Resistant effect of non-equilibrium inter-particle collisions on dense solids transport

There exist big gaps between measurements and modeling predictions on solids holdup and pressure drop in dense solids transport, such as those occuring in the bottom sections of gas–solids risers. The inability of closing this gap by common modeling approaches indicates certain missing and/or misrepresentation of some controlling mechanisms in modeling the transport. Previous research efforts show that the gap can not be effectively narrowed by simply modifying the drag force formulations without inclusion of the collision effect. This paper explores the origin of some controlling mechanisms that might have been overlooked in previous modeling approaches, and recommends how to make the model dense solids transport better. Our analysis shows the presence of a resistant force arising from inter-particle collision when the solids are accelerated in dense-phase transport. This may be caused by non-equilibrium collision during solids acceleration, which differs from local-equilibrium assumptions on which the current kinetic theory modeling of granular particles is based. A complete modeling of this collision-induced resistance calls for a total revision of the kinetic theory, with the inclusion of non-equilibrium collisions and off-center collisions in dense solids transport.

Graphical abstractOur analysis shows the presence of a resistant force arising from inter-particle collision when the solids are accelerated in dense-phase transport. This may be caused by non-equilibrium collision during solids acceleration. A complete modeling of this collision-induced resistance calls for a total revision of the kinetic theory, with the inclusion of non-equilibrium collisions and off-center collisions in dense solids transport.Figure optionsDownload full-size imageDownload as PowerPoint slide