Numerical Analysis of Particle Mixing in a Rotating Fluidized Bed
Numerical Analysis of Particle Mixing in a Rotating Fluidized Bed
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DOI：
10.1016/j.ces.2007.02.043
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发表时间：
2007-06
影响因子：
4.7
通讯作者：
Hideya Nakamura;T. Tokuda;T. Iwasaki;S. Watano
中科院分区：
文献类型：
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作者：
Hideya Nakamura;T. Tokuda;T. Iwasaki;S. Watano
本文描述了旋转流化床 (RFB) 中颗粒混合的数值分析。提出了二维离散元法 (DEM) 和计算流体动力学 (CFD) 耦合模型来分析 RFB 中的径向颗粒混合。使用球形聚乙烯颗粒（Geldart B 类颗粒）作为模型颗粒，假设它们是无内聚且单分散的，直径为 0.5mm。通过将计算出的颗粒混合程度与通过测量高速摄像机拍摄的记录图像的亮度获得的实验结果进行比较，证实了该模型的有效性。数值分析了操作参数（气体速度、离心加速度、颗粒床高度和容器半径）对径向颗粒混合速率的影响。发现径向颗粒混合速率受气泡特性、尤其是气泡尺寸的强烈影响。根据经验提出了颗粒混合速率系数作为操作参数函数的数学模型。 RFB 中的径向颗粒混合速率可以与三个无量纲数很好地相关：无量纲加速度 (Ac)、气泡弗劳德数 (Frb) 和颗粒床表面无量纲半径 (βs)。
This paper describes the numerical analysis of particle mixing in a rotating fluidized bed (RFB). A two-dimensional discrete element method (DEM) and computational fluid dynamics (CFD) coupling model were proposed to analyze the radial particle mixing in the RFB. Spherical polyethylene particles (Geldart group B particles) were used as model particles under the assumptions that they were cohesionless and mono-disperse with their diameter of 0.5mm. The validity of the proposed model was confirmed by the comparison between the calculated degree of particle mixing and the experimental one, which was obtained by measuring the lightness of the recorded image taken by a high-speed video camera. Effects of the operating parameters (gas velocity, centrifugal acceleration, particle bed height, and vessel radius) on the radial particle mixing rate were numerically analyzed. The radial particle mixing rate was found to be strongly affected by the bubble characteristics, especially by the bubble size. The mathematical model for the rate coefficient of particle mixing as functions of operating parameters was empirically proposed. The radial particle mixing rate in a RFB could be well correlated by the three dimensionless numbers: dimensionless acceleration (Ac), bubble Froude number (Frb), and dimensionless radius on the surface of particle bed (βs).