摘要
在耦合流化床反应器大型冷模实验装置上,考察了不同表观气速下FCC颗粒在耦合流化床内截面平均密度的轴向分布.结果表明,反应器轴向固含率可分为底部流化床区域和上部提升管区域.前者的密相区平均固含率随表观气速增大而减小;后者的平均固含率随表观气速Ug增大而增大,Ug<0.58 m/s时固含率分布均匀,Ug=0.70～1.04 m/s时提升管出口出现约束返混区(>8.62 m),Ug>1.16 m/s时提升管底部出现密度重整区(3.82～4.57 m)、加速平稳区(4.57～8.62 m)和出口返混区(>8.62 m).确定了耦合反应器内提升管区域截面平均固含率的影响参数,并利用实验数据回归了平均固含率的轴向分布经验模型,计算值与实验值吻合较好.
The axial distributions of cross-sectional averaged density of FCC particles were measured in a large scale cold model turbulent fluidized bed-riser coupled reactor. The results showed that the flow behaviors of FCC particles in the coupled reactor presented fairly different characteristics with changing of superficial gas velocity. The flow behavior could be divided into three types based on superficial gas velocity. A steady flow was observed in the reactor for superficial gas velocity below 0.58 m/s, while a back-mixing zone in the top of the riser appeared as the superficial gas velocity varied between 0.7-1.04 m/s. When superficial gas velocity was greater than 1.16 m/s, the riser concentration reforming and accelerating zones occurred in the bottom of the reactor, with the fully developed zone appearing in the middle of the reactor, and the back-mixing zone was enhanced in the top of the reactor. The cross-sectional averaged density increased with the increase of superficial gas velocity. The static bed height had no obvious effect on the axial local solids hold-up in different cross-sections. The critical superficial gas velocity responsible for the appearance of the riser concentration reforming zone was smaller for the higher static bed height than that for the lower static bed height. Furthermore, an empirical model for estimating the axial distribution of averaged cross-sectional solids hold-up was established based on the experimental data and theoretical analysis, respectively, which agreed with the experimental data.
出处
《过程工程学报》
CAS
CSCD
北大核心
2014年第4期556-561,共6页
The Chinese Journal of Process Engineering
基金
国家重点基础研究发展规划(973)基金资助项目(编号:2012CB215004)
关键词
耦合流化床
固含率
轴向分布
流动特性
coupled fluidized bed
solids hold-up
axial distribution
flow behavior
