基于快速流态化统一动力学模型的床层固含率分布规律模拟
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摘要
快速流态化作为一种新型高效的气固接触技术,现广泛应用于各行各业。以快速流态化统一动力学模型为基础,分别探究了床料物性参数、操作运行条件以及床层直径大小对床层上部稀相区固体颗粒浓度分布规律的影响,并对相关结果进行了分析,以期为快速流态化统一动力学模型的工程推广应用提供进一步的指导。结果表明:在其他参数不变的条件下,快速床上部稀相固含率随颗粒密度的增大而减小;随颗粒直径的增大而减小;随床层直径的增大而增大;随固体循环流率的增大而增大;随操作风速的增大而减小。
As a new and efficient gas-solid contacting technology,fast fluidization has been applied in many fields.Based on the type-A-choking-oriented unified model for fast fluidization dynamics,we study the influences of solids characteristics,operating conditions and riser diameter on the solids holdup in the upper dilute region in fast fluidized beds,respectively.The results show that solids holdup in the upper dilute region increases with increasing solids diameter and solids density.When the circulated solid flux increases or the superficial gas velocity decreases,solids holdup in the upper dilute region increases.The solids holdup in the upper dilute region should be greater in a larger riser than in a smaller one.We hope the above results can give some instructions to the type-A-choking-oriented unified model to be used for engineering practice.
As a new and efficient gas-solid contacting technology,fast fluidization has been applied in many fields.Based on the type-A-choking-oriented unified model for fast fluidization dynamics,we study the influences of solids characteristics,operating conditions and riser diameter on the solids holdup in the upper dilute region in fast fluidized beds,respectively.The results show that solids holdup in the upper dilute region increases with increasing solids diameter and solids density.When the circulated solid flux increases or the superficial gas velocity decreases,solids holdup in the upper dilute region increases.The solids holdup in the upper dilute region should be greater in a larger riser than in a smaller one.We hope the above results can give some instructions to the type-A-choking-oriented unified model to be used for engineering practice.
引文
[1]ZHANG M C,ZHANG C.A type-A-choking-oriented unified model for fast fluidization dynamics[J].Powder Technology,2013,241(3):126-141.
[2]ZHANG M C,ZHANG C.Further integration of the typeA-choking-oriented unified model for fast fluidization dynamics[J].Powder Technology,2015,286:132-143.
[3]章明川,张楚.快速床动力学统一模型IV:介观解析与子模型优化[J].工程热物理学报,2013,34(4):765-770.
[4]章明川,张楚,林郁郁,等.快速床动力学统一模型-由A型噎塞向C型噎塞的连续转变Ⅰ:模型构建[J].工程热物理学报,2011,32(5):895-899.
[5]张楚,章明川.快速床动力学统一模型V:固含率轴向分布的预报[J].工程热物理学报,2014,35(2):382-387.
[6]张楚,林郁郁,章明川.快速床动力学统一模型Ⅲ:高密度流化床的预报[J].工程热物理学报,2013,34(1):177-180.
[7]YANG W C.Criteria for choking in vertical pneumatic conveying lines[J].Powder Technology,1983,35(2):143-150.
[8]YOUSFI Y,GAU G.Aerodynamique de l'ecoulement vertical de suspensions concentrees gaz-solides-I.Regimes d'ecoulement et stabilite aerodynamique[J].Chemical Engineering Science,1974,29(9):1939-1946.
[9]RICHARDSON J F,ZAKI W N.Sedimentation and Fluidization,Part I[J].Transactions of the Institution of Chemical Engineers,1954,32:35-53.
[10]HARRIS A T,DAVIDSON J F,THORPE R B.The prediction of particle cluster properties in the near wall region of a vertical riser(200157)[J].Powder Technology,2002,127(2):128-143.
[11]DAVIDSON J F,HARRISON D.Fluidised particles[M].Cambridge:Cambridge University Press,1963.
