Modeling And Simulation Of FCC Riser Reactor

Fluid catalytic cracking (FCC) is a dominant refining conversion process in China’s most refineries. The main materials for FCC is heavy oil, such as distillate oil and residue, its products include liquefied petroleum gas, diesel, gasoline and propylene. After decades of development, China has already become one of the major FCC technology licensors in the world. At present, the capacity of catalytic cracking in China is146Mt/a. In the area of FCC study, most research focus on FCC units or modeling and simulation.Reactor-regenerator system is most important and complex part of FCC unit, Therefore, almost all the research of modeling and simulation are directed at this part. In the riser reactor section of this part, feed and product oils are complicated mixtures of numerous hydrocarbons and non-hydrocarbons. It is important to establish a reactor scheme to describe the reactions of these compounds. The stock oil and product oils are divided into different lumps according to their physicochemical properties in the traditional method, and then build kinetic reactions of catalytic cracking by describing the reaction between lumps. However, this model is valid only for specific oil, if the properties of oil changed, the kinetic parameters need to be recalculated.For the above reasons, standard pseudo-components (SPCs) are proposed which have invariant and definite physicochemical properties: normal boiling temperatures and densities, and are defined in pairs of light and heavy cuts of narrow boiling range. A true boiling point distillation narrow cut of a stock or product oil is then expressed with a pair of SPCs, which constitutes the basis for the characterization procedure developed in this paper. A steady state model for a prototype fluid catalytic riser with a side feed stream is formulated where material and heat balance is strictly observed, the hydraulic behavior is considered, and the improved kinetic scheme is adopted. Results of tests with production data from three commercial risers show that the kinetic scheme is predictive as coupled with the suggested characterization procedure in the sense that the kinetic parameters are independent of stock oils. Meanwhile, the parameters identifiability were studied this paper.