Fundamental Research on an Innovative Fluid-Bed Type Reactor For Fluidization of Ultra-Fine Particles

为研制新型超细颗粒流态化流化床反应器，进行了冷模试验。平均粒径为70 μm左右的粗颗粒（即Geldart A组中的FCC颗粒）以0.5 ~ 1.0 m/s的表面气速流化，而平均粒径为0.5 ~ 15.0 μm的细颗粒（即Geldart C组中的几种）则连续进入致密相。在不同的操作条件下，研究了固体夹带速率、细颗粒分离速率和稳态区域与细颗粒占比（单位重量床颗粒的细颗粒重量）的依赖关系。当细颗粒含率较高时，对于粒径小于几μm的细颗粒，流态化现象发生改变，形成颗粒聚集复合物。固相夹带速率随细颗粒含率的减小、表面气速的增大和细颗粒尺寸的增大而增大。细颗粒的分离率随细颗粒含率、表面气速和细颗粒粒径的增大而增大。细颗粒连续进料试验表明，操作范围分为两个不同的范围。一个是维持稳定状态的区域，另一个是细粒子聚集的区域。当细颗粒的出料率与进料率之比小于1时，由于床层内的致命团聚，使其无法稳定运行。由于旋流器对细颗粒的收集，当细颗粒的粒径大于一定值时，也不可能进行稳态操作。稳定状态下，细颗粒的含率随着表面气速和细颗粒尺寸的减小以及细颗粒进料速率的增大而增大。

Cold model experiments were carried out for the development of an innovative fluid-bed type reactor for fluidization of ultra-fine particles. Coarse particles with mean size about 70 μm (FCC particles in Geldart group A) were fluidized with superficial gas velocities 0.5〜1.0 m/s, while fine powders with mean size 0.5 to 15.0 μm (several kinds in Geldart group C) were fed continuously into the dense phase. Investigations were carried out under various operating conditions on the dependent relationship of solid entrainment rate, separation rate of fine particles, and steady state region to fine particles hold-up (weight of fine particles per unit weight of bed particles).When fine particles hold-up was high, fluidization phenomena changed due to formation of particulate aggregate complex for the cases of fine particle sizes less than several μm. Solid entrainment rate increased with decreasing fine particles hold-up, and increasing superficial gas velocity and size of fine particles. Separation rate of fine particles increased with increasing fine particles hold-up, superficial gas velocity and size of fine particles.Tests of continuous feeding of fine particles demonstrated that the operational range was separated into two distinctive ones. One was the region where steady state was maintained, and another was the region where accumulation of fine particles occurred. Steady state operation was impossible when the ratio of discharge rate to feed rate of fine particles fell below unity due to fatal agglomeration in the bed. Steady state operation was also impossible when the size of fine particles was larger than a certain value due to collection of fine particles by cyclone. Hold-up of fine particles in the steady state increased with decreasing superficial gas velocity and size of fine particles and increasing feeding rate of fine particles.