振动流化床临界流化速度理论预测与实验研究

Theoretical Prediction and Experimental Investigation on the Critical Fluidization Velocity of Vibrated Fluidized Bed

根据振动流化床床层动力学特性,提出了第一、第二流化段,第一、第二临界流化速度的概念。从流化床临界流化速度的定义出发,得出了振动流化床第一临界流化速度数学模型。在二维振动流化床内,以不同粒径的玻璃珠为床料进行实验研究,分析了振动和其它操作条件对临界流化速度的影响,通过实验数据关联得到了振动能量传递系数的数学表达式,并将模型预测与实验结果进行了对比。结果表明振动强度增加,第一、第二临界速度均减小,振动对第一临界流化速度影响更显著,当振动强度超过1.57后,不通气体床层也能流化,第一临界流化速度降为零,模型预测与实验结果有较好的一致性。

According to the dynamical characteristic of the vibrated fluidized bed, the first and second fluidization stages and the first and seeond eritieal fluidization velocities were put forward. Based on the original definition of the eritieal fluidization veloeity, a mathematieal model was proposed to predict the first eritieal fluidization veloeity. Experiments using glass beads with different diameters were eondueted in a two-dimensional vibrated fluidized bed. The influences of bed vibration and other operation conditions on the eritieal fluidization veloeities were analyzed. An empirieal correlation equation used to prediet the eoeffieient of vibration energy transfer was established, and the results of the model predietion were compared with the experimental data. The results show that with the inerease of the bed vibration strength, the two eritieal fluidization velocities both decrease, while the bed vibration has a stronger influence on the first critical fluidization veloeity, and that when the vibration strength is above 1.57, fluidization eould be also oecurred without aeration. The values of predietion for two eritieal fluidization veloeities are in good agreement with experimental data.