乙烯气相聚合流化床反应器内Geldart B类和Geldart D类颗粒流动特性的三维数值模拟
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摘要
乙烯气相聚合流化床反应器的设计、操作和优化依赖于对聚合物颗粒粒径大小和分布、气泡运动特性及聚合反应状况的准确描述。采用Eulerian-Eulerian双流体模型和群体平衡模型耦合方法对某乙烯气相聚合中试规模的工业流化床反应器分别处于常规聚合工艺(属Geldart B类颗粒)和免造粒工艺(属Geldart D类颗粒)时床体的气固流动特征以及不同颗粒类型对反应器操作状态和颗粒运动特性的影响进行了三维数值模拟研究。与传统聚乙烯生产工艺相比,免造粒工艺时的Geldart D类聚合物颗粒更易聚集于气体入口处区域,而且会产生明显的旋涡并出现较大的气泡。研究结果可为免造粒聚乙烯生产工艺的工业推广应用提供参考。
The status of polyethylene(PE) particle size and distribution, bubble generation and movement, and polymerization reaction in gas phase ethylene polymerization fluidized-bed reactor(FBR) is significant for PE production process, reactor design, optimization and control. Based on 3 dimensional(3D) Eulerian-Eulerian two-fluid model combined with a population balance model(PBM), this work aims to explore the two-phase flow characteristics and the effects of traditional PE production process(Geldart B particles) and non-pelletizing PE production process(Geldart D particles) on the operating behaviors in a pilot-plant FBR. The simulation results match well with the industrial measured pressure drop and temperature data. It is also found that the polymer particles observably concentrated on the bed inlet region for the effects of Geldart D particles and superfical gas velocity. In addition, the obvious vortexes and large bubbles can be clearly observed in the bed height direction. The results could provide foundation for the extension and application of the non-pelletizing PE production process.
The status of polyethylene(PE) particle size and distribution, bubble generation and movement, and polymerization reaction in gas phase ethylene polymerization fluidized-bed reactor(FBR) is significant for PE production process, reactor design, optimization and control. Based on 3 dimensional(3D) Eulerian-Eulerian two-fluid model combined with a population balance model(PBM), this work aims to explore the two-phase flow characteristics and the effects of traditional PE production process(Geldart B particles) and non-pelletizing PE production process(Geldart D particles) on the operating behaviors in a pilot-plant FBR. The simulation results match well with the industrial measured pressure drop and temperature data. It is also found that the polymer particles observably concentrated on the bed inlet region for the effects of Geldart D particles and superfical gas velocity. In addition, the obvious vortexes and large bubbles can be clearly observed in the bed height direction. The results could provide foundation for the extension and application of the non-pelletizing PE production process.
引文
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[18]SUN J Y,WANG J D,YANG Y R.CFD investigation of particle fluctuation characteristics of bidisperse mixture in a gas-solid fluidized bed[J].Chemical Engineering Science,2012,82:285-298.
[19]YAN W C,LI J,LUO Z H.A CFD-PBM coupled model with polymerization kinetics for multizone circulating polymerization reactors[J].Powder Technology,2012,231:77-87.
[20]KANELLOPOULOS V,DOMPAZIS G,GUSTAFSSON B,et al.Comprehensive analysis of single-particle growth in heterogeneous olefin polymerization:the random-pore polymeric flow model[J].Industrial&Engineering Chemistry Research,2004,43(17):5166-5180.
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[22]WEI L H,YAN W C,LUO Z H.A preliminary CFD study of the gas-solid flow fields in multizone circulating polymerization reactors[J].Powder Technology,2011,214(1):143-154.
[23]LOHA C,CHATTOPADHYAY H,CHATTERJEE P K.Assessment of drag models in simulating bubbling fluidized bed hydrodynamics[J].Chemical Engineering Science,2012,75:400-407.
[24]HAN Y,WANG J J,GU X P,et al.Homogeneous fluidization of Geldart D particles in a gas-solid fluidized bed with a frame impeller[J].Industrial&Engineering Chemistry Research,2012,51(50):16482-16487.
[25]张翠宣,叶京生,宋继田.喷动床研究与进展[J].化工进展,2002,21(9):630-634.ZHANG C X,YE J S,SONG J T.Development and prospect of modified spouted beds[J].Chemical Industry and Engineering Progress,2002,21(9):630-634.
[2]XIE T Y,MCAULEY K B,HSU J C,et al.Gas phase ethylene polymerization:production processes,polymer properties,and reactor modeling[J].Industrial&Engineering Chemistry Research,1994,33(3):449-479.
[3]CHE Y,TIAN Z,LIU Z,et al.CFD prediction of scale-up effect on the hydrodynamic behaviors of a pilot-plant fluidized bed reactor and preliminary exploration of its application for non-pelletizing polyethylene process[J].Powder Technology,2015,278:94-110.
