Hydrodynamic Characteristic Study of a Three Phase Co-current Trickle-bed Reactor: CFD analysis

Abstract

Trickle-bed has been extensively used in chemical process industries mainly in petrochemical and refinery process since it provide flexibility and simplicity of operation as well as high throughputs. The basic parameter for design, scale-up and operations of a trickle bed reactor are the pressure gradient and liquid saturation. Knowledge of these hydrodynamics parameters and prevailing flow regime is essential for design and performance evaluation of the reactor. But hydrodynamics of trickle bed reactor involve complex interaction of gas and liquid phase with packed solid which is very difficult to understand. Many computational models have been developed and extensive CFD study of hydrodynamics parameters has been done is last few decades to understand the behaviour of trickle bed reactor.
In the present work an attempt has been made to study the hydrodynamics of a co-current gas-liquid-solid trickle bed reactor using FLUENT 6.3.26. CFD simulations has been done using Eulerian-Eulerian approach for a trickle bed system with column of height 1 m and diameter 0.194 m containing glass beads of diameter 6mm as solid packing. GAMBIT 2.3.16 has been used to generate a 2D coarse grid. The phase holdup and pressure drop behaviours have been studied and their axial and radial distributions have been illustrated. The results show that liquid holdup increases with increase in liquid velocity and decrease with increase in gas velocity. The trend is reverse for gas holdup i.e. it increases with increase in gas velocity and decrease with increase in liquid velocity. Pressure drop increases with increase in both gas and liquid velocity. Quantification of this behaviour has been done. The results have been compared with previous literature data available and found to agree well.