CFD simulation of solids residence time distribution in a CFB riser

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	CFD simulation of solids residence time distribution in a CFB riser
	Hua, Leina; Wang, Junwu; Li, Jinghai
刊名	CHEMICAL ENGINEERING SCIENCE
	2014-09-27
卷号	117 期号:9 页码:264-282
关键词	Fluidization Multiphase flow Computational fluid dynamics Circulating fluidized bed Particle clusters Solids residence time distribution
ISSN号	0009-2509
其他题名	Chem. Eng. Sci.
中文摘要	Solids residence time distribution (RTD) in circulating fluidized bed risers is a critical parameter for evaluating reactor performances, however, it is still very difficult to be predicted via computational fluid dynamics (CFD) simulation due to the complexity of particle clustering phenomenon. This paper tries to establish an effective CFD model to reasonably predict solids RTD of gas solids riser flows by means of properly addressing the paramount role of particle clusters in determining solids RTD. The gas solids hydrodynamic characteristics were solved by Eulerian-Eulerian model, where an energy minimization multi scale (EMMS) drag model was applied to modify the gas solids drag force to account for the influence of particle clusters. The motion of tracer particles was calculated using species transport equation, where the diffusion coefficient of particles, a vital parameter indicating particle diffusion capacity, was investigated thoroughly. The established CFD model was validated against the available experimental data in the literature It was shown that axial profiles of solids volume fraction and radial profiles of solids mass flux can be well predicted with EMMS drag model, but not with homogeneous drag model. The proper prediction of bed hydrodynamics is also very crucial to the success of solids RTD simulation. On the other hand, the effect of the diffusion coefficient of particles, the magnitude of which can span a range from 10(-5) m(2)/s to 10 m(2)/s, is minor when compared with the convective transport mechanism, at least for the specific cases we studied. In addition, the importance of the sampling time resolution and tracer injection time for a RTD curve was addressed. The simulation results showed that a low time resolution often results in the loss of some micro-scale information, i.e. drastically smoothing the fluctuations of the RTD curve, and an inappropriate assessment of the tracer injection time can lead to a significant change of the RTD curve. (C) 2014 Elsevier Ltd. All rights reserved.
英文摘要	Solids residence time distribution (RTD) in circulating fluidized bed risers is a critical parameter for evaluating reactor performances, however, it is still very difficult to be predicted via computational fluid dynamics (CFD) simulation due to the complexity of particle clustering phenomenon. This paper tries to establish an effective CFD model to reasonably predict solids RTD of gas solids riser flows by means of properly addressing the paramount role of particle clusters in determining solids RTD. The gas solids hydrodynamic characteristics were solved by Eulerian-Eulerian model, where an energy minimization multi scale (EMMS) drag model was applied to modify the gas solids drag force to account for the influence of particle clusters. The motion of tracer particles was calculated using species transport equation, where the diffusion coefficient of particles, a vital parameter indicating particle diffusion capacity, was investigated thoroughly. The established CFD model was validated against the available experimental data in the literature It was shown that axial profiles of solids volume fraction and radial profiles of solids mass flux can be well predicted with EMMS drag model, but not with homogeneous drag model. The proper prediction of bed hydrodynamics is also very crucial to the success of solids RTD simulation. On the other hand, the effect of the diffusion coefficient of particles, the magnitude of which can span a range from 10(-5) m(2)/s to 10 m(2)/s, is minor when compared with the convective transport mechanism, at least for the specific cases we studied. In addition, the importance of the sampling time resolution and tracer injection time for a RTD curve was addressed. The simulation results showed that a low time resolution often results in the loss of some micro-scale information, i.e. drastically smoothing the fluctuations of the RTD curve, and an inappropriate assessment of the tracer injection time can lead to a significant change of the RTD curve. (C) 2014 Elsevier Ltd. All rights reserved.
WOS标题词	Science & Technology ; Technology
类目[WOS]	Engineering, Chemical
研究领域[WOS]	Engineering
关键词[WOS]	CIRCULATING FLUIDIZED-BED ; RADIOACTIVE PARTICLE TRACKING ; NEAR-WALL REGION ; KINETIC-THEORY ; NUMERICAL-SIMULATION ; FLOW STRUCTURE ; 2-FLUID MODEL ; FCC PARTICLES ; GAS ; DISPERSION
收录类别	SCI
原文出处	://WOS:000340931800026
语种	英语
WOS记录号	WOS:000340931800026
公开日期	2014-09-30
内容类型	期刊论文
版本	出版稿
源URL	[http://ir.ipe.ac.cn/handle/122111/11408]
专题	过程工程研究所_研究所（批量导入）
作者单位	Chinese Acad Sci, Inst Proc Engn, State Key Lab Multiphase Complex Syst, Beijing 100190, Peoples R China
推荐引用方式 GB/T 7714	Hua, Leina,Wang, Junwu,Li, Jinghai. CFD simulation of solids residence time distribution in a CFB riser[J]. CHEMICAL ENGINEERING SCIENCE,2014,117(9):264-282.
APA	Hua, Leina,Wang, Junwu,&Li, Jinghai.(2014).CFD simulation of solids residence time distribution in a CFB riser.CHEMICAL ENGINEERING SCIENCE,117(9),264-282.
MLA	Hua, Leina,et al."CFD simulation of solids residence time distribution in a CFB riser".CHEMICAL ENGINEERING SCIENCE 117.9(2014):264-282.