循环流化床锅炉旋风分离器气固两相流动特性及性能研究
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摘要
循环流化床燃烧是一种燃料适应性广、清洁燃烧的技术。由于它的这些特点,近10年来在世界各国得到了迅速的发展。旋风分离器作为循环流化床锅炉的一个核心部件,其性能的优劣对整个循环流化床锅炉机组的运行表现影响很大。
旋风分离器的分离效率和分离器内的流场是密切相关的,深入研究分离器内的气固两相流动特性对于其结构优化、提高分离效率有重要意义。本文采用实验研究和数值模拟相结合的方法对旋风分离器的气相流场进行了研究。分析研究了分离器内部的气相流场、气固两相流场、浓度分布,并且模拟了不同入口流速、不同入口截面比等条件下分离器的压降和分离效率,并在此基础上提出了改进结构的旋风分离器。
(1)通过对比分析,采用RSM模型(雷诺应力模型)模拟的速度分布和压力分布与实验值吻合较好,模拟结果能较好预测分离器内部流场。
(2)采用随机轨道模型对颗粒相进行了模拟,分析了颗粒相在分离器内的运动规律,并对分离器内部的颗粒相浓度分布进行了分析,预测了“短路流”、“顶灰环”和灰斗返混现象,得到了不同粒径颗粒的分级效率与旋风分离器的总分离效率。
(3)模拟了不同入口流速条件下旋风分离器的压降、粒级效率和总效率。分析了入口条件改变对分离器性能的影响。
(4)对具有不同入口截面高宽比的三种旋风分离器的压降、粒级效率和总效率进行了数值模拟,通过分析发现,入口截面高宽比应在合适的范围内选择,过高和过低都会影响分离器性能。
(5)在分析入口流速、入口截面高宽比的基础上,提出了改进型的旋风分离器,并进行数值模拟,和普通的旋风分离器进行了比较分析。结果显示改进型的旋风分离器能较大幅度的提高分离性能。
Circulating fluidized bed boiler(CFB) is a kind of technology which is fuel adaptable broadly and clean-burning. Because of those characteristics, CFB had been rapid developed in the past decade years in world wildly. As its core component, cyclone separator’s performance plays a deep role in the operation of CFB boiler.
The separating efficiency of cyclone separator is closely related to the flow field inside. It is significant for optimizing the structural and separating efficency of cyclone separator that studying the gas-solid two-phase flow characteristics deeply. The method which combines the experimental study and numerical simulation has used in this dissertation. It has been analyzed in this dissertation such as gas flow field, gas-solid flow field and concentration field. It has been simulated that the pressure drop and separating efficiency of cyclone separator at different inlet velocity and inlet height-width aspect ratio. And on this basis, a structure-ameliorated cyclone separator has been brought forward.
(1) Through comparation and analysis, the velocity distribution and pressure distribution simulated by RSM model (Reynolds Stress Model) fit the results of experiment well. The results of CFD can predict the internal flow field of separator well.
(2) Particle stochastic trajectory model has been used to simulate the particle phase. The motion of particle and particle concentration in the cyclone separator has been analyzed. Based on those analysis, the short-circuit flow, upper dust rin and re-entrainment are predicted and the grain size efficiency and separating efficiency are obtained.
(3) It has been simulated that the pressure, grain size efficiency and separating efficiency at different inlet velocity. It has been analyzed that the influence of performance at different inlet velocity.
(4) It has been simulated that the pressure, grain size efficiency and separating efficiency with different inlet height-width aspect ratio. The result shows that there is proper inlet height-width aspect ratio which can make the cyclone display the best performance.
(5) Based on the analysis of inlet velocity and the inlet section height-width ratio, a structural developed cyclone separator has been raised. The simulating result shows that the separating performance of the new separator has been improved greatly compared with the common style.
