(480h) Investigation of Mixing and Segregation Behavior of Binary Mixture in Liquid-Solid Conical Fluidized Bed Using Radioactive Particle Tracking | AIChE

(480h) Investigation of Mixing and Segregation Behavior of Binary Mixture in Liquid-Solid Conical Fluidized Bed Using Radioactive Particle Tracking

Authors 

Kalo, L. - Presenter, Indian Institute of Technology Guwahati
Upadhyay, R. K., Indian Institute of Technology Guwahati
Conical liquid-solid fluidized beds are mostly adopted for biochemical reactions, biological treatment of waste water and as crystallizer in both laboratory and industry. These beds provide excellent heat and mass transfer due to homogeneous distribution of solids across the column. Due to these advantages the conical liquid-solid fluidized bed has become an interesting topic for research. However, most of the studies in recent decade involve overall measurement of hydrodynamic parameters and information regarding local parameters are still missing. Therefore, in current work an in-situ measurement technique, radioactive particle tracking (RPT) technique, has been used to investigate the behavior of liquid-solid binary fluidized bed. Further, the variation of the hydrodynamic parameters with inlet velocity, bed composition, particle size and type (group B and group D) has been studied.

In RPT technique a single radioactive particle emitting gamma ray is used to track the motion of solids present in the bed. The particle is prepared to be identical to the phase of interest so that it exactly follows the solid present in the bed. Scandium-46 was used as tracer particle for present study. An experimental setup of 5 cm bottom diameter and 20 cm top diameter was used with 1.05 m height. The material used was glass bead with 0.6 and 1 mm size having density of 2500 kg/m3. The fluid used was tap water. The inlet velocity used for experiment was 2, 3 and 4 times of the minimum fluidization velocity (umf) of 1 mm particle. The bed composition was maintained as 0:100, 50:50, 75:25 and 25:75 for binary mixture. The total amount of solid used for all the experiment is kept constant i.e. 2.36 kg. Two different sizes of tracers are used to track both the particle. In binary mixture individual particles are tracked for each set of experiment. An array of scintillation detectors are strategically arranged around the vessel of interest to record the photons emitted by the tracer particle. The lagrangian position of tracer particle is reconstructed by using photon count time series data. Thereafter, rich data base, like instantaneous velocities, mean velocities, rms velocities, kinetic energy of fluctuations etc., is calculated by suitable post processing. Further, autocorrelation function, Hurst exponent, solid diffusivities are calculated using time series analysis to understand the mixing and chaotic behaviour of the fluidized bed for each set of data. Finally, mixing index values for both the particles in binary be is calculated at different zone to find the mixing and segregation scharecteristic of the bed.