Estimation of physical properties and hydrodynamics of slurry bubble column reactor for catalytic hydrocracking of vacuum residue

Abstract

Vacuum residue (VR) was subjected to catalytic hydrocracking with H2 in a pilot-scale slurry bubble column reactor (SBCR) with 0.05 m diameter and 2 m height at 425 °C and 160 bar in the homogeneous regime. The gas holdup (αG) and composition of the product classified into five pseudo-components were measured in the SBCR. The physical properties such as density, viscosity, and surface tension of VR (feed) were analyzed prior to a three-dimensional Eulerian computational fluid dynamics (CFD) simulation to predict axial and radial hydrodynamics in the SBCR. Rather than considering the hydrocracking reactions in the CFD model, a reaction-mixture model was used to predict the variation of the axial physical properties as the reaction progresses. A customized drag coefficient based on experimental data was applied to the CFD model. The value of αG predicted by the CFD model at a superficial gas velocity of 6.4 mm/s was 6.2% which is comparable to the experimental value (6.6%). The Sauter mean diameter and specific surface area were estimated to be 1.2 mm and 304 m2/m3, respectively. The proposed CFD model, which was integrated with the axial physical properties but decoupled from chemical reaction, successfully predicted the hydrodynamics of the H2-VR SBCR.