Korean Chemical Engineering Research

The Korean Institute of Chemical Engineers (한국화학공학회)
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Prediction of Axial Solid Holdups in a CFB Riser

  • Park, Sang-Soon (Green Chemistry Research Division, Korea Research Institute of Chemical Technology) ;
  • Chae, Ho-Jeong (Green Chemistry Research Division, Korea Research Institute of Chemical Technology) ;
  • Kim, Tae-Wan (Green Chemistry Research Division, Korea Research Institute of Chemical Technology) ;
  • Jeong, Kwang-Eun (Green Chemistry Research Division, Korea Research Institute of Chemical Technology) ;
  • Kim, Chul-Ung (Green Chemistry Research Division, Korea Research Institute of Chemical Technology) ;
  • Jeong, Soon-Yong (Green Chemistry Research Division, Korea Research Institute of Chemical Technology) ;
  • Lim, JongHun (Department of Chemical Engineering, Sungkyunkwan University) ;
  • Park, Young-Kwon (School of Environmental Engineering, University of Seoul) ;
  • Lee, Dong Hyun (Department of Chemical Engineering, Sungkyunkwan University)
  • Received : 2018.09.26
  • Accepted : 2018.10.22
  • Published : 2018.12.01
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Abstract

A circulating fluidized bed (CFB) has been used in various chemical industries because of good heat and mass transfer. In addition, the methanol to olefins (MTO) process requiring the CFB reactor has attracted a great deal of interest due to steep increase of oil price. To design a CFB reactor for MTO pilot process, therefore, we has examined the hydrodynamic properties of spherical catalysts with different particle size and developed a correlation equation to predict catalyst holdup in a riser of CFB reactor. The hydrodynamics of micro-spherical catalysts with average particle size of 53, 90 and 140 mm was evaluated in a $0.025m-ID{\times}4m-high$ CFB riser. We also developed a model described by a decay coefficient to predict solid hold-up distribution in the riser. The decay coefficient developed in this study could be expressed as a function of Froude number and dimensionless velocity ratio. This model could predict well the experimental data obtained from this work.

Keywords

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Fig. 1. Flow chart for the axial solid holdup in a CFB riser.

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Fig. 2. Schematic diagram of the experimental apparatus. 1. Riser 7. Pressure tap 2. Seal-pot 8. Pressure transmitter 3. Bubbling bed 9. A/D converter 4. Cyclone 10. Compressor 5. Ball valve 11. Personal computer 6. Air flow meter 12. Bag filter

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Fig. 3. Variation of the axial solid hold-up profile with the experimental variables.

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Fig. 4. Comparison between measured solid holdup and predicted values with experimental variables in a 0.0254 m-ID x 4 mhigh CFB riser. (a) Adanez et al. [13]'s correlation and (b) Lei and Horio [14]'s correlation.

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Fig. 5. Comparison between measured solid holdup and predicted values with experimental variables in a 0.0254 m-ID x 4 m high CFB and previous data.

Table 1. Physical properties of bed materials

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