Analysis of particle segregation and intermixing in solid-liquid fluidized beds

Abstract

Particle segregation and intermixing have been studied in 50 mm i.d. and 1.2 m long solid-liquid fluidized bed (SLFB). An ion-exchange resin was used as a solid phase in five size ranges with average particle sizes (dry basis) of 427, 500, 605, 725, and 855 μ m. Expansion characteristics of beds were investigated separately for all the particle sizes. The expansion characteristics were also investigated using 2, 3, 4, and 5 sizes having all the combinations among 427, 500, 605, 725, and 855 μm. In all cases, the concentration profiles of the individual sizes were measured along the bed height. The segregation velocity of dense and light particle was predicted and compared with experimental results for binary mixtures. Criteria have been developed for segregation/intermixing in laminar (Re_∞ < 0.1), transition (0.1 < Re_∞ < 500), and turbulent (Re_∞ > 500) regimes for binary particle systems. The solid dispersion coefficient has also been evaluated for each particle size present in the mixture of particles of different sizes at given operating conditions.