The worldwide demand for gasoline, diesel and petrochemicals is shifting toward a greater emphasis on diesel and propylene, and flexibility to meet changing demands will be vital for refinery profitability. Axens has developed the new FlexEne technology to expand the capabilities of the fluid catalytic cracking (FCC) process, which is the main refinery conversion unit traditionally oriented to maximize gasoline and at times propylene.
FlexEne relies on the integration of an FCC and an oligomerization unit called Polynaphtha to process light FCC olefins and to deliver good molecules back to the FCC and to provide product flexibility required by the marketplace.
By adjusting the catalyst formulation and operating conditions, the FCC process is able to operate in different modes: maxi distillate, maxi gasoline and high propylene. The combination with Polynaphtha delivers the flexibility expected by the market.
In a maxi gasoline environment, the olefin-rich C4 FCC cut is usually sent to an alkylation unit to produce alkylate and to increase the overall gasoline yield. In most recent max gasoline production schemes, alkylation has been advantageously substituted by Polynaphtha, which delivers high-quality gasoline at a much lower cost.
For greater distillate production, Polynaphtha technology may be operated at higher severity to produce distillates from C4 olefins. Additional diesel production may be supplied by operating the FCC unit in the maxi distillate mode.
For greater propylene production, Axens/IFP R&D has shown that either the Polynaphtha gasoline or distillate fractions can easily crack in the FCC unit to produce Propylene. Consequently, depending upon market conditions, gasoline or diesel can be recycled to the FCC to produce high-value propylene and C4 olefins.
Thanks to optimized combination of FCC and oligomerization, Flex-Ene delivers the largest market product flexibility when targeting production of propylene and/or gasoline and/or distillates.