(465d) Numerical Study of Flow Hydrodynamics in Scaled Models of Syncrude's Fluid Cokers

Authors: 
Li, T., National Energy Technology Laboratory
Grace, J. R., University of British Columbia
Bi, X., University of British Columbia
Reid, K., Syncrude Canada Ltd.
Wormsbecker, M., Syncrude Canada Ltd.


The hydrodynamics of fluid cokers were investigated by means of computational fluid dynamics (CFD). This work consists of two parts. In the first, a scaled cold model based on an experimental column was constructed numerically, and the flow hydrodynamics were investigated in terms of voidage distribution and solid velocity. The influence of simulation time on results interpretation and analysis was evaluated first, and a short-time simulation was shown to be able to provide useful information. Predicted flow behaviour was compared quantitatively and qualitatively with previous experimental findings. The effects of such operating variables as nozzle insertion, feed distribution and solids circulation rate were investigated, leading to qualitative trends consistent with experimental results. In the second part of study, the evaporation of liquid feed was simulated based on several different limiting assumptions to simplify the process: (a) Liquid feed vaporizes before entering the column; (b) Liquid feed vaporizes immediately upon contact with the coke particles; and (c) Liquid uniformly coats particles and vapour is then generated uniformly throughout the bed. After analysing these extreme scenarios, two cases with a more realistic description of liquid-solid interaction and feed evaporation were simulated. The evaporation rate was found to play an important role in affecting the flow hydrodynamics in the bed. The local liquid-to-solid ratio and shear stress distribution were evaluated by means of numerical simulations. An agglomeration index was then introduced to characterize the stability of agglomerates in the reactor. The evaporation rate of liquid film coating on particles affected the distribution of agglomeration index, with a high evaporation rate tending to decrease the probability of both agglomeration and stripper fouling.