摘要
在无负压差的环境下,采用PV6D型颗粒速度测量仪,考察了垂直立管中FCC催化剂颗粒移动床的蠕动流动特性.结果表明,颗粒质量流率较小时立管中颗粒流动具有明显的蠕动流动特性,可划分为两种流态,拟气固雷诺数Re<500时为间歇式蠕动流动,500<Re<2300时为波动式蠕动流动.当Re>4000时颗粒的蠕动流动转变为密相流化流动.立管中颗粒的蠕动流动主要是出口区颗粒成拱与崩塌交替进行产生的,其次为颗粒与器壁滑动摩擦力的不稳定性变化起作用.微观上颗粒流动的蠕动行为是颗粒之间力链作用变化的结果.
Under the condition without negative pressure gradient, experiments were carried out to study the characteristics of moving-bed creeping flow in a standpipe using FCC catalyst particles. The particle velocity in the standpipe was measured with PV6D particle velocity measuring device. The results indicate that there exists an observable creeping flow in the standpipe when the solids flux rate is low. Based on the designed gas-solid Re number, this creeping flow can be divided into intermittent creeping flow（Re〈500） and fluctuant creeping flow（500〈Re〈2300）. The creeping flow is transformed into dense fluidized flow at Re4000. The particle creeping flow results from the discharging and clogging occurring at the orifice alternately, because the particles forms the static arch just above the orifice, and the bridge collapse takes place periodically. And the sliding friction force between the particles and wall also affects creeping flow. It is the evolution of force chain among the particles that contributes to the creeping flow behavior.
出处
《过程工程学报》
CAS
CSCD
北大核心
2014年第3期383-387,共5页
The Chinese Journal of Process Engineering
基金
国家自然科学基金资助项目(编号:21176250)
关键词
立管
移动床
蠕动
颗粒
速度
力链
standpipe
moving-bed
creeping flow
particle
velocity
force chain
