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

对一种新型超细颗粒流化床反应器进行了冷模实验研究。在表观气速为0.5 ~ 1.0 m/s的条件下，流化了平均粒径约为70 μm的粗颗粒（GeldartA组FCC颗粒），而将平均粒径为0.5 ~ 15.0 μm的细粉（GeldartC组中的几种）连续送入密相。研究了不同操作条件下固体夹带率、细颗粒分离率和稳态区与细颗粒含率（单位床重细颗粒的重量）的关系，当细颗粒含率较高时，对于粒径小于几μm的细颗粒，由于形成颗粒聚集体，流化现象发生变化。固体夹带率随细颗粒含率的减小而增大，随表观气速的增大而增大，随细颗粒粒径的增大而增大。细颗粒的分离率随细颗粒含率、表观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，该装置的操作范围分为两个明显的区域。一个是维持稳态的区域，另一个是发生细颗粒积聚的区域。当细颗粒的出料速率与进料速率之比低于1时，由于床内的致命团聚，稳态操作是不可能的。当细颗粒的尺寸大于一定值时，由于旋风分离器收集细颗粒，稳态操作也是不可能的。稳态下细颗粒的含率随表观气速的减小和细颗粒粒径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.