Mass transfer in vertical liquid-solids flow of coarse particles
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Wall-to-bed mass transfer in the hydraulic transport of spherical glass particles was studied. The experiments were performed by transporting spherical glass particles 1.20, 1.94 and 2.98 mm in diameter with water in a 25.4 mm I.D. tube. The mass transfer coefficients were determined by following rate of dissolution of a segment of the transport tube prepared from benzoic acid. In the runs in hydraulic transport, the Reynolds number of the tube varied between 1826 and 27597. The loading ratio (Gp/Gf) was between 0.026 and 0.474, and the fluid superficial velocity was between 0.267 · Ut and 4.904 · Ut, where Ut represents the single particle terminal velocity. For these ratios, the voidage ranged from 0.7123 to 0.9228. Also, wall-to-bed mass transfer in the single phase flow regime was studied. In the runs without particles, the Reynolds number of the tube varied between 122 and 39132. The data for the mass transfer factor (jD) in single phase flow are correlated for turbulent flow regi...me, using the Chilton-Colburn's type equations, jD = f(Re). Those investigations were conducted in aim to compare with results for wall-to-bed mass transfer in hydraulic transport. The data for wall-to-bed mass transfer (jD) in hydraulic transport of spherical particles were correlated by treating the flowing fluid-particle suspension as a pseudofluid, by introducing a modified suspension-wall friction coefficient (fw) and a modified Reynolds number (Rem). The data for wall-to-bed mass transfer in the hydraulic transport of particles show that an analogy between mass and momentum transfer exists.
Keywords:Flow pattern / Mass transfer / Vertical liquid-solids flow
Source:Powder Technology, 2009, 189, 1, 130-136
- Research Council of Serbia