CFD study of the minimum bubbling velocity of Geldart A particles in gas-fluidized beds
CFD study of the minimum bubbling velocity of Geldart A particles in gas-fluidized beds
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DOI：
10.1016/j.ces.2010.03.023
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发表时间：
2010-06
影响因子：
4.7
通讯作者：
Junwu Wang;van der M.A. Hoef;J. Kuipers
中科院分区：
文献类型：
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作者：
Junwu Wang;van der M.A. Hoef;J. Kuipers
最小鼓泡速度是GeldartA颗粒均相和非均相流化的分界线，在气体流化中起着关键作用。采用欧拉-欧拉模型和欧拉-拉格朗日模型系统地研究了气体和颗粒性质对气体流化床中GeldartA颗粒最小鼓泡速度的影响。我们发现，从模拟中获得的最小鼓泡速度与Abrahamsen和Geldart（Powder Technology，1980，26：35-46）的众所周知的实验相关性相当一致。据我们所知，这是第一次正确预测的最小鼓泡速度的欧拉-欧拉模型，而不使用人为的ad-hoc修改的气固相互作用力。此外，我们已经进行了系统的调查，用于确定最小鼓泡速度的具体方法的效果。模拟结果表明，由模拟床层收缩得到的最小鼓泡速度大于由目测得到的最小鼓泡速度，而由目测得到的最小鼓泡速度又大于由压降标准差突变得到的最小鼓泡速度。我们发现，颗粒温度随表观气速增加的突变可能是一个更合适的指标，用于识别非均相流化的开始。
The minimum bubbling velocity, which demarcates the homogeneous and heterogeneous fluidization regimes, plays a pivotal role in gas fluidization of Geldart A particles. We systematically study the effect of gas and particle properties on the minimum bubbling velocity of Geldart A particles in gas-fluidized beds using both Eulerian–Eulerian and Eulerian–Lagrangian models. We find that the minimum bubbling velocities as obtained from the simulations are in reasonable agreement with the well-known experimental correlation of Abrahamsen and Geldart (Powder Technology, 1980, 26: 35–46). To our best knowledge, this is the first time that the minimum bubbling velocity is correctly predicted by Eulerian–Eulerian models, without using an artificial ad-hoc modification of the gas–solid interaction force. Furthermore, we have performed a systematic investigation into the effect of the specific method that is used for determining minimum bubbling velocity. Our simulations show that the minimum bubbling velocity that would be obtained from the simulated bed contraction is larger than the one obtained from visual observation, which in its turn exceeds the one obtained from sudden change of standard deviation of pressure drop. We find that the abrupt change of the granular temperature with increasing superficial gas velocity may be a more suitable indicator for identifying the onset of heterogeneous fluidization.