Characterization and modelling of a maldistributed Trickle Bed Reactor

Abstract

A Trickle Bed Reactor equipped with a non‐ideal distribution tray is investigated. First, a non‐ideal co‐current trickling flow of nitrogen and heptane, induced by a partially plugged tray, is characterized experimentally using the γ‐tomography technique. Resulting liquid saturation data are used to validate the Euler‐Euler CFD model developed in previous work of Solomenko et al.[16] on a 3D realistic flow. The resulting 3D CFD model is then coupled with simple isothermal kinetics of heteroatom removal of heavy petroleum cuts, and the effect of maldistribution on reactor performance is discussed. The problem of CFD model reduction to a 1D reactor model is finally addressed based on transport of internal ages distribution theory. Different 1D models are compared based on reactor effluent throughput. It is shown that a 1D‐Multi Exit reactor model that respects both the age variance at the system outlet as well as the degree of mixing inside the reactor gives the best prediction of the reactor performance.

CFD study and experimental validation of multiphase packed bed hydrodynamics in the context of Rolling Sea conditions

“…There is certainly no escape from conducting well‐thought and reliable experimental studies to characterize the hydrodynamics prevailing inside packed‐bed reactors. However, the associated restrictions and difficulties have limited the application of experimental methods to small laboratory‐scale setups, narrow operating ranges, and generally to cold fluid conditions . Therefore, procurement of a validated first‐principle‐based model can greatly enhance our understanding of the multiphase flow hydrodynamics in packed beds especially with an ambition to help in the scale up.…”

“…So far Eulerian CFD models with appropriate closure laws were able to successfully predict bed overall pressure drop and liquid holdup for vertical gas–liquid cocurrent downflow packed beds . Meanwhile, application of a two‐fluid Eulerian CFD framework combined with the relative permeability closure model was limited to qualitative descriptions of the hydrodynamics of stationary tilted packed beds .…”

Hydrodynamics of inclined packed beds under flow modulation ‐ CFD simulation and experimental validation

“…A modification to the capillary pressure correlation developed by Attou and Ferschneider was suggested by the authors to further validate their predictions. The mechanical dispersion forces together with the capillary pressure force were taken into account as the closure laws in the Eulerian multifluid model to simulate the liquid spreading and maldistribution in the vertical trickle bed reactor as well . Lappalainen et al showed that as long as the liquid phase flows through packed beds, both the capillary and mechanical dispersion mechanisms consistently exist; however, their relative significance is determined by the properties of the porous medium.…”

“…12 These experimental findings thus highlight the fact that cyclic operation can be regarded as a potential method for process intensification in offshore floating packed bed reactors extending it beyond the realm of conventional trickle beds where cyclic operation has been successfully applied to enhance mass transfer, improve phase distribution, reduce fines deposition, or control foam formation, to name just a few examples. [13][14][15] Several researchers successfully applied the Eulerian multifluid CFD model along with well-established interphase interaction forces as closure laws to predict bed overall pressure drop and liquid holdup in conventional vertical gas-liquid cocurrent downflow packed beds (i.e., trickle-bed reactors) under steadystate (i.e., iso-flow) [16][17][18][19][20][21][22][23][24][25] and unsteady-state cyclic operation. 17,26 Hamidipour et al 17 were able to precisely capture the transient hydrodynamic behaviors of trickle-bed reactors under gas, liquid, and gas/liquid alternating cyclic operations using an unsteady multifluid Euler framework combined with the closure laws developed by Attou et al 27 for fluid-solid drag forces and fluid-fluid interaction force.…”

“…The mechanical dispersion forces together with the capillary pressure force were taken into account as the closure laws in the Eulerian multifluid model to simulate the liquid spreading and maldistribution in the vertical trickle bed reactor as well. 16,18,30,34 Lappalainen et al 30 showed that as long as the liquid phase flows through packed beds, both the capillary and mechanical dispersion mechanisms consistently exist; however, their relative significance is determined by the properties of the porous medium. The decreasing particle size causes an increase in the capillary pressure force and a decrease in the mechanical dispersion forces.…”