(22g) 3d Simulation of the Fcc Particle Contact with Oil Droplet at High Temperatures

In fluid catalytic cracking (FCC) reactors, gas oil is injected from the nozzle at the bottom of the riser and the mist droplets formed from the spray are in contact with high-temperature fluidized catalyst particles. Such a three-phase contact yields a complex interfacial transport phenomenon coupled with complex heterogeneous reactions. Understanding the droplet and particle contact mechanics is important to accurate prediction of hydrocarbon product distributions resulting from catalytic and thermal cracking reactions in the riser. A 3-dimensional numerical model is developed to simulate the contact process of a high temperature FCC particle with an evaporative oil droplet. The numerical technique involving level-set and the immersed-boundary methods are used to simulate the droplet-particle contact dynamics in a fixed Eulerian grid. The variation of droplet interface characterizing its deformation is quantified using one level-set function and the solid-fluid boundary condition is imposed at the particle surface through the immersed boundary method involving another level-set function. A 2-D vapor layer model is developed to simulate the vapor flow dynamics, and the heat transfer equations in the entirely flow field are formulated for each of the solid, liquid and gas phases. The incompressible flow governing equations are solved using the finite volume method with the ALE technique. The simulation results are validated through comparisons with experimental data obtained from the experiments of this study. The effects of the Weber number and the particle size on the contact behavior are analyzed. Both the normal collision and oblique contacts are considered.