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Axial Gas Dispersion in a Fluidized Bed of Polyethylene Particles

Hong Il Cho Chan-Hwa Chung Gui Young Han^† Gui Ryong Ahn¹ Jong Su Kong¹

Dept. of Chemical Engineering, Sungkyunkwan University, Suwon 440-746, Korea ¹Hanwha Petrochemical Corp., Taejon, Korea

Korean Journal of Chemical Engineering, May 2000, 17(3), 292-298(7), 10.1007/BF02699043

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Abstract

Gas mixing behavior was investigated in a residence time distribution experiment in a bubbling fluidized bed of 0.07 m ID and 0.80 m high. Linear low density polyethylene (LLDPE) particles having a mean diameter of 772㎛ and a particle size range of 200-1,500㎛ were employed as the bed material. The stimulus-response technique with CO₂ as a tracer gas was performed for the RTD study. The effects of gas velocity, aspect ratio (H₀/D) and scale-up on the axial gas dispersion were determined from the unsteady-state dispersion model, and the residence time distributions of gas in the fluidized bed were compared with the ideal reactors. It was found that axial dispersion depends on the gas velocity and aspect ratio of the bed. The dimensionless dispersion coefficient was correlated with Reynolds number and aspect ratio.

Keywords

Fluidized Bed Residence Time Distribution Gas Backmixing Axial Dispersion

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