Optimization Study on Increasing Yield and Capacity of Fluid Catalytic Cracking (FCC) Units

The fluidized catalytic cracking (FCC) unit is the primary production unit for gasoline and olefins in refineries. Improving product yield and processing capacity is closely related to the economic benefits of refineries. In this paper, we use the Aspen HYSYS software to model the mechanism of an 800 kt/a FCC unit in China. The simulation of the FCC unit based on the 21-lump models and the simulation results are in good agreement with the actual factory production data. Then we find out the optimization method to improve the product yield and processing capacity through the model research. The results of the study indicate the following optimization plans: when keeping the riser outlet temperature (ROT) in the range of 535~545 °C, it can increase the yield of gasoline and liquefied petroleum gas (LPG) by up to 5%; when keeping the riser outlet temperature (ROT) in the range of 510~520 °C, it can increase the yield of gasoline and diesel by up to 0.5%; the optimal ROT of control temperature should be 530 °C when ensuring the same gasoline yield and increasing processing capacity, it can increase the feed rate by 14.3% which in turn increases gasoline production. Through the above plans, the refinery can achieve the production goals of yield and capacity. Therefore, the refinery can get more profits