Addressing Tier 3 Specifications in a Declining Gasoline Market: Options for the Future

The anticipated Tier 3 regulations for gasoline sulfur pose an interesting challenge for North American refiners in a market where gasoline demand is stable or declining. This presentation will address evaluation of existing assets to meet the sulfur specification with minimum investment as well as options for future investment to maximize profitability and flexibility.

With the implementation of Tier 3 regulations, the requirement for the FCC naphtha will typically be 10-25 wppm sulfur with additional processing of orphan streams blended to the gasoline pool so that an overall pool sulfur limit of 10 wppm S is met. Many factors affect the optimum solution for Tier 3 in a particular refinery. In some cases, the existing Cat Feed Hydrotreater (CFHT) or FCC gasoline post-treater is capable of meeting the sulfur target for the FCC gasoline. However, the adequacy of existing facilities requires analysis beyond the ability of the unit to meet the sulfur target. The impact on product octane, hydrogen consumption, and cycle length are important for identification of a viable solution. The ability to synchronize with the FCC turnaround schedule is critical. The possibility of a future shift to a more sour crude slate should also be taken into account during Tier 3 planning.

The more stringent regulations will also limit the ability to blend low to moderate sulfur orphan streams directly to the pool. Raw Light Straight Run Naphtha (LSR), condensate gasoline (NGL), and pyrolysis gasoline will require hydrotreatment in most cases. The ability to handle Coker Naphtha at all times with also need to be addressed.

The presentation will also discuss the production of gasoline and middle distillates product from light Olefins conversion. As FCC feed pre-treatment increases in prevalence and severity to address gasoline sulfur, the resulting increased production of light olefins offers many options to refiners. Modern oligomerization technologies such as Polynaphtha can convert the light olefins into an ideal gasoline and middle distillates blending components with zero sulfur. As the market shifts toward distillate demand the ability of the technology to switch from gasoline to distillate mode is very attractive.

To further increase distillates production, Axens has developed a breakthrough technology offering oligomerization of the C₅ and C₆ olefins in the FCC naphtha to shift gasoline into a high quality kero/jet product.