Hernando Salgado - Saudi Aramco, Downstream Portfolio Planning
Fluid catalytic cracking (FCC) is one of the key process technologies in the refining industry. The FCC unit increases refining margins by upgrading low-value streams, such as vacuum gasoils or atmospheric and vacuum residues, to more valuable products, such as propylene, butylenes and high-octane naphtha. Due to the greater availability of heavy crude oils, the quality of FCC feeds has become poorer. These types of poorer feeds contain higher contents of carbon, sulfur, nitrogen and metals. Regarding catalyst performance, metals are one of the most harmful contaminants. These contaminants can lead to undesirable problems, such as equilibrium catalyst (Ecat) deactivation and dehydrogenation, that can cause extra coke formation and poor selectivity in cracking reactions. Although the easy solution could be increasing the fresh catalyst makeup rate to keep the metals loading in the Ecat low enough, this can be a costly option that will affect FCC economics. The following provides a method to determine the optimal fresh catalyst makeup rate, with the objective to maximize FCC profits.