[4]KHAN M J H,HUSSAIN M A,MANSOURPOUR Z,et al.CFD simulation of fluidized bed reactors for polyolefin production—a review[J].Journal of Industrial and Engineering Chemistry,2014,20(6):3919-3946.
[5]TERANO M,SUEHIRO K,SAGAE T,et al.Studies in Surface Science and Catalysis[M].Amsterdam:Elsevier,2006:7-12.
[6]WU L,WANKE S E.Handbook of Transition Metal Polymerization Catalysts[M].New Jersey:John Wiley&Sons Inc.,2010:231-259.
[7]TIAN Z,GU X P,FENG L F,et al.An atmosphere-switching polymerization process:a novel strategy to advanced polyolefin materials[J].AICh E Journal,2013,59(12):4468-4473.
[8]GALLI P,VECELLIO G.Technology:driving force behind innovation and growth of polyolefins[J].Progress in Polymer Science,2001,26(8):1287-1336.
[9]GELDART D.Types of gas fluidization[J].Powder Technology,1973,7(5):285-292.
[10]FAN L S,ZHU C.Principles of Gas-Solid Flows[M].Cambridge:Cambridge University Press,2005:371-420.
[11]李倩,程景才,杨超,等.群体平衡方程在搅拌反应器模拟中的应用[J].化工学报,2014,65(5):1607-1615.LI Q,CHENG J C,YANG C,et al.Application of population balance equation in numerical simulation of multiphase stirred tanks[J].CIESC Journal,2014,65(5):1607-1615.
[12]MARCHISIO D L,FOX R O.Computational Models for Polydisperse Particulate and Multiphase Systems[M].Cambridge:Cambridge University Press,2013:47-101.
[13]YAN W C,LUO Z H,LU Y H,et al.A CFD-PBM-PMLM integrated model for the gas-solid flow fields in fluidized bed polymerization reactors[J].AICh E Journal,2012,58(6):1717-1732.
[14]MCGRAW R.Description of aerosol dynamics by the quadrature method of moments[J].Aerosol Science and Technology,1997,27(2):255-265.
[15]CHEN X Z,LUO Z H,YAN W C,et al.Three-dimensional CFD-PBM coupled model of the temperature fields in fluidized-bed polymerization reactors[J].AICh E Journal,2011,57(12):3351-3366.
[16]HATZANTONIS H,GOULAS A,KIPARISSIDES C.A comprehensive model for the prediction of particle-size distribution in catalyzed olefin polymerization fluidized-bed reactors[J].Chemical Engineering Science,1998,53(18):3251-3267.
[17]CHE Y,TIAN Z,LIU Z,et al.A CFD-PBM model considering ethylene polymerization for the flow behaviors and particle size distribution of polyethylene in a pilot-plant fluidized bed reactor[J].Powder Technology,2015,286:107-123.
[18]SUN J Y,WANG J D,YANG Y R.CFD investigation of particle fluctuation characteristics of bidisperse mixture in a gas-solid fluidized bed[J].Chemical Engineering Science,2012,82:285-298.
[19]YAN W C,LI J,LUO Z H.A CFD-PBM coupled model with polymerization kinetics for multizone circulating polymerization reactors[J].Powder Technology,2012,231:77-87.
[20]KANELLOPOULOS V,DOMPAZIS G,GUSTAFSSON B,et al.Comprehensive analysis of single-particle growth in heterogeneous olefin polymerization:the random-pore polymeric flow model[J].Industrial&Engineering Chemistry Research,2004,43(17):5166-5180.
[21]FAN Rong.Computational fluid dynamics simulation of fluidized bed polymerization reactors[D].Iowa:Iowa State University,2006.
[22]WEI L H,YAN W C,LUO Z H.A preliminary CFD study of the gas-solid flow fields in multizone circulating polymerization reactors[J].Powder Technology,2011,214(1):143-154.
[23]LOHA C,CHATTOPADHYAY H,CHATTERJEE P K.Assessment of drag models in simulating bubbling fluidized bed hydrodynamics[J].Chemical Engineering Science,2012,75:400-407.
[24]HAN Y,WANG J J,GU X P,et al.Homogeneous fluidization of Geldart D particles in a gas-solid fluidized bed with a frame impeller[J].Industrial&Engineering Chemistry Research,2012,51(50):16482-16487.
[25]张翠宣,叶京生,宋继田.喷动床研究与进展[J].化工进展,2002,21(9):630-634.ZHANG C X,YE J S,SONG J T.Development and prospect of modified spouted beds[J].Chemical Industry and Engineering Progress,2002,21(9):630-634.