旋风分离器的分离效率和分离器内的流场是密切相关的,深入研究分离器内的气固两相流动特性对于其结构优化、提高分离效率有重要意义。本文采用实验研究和数值模拟相结合的方法对旋风分离器的气相流场进行了研究。分析研究了分离器内部的气相流场、气固两相流场、浓度分布,并且模拟了不同入口流速、不同入口截面比等条件下分离器的压降和分离效率,并在此基础上提出了改进结构的旋风分离器。
(1)通过对比分析,采用RSM模型(雷诺应力模型)模拟的速度分布和压力分布与实验值吻合较好,模拟结果能较好预测分离器内部流场。
(2)采用随机轨道模型对颗粒相进行了模拟,分析了颗粒相在分离器内的运动规律,并对分离器内部的颗粒相浓度分布进行了分析,预测了“短路流”、“顶灰环”和灰斗返混现象,得到了不同粒径颗粒的分级效率与旋风分离器的总分离效率。
(3)模拟了不同入口流速条件下旋风分离器的压降、粒级效率和总效率。分析了入口条件改变对分离器性能的影响。
(4)对具有不同入口截面高宽比的三种旋风分离器的压降、粒级效率和总效率进行了数值模拟,通过分析发现,入口截面高宽比应在合适的范围内选择,过高和过低都会影响分离器性能。
(5)在分析入口流速、入口截面高宽比的基础上,提出了改进型的旋风分离器,并进行数值模拟,和普通的旋风分离器进行了比较分析。结果显示改进型的旋风分离器能较大幅度的提高分离性能。
Circulating fluidized bed boiler(CFB) is a kind of technology which is fuel adaptable broadly and clean-burning. Because of those characteristics, CFB had been rapid developed in the past decade years in world wildly. As its core component, cyclone separator’s performance plays a deep role in the operation of CFB boiler.
The separating efficiency of cyclone separator is closely related to the flow field inside. It is significant for optimizing the structural and separating efficency of cyclone separator that studying the gas-solid two-phase flow characteristics deeply. The method which combines the experimental study and numerical simulation has used in this dissertation. It has been analyzed in this dissertation such as gas flow field, gas-solid flow field and concentration field. It has been simulated that the pressure drop and separating efficiency of cyclone separator at different inlet velocity and inlet height-width aspect ratio. And on this basis, a structure-ameliorated cyclone separator has been brought forward.
(1) Through comparation and analysis, the velocity distribution and pressure distribution simulated by RSM model (Reynolds Stress Model) fit the results of experiment well. The results of CFD can predict the internal flow field of separator well.
(2) Particle stochastic trajectory model has been used to simulate the particle phase. The motion of particle and particle concentration in the cyclone separator has been analyzed. Based on those analysis, the short-circuit flow, upper dust rin and re-entrainment are predicted and the grain size efficiency and separating efficiency are obtained.
(3) It has been simulated that the pressure, grain size efficiency and separating efficiency at different inlet velocity. It has been analyzed that the influence of performance at different inlet velocity.
(4) It has been simulated that the pressure, grain size efficiency and separating efficiency with different inlet height-width aspect ratio. The result shows that there is proper inlet height-width aspect ratio which can make the cyclone display the best performance.
(5) Based on the analysis of inlet velocity and the inlet section height-width ratio, a structural developed cyclone separator has been raised. The simulating result shows that the separating performance of the new separator has been improved greatly compared with the common style.
引文
[1]路春美,程世庆,王永征著,循环流化床锅炉设备与运行,北京,中国电力出版社,2003年。
[2]能源与环境,中国动力工程学会第三次全国代表大会学术论文集,杭州,1998
[3] A.C霍夫曼, L. E.斯坦因著,彭维明,姬忠礼译,旋风分离器——原理、设计和工程应用,化学工业出版社,2004.9
[4]小川明著,周世辉,刘隽人译,气体中颗粒的分离,北京,化学工业出版社,1991年。
[5]李荣先,李勇,张会强,崔龙铉,旋风筒内强旋湍流流动的实验研究,燃烧科学与技术,1996年第2期,pp134-138。
[6]刘金红.旋风分离器的发展与理论研究现状[M] .化工装备技术,1998 ,19 (5):49 - 50.
[7] Raser S M ,Abdullah M Z. LDA measurement on modified cyclone [J ] . Laser Anemometry ASME ,1995 ,229 :395 - 403.
