摘要
为了研究提升管底部区域内颗粒的运动行为及浓度分布情况,采用电荷耦合（CCD）高速摄像机对提升管底部距离入风口20~30 cm轴向区域内的流动过程进行拍摄,根据流动图像对颗粒分布规律和流动结构进行了分析,并基于图像法实现了对稀相气力输送过程颗粒浓度的检测。结果显示：受送风方式的影响,在快速床阶段,颗粒在整体上呈现环核流动结构,同时在环隙区呈现左疏右密的分布形式;在节涌床和湍动床阶段,颗粒依次呈现柱塞式流动结构以及顺时针内循环流动结构。结合压差法测定的实验结果发现,图像法对稀相输送过程颗粒浓度的检测比较准确,其相对误差小于20%,且相对误差超过5%的情况只出现在表观气速相对较低的阶段。
In order to investigate the flow behaviors of the particles in the bottom of a CFB riser and detect the particle concentration distribution,a charge coupled device（CCD） high speed camera was employed to record the flow process of the particles in the fixed region which was 20-3 Ocm above the air inlet in the axial direction.The particle distribution and flow structure were analyzed according to the images,and the detection of particle concentration in pneumatic conveying process was realized based on the digital image technique.The results showed that the particle flow behaviors were influenced by the air supply pattern.In the fast fluidized bed,the core-annuls flow structure was presented in general while the distribution pattern that sparse particles in the left wall and dense particles in the right wall was also presented in the annul region.In the slugging bed and turbulent bed,the plunger type flow structure and clockwise internal circulation flow structure was respectively presented.Besides,it was proved by combination of the particle concentration results determined by the differential pressure,it was proved that the particle concentration which was detected by the image technique was accurate in view of the absolute value and the relative errors were less than 20 percent.The absolute value of the relative errors which were more than 5 percent only showed in the stage of lower superficial gas velocities.
出处
《化学反应工程与工艺》
CAS
CSCD
北大核心
2016年第3期244-251,共8页
Chemical Reaction Engineering and Technology
基金
国家自然科学基金(51276033)
关键词
提升管
流动结构
图像法
颗粒浓度
稀相输送
riser
flow structure
image technique
particle concentration
pneumatic conveying
