Maximization of Gasoline in an Industrial Fluidized Catalytic Cracking Unit

The riser of a fluid catalytic cracking (FCC) unit cracks gas oil to make fuels such as gasoline and diesel. However, changes in quality, the nature of crude oil blends feedstocks, environmental changes, and the desire to obtain higher profitability lead to many alternative operating conditions of the FCC riser. The production objective of the riser is usually the maximization of gasoline and diesel. Here, an optimization framework is developed in gPROMS to maximize the gasoline in the riser of an industrial FCC unit (reported in the literature) while optimizing mass flow rates of catalyst and gas oil. A detailed mathematical model of the process developed is incorporated in the optimization framework. It was found that concurrent use of the optimal values of mass flow rates of catalyst (310.8 kg/s) and gas oil (44.8 kg/s) gives the lowest yield of gases, but when these optimum mass flow rates are used one at a time, they produced the same and better yield of gasoline (0.554 kg of lump/(kg of feed)).