CIESC Journal ›› 2019, Vol. 70 ›› Issue (7): 2472-2479.DOI: 10.11949/0438-1157.20190013

• Fluid dynamics and transport phenomena • Previous Articles     Next Articles

Bed expansion and fluidized states change of Geldart-B particle gas-solid fluidized bed

Wangyu MA(),Zhenghong LUO()   

  1. Department of Chemical Engineering, School of Chemistry and Chemical Engineering, State Key Laboratory of Metal Matrix Composites, Shanghai Jiao Tong University, Shanghai 200240, China
  • Received:2019-01-04 Revised:2019-04-15 Online:2019-07-05 Published:2019-07-05
  • Contact: Zhenghong LUO

Geldart-B类颗粒在气固流化床中的床层膨胀与流型转变

马旺宇(),罗正鸿()   

  1. 上海交通大学化学化工学院化学工程系,金属基复合材料国家重点实验室,上海 200240
  • 通讯作者: 罗正鸿
  • 作者简介:马旺宇(1995—),男,硕士研究生,<email>1017540809@qq.com</email>
  • 基金资助:
    国家自然科学基金项目(21776173,21625603,U1862201,91834303)

Abstract:

Based on the combination of theoretical derivation and empirical formula, the general formula of the bed expansion ratio of fluidized process of Geldart-B particles in fluidized bed is established, and the convergence iteration formula of bed expansion ratio is constructed in the whole value range. The formula has divergence when the initial bed height is small or the gas velocity is large and is not always available. Bed expansion ratio iteration formulas that converge across the full range of values are constructed by introducing power series and numerical processing. The calculation results are closed to the experimental data of silica, Diakon and a small Geldart-B particles. The relationship between bed expansion ratio and bubbling fluidized flow regimes is further discussed. At the critical point of the flow regime transitions, the critical expansion ratio can be obtained from particle properties and bed structure parameters. The main factors affecting bed expansion ratio can be divided into three aspects: operating conditions, particle properties and bed structure. It is difficult for the bed to expand when the Archimedes number of particles is large, the initial bed height is high and the bed diameter is small.

Key words: fluidized-bed, two-phase flow, fluidization, Geldart-B particles, bed expansion, fluidized states change

摘要:

采用理论推导和经验公式相结合方法,建立了Geldart-B类颗粒在流化床中流化过程的床层膨胀比(R)的通式,并在全取值范围内构建了床层膨胀比的收敛迭代公式。采用不同颗粒的流化实验数据对上述通式(模型)进行了验证,结果表明该模型很好地预测了床层膨胀比。进一步讨论了床层膨胀比与鼓泡流化流型变化之间的关系,给出了临界膨胀比的取值规律。有关床层膨胀比的研究结果一定程度上可有效改善流化床的监控,优化操作条件选取。

关键词: 流化床, 两相流, 流态化, Geldart-B类颗粒, 床层膨胀, 流型转变

CLC Number: