Numerical study on the influence of various physical parameters over the gas–solid two-phase flow in the 2D riser of a circulating fluidized bed
Numerical study on the influence of various physical parameters over the gas–solid two-phase flow in the 2D riser of a circulating fluidized bed
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DOI：
10.1016/s0032-5910(03)00071-8
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发表时间：
2003-06
影响因子：
5.2
通讯作者：
L. Gómez;F. E. Milioli
中科院分区：
文献类型：
--
作者：
L. Gómez;F. E. Milioli
采用数值模拟的方法研究了不同物理因素对循环流化床提升管内气固两相流动特性的影响。所解决的功能是固相粘度，气固界面动量传递的相关性，和坐标系。一个欧拉连续体配方适用于这两个阶段。由此产生的双流体模型和数值程序遵循一个版本的MICEFLOW代码。模拟结果进行了比较，可用的实验数据。有关的功能上的流动行为的影响，主要是关于集群的演变。观察到典型的CFB锅炉的流量频率波动。还观察到，对于高固相粘度值，在出口附近存在固体积聚，形成大的团簇。当这些团簇下落时，瞬时横截面平均固体质量速度变为负值。对于无粘固相，没有观察到团簇的形成。结果表明，使用柱坐标时，假设立管轴线对称边界条件是不正确的。对于气固界面动量传递，不同的关联式得到的结果有很大差异。最后，伊利诺伊理工学院（IIT）的流体动力学模型A和B的预测进行了比较。
A numerical parametric study was performed on the influence of various physical aspects over the hydrodynamics of gas–solid two-phase flow in the riser of a circulating fluidized bed (CFB). The addressed features were the solid phase viscosity, the gas–solid interface momentum transfer correlations, and the coordinate system. An Eulerian continuum formulation was applied for both phases. The resulting two-fluid model and numerical procedure followed a version of the MICEFLOW code. The simulation results are compared to available experimental data. The effects of the concerning features on the flow behavior are shown, mainly regarding cluster evolution. The flow frequency fluctuations typical to CFB risers were observed. It was also observed that for high values of solid phase viscosity there is an accumulation of solids near the outlet forming large clusters. When those clusters fall down, the instantaneous cross-sectional average solid mass velocity becomes negative. For inviscid solid phase, no cluster formation is observed. The results show the incorrectness of assuming symmetry boundary condition at the axis of the riser when cylindrical coordinates are used. Quite different results were obtained for different correlations for gas–solid interface momentum transfer. Finally, a comparison is presented of predictions from the Illinois Institute of Technology (IIT) hydrodynamic models A and B.