Investigating Multiphase flow Behavior in Trickle Bed Reactors using eXtended Discrete Element Method (XDEM)

The existence of multiphase flows through packed bed of solid particles in broad spectrum of engineering disciplines such as chemical industries, petroleum engineering, wastewater treatment is undeniable. One frequently used reactor of this type is a trickle bed reactor that usually contains particulate phase of which the interstitial space is filled with gas and liquid phases. Based on the direction of the fluid flow they can be classified as cocurrent downflow trickle bed reactors, counter-current trickle bed reactors and cocurrent upflow packed bubble reactors. In these kind of problems numerical simulations can help to gain a better process understanding.

In the current distribution, a numerical method so called Extended Discrete Element Method (XDEM) was applied to model multiphase flow through packed bed of solid particles which has the ability to be coupled to Computational Fluid Dynamics (CFD) through interphase momentum transfer. In this coupled solver the fluid phases are treated by CFD while the position and orientation of the particles in each CFD cell and the porosity distribution through packed bed are provided by XDEM.

In order to validate the code, two important hydrodynamic parameters such as pressure drop and liquid hold up were investigated and satisfactory agreement between predicted and experimental data was achieved. The model results demonstrate enormous effect of solid particles on the deviation of fluid phases while passing through packed bed by investigating parameters such as velocity and drag force.