振动流化床内双组分颗粒的混合与分离特性

Mixing and Segregation of Binary Mixture in a Vibration Fluidized Bed

在300mm×300mm×20mm的二维振动流化床中,装入平均粒径2和4mm的分子筛颗粒,在低于流化速度(u<umf,m)的条件下,研究了振动和风速对颗粒混合物分布的影响.结果表明,随着振动或风速的加大,双组分颗粒依次出现稳定"巴西果"分离(小颗粒沉积)、不稳定"反巴西果"分离(大颗粒沉积)、大颗粒对流运动和稳定"反巴西果"分离.大颗粒出现沉降的临界速度ums小于床层混合物的临界流化速度umf,m,并满足Γ/(1-ums/umf,m)=8.

Putting the mixture of 2 mm and 4 mm zeolite particles in a 2D vibration fluidized bed with the size of 300 mm×300 mm×20 mm, the effects of influential factors including vibration intensity and gas velocity on the distribution of particles were studied at u〈umf, m in this work. The result indicates that the ＂Brazil nut segregation＂ （small particles settlement）, stable ＂reverse Brazil nut segregation＂ （big particles settlement）, big particles convection and unstable ＂reverse Brazil nut segregation＂ of mixture occurred in turn by increasing the vibration intensity or gas velocity. The minimum velocity of ＂reverse Brazil nut segregation＂, ums, is smaller than the minimum fluidization velocity of mixture, umf, m, which is satisfied with the expression of П（1-ums/umf, m）=8.