Abstract:

Considering the pressing needs of developing micro fluidized bed reaction analyzer (MFBRA) suitable for analyzing chemical vapor deposition reaction,this study conducted a preliminary research on the hydrodynamics of internally circulating micro fluidized bed.It investigated the influences of central jetting tube height,in-bed draft tube diameter and initial particle bed height on the start-up gas velocity of internal particle circulation and the gas bypass into the annulus.The results showed that raising the height of jetting tube increases the start-up gas velocity for particle internal circulation.There is an existed optimal draft tube diameter (20 mm) that minimizes such a start-up gas velocity.The start-up gas velocity becomes lower with the increase of initial particle bed height.The gas bypass into the annulus was evaluated according to the mass-spectrum intensities of the tracer gas.For the tested experimental conditions,the bypass of gas from draft tube to annulus was ignorable in the bottom section but discernable at the top of the annulus.

Key words: micro fluidized bed, internal circulation, hydrodynamics, chemical vapor deposition

摘要：

针对开发适用于化学气相沉积反应动力学研究的微型流化床反应分析仪的应用需求，研究了外径为30 mm的内循环微型流化床中气固流动特性，具体考察了中心射流管伸入高度、内导流管直径和颗粒装载量对实现固体物料内循环的最小操作气速和导流管与环隙区间窜气的影响。结果表明，随着射流管伸入高度的增大，实现颗粒内循环流动的最小操作气速变大；存在最优的导流管直径（20 mm），使得实现颗粒环流的最小操作气速较小；增大颗粒装载量有利于降低颗粒内循环的最小操作气速。通过检测示踪气体在环隙区内的质谱信号，发现在所考察的参数范围内，反应器底部不存在导流管区向环隙区的窜气；在反应器上部，由于颗粒对气体的夹带，环隙区上部总能检测到示踪气体，且窜气特性随操作气速的增大而增强。研究结果可为设计适用于化学气相沉积反应的内循环微型流化床反应器提供参考。

关键词: 微型流化床, 内循环, 流体力学, 化学气相沉积