Feed streams to fluid catalytic cracking units (FCC) have to be desulfurized to meet the stringent gasoline sulfur specifications. This typically requires FCC pretreaters to operate at high severity (high temperature) to meet clean fuels specifications. The high-temperature operation, however, significantly reduces the polynuclear aromatics (PNA) saturation due to equilibrium. Equally important, it lowers margins and the profitability of FCC units as well.
A revamp with Topsoe’s patented Aroshift™ process effectively reverses the adverse effects of increased severity. Aroshift™ works by combining technology and catalysts to lower the PNA content of the feed.
Given the dynamics of the industry today, the FCC unit is critical to refinery margins, and profitability cannot be underestimated. Aroshift™ can unlock much value for refiners. The bottom line is that it increases FCC conversion, gasoline yields, and C3/C4 olefins while reducing the amount of light and heavy cycle oil. The quality of the FCC gasoline is also improved.
Typical Aroshift™ process layout
Aroshift™ accommodates the inclusion of coker feedstocks and deasphalted oils (DAO) in the feed and provides a uniform product quality throughout the cycle length of the FCC pretreater.