[8]娄新生.旋转分离器的实验研究及其CAD[D] .硕士学位论文.华中科技大学动力系,1993.
[9] Ogawa A.,Fujita Y., On the diffusion of fine solid particles and on the intensity of turbulences in a cyclindrical cyclone dust collector, 2nd Congr. Mediterr. Ingenieria Quimica, Barcelona, November,1981。
[10]姬忠礼,时铭显,蜗壳式旋风分离器内流场的特点,石油大学学报,1992年第1期, pp47-59。
[11]时铭显,吴小林,旋风分离器的大型冷模试验研究,化工机械,1993年第4期,pp1-6。
[12] Reinhardt B.,Cordonnier A.,Florent P., Use of an isokinetic sampling probe.Results in a cyclone, Powder tech. 101(1999), pp81-89。
[13] Zhou L.X.,Soo S.L., Gas-solid flow and collection of solids in a cyclone separator, Powder tech. 63(1990), pp45-53。
[14] Zhou L.X.,Li Y.,Chen T.,Xu Y., Studies on the effect of swirl numbers on strongly swirling turbulent gas-particle flows using a phase-Doppler particle anemometer, Powder tech. 112(2000), pp79-86。
[15] Fraser S.M.,Abdel Razek A.M.,Abdullah M.Z., Computational and experimental investigations in a cyclone dust separator, Proc. Instn. Mech. Engrs. 211(1997), pp247-257。
[16] Hoekstra A.J.,Derksen J.J.,Van Den Akker H.E.A., An experimental and numerical study of turbulent swirling flow in gas cyclones, Chem. Engng. Sci. 54(1999), pp2055-2065。
[17] Zhou L.X.,Li Y., Simulation of swirling gas-particle flows using a DSM-PDF two-phase turbulence model, Powder tech. 113(2000), pp70-79。
[18] Boysan F.,Ayers W.H.,Swithenbank,J., A fundamental mathematical modeling approach to cyclone design, Trans. Inst. Chem. Engrs. 60(1982), pp222-230。
[19] Dyakowski T.,Williams, R.A., Modelling turbulent flow within a small-diameter hydrocyclone, Chem. Engng. Sci. 48(1993), pp1143-1152。
[20] Fraser S M ,Aabdel Raxek A M ,Abdullah M Z. Computational and experimental investigations in a cyclone dust separator [J ] .Proceedings of the Institution of Mechanical Engineers , 1997 ,211 ( E4) :247 - 257.
[21] Griffiths W.D.,Boysan F., CFD and empirical modeling of the performance of a number of cyclone samplers, J. Aerosol Sci. 27(1996), pp281-304。
[22] Ma L.,Ingham D.B., Wen X., Numerical modeling of the fluid and particle penetration through small sampling cyclones, J. Aerosol Sci. 31(2000), pp1097-1119。
[23]陶文铨,数值传热学(第2版)[M],西安交通大学出版社,2001
[24]刁永发等.高温旋风分离分级效率的理论计算及其分析[J].化工机械,2000,27(1):16-19
[25]王海刚,刘石.用雷诺应力模型计算旋风分离器中气固两相流动[J].工程热物理学报,2004,25(Suppl):189-192.
[26]王乐勤,郝宗睿,王循明,焦磊等.筒体长度对旋风分离器内流场影响的数值模拟[J].工程热物理学报,2009,2(2):223-226.
[27]曹晴云,姬广勤,金有海,王建军等.不同结构参数下旋风分离器气相流场的数值研究[J].流体机械,2008,06(1):34-39.
[28]宋健斐,魏耀东,时铭显.旋风分离器内颗粒浓度场的数值模拟[J].中国石油大学学报(自然科学版),2008,32(1):90-94.
[29]王海刚,刘石.不同湍流模型在旋风分离器三维数值模拟中的应用和比较[J].热能动力工程.,2003,16(4):337-342.
