旋转流化床粉体混合机混合效果数值模拟和实验验证

Numerical simulation and experimental verification of mixing effect in rotating fluidized bed powder mixer

为了对旋转流化床粉体混合机进行优化设计,采用CFD-DEM联合仿真的方法,对旋转流化床粉体混合机内球形颗粒的混合过程进行数值模拟,通过Lacey指数具体评价颗粒的混合效果,研究了进气管倾斜角度、进气管布置方式、进气方式对球形颗粒混合效果的影响,并进行球形颗粒混合实验验证。结果表明,进气管最合适的倾斜角度应保证气流作用区域面积恰好为底部颗粒物料区域面积的一半。进气管水平布置时能够保证很好的混合质量及较快的混合速率。脉冲及连续方式进气均能实现均匀混合,脉冲进气方式比连续进气方式耗气量更低。颗粒混合实验有很好的混合效果,与数值模拟的结果具有较高的一致性,从而获得了一种混合效果优越的结构形式,进气管倾斜角度α=35°,水平布置。

In order to get structure optimal design of a rotating fluidized bed powder mixer,the mixing progress of spherical powder granules in a rotating fluidized bed powder mixer was simulated by a combined approach of computational fluid dynamics(CFD)and discrete element method(DEM).Lacey mix index was used to quantitatively analyze the mixing degree of granules in the mixer.The effects of different parameters including the tilt angle of the intake pipe,the arrangement of the intake pipe and intake method were studied respectively.To verify the mixing performance of the rotating fluidized bed powder mixer,a granule mixing experiment was carried out.Simulation results showed that the most appropriate angle of intake pipe should ensure the area of airflow is just half of the area of granular materials in the bottom of the mixer.Besides,if the intake pipe is horizontal arranged,effective mixing quality and mixing rate could be achieved.Moreover,whether the intake is continuous or pulsed,spherical granules could achieve uniform mixing.Compared with the continuous intake,the air comsumption of pulsed intake was less.Finally,the powder mixing experimental results showed a positive mixing quality,which were in good agreement with the numerical data.It could be drawn that it is a structure with superior mixing effect if the intake pipe is tilted at an angle of 35 degrees and horizontal arranged.