Numerical simulation of flow regions in red mud separation thickener's feedwell by analysis of residence-time distribution

赤泥分离沉降槽中心桶内停留时间分布的数值模拟(英文)

The residence-time distribution （RTD） and the compartment model were applied to characterizing the flow regions in red mud separation thickener’s feedwells. Combined with the experimental work, validated mathematical model as well as three-dimensional computational fluid dynamics （CFD） model was established to analyze the flow regions of feedwells on an industrial scale. The concept of RTD, although a well-known method for the characterization of mixing behavior in conventional mixers and reactors, is still a novel measure for the characterization of mixing in feedwells. Numerical simulation results show that the inlet feed rate and the aspect ratio of feedwells are the most critical parameters which affect the RTD of feedwell. Further simulation experiments were then carried out. Under the optimal operation conditions, the volume fraction of dead zone can reduce by10.8% and an increasement of mixing flow volume fraction by 6.5% is also observed. There is an optimum feed inlet rate depending on the feedwell design. The CFD model in conjunction with the RTD analysis then can be used as an effective tool in the design, evaluation and optimization of thickener feedwell in the red mud separation.

通过引入停留时间分布(RTD)和隔室模型,对赤泥分离沉降槽中心桶内流场流形开展数值模拟研究。结合实验结果,建立沉降槽中心桶的3D计算流体力学(CFD)模型。结果表明:在中心桶内存在复杂的流形,进料流量和中心桶的径高比对中心桶内流场流形有重要影响。通过进一步的优化实验,中心桶内死区的体积分数可减少10.8%,混合区的体积分数可提升6.5%。结合数值仿真模型计算和停留时间分布分析方法,该数值模拟可以应用于赤泥沉降槽中心桶的设计、评估以及优化。