Hydrodynamic continuum model for gas-liquid fixed beds operating in trickle flow and pre-loading regimes

A one-dimensional two-fluid continuum model based on the volume-average mass and momentum balance equations was developed for the prediction of the two-phase pressure drop and the total liquid hold-up in co-current down-flow and counter-current fixed-bed reactors operating respectively in the trickle flow regime and in the pre-loading zone. The slit model drag force closures, as well as the drag closures derived from the modified Kozeny-Carman theory based on a two-dimensional tortuosity model, were adapted. The inertial term in the drag force expressions was corrected to predict satisfactorily the two-phase pressure drops at high pressures. Wall effect functions were incorporated into the drag force equations. Associating the drag forces based on the modified Kozeny-Carman theory and the presently developed continuum model resulted in a fully predictive tool with no adjustable parameter both in co-current down-flow and counter-current flow.