FLOW STRUCTURE IN A 3-DIMENSIONAL BUBBLE-COLUMN AND 3-PHASE FLUIDIZED-BED
FLOW STRUCTURE IN A 3-DIMENSIONAL BUBBLE-COLUMN AND 3-PHASE FLUIDIZED-BED
复制标题
DOI：
10.1002/aic.690400702
复制
发表时间：
1994-07-01
期刊：
影响因子：
3.7
通讯作者：
FAN, LS
中科院分区：
文献类型：
--
作者：
CHEN, RC;REESE, J;FAN, LS
利用粒子图像测速技术研究了不同操作条件下三维鼓泡塔和气-液-固流化系统的宏观流动结构。流动可视化也进行了激光压片技术的帮助下。采用折射率匹配技术消除了气-液-固流态化可视化研究中固体颗粒的不透明现象。三种流动状态（分散气泡，旋涡螺旋流，湍流）被确定。流动结构的各种操作变量，包括液体速度，气体速度，和颗粒含率进行了研究。四个流动区域（下降流，旋涡螺旋流，快速气泡流，和中央羽流）的特点一般可以在旋涡螺旋流制度的总循环模式发生。本文讨论了旋涡-螺旋流区流动结构的概念模型。涡旋流态的流型和结构的转变被假定为与两个同心旋转圆柱之间的流动的泰勒不稳定性有关。二维和三维床层的流动结构之间的相似性进行了讨论。
Macroscopic flow structures of 3-D bubble columns and gas-liquid-solid fluidization systems under various operating conditions are studied using particle image velocimetry. Flow visualization is also conducted with the aid of a laser sheeting technique. The refractive index matching technique is used to eliminate the opaqueness of solid particles occurred in the visualization study of gas-liquid-solid fluidization. Three flow regimes (dispersed bubble, vortical-spiral flow, and turbulent flow) are identified. The flow structure is investigated for various operating variables including liquid velocity, gas velocity, and particle holdups. Four flow regions (descending flow, vortical-spiral flow, fast bubble flow, and central plume) can generally be characterized in the vortical-spiral flow regime where the gross circulation pattern occurs. A conceptual model for the flow structure in the vortical-spiral flow regime is discussed. The transition of the flow regimes and structure in the vortical-spiral flow regime is postulated to be related to the Taylor instability for flow between two concentric rotating cylinders. Similarities between the flow structures of 2- and 3-D beds are also discussed.