大差异双组分混合颗粒的最小流化特性

Minimum Fluidization Characteristics of Binary Mixtures of Particles with Significant Size Difference

在一套φ260mm×2000mm的有机玻璃实验装置中,对大差异双组分混合颗粒的最小流化特性进行了实验研究,得到了混合颗粒的流化曲线,由此给出了其起始流化速度、最小流化速度、临界分离速度、完全流化速度等特征速度.实验结果表明,流化过程可分为4个阶段,即完全流化、大小颗粒分离、大颗粒静止小颗粒流化、固定床阶段,对应混合颗粒的3个状态:完全混合、部分混合部分分离、完全分离状态;混合颗粒的特征速度随小颗粒质量分率的增加而减小,且在小颗粒质量分率达到0.4～0.5后其减小的趋势减缓;混合颗粒的固定床阶段和完全流化阶段的床层空隙率及混合颗粒的体积收缩比在小颗粒质量分率为0.4时达到极值.

Minimum fluidization characteristics of binary mixture of particles with significant size difference are studied in cold model perspex experimental equipment with the dimensions of Ф260 mm×2000 mm. The fluidization curves and characteristic velocities including initial velocity, minimum fluidization velocity, segregated velocity and full fluidization velocity are obtained. It is indicated that fluidization curves could be divided into four zones, corresponding to three states： mixing state, intermediate state and full segregated state. Characteristic velocities of binary mixtures decrease with increasing of mass fraction of fine particles, and the trend is not obvious when mass fraction of fine particles is about 0.4-0.5. Bed voidage of binary mixtures of particles in fixed bed and full fluidization states and volume contraction ratio of binary mixtures of particles arrived at extremum when the mass fraction of fine particles is equal to 0.4.