Hydrodynamic study of Three Phase semi Fluidized Bed with Irregular and homogeneous binary mixtures

Abstract

Fluidization refers to a process by which a fluid like state is imparted to granular solid particles by the passing of a fluid upwards through the bed of particles. A semi fluidized bed is characterized by a fluidized bed and a packed bed in a series within a single contacting vessel. Gas-liquid-solid semi fluidization is defined as an operation in which a bed of solid particles is suspended in gas and/or liquid upward flowing media due to the net gravitational force on the particles and the motion of the particles is restricted by a top restraint. Such an operation generates intimate contact between the gas, liquid and solid particles in these systems and provides substantial advantages for applications in physical, Chemical and biochemical processing involving gas, liquid and solid phases. The experiments were conducted using liquid as the continuous phase and gas as the discontinuous phase. In this work air, water and dolomite (2.31mm, and 1.7mm) are used as the gas, liquid and solid phases respectively. The experiments were carried out in a 100 mm ID of 2m height vertical Plexiglas column. Knowledge of minimum liquid semi fluidization velocity is essential for the successful operation of gas-liquid-solid semi fluidized beds. Bed pressure measurements have been made to predict the values of the minimum liquid semi fluidization velocity. In the present work, hydrodynamic characteristics viz., the pressure drop, bed expansion of a co-current gas-liquid-solid semi fluidized bed has been studied. These have done in order to develop a good understanding of each of the flow regime in gas-liquid and liquid-solid semi fluidization. The effect of static bed height, particle size, liquid velocity and gas velocity on hydrodynamics parameters like minimum semi fluidization velocity, pressure drop, expansion ratio have been investigated. Experimental study based on statistical design has been made to investigate the expansion ratio of semi fluidized bed.. The experimental values have been compared with those predicted by the correlations and have been found to agree well.