Análise numérica da influência de defletores sobre o escoamento gás-sólido em risers de FCC via fluidodinâmica computacional

Abstract

Many industrial processes with fluids flow include multiphase phenomena, such as fluidized catalytic cracking (FCC), which is present in oil refineries. This process consists of cracking the heavy oil fractions and converting them into high added-value products. Despite its economic viability, this process operates under extreme conditions of temperature and pressure and is characterized by the presence of multiphase reactive flow and a series of complex phenomena, which makes the process difficult to be evaluated experimentally. In this context, Computational Fluid Dynamics (CFD) has proved to be a powerful tool for the study of many practical engineering problems in which a flow pattern is observed because, besides the reduced costs, it is possible to evaluate equipment even under extreme operating conditions. The fluid dynamics inside the riser is heterogeneous and characterized by accumulation of catalyst particles onto the wall. This flow pattern known as core-annulus causes a decrease in process yields. In this sense, the use of baffles in FCC risers has attracted the interest of researchers with the purpose of minimizing the accumulation of solid particles onto the wall and ensuring better distribution and uniformity between the phases within FCC risers. Therefore, the main objective of this work was to evaluate the influence of baffles in FCC riser on the gas-solid flow using computational fluid dynamics. Numerical simulations were performed using a three-level factorial design by varying the geometric parameters: quantity (Z), length (H) and throttling (E) of baffles in the FCC riser. The results of the numerical simulations showed that baffles in FCC riser can cause changes to the flow, providing greater homogenization in the system. The statistical analysis of the results pointed out the parameters that most influenced the yields of gasoline, coke, light fractions and heavy fractions, as well as the increase or decrease of pressure.