Liquid-solids fluidized beds are widely used in chemical, petrochemical, food, biochemical, waste treatment, mining and many other industries. The major advantage of liquid solid fluidized bed is its uniform solid distribution throughout the bed and excellent solid mixing which stimulates better heat and mass transfer. However, in many of liquid-solids fluidized bed applications mixture of solids having different size, shape and density are used. The mono-sized liquid-solid bed gives homogeneous fluidization where bed expansion increases with increasing liquid velocity. However, when a mixture of solids having different size and/or density is fluidized, the behavior of fluidized bed is markedly different from the behavior of mono-disperse bed. In such case, a particular mixing/segregation pattern is reached which in turn gives rise to a steady distribution of mixture components along the bed height which depends both on constitutive solids properties and on the operating and geometric conditions of the process. In literature, many researchers have attempted to find the effect of different size and density of particles on behavior of liquid solids fluidized bed using binary mixtures. A large number of studies have been carried out to find the effect of bed composition on minimum fluidization velocity and pressure drop. Some studies have also been reported on the mixing of solids in binary mixture fluidized bed. Though lot of studies has been conducted on binary bed, in-situ measurement of individual phase fraction, velocity field and mixing characteristics are still missing. Further, most of the CFD models for liquid-solids fluidized beds have mainly concentrated on Euler-Euler methods, considering both the liquid and solids to be interpenetrating pseudocontinuous. Limited number of studies or available on Euler-Lagrangian simulation of liquid solids binary fluidized bed wherein no arbitrary assumptions are made and time history of each particle is tracked by solving Newton’s second law of motion.

 In the current work, hydrodynamics of liquid-solid binary fluidized bed having same density different size is studied through state-of-the-art experimental technique and advanced CFD simulations. Glass beads of two different sizes 0.6 mm and 1 mm are used in a bed of 10 cm id and 2 meter height. Water is used as a liquid phase. Radioactive particle tracking (RPT) technique is used to track the motion of both the particle in binary bed and duel source gamma-ray densitometry is used to measure the solid distribution and mixing on the bed for different bed compositions and liquid velocities. Further, Euler-Lagrangian model of liquid solid fluidized bed is developed in which history of both the particle is tracked with the time. Both experiments and simulations are performed for a bed composition of 100:0, 75:25, 50:50, 25:75 and 0:100 mass fractions of 0.6 mm and 1 mm particle respectively at different liquid velocites. The results of Euler-Lagrangian simulations are matched with experimental data. The profiles of mean solid velocities, rms velocities, granular temperature and phase distributions of both the solids are matched with experimental the finding for different operating conditions. Finally, detailed analysis on mixing/segregation behavior of solids at different operating conditions for different bed composition is presented to quantify the characteristic of the bed.