Hydrodynamic study on inverse fluidization: A CFD analysis

Abstract

The term 'fluidization' is usually associated with two or three phase systems, in which the solid particles are fluidized by a liquid or gas stream flowing in the direction opposite to that of gravity. Fluidization where the liquid is a continuous phase is commonly conducted with an upward flow of the liquid in liquid-solid systems or with an upward co-current flow of the gas and the liquid in three phase systems. Under these conditions, a bed of particles with a density greater than that of the liquid is fluidized with an upward flow of the liquid counter to the net gravitational force of the particles. Fluidization can be achieved by downward flow of the liquid when the particles are having lesser density as compared to the continuous liquid medium. This phenomenon is termed as inverse fluidization. The inverse fluidization system has gained significant importance during the last decade in the field of environmental, biochemical engineering, and oil–water separation. The minimum fluidization velocity is lower in this case. Also it takes lesser energy to pump a fluid to force the particles in this case. Hence viewing on a larger scale, at the industrial level, it can save a lot of energy. Such energy efficient processes are the need of today when energy crisis is at its peak. The application of inverse fluidization technique in biotechnology is one of the most important areas in bioreactor engineering. In this report various hydrodynamic characteristics of the inverse fluidized bed is studied based on literature and CFD is proposed to be applied on the system for further analysis.