喷动床粉体混合机混合性能的数值模拟

Numerical simulation on mixing performance of spouted bed powder mixer

喷动床中粉体的混合本质上是气固两相流动问题,为研究喷动床中粉体的混合性能,采用数值模拟的方法,研究了直径为165μm的同种淀粉颗粒在喷动床混合机中的混合过程及运动行为规律。研究结果表明在喷动床混合机中,粉体的运动区域主要包括喷射区、喷泉区和环隙区,粉体的混合主要发生在喷泉区;粉体在喷动床中循环运动的周期约为9.4 s,其中在环隙区的运动时间占整个循环周期的90%以上,粉体在喷射区和喷泉区的停留时间极短;喷动床混合机中粉体混合均匀性指数可达到0.99以上。

The mixing of powder particles in the spouted bed is essentially a gas-solid two-phase flow problem.In order to study the mixing performance of the powder in the spouted bed,computational fluid dynamics-discrete element method(CFD-DEM)was used to study the same starch particles with a diameter of 165μm.The mixing process and movement behavior of the body in the spouted bed mixer.The research results showed that in the spouted bed mixer,the movement area of the powder included the spray area,the fountain area and the annulus area.The mixing of the powder mainly occurs in the fountain area;the cyclic movement period of the powder in the spouted bed was about 9.4 s,and the movement time in the annulus area accounts for more than 90%of the entire cycle period.The residence time of the powder in the spray area and the fountain area was extremely short;powder mixing uniformity index can reach above 0.99.