Problem statement:The effective simulation of the Fluid Catalytic Cracking (FCC) operation requires a good understanding of many factors such as, reaction kinetic, fluid dynamics and feed and catalyst effects. Approach: In this model the reactor has been considered as an isothermal riser. The reactions in the riser occur with the fluid and the solids in ideal plug flow. Because of complication of the catalytic cracking mechanism and existence of multi-components in the feed, to decrease the calculation content in the kinetic models, the reactants and products have been considered as a set of hydrocarbons, so these models are called "Lumped Models". Results: To simulate the FCC riser, the seven-lump model involved residual oil, heavy lump, light lump, liquefied petroleum gas, gasoline, dry gas and coke (to predict the feed conversion and the product distribution) has been developed. Conclusion: Simulation studies are performed to investigate the effect of changing various process variables, such as temperature and residence time. Comparison of simulation results with industrial ones shows that the simulation has been achieved accurately.

Problem statement: The aim of this study is to obtain a model that can simulate the performance of an industrial fluid catalytic cracking unit in steady state. Approach: The reactions in the riser occur in a transported bed with the fluid and the solids in ideal plug flow. One of the main advantages of the model is that it does not include any partial differential equations. This facilitates the solution of the equations and makes the model particularly suitable for control studies. Results: To simulate the FCC riser, the four-lump model involved gas oil, gasoline, light gas and coke (to predict the Gas oil conversion and the product distribution) has been developed. Conclusion: Simulation studies are performed to investigate the effect of changing various process variables, such as temperature, catalyst circulation rate and gasoil feed rate. The calculated data of the product distribution were agreed well with the experimental results.