摘要
在自行设计的一套高密度下行循环流化床中(80 mm ID, 高5.6 m),对下行床内相结构进行了实验研究.实验结果显示:稀密两相时间分率的径向分布中心区域比较均匀,变化范围在10%～20%之间;轴向密相尺寸在十几毫米之间,密相内颗粒平均浓度为床层浓度的1.7倍,稀相颗粒浓度约为平均浓度的40%.在下行床中,稀密两相的转变是一渐变过程,而提升管内两相的转变是突变.通过比较高密度下行床与高密度提升管内密相特性,发现下行床内的密相因停留时间短、尺寸小和密度低而难以观察到.
Experimental study of phase characteristics in a high-density downer （5.6 m tall, 80 mm ID） is presented in this work. Phase time fractions was essentially uniform in the central region, and then increased with increasing （1- εav）. Dense phase time fraction varied from 10% to 20%, and approximated to dilute phase time fraction. The axial size of dense phase in downer was about 10--15 mm, which was as large as tens times to one hundred times of particles diameter. The averaged solids concentration in the dense phase was as 1.7 times as the local solids concentration, while that in dilute phase was about 40%. The transformation from dense phase to dilute phase in the riser was a sharp transition, while for the downer such transition was gradual. Dense phase in downer was much more difficult to observe than in riser due to its shorter duration time, smaller size and lower density.
出处
《化工学报》
EI
CAS
CSCD
北大核心
2005年第8期1456-1461,共6页
CIESC Journal
基金
国家自然科学基金项目(90210034
20221603)~~
关键词
高密度下行床
相结构
提升管
密相
high-density downer
phase structure
riser
dense phase
