AM-13-74 Optimizing FCC – Pre-Treat Unit Operation To Reach Tier 3 Gasoline Sulfur Targets

Description:

The United States Environmental Protection Agency is considering implementation of more stringent Tier 3 ultra low sulfur gasoline (ULSG) sulfur specifications that would likely require all gasoline to contain ≤10 wppm sulfur. While the anticipated Tier 3 sulfur limit would seem to be a small step from the current Tier 2 limit of ≤30 wppm, the impacts on refiners, especially those without FCC naphtha post-treat capabilities, could be significant. Likely consequences for the refiner of having to meet the lower FCCU feed sulfur limits are that FCC-PT (FCC feed pretreater) unit cycle lengths will be decreased significantly and operating costs for these units will be increased. This paper examines the likely impacts of the anticipated Tier 3 ULSG specs on refinery FCCPT unit operations and the consequences for refineries. Units operating in different pressure regimes are simulated to show practical examples of the expected impacts for different types of FCC-PT units. These case studies assume 100% hydrotreatment of FCC feed and are for illustration purposes only. Actual impacts of the Tier 3 specifications will be highly dependent upon specific unit feed compositions, unit capabilities and constraints, and FCC-PT operation strategies.