A coupled DEM-CFD analysis of asphaltene particles agglomeration and fragmentation

Abstract

In the present paper, a Discrete Element Method-Computational Fluid Dynamics (DEM-CFD) approach along with a new coalescence model is adopted to study agglomeration and fragmentation of asphaltene particles, thoroughly. The collisions of asphaltene particles are investigated in three categories: collisions between individual primary particles (P-P collisions), individual primary particles and flocs (P-F collisions) and between flocs (F-F collisions). In addition, corresponding collision efficiencies have been determined based on the proposed coalescence model. Moreover, the importance of three different fragmentation modes including binary flocs fragmentations (binary fragmentation), detachment of a primary particle from floc (erosion) and splitting of floc into smaller flocs (large-scale fragmentation) is comparatively assessed. Eventually, the effect of fluid velocity and primary particles concentration on the aforementioned processes as well as asphaltene flocs properties are examined. Simulation results reveal P-P collisions contribution decreases continuously to reach a plateau in steady state condition while the contribution of P-F collisions increases initially and then it shows a gentle downward trend. F-F collisions contribution grows constantly up to steady state condition. The P-P and P-F collision efficiencies approximately remain constant whereas F-F collision efficiency continuously increases. In terms of fragmentation modes, contributions of binary fragmentation and erosion gradually decrease while large-scale fragmentation contribution constantly increases before steady state condition.