 200 250 [8]Saastamoinen JJ.Tourunen A.Hamalainen J.et al.Analytical 时间s solution for steady and unsteady state particle size distribution in FBC and CFBC boiler for non-breaking char particle.Combust 图5比表面积随燃绕时间变化 Flame,2003.132,395 Fig.5 Change in specific surface area with combustion time [9]Eaton A M.Smoot L D.Hill C.et al.Components,formula- tions.solutions,evaluation and application of comprehensive com 由图5可见，煤颗粒比表面积随时间的变化总 bustion models.Prog Energy Combust Sei.1999.25:387 体是增大的，由前面孔隙长大的研究可知，燃烧过 [10]Yates J G.Effects of temperature and pressure on gas solid flu- 程中孔隙数量及其面积分数均增加，而煤颗粒内表 idization.Chem Eng Sci.1996,51(2):167 面积增大更为显著，内表面积在煤颗粒总面积中比 [11]Sriramulu S,Sane S.Pradeep,et al.Mathematical modeling of 外表面积大得多，在持续的燃烧过程中起主导作用 fluidized bed combustion.Fuel,1996,75(12):1351 比表面积的变化与孔隙的变化是相一致的， [12]Govender A.van Dyk J C.Effect of wet screening on particle size distribution and coal properties.Fuel.2003.82:2231 4结论 [13]Castleman J M.Process performance of the TVA 20MW atmo- spheric fluidized bed combustion pilot plant//Proceedings of the (1)大颗粒煤在流化床燃烧过程中，颗粒表面 8th International conference on FBC.1985:196 孔隙的面积分数随燃烧时间增加而增加：在燃烧初 [14]Chandran RR.Duqum J N.Perna M A.et al.A New method 始阶段增加较快，后续残碳燃烧阶段增加较慢， for AFBC fuels characterization//Mustonen J P.Proceedings of the 9th International conference on FBC.1987:292 (2)扫描电镜图像的孔隙轮廓图分析表明，在 [15]Duqum J N.Tang JT,Morris T A.AFBC performance com- 流化床燃烧过程中，大于400像素的孔隙数量几乎 parison for under hed and over bed feed systems//Proceedings of 不变，而小于400像素的孔隙呈指数方式增长，表 the 8th International conference on FBC.1985:255图4 燃烧时间为10s 和80s 时孔隙分布对比 Fig．4 Pore distribution comparison between10s and80s combustion time 3 氮吸附法测量煤颗粒的比表面积 为验证图像处理的可靠性利用气体吸附方法 测量相同条件下煤颗粒比表面积变化见图5． 图5 比表面积随燃烧时间变化 Fig．5 Change in specific surface area with combustion time 由图5可见煤颗粒比表面积随时间的变化总 体是增大的．由前面孔隙长大的研究可知燃烧过 程中孔隙数量及其面积分数均增加而煤颗粒内表 面积增大更为显著．内表面积在煤颗粒总面积中比 外表面积大得多在持续的燃烧过程中起主导作用． 比表面积的变化与孔隙的变化是相一致的． 4 结论 （1） 大颗粒煤在流化床燃烧过程中颗粒表面 孔隙的面积分数随燃烧时间增加而增加：在燃烧初 始阶段增加较快后续残碳燃烧阶段增加较慢． （2） 扫描电镜图像的孔隙轮廓图分析表明在 流化床燃烧过程中大于400像素的孔隙数量几乎 不变而小于400像素的孔隙呈指数方式增长．表 明微孔和小孔的数量占绝大多数与燃烧时间有关； 大孔数量不随燃烧过程而增加． （3） 煤颗粒的比表面积随燃烧时间的增加呈现 明显的上升趋势与孔隙结构的变化基本相符合． 参 考 文 献 ［1］ Cen K FNi M JLuo Z Yet al．TheoryDesign and Operation of Circulating Fluidized Bed Boilers．Beijing：China Electric Power Press1998：207 （岑可法倪明江骆仲泱等．循环流化床锅炉理论设计与运 行．北京：中国电力出版社1998：270） ［2］ Adanez Jde Diego L FGayan Pet al．A model for predication of carbon combustion efficiency in circulating fluidized bed combustor．Fuel199574（7）：1049 ［3］ Arena UChiroe RAmore M Det al．Some issues in modeling bubbling and circulating fluidized bed coal combustors．Pow der Technol199582（3）：301 ［4］ Knoebig TLuecke KWerther J．Mixing and reaction in the circulating fluidized beda three-dimensional combustor model． Chem Eng Sci199954：2151 ［5］ Winter FPrah M EHofbauer H．Temperature in a fuel particle burning in a fluidized bed：the effect of dryingdevolatilization and char combustion．Combust Flame1997108：302 ［6］ Marban GPis J JFuertes A B．Charactering fuels for atmospheric fluidized bed combustion．Combust Flame1995103： 41 ［7］ Zhou H SFlamant GGauthier D．DEM-LES simulation of coal combustion in a bubbling fluidized bed Ⅱ：Coal combustion at a particle level．Chem Eng Sci200459：4205 ［8］ Saastamoinen J JTourunen AHamalainen Jet al．Analytical solution for steady and unsteady state particle size distribution in FBC and CFBC boiler for non-breaking char particle．Combust Flame2003132：395 ［9］ Eaton A MSmoot L DHill S Cet al．Componentsformulationssolutionsevaluation and application of comprehensive combustion models．Prog Energy Combust Sci199925：387 ［10］ Yates J G．Effects of temperature and pressure on gas solid fluidization．Chem Eng Sci199651（2）：167 ［11］ Sriramulu SSane SPradeepet al．Mathematical modeling of fluidized bed combustion．Fuel199675（12）：1351 ［12］ Govender Avan Dyk J C．Effect of wet screening on particle size distribution and coal properties．Fuel200382：2231 ［13］ Castleman J M．Process performance of the TVA20MW atmospheric fluidized bed combustion pilot plant∥ Proceedings of the 8th International conference on FBC1985：196 ［14］ Chandran R RDuqum J NPerna M Aet al．A New method for AFBC fuels characterization∥Mustonen J P．Proceedings of the9th International conference on FBC1987：292 ［15］ Duqum J NTang J TMorris T A．AFBC performance comparison for under bed and over bed feed systems∥ Proceedings of the8th International conference on FBC1985：255 第3期 刘柏谦等： 大颗粒煤流化床燃烧的微观过程 ·301·