[12]GRACE J R,CLIFT R.On the two-phase theory of fluidization[J].Chemical Engineering Science,1974,29(2):327-334.
[13]LI J,KUIPERS J A M.Gas-particle interactions in dense gas-fluidized beds[J].Chemical Engineering Science,2003,58(3):711-718.
[14]HARRIS B J,DAVIDSON F J,XUE Y.Axial and radial variation of flow in circulating fluidized bed risers[C]//Proceedings of the Fourth International Conference on Circulating Fluidized Beds,Pennsylvania,USA:1993.
[15]XU G,NOMURA K,NAKAGAWA N,et al.Hydrodynamic dependence on riser diameter for different particles in circulating fluidized beds[J].Powder Technology,2000,113(1):80-87.
[16]BRERETON C,STROMBERG L.Some aspects of the fluid dynamic behavior of fast fluidised beds[C]//Proceedings of the First International Conference on Circulating Fluidized Beds,Halifax,Nova Scotia,Canada:1986,133-144.
[17]ARENA U,CAMMAROTA A,MASSIMILLA L,et al.The Hydrodynamic Behavior of Two Circulating Fluidized Bed Units of Different Sizes[C]//Proceedings of the Second International Conference on Circulating Fluidized Beds,Compiégne,France:1988.
[18]ARENA U,MALANDRINO A,MANOCCHELLA A,et al.Flow structure in the riser of laboratory and pilot CFBunit[C]//Proceedings of the Third International Conference on Circulating Fluidized Beds,Nagoya,Japan:1991.
[19]BAI D R,JIN Y,YU Z Q,et al.The axial distribution of the cross-sectionally averaged voidage in fast fluidized beds[J].Chemical Reaction Engineering&Technology,1990,71(1):51-58.
[20]YUANKI T.Radial Voidage Profiles in a Fast Fluidized Bed[J].Chemical Reaction Engineering&Technology,1988,4(1):75-81.
[21]ZHANG W,TUNG Y,JOHNSSON F.Radial voidage profiles in fast fluidized beds of different diameters[J].Chemical Engineering Science,1991,46(12):3045-3052.
[22]GRACE J.Influence of riser geometry on particle and fluid dynamics in circulating fluidized bed risers[J].Adults Learning,1993(4).
[23]YI C,FEI W,YANG G,et al.Inlet and outlet effects on flow patterns in gas-solid risers[J].Powder Technology,1998,98(2):151-156.
[24]HORIO M,MORISHITA K,TACHIBANA O,et al.Solid Distribution and Movement in Circulating Fluidized Beds[C]//Proceedings of the Second International Conference on Circulating Fluidized Beds,Compiégne,France:1988.
[25]RHODES M J,WANG X S,CHENG H,et al.Similar Profiles of Solids Flux in Circulating Fluidized-Bed Risers[J].Chemical Engineering Science,1992,47(7):1635-1643.
[26]Arena U,Camarota A,Mazocchella A,et al.Hydrodynamics of a circulating fluidized bed with secondary air injection[C]//Proceedings of the 1993International Conference on Fluidized Bed Combustion,San Diego,California,USA:1993.
[2]ZHANG M C,ZHANG C.Further integration of the typeA-choking-oriented unified model for fast fluidization dynamics[J].Powder Technology,2015,286:132-143.
[3]章明川,张楚.快速床动力学统一模型IV:介观解析与子模型优化[J].工程热物理学报,2013,34(4):765-770.
[4]章明川,张楚,林郁郁,等.快速床动力学统一模型-由A型噎塞向C型噎塞的连续转变Ⅰ:模型构建[J].工程热物理学报,2011,32(5):895-899.
[5]张楚,章明川.快速床动力学统一模型V:固含率轴向分布的预报[J].工程热物理学报,2014,35(2):382-387.
[6]张楚,林郁郁,章明川.快速床动力学统一模型Ⅲ:高密度流化床的预报[J].工程热物理学报,2013,34(1):177-180.
