CHEMICAL ENGINEERING TRANSACTIONS VOL. 43, 2015 A publication of The Italian Association of Chemical Engineering Online at www.aidic.it/cet Chief Editors: Sauro Pierucci, Jiří J. Klemeš Copyright © 2015, AIDIC Servizi S.r.l., I SBN 978-88-95608-34-1; I SSN 2283-9216 Effect of Injection Zone on Catalyst and Gas Homogenization in FCC Riser Daniel C. Pelissari a , Helver C. Alvarez-Castro a , Milton Mori* a , Waldir P. Martignoni b , Raffaella Ocone c a School of Chemical Engeneering, University of Campinas, 500 Albert Einstein Avenue, 13083-970 Campinas –SP, Brazil b Petrobras, 65 República do Chile Avenue, 20031-912 Rio de Janeiro, Brazil c Chemical Engineering, Heriot-Watt University, Edinburgh EH144AS,UK. danielcicero21@hotmail.com In the fluid catalytic cracking (FCC) process, the riser is the most important equipment where the reaction taken place. In the riser operation, the feedstock is fed through injectors and mixed with catalyst and steam. A good design and localization of the injectors to ensure rapid evaporation of the feedstock and a good contact of the droplets with the catalyst is important to improve the process efficiency due to a better reagent distribution which ensures a good feedstock conversion and product yields. Hydrodynamic modelling, heat transfer and cracking reactions were studied in this paper using Computational Fluid Dynamic (CFD) in order to evaluate the effect of nozzles design and configuration on the homogeneity of the gas-solid distribution. A 3D model was solved with the Eulerian – Eulerian approach using ANSYS/CFX version 14.0 as calculation tool. The simulation results showed that the distribution of gas-solid depends significantly on the configuration of the feedstock injectors. 1. Introduction The fluid catalytic cracking unit ( FCCU ) converts residues of oil gas vacuum (VGO) of low commercial value into a number of derivatives like gasoline , diesel , LPG, dry gases and coke with high economic value; it is considered by many authors (e.g., Fahim et al., 2010) one of the most important and profitable processes in petroleum refineries. The FCCU can be divided into three main sections: riser, separator and regenerator. The catalytic cracking occurs mainly in the riser, the riser of FCCU is a long vertical tube with a high ratio height/diameter, in which the catalyst and gasoil enter in contact and the reaction takes place. The bottom region of the riser is known as the lift region; the catalyst is fed at the bottom of the lift region and then it is fluidized by steam which is fed at the bottom of the riser. The feedstock is injected into the riser through nozzles, which aim to atomize the gasoil in small droplets and introduce them into the riser increasing the contact area between the catalyst and the gasoil. Additionally, the nozzles assure appropriate feed distribution inside the riser to minimize zones of high concentration of catalyst thus avoiding high temperature gradients that are not beneficial to the process. The injection zone is considered the most complex region of the reactor, due to the intense turbulence and not homogeneous regime, resulting in high gradients of temperature and concentration. According to previous works (e.g., Mauleon and Coorcelle (1985), the nozzles’ design has a big influence on the hydrodynamics and catalytic cracking, thereby influencing the yield. Theologos et al. (1997) presented a one-dimensional model with 10-lumps kinetic model to describe the catalytic cracking reactions and studied the influence of nozzles’ number on the reactor performance. The simulation result showed that the yield of the desired reaction is improved by increasing the nozzles’ number, since it provides a more homogeneous catalyst distribution. Lopes et al. (2011a) used a three-dimensional model for gas-solid flow using a 4-lumps kinetic model. The results also showed that non-uniform catalyst distribution affects the reactor performance. Furthermore, the referenced authors emphasized that the use of DOI: 10.3303/CET1543283 Please cite this article as: Pelissari D.C., Alvarez-Castro H.C., Mori M., Martignoni W.P., Ocone R., 2015, Effect of injection zone on catalyst and gas homegenization in fcc riser, Chemical Engineering Transactions, 43, 1693-1698 DOI: 10.3303/CET1543283 1693