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在环隙下料式流化床-提升管耦合反应器大型冷模实验装置中,研究了提升管和环隙下料管内FCC颗粒截面平均固含率(εp)的轴向分布.结果表明,流化床区域内pe随操作气速增大而减小,提升管区域可分为充分发展区(3.91~6.81 m)和约束返混区(6.81~8.60 m),提升管区域内εp随操作气速增大而增大,操作气速小于0.7 m/s时,εp沿轴向分布均匀;其大于0.7 m/s时,约束返混区的pe明显增大.在环隙下料管内,由于受窜气的影响,颗粒沿重力场流动阻力增大.操作气速小于0.75 m/s时,环隙下料管内εp沿轴向分布较均匀;其大于0.75 m/s时,变径段出现脱空现象.总体上,εp沿轴向向下略有增加,颗粒可顺畅通过环隙下料管循环返回流化床内.确定了提升管区域内εp沿轴向分布的经验模型,计算值与实验值吻合较好.
The axial distribution of the average solid fraction (εp) of the cross section of FCC particles in the riser and the annulus under the annular gap was investigated in a large-scale cold model experimental unit with annular gap underfill fluidized bed-riser-coupled reactor. The pe in the fluidized bed decreases with the increase of operating gas velocity. The riser area can be divided into fully developed zone (3.91-6.81 m) and confinement back mixed zone (6.81-8.60 m) When the operating gas velocity is less than 0.7 m / s, εp distributes uniformly in the axial direction, and when it is larger than 0.7 m / s, the pe of confinement back-mixing zone obviously increases. Due to the blow-by gas, the particle flow resistance increases along the gravitational field. When the operating gas velocity is less than 0.75 m / s, the axial distribution of εp in the material under the annular gap is more uniform. When it is larger than 0.75 m / s, There is a phenomenon of void.Overall, εp increases slightly downward along the axial direction, and the particles can smoothly return to the fluidized bed through the lower annulus.An empirical model of axial distribution of εp in the area of the riser is determined, The values agree well with the experimental values.