[7]YANG W C.Criteria for choking in vertical pneumatic conveying lines[J].Powder Technology,1983,35(2):143-150.
[8]YOUSFI Y,GAU G.Aerodynamique de l'ecoulement vertical de suspensions concentrees gaz-solides-I.Regimes d'ecoulement et stabilite aerodynamique[J].Chemical Engineering Science,1974,29(9):1939-1946.
[9]RICHARDSON J F,ZAKI W N.Sedimentation and Fluidization,Part I[J].Transactions of the Institution of Chemical Engineers,1954,32:35-53.
[10]HARRIS A T,DAVIDSON J F,THORPE R B.The prediction of particle cluster properties in the near wall region of a vertical riser(200157)[J].Powder Technology,2002,127(2):128-143.
[11]DAVIDSON J F,HARRISON D.Fluidised particles[M].Cambridge:Cambridge University Press,1963.
[12]GRACE J R,CLIFT R.On the two-phase theory of fluidization[J].Chemical Engineering Science,1974,29(2):327-334.
[13]LI J,KUIPERS J A M.Gas-particle interactions in dense gas-fluidized beds[J].Chemical Engineering Science,2003,58(3):711-718.
[14]HARRIS B J,DAVIDSON F J,XUE Y.Axial and radial variation of flow in circulating fluidized bed risers[C]//Proceedings of the Fourth International Conference on Circulating Fluidized Beds,Pennsylvania,USA:1993.
[15]XU G,NOMURA K,NAKAGAWA N,et al.Hydrodynamic dependence on riser diameter for different particles in circulating fluidized beds[J].Powder Technology,2000,113(1):80-87.
[16]BRERETON C,STROMBERG L.Some aspects of the fluid dynamic behavior of fast fluidised beds[C]//Proceedings of the First International Conference on Circulating Fluidized Beds,Halifax,Nova Scotia,Canada:1986,133-144.
[17]ARENA U,CAMMAROTA A,MASSIMILLA L,et al.The Hydrodynamic Behavior of Two Circulating Fluidized Bed Units of Different Sizes[C]//Proceedings of the Second International Conference on Circulating Fluidized Beds,Compiégne,France:1988.
[18]ARENA U,MALANDRINO A,MANOCCHELLA A,et al.Flow structure in the riser of laboratory and pilot CFBunit[C]//Proceedings of the Third International Conference on Circulating Fluidized Beds,Nagoya,Japan:1991.
[19]BAI D R,JIN Y,YU Z Q,et al.The axial distribution of the cross-sectionally averaged voidage in fast fluidized beds[J].Chemical Reaction Engineering&Technology,1990,71(1):51-58.
[20]YUANKI T.Radial Voidage Profiles in a Fast Fluidized Bed[J].Chemical Reaction Engineering&Technology,1988,4(1):75-81.
[21]ZHANG W,TUNG Y,JOHNSSON F.Radial voidage profiles in fast fluidized beds of different diameters[J].Chemical Engineering Science,1991,46(12):3045-3052.
[22]GRACE J.Influence of riser geometry on particle and fluid dynamics in circulating fluidized bed risers[J].Adults Learning,1993(4).
[23]YI C,FEI W,YANG G,et al.Inlet and outlet effects on flow patterns in gas-solid risers[J].Powder Technology,1998,98(2):151-156.
[24]HORIO M,MORISHITA K,TACHIBANA O,et al.Solid Distribution and Movement in Circulating Fluidized Beds[C]//Proceedings of the Second International Conference on Circulating Fluidized Beds,Compiégne,France:1988.
[25]RHODES M J,WANG X S,CHENG H,et al.Similar Profiles of Solids Flux in Circulating Fluidized-Bed Risers[J].Chemical Engineering Science,1992,47(7):1635-1643.
[26]Arena U,Camarota A,Mazocchella A,et al.Hydrodynamics of a circulating fluidized bed with secondary air injection[C]//Proceedings of the 1993International Conference on Fluidized Bed Combustion,San Diego,California,USA:1993.