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›› 2007, Vol. 7 ›› Issue (1): 14-18.

• 流动与传递 • 上一篇    下一篇

固-液导流筒搅拌槽内流体流动和颗粒悬浮特性

陈文民,黄雄斌,高正明   

  1. 北京化工大学化学工程学院
  • 出版日期:2007-02-20 发布日期:2007-02-20

Characteristics of Fluid Flow and Particle Suspension in a Solid-Liquid Draft-tube Stirred Tank

CHEN Wen-min,HUANG Xiong-bin,GAO Zheng-ming   

  1. College of Chemical Engineering, Beijing University of Chemical Technology
  • Online:2007-02-20 Published:2007-02-20

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摘要： 在直径0.8 m的导流筒搅拌槽内，对单相液体的三维速度分布、固-液两相的固体颗粒浓度分布和离底悬浮特性进行了系统的实验研究. 结果表明，导流筒内外的轴向液相速度远大于径向和切向速度，导流筒外壁附近存在一个与主体轴向流动方向相反的二次流区域；搅拌槽底部结构对固体颗粒的临界离底悬浮转速(NJS)有显著的影响，浅锥底的NJS比平底的低14%以上；NJS随固相浓度的增加而增加，但当浓度超过50%时，NJS略有降低；槽内固相浓度分布的均匀性随固相浓度的增加而得到改善. 本研究结果对导流筒搅拌槽的优化设计具有一定的指导意义.

关键词: 导流筒搅拌槽, 液相速度分布, 固相浓度分布, 临界离底悬浮转速

Abstract: The three-dimension velocity distribution of single liquid phase, solid concentration distribution and particle off-bottom suspension characteristics in the liquid-solid phases were systemically investigated in a draft-tube stirred tank of 0.8 m diameter. The results showed that the axial velocity of liquid phase was far larger than radial and tangential velocities inside and outside the draft tube. And there was a second circulation zone close to the outside wall of the draft tube. The shallow conical bottom leads to a critical just off-bottom suspension impeller speed (NJS) at least 14% lower than that in the flat bottom. As expected, NJS increased as the solid concentration increased. NJS decreased slightly as the solid concentration exceeded 50%. The homogeneity of vertical solid concentration distribution was enhanced with the increase of solid concentration. The results are of importance to the optimization of industrial draft-tube stirred reactors.

Key words: draft-tube stirred tank, liquid velocity distribution, solid concentration distribution, critical just off-bottom suspension impeller speed