SCI和EI收录∣中国化工学会会刊

中国化学工程学报 ›› 2020, Vol. 28 ›› Issue (12): 2985-2992.DOI: 10.1016/j.cjche.2020.07.054

• Fluid Dynamics and Transport Phenomena • 上一篇    下一篇

Effect of elevated temperature and silica sand particle size on minimum fluidization velocity in an atmospheric bubbling fluidized bed

A. Al-Farraji1, Haidar Taofeeq1,2   

  1. 1 Chemical Engineering Department, College of Engineering, Al-Nahrain University, Baghdad, Iraq;
    2 Prosthetics and Orthotics Engineering Department, College of Engineering, Al-Nahrain University, Baghdad, Iraq
  • 收稿日期:2020-02-15 修回日期:2020-07-23 出版日期:2020-12-28 发布日期:2021-01-11
  • 通讯作者: A. Al-Farraji

Effect of elevated temperature and silica sand particle size on minimum fluidization velocity in an atmospheric bubbling fluidized bed

A. Al-Farraji1, Haidar Taofeeq1,2   

  1. 1 Chemical Engineering Department, College of Engineering, Al-Nahrain University, Baghdad, Iraq;
    2 Prosthetics and Orthotics Engineering Department, College of Engineering, Al-Nahrain University, Baghdad, Iraq
  • Received:2020-02-15 Revised:2020-07-23 Online:2020-12-28 Published:2021-01-11
  • Contact: A. Al-Farraji

摘要: The impact of temperature and particle size on minimum fluidizing velocity was studied and analyzed in a small pilot scale of bubbling fluidized bed reactor. This study was devoted to providing some data about fluidization to the literature under high temperature conditions. The experiments were carried out to evaluate the minimum fluidizing velocity over a vast range of temperature levels from 20℃ to 850℃ using silica sand with a particle size of 300-425 μm, 425-500 μm, 500-600 μm, and 600-710 μm. Furthermore, the variation in the minimum fluidized voidage was determined experimentally at the same conditions. The experimental data revealed that the Umf directly varied with particle size and inversely with temperature, while εmf increases slightly with temperature based on the measurements of height at incipient fluidization. However, for all particle sizes used in this test, temperatures above 700℃ has a marginal effect on Umf. The results were compared with many empirical equations, and it was found that the experimental result is still in an acceptable range of empirical equations used. In which, our findings are not well predicted by the widely accepted correlations reported in the literature. Therefore, a new predicted equation has been developed that also accounts for the affecting of mean particle size in addition to other parameters. A good mean relative deviation of 5.473% between the experimental data and the predicted values was estimated from the correlation of the effective dimensionless group. Furthermore, the experimental work revealed that the minimum fluidizing velocity was not affected by the height of the bed even at high temperature.

关键词: Minimum fluidization velocity, Voidage, Elevated temperature, Silica sand, Fluidized bed, Bed height

Abstract: The impact of temperature and particle size on minimum fluidizing velocity was studied and analyzed in a small pilot scale of bubbling fluidized bed reactor. This study was devoted to providing some data about fluidization to the literature under high temperature conditions. The experiments were carried out to evaluate the minimum fluidizing velocity over a vast range of temperature levels from 20℃ to 850℃ using silica sand with a particle size of 300-425 μm, 425-500 μm, 500-600 μm, and 600-710 μm. Furthermore, the variation in the minimum fluidized voidage was determined experimentally at the same conditions. The experimental data revealed that the Umf directly varied with particle size and inversely with temperature, while εmf increases slightly with temperature based on the measurements of height at incipient fluidization. However, for all particle sizes used in this test, temperatures above 700℃ has a marginal effect on Umf. The results were compared with many empirical equations, and it was found that the experimental result is still in an acceptable range of empirical equations used. In which, our findings are not well predicted by the widely accepted correlations reported in the literature. Therefore, a new predicted equation has been developed that also accounts for the affecting of mean particle size in addition to other parameters. A good mean relative deviation of 5.473% between the experimental data and the predicted values was estimated from the correlation of the effective dimensionless group. Furthermore, the experimental work revealed that the minimum fluidizing velocity was not affected by the height of the bed even at high temperature.

Key words: Minimum fluidization velocity, Voidage, Elevated temperature, Silica sand, Fluidized bed, Bed height