[30] Fluent Inc.FLUENT User’s 2003.2003
[31]窦国仁,湍流力学(上册),高等教育出版社,1985
[32] P.J.罗奇著,钟锡昌、刘学宗译,计算流体动力学[M],科学出版社1983
[33]周力行.湍流两相流动与燃烧的数值模拟[M].北京:清华大学出版社,1991.
[34] Orszag, S.A., Numerical Simulation of Turbulence Flows, Handbook of Turbulence, Vol.1, 1977
[35] Hinze J O.Turbulence(2nd edn).New York:McCrraw-Hill Book Company, 1979:87
[36]胡砾元,吴小林,时铭显.旋风分离器内颗粒轨迹的计算方法[J] .石油大学学报(自然科学版),1998,22(4):64-67
[37]王建军,金有海.旋风管不同排尘结构内流场及颗粒浓度场分析.化学工程,2003.
[38]杨成禹.大型CFB锅炉旋风分离器的冷模试验研究.重庆大学硕士学位论文.2006:45~50
[39]吴小林,黄学东,时铭显.旋风分离器的颗粒浓度分布的实验研究.石油大学学报(自然科学版),1993,17(4):54~59
[40] Hoffmann AC,Arends H and Sie H(1991)An experimental investigation elucidatingthe effect of solid loading on cyclone performance.Filtration and Separation 28:188-193
[41]彭雷,李军,王国鸿.排气管偏置对CFB锅炉旋风分离器性能的影响.热能动力工程,2004,19(2):153~157
[42]罗志浩.方形上排气型分离器内气固两相流动特性的数值模拟研究〔D].浙江:浙江大学,2001.
[43]赵萍.旋风除尘器结构尺寸优化设计的研究.阜新:辽宁工程技术大学,2002
[2]能源与环境,中国动力工程学会第三次全国代表大会学术论文集,杭州,1998
[3] A.C霍夫曼, L. E.斯坦因著,彭维明,姬忠礼译,旋风分离器——原理、设计和工程应用,化学工业出版社,2004.9
[4]小川明著,周世辉,刘隽人译,气体中颗粒的分离,北京,化学工业出版社,1991年。
[5]李荣先,李勇,张会强,崔龙铉,旋风筒内强旋湍流流动的实验研究,燃烧科学与技术,1996年第2期,pp134-138。
[6]刘金红.旋风分离器的发展与理论研究现状[M] .化工装备技术,1998 ,19 (5):49 - 50.
[7] Raser S M ,Abdullah M Z. LDA measurement on modified cyclone [J ] . Laser Anemometry ASME ,1995 ,229 :395 - 403.
[8]娄新生.旋转分离器的实验研究及其CAD[D] .硕士学位论文.华中科技大学动力系,1993.
[9] Ogawa A.,Fujita Y., On the diffusion of fine solid particles and on the intensity of turbulences in a cyclindrical cyclone dust collector, 2nd Congr. Mediterr. Ingenieria Quimica, Barcelona, November,1981。
[10]姬忠礼,时铭显,蜗壳式旋风分离器内流场的特点,石油大学学报,1992年第1期, pp47-59。
[11]时铭显,吴小林,旋风分离器的大型冷模试验研究,化工机械,1993年第4期,pp1-6。
[12] Reinhardt B.,Cordonnier A.,Florent P., Use of an isokinetic sampling probe.Results in a cyclone, Powder tech. 101(1999), pp81-89。
[13] Zhou L.X.,Soo S.L., Gas-solid flow and collection of solids in a cyclone separator, Powder tech. 63(1990), pp45-53。
[14] Zhou L.X.,Li Y.,Chen T.,Xu Y., Studies on the effect of swirl numbers on strongly swirling turbulent gas-particle flows using a phase-Doppler particle anemometer, Powder tech. 112(2000), pp79-86。
[15] Fraser S.M.,Abdel Razek A.M.,Abdullah M.Z., Computational and experimental investigations in a cyclone dust separator, Proc. Instn. Mech. Engrs. 211(1997), pp247-257。
[16] Hoekstra A.J.,Derksen J.J.,Van Den Akker H.E.A., An experimental and numerical study of turbulent swirling flow in gas cyclones, Chem. Engng. Sci. 54(1999), pp2055-2065。
[17] Zhou L.X.,Li Y., Simulation of swirling gas-particle flows using a DSM-PDF two-phase turbulence model, Powder tech. 113(2000), pp70-79。
[18] Boysan F.,Ayers W.H.,Swithenbank,J., A fundamental mathematical modeling approach to cyclone design, Trans. Inst. Chem. Engrs. 60(1982), pp222-230。
[19] Dyakowski T.,Williams, R.A., Modelling turbulent flow within a small-diameter hydrocyclone, Chem. Engng. Sci. 48(1993), pp1143-1152。
[20] Fraser S M ,Aabdel Raxek A M ,Abdullah M Z. Computational and experimental investigations in a cyclone dust separator [J ] .Proceedings of the Institution of Mechanical Engineers , 1997 ,211 ( E4) :247 - 257.
[21] Griffiths W.D.,Boysan F., CFD and empirical modeling of the performance of a number of cyclone samplers, J. Aerosol Sci. 27(1996), pp281-304。
[22] Ma L.,Ingham D.B., Wen X., Numerical modeling of the fluid and particle penetration through small sampling cyclones, J. Aerosol Sci. 31(2000), pp1097-1119。
[23]陶文铨,数值传热学(第2版)[M],西安交通大学出版社,2001
[24]刁永发等.高温旋风分离分级效率的理论计算及其分析[J].化工机械,2000,27(1):16-19
[25]王海刚,刘石.用雷诺应力模型计算旋风分离器中气固两相流动[J].工程热物理学报,2004,25(Suppl):189-192.
[26]王乐勤,郝宗睿,王循明,焦磊等.筒体长度对旋风分离器内流场影响的数值模拟[J].工程热物理学报,2009,2(2):223-226.
[27]曹晴云,姬广勤,金有海,王建军等.不同结构参数下旋风分离器气相流场的数值研究[J].流体机械,2008,06(1):34-39.
[28]宋健斐,魏耀东,时铭显.旋风分离器内颗粒浓度场的数值模拟[J].中国石油大学学报(自然科学版),2008,32(1):90-94.
[29]王海刚,刘石.不同湍流模型在旋风分离器三维数值模拟中的应用和比较[J].热能动力工程.,2003,16(4):337-342.
[30] Fluent Inc.FLUENT User’s 2003.2003
[31]窦国仁,湍流力学(上册),高等教育出版社,1985
[32] P.J.罗奇著,钟锡昌、刘学宗译,计算流体动力学[M],科学出版社1983
[33]周力行.湍流两相流动与燃烧的数值模拟[M].北京:清华大学出版社,1991.
[34] Orszag, S.A., Numerical Simulation of Turbulence Flows, Handbook of Turbulence, Vol.1, 1977
[35] Hinze J O.Turbulence(2nd edn).New York:McCrraw-Hill Book Company, 1979:87
[36]胡砾元,吴小林,时铭显.旋风分离器内颗粒轨迹的计算方法[J] .石油大学学报(自然科学版),1998,22(4):64-67
[37]王建军,金有海.旋风管不同排尘结构内流场及颗粒浓度场分析.化学工程,2003.
[38]杨成禹.大型CFB锅炉旋风分离器的冷模试验研究.重庆大学硕士学位论文.2006:45~50
[39]吴小林,黄学东,时铭显.旋风分离器的颗粒浓度分布的实验研究.石油大学学报(自然科学版),1993,17(4):54~59
[40] Hoffmann AC,Arends H and Sie H(1991)An experimental investigation elucidatingthe effect of solid loading on cyclone performance.Filtration and Separation 28:188-193
[41]彭雷,李军,王国鸿.排气管偏置对CFB锅炉旋风分离器性能的影响.热能动力工程,2004,19(2):153~157
[42]罗志浩.方形上排气型分离器内气固两相流动特性的数值模拟研究〔D].浙江:浙江大学,2001.
[43]赵萍.旋风除尘器结构尺寸优化设计的研究.阜新:辽宁工程技术大学,2002