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Chaotic behavior of gas-solids flow in the riser of a laboratory-scale circulating fluidized bed

Authors

  • Antonio Marzocchella,

    Corresponding author
    1. Dipt. di Ingegneria Chimica, Università degli Studi di Napoli “Federico II,”, Istituto di Ricerche sulla Combustione-CNR, 80125 Naples, Italy
    • Dipt. di Ingegneria Chimica, Università degli Studi di Napoli “Federico II,”, Istituto di Ricerche sulla Combustione-CNR, 80125 Naples, Italy
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  • Robert C. Zijerveld,

    1. Faculty of Chemical Technology and Materials Science, Delft University of Technology, 2628 BL Delft, The Netherlands
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  • Jaap C. Schouten,

    1. Faculty of Chemical Technology and Materials Science, Delft University of Technology, 2628 BL Delft, The Netherlands
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  • Cor M. van den Bleek

    1. Faculty of Chemical Technology and Materials Science, Delft University of Technology, 2628 BL Delft, The Netherlands
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Abstract

A cold model of a circulating fluidized bed with a 0.030-m-ID, 2.77-m-high riser was operated in a wide range of operating conditions. Several solids were tested, from 57 μm to 1,830 μm in size and from 1,100 kg/m3 to 2,540 kg/m3 in density. Pressure fluctuations were measured at several points along the riser, and time series were processed to evaluate chaotic invariants (Kolmogorov entropy and correlation dimesion). Axial profiles of average values of pressure and voidage were also evaluated. At fixed operating conditions, the Kolmogorov entropy changed along the riser, which appeared to be a fuction of the local voidage and showed a minimum when voidage decreases from 1.00 until about 0.90. Changes of the Kolmogorov entropy with local voidage were interpreted based on interactions among solids and gas turbulence structure. Three regions were identified in the voidage range investigated: particles-controlled region, clusters-controlled region, and bottom-bed-controlled region.

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