NUMERICAL OPTIMIZATION OF CRYOGENIC SEPARATION OF OIL SANDS AND CLAY IN FLUIDIZED BEDS

Abstract: Fluidized beds offer efficient solutions for segregation of clay and bitumen pellets in the oil production industry. However, the hydrodynamics of these systems is not well-known and they are mostly operated as ``black box''. The removal of clay pellets in the mechanical separation of oil sands method, requires an efficient method of separation of the pellets. By using computational fluid dynamics (CFD), the hydrodynamics of these equipments can be studied and the affecting parameters on the flow behavior be identified. In this thesis challenges in preparation of a validated CFD model are addressed and the effects of design and operating parameters on the efficiency of the method are studied. The Eulerian-Lagrangian approach is used in the CFD simulations of a slice of the bed and results are compared to a 3D full size bed and to results from literature for validation. The first study is dedicated to the analysis of the fluidization process in a fluidized bed formed with mono-dispersed sand particles. Results of the simulations are compared against experimental data and empirical solutions. A validated and grid-converged numerical model which can present the hydrodynamics of the fluidized bed is the outcome of this study. Later, bitumen pellets are added to the fluidized bed simulations, as the third phase, to study the segregation process. Results of simulations are compared to the published experimental and analytical works. To study the effect of design and operating parameters of the fluidized bed on the segregation of particles, the density ratio of the particles is decreased to increase the sensitivity of the problem. The results of the simulations showed that the carrier phase properties, as well as the width and the height of the bed, are not affecting the final degree of the mixture. However, the rate of segregation of particles is increased by reducing the static height of the bed. Also, the model showed that there should be an optimum inlet velocity at which the rate of segregation of particles is fastest and which produces the best level of segregation of particles, as expected. Among the tested values in the current study the inlet velocity of 1.25 times the minimum fluidization velocity of the jetsam was the fastest rate of segregation and most segregated state of the mixture.