EPTT 2020

12th Spring School on Transition and Turbulence

Influence of ultrasonic waves and airfoil-shaped ring baffles on the gas-solid dispersion in a CFB riser

Submission Author: Vivien Rossbach , SC
Co-Authors: Vivien Rossbach, Sarah Laysa Becker, Natan Padoin, Henry França Meier, Cíntia Soares
Presenter: Vivien Rossbach

doi://10.26678/ABCM.EPTT2020.EPT20-0012

 

Abstract

Circulating fluidized beds (CFB) are used in several industrial applications, in which more homogeneous fluidization of solid particles is desired. In these devices, the core-annulus profile and the clusters of particles decrease the gas-solid contact. Two alternatives to improve solids dispersion are the use of aerodynamic ring-type baffles and ultrasonic waves. In this work, the influence of these devices on the solids dispersion in a lab-scale CFB riser were evaluated using Phase Doppler Anemometry (PDA) measurements. We used 5 airfoil-shaped ring baffles with 10 mm of thickness and 20 transducers with a frequency of 40 kHz and an input power of 10, respectively, above the riser inlet. The ring baffles increase the solid velocity near the wall and the ultrasound decreases it. With a velocity of 5.6 m/s, the solids distribution in the cross-section improves with the rings and worsens with the influence of ultrasound, but with 8.3 m/s rings and ultrasound improve the solids distribution. The gas-solid dispersion improved 18% with baffles at 8.3 m/s and 17% with ultrasound at 5.6 m/s. This study indicates that both the ring baffles and the ultrasonic field applied in the riser inlet region increase the gas-solid dispersion and contribute to reducing the concentration of particles near the riser walls and the development of clusters.

Keywords

circulating fluidized bed (CFB), Airfoil-shaped ring baffles, Ultrasonic waves, gas-solid dispersion

 

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