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13th Spring School on Transition and Turbulence
Dynamics of Fluid-Sound Waves Interaction in a CFB Riser with Calcium Oxide Particles and Air with CO2
Sarah Laysa Becker , SC
Co-Authors: Sarah Laysa Becker, Vivien Rossbach, Henry França Meier, Natan Padoin, Cíntia Soares
Presenter: Sarah Laysa Becker
Circulating fluidized bed is a great equipment to process solids in post combustion CO2 capture. It enhances particles distribution, promoting phase contact, adsorption, and reaction. Fluidization of particles can be difficult to achieve, depending on flow and solid characteristics. Based on this, different investigations of intrusive and non-intrusive alternatives to avoid agglomerates, core-annulus profile, and back-mixing are found in the literature. This study aims to investigate the multiphase turbulence of the gas-solid flow of calcium oxide with air and CO2 in a CFB applying ultrasound waves to improve solids dispersion. It was carried out by CFD simulations employing a URANS-k-ε-KTGF-EMMS model. Results of volume fraction, velocity, pressure drop, Péclet, and dispersion coefficient were evaluated with and without ultrasounds. Acoustic waves change solids velocity and volume fraction profiles along the riser height. Pressure drop increases near the transducers, since they act as flow resistance, but drops above them, becoming lower when compared with the case without acoustics. Solids radial Péclet number also increases near the ultrasound device and the dispersion coefficient decreases, showing that solids dispersion is improved in the region responsible for the first contact between phases. Results reveal the necessity of more investigation about increasing the number of transducers.
circulating fluidized bed, multiphase turbulence, fluid-sound waves interaction, Computational fluid dynamics (CFD)