Comparative study of two fluid model and dense discrete phase model for simulations of gas-solid hydrodynamics in circulating fluidized beds

Computational fluid dynamics(CFD)has become a valuable tool to study the complex gas-solid hydrodynamics in the circulating fluidized bed(CFB).Based on the two fluid model(TFM)under the Eulerian-Eulerian framework and the dense discrete phase model(DDPM)under the Eulerian-Lagrangian framework,this work conducts the comparative study of the gas-solid hydrodynamics in a CFB riser by these two different models.Results show that DDPM could be used to predict gas-solid hydrodynamics in the circulating fluidized bed,and there are differences between TFM and DDPM,especially in the radial distribution profiles of solid phase.Sensitivity analysis results show that the gas-solid drag model exhibits significant effects on the results for both the two models.The specularity coefficient and the restitution coefficient in the TFM,as well as the reflection coefficient and the parcel number in the DDPM,exhibit less impact on the simulated results.

单段高料位气-固环流汽提器内颗粒速率分布的研究

在直径为60 0mm的半圆形有机玻璃塔内对高料位密相环流汽提器进行了研究 ,在不同的操作气速下对其不同轴向、径向位置进行了速率的测量 ,得出了轴、径向速率分布规律。在动量平衡的基础上 ,建立了单段高料位环流汽提器催化剂环流速率的半经验模型 。

单段高料位气-固密相环流汽提器的密度分布

在直径 60 0mm的半圆形有机玻璃塔内对高料位密相环流汽提器进行了研究 ,在不同的操作气速下对其不同轴向、径向位置进行了密度的测量 ,得出了轴、径向密度分布的规律。从理论上推导了汽提器平均空隙率与内环表观气速的关系 ,根据试验结果建立了单段高料位环流汽提器内环平均空隙率与内环表观气速的半经验模型 ,模型计算结果与试验结果能较好的吻合。