3 Questions for Nicolas Lambert on High Severity Cat Cracking
1. What’s HS-FCC™?
FCC and HS-FCC™ both target the conversion of heavy feedstock to valuable, lighter products, using a fluidized, powder-like catalyst circulating between a reaction vessel and a regeneration vessel. The severity of the operation is dramatically increased with HS-FCC™ though, making it possible to reach a much higher level of light olefin production, in particular propylene.
At the same time, the gasoline product is mostly preserved, allowing either a recovery of valuable aromatic components or usage in the motor fuel pool.
This technology is therefore bridging the gap between refining and petrochemicals: a highly valuable asset when looking at the opportunity of refining and petrochemical integration, in terms of flexibility, synergies, and cost savings!
2. What are the key features of HS-FCC™ when compared with conventional FCC?
HS-FCC™ provides a complete system to boost product selectivity and, in particular, propylene yield. Three key features are required to achieve this performance:
- Highly selective catalyst and additive system
- Optimized reaction conditions:
High reaction temperature coupled with short contact time increases the primary reactions towards olefins while limiting the unwanted secondary reactions of hydrogen transfer and thermal degradation. A consequence of the increased severity and short contact time is the need for higher catalyst circulation to provide the required heat to the reactor and sufficient catalyst activity to achieve high conversion at short contact time.
- Downflow, short contact time reaction system with rapid catalyst separation:
When targeting maximum olefins production, a highly selective downflow reaction environment is the best way to produce substantially more light olefins (including propylene) at the same gasoline yield compared to a conventional upflow system. Those parameters boost the propylene yields without sacrificing valuable components to overcracking into less valuable molecules, such as fuel gas components. This downflow circulation requires the use of a Tempest® Separator, a feature specially developed for this process that ensures a quick and efficient separation of cracked hydrocarbons from the catalyst.
Last but not least, the HS-FCC™ is able to process a large spectrum of feedstock, ranging from very light/clean to very heavy/polluted.
3. How mature is this technology?
First and foremost, Axens is backed by nearly 35 years of experience with the FCC Alliance (Total, IFPEN and Technip Stone & Webster Process Technology).
Second, after years of R&D at JX Nippon Oil & Energy Corp., King Fahd University of Petroleum and Minerals and Aramco, a complete 3,000 BPD HS-FCC semi-commercial unit with a fully independent main fractionator, gas plant, and flue gas treatment has been operating for 3 years in Mizushima, Japan.
This demonstrates the ability of this new technology to operate on various feeds (vacuum gas oil, residue, deasphalted oil…) while reaching the expected high yields of propylene. Moreover, the mechanical resistance and general performance of the Tempest® system was also validated through a series of shutdowns and restarts.
Those were strong elements contributing to Axens’ first two commercial awards, including a world scale unit to be started up circa 2018 at S-Oil’s plant in South Korea .
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