The influence on products yield and feedstock conversion of feedstock injection position along the industrial riser

The fluid catalytic cracking (FCC) process is at the heart of a modern refinery oriented toward maximum gasoline and diesel production. Within the entire refinery process, this process offers the greatest potential for increasing profitability; even a small improvement in the gasoline yield it implies a substantial economical profit when dealing with a production of millions of barrels of gasoline a day. There are several articles published in the last two decades focusing the attention on 2-D and 3-D computational fluid dynamic models of the industrial riser of a circulating fluidized bed. Nevertheless, there are few research works published in the literature that include studies on how the localization of feedstock along the riser affects the yield products. A 3D hydrodynamic model coupled with a 12 lump kinetic model is presented in this work. Four different injection points in an FCC industrial riser were considered in order to evaluate the hydrodynamic behavior and their effect in the gas oil conversion and products yield. The equations were solved numerically by finite volume method using the Eulerian-Eulerian approach and a commercial CFD code, CFX version 14.0. Appropriate functions were implemented in the model via user defined functions considering the heterogeneous kinetics and catalyst deactivation. The results from the model were validated against the experimental industrial results and it was found that the conversion of gas oil and the production yield significantly change with the feedstock localization.