Developing a Next-generation FCC (HS-FCC) Process
HS-FCC (High Severity Fluid Catalytic Cracking) is a refining process where heavy oils are efficiently converted to light olefins such as propylene, butylene and other raw materials for petrochemicals with higher values.
Among the light olefins, demand for propylene (in particular) has been on a steady rise, most notably in Asia. Propylene is used as a raw material to produce petrochemical products including the common plastic, polypropylene. The oil refining sector is expected to supply propylene in growing volumes.
The HS-FCC process was developed through joint research with Saudi Arabia under the leadership of the Japan Cooperation Center Petroleum. We then began a project on a semi-commercial plant with support from the Ministry of Economy, Trade and Industry. In April 2011, we put this plant into operation with a heavy oil processing capacity of 3,000 B/D (equivalent to a propylene production capacity of 140,000 tons/year) at our Mizushima Refinery. At present, HS-FCC is in operation overseas as a commercial process.
Efficient Propylene Production
FCC process using a down-flow reactor
Heavy oil is fed into a down-flow reactor together with a powdered catalyst, and the reaction occurs almost instantaneously as it falls through the reactor. This reaction occurs at a high-temperature (600°C) and over a short time (0.5 seconds) (Fig. 1).
After the reaction, the reaction products are separated from the catalyst in a separator and removed from the reactor.
Meanwhile, the catalyst travels through a catalyst cleansing tower (Stripper) to a catalyst regeneration tower, where it is regenerated by removing carbon that had built up on it during the reaction.
Moreover, the heat produced during the combustion of carbon in the regeneration process is used to heat the catalyst.
Outstanding light olefin yield
Whereas demand for fuel oil has peaked, that for light olefins such as propylene and butylene remains strong. To meet it, licensors around the world have been developing processes for producing light olefins from heavy oil.
HS-FCC boasts the highest light olefin yield (Table 1) of any developed thus far.
And although gasoline yield typically declines as light olefin production is increased, with HS-FCC, the drop in gasoline yield is smaller.
Table 1 - Yield by process
Scale-up Studies and Commercialization
Over a period from 2003 to 2005, an HS-FCC demonstration plant was constructed and operated at Saudi Aramco's Ras Tanura Refinery. The plant had a heavy oil processing capacity of 30 B/D (propylene production capacity of 1,400 tons/year). Fifteen of our employees relocated there to carry out demonstration research aimed at commercialization.
Using what we had learned from that experience, we began construction of a semi-commercial plant at 100 times the scale at our Mizushima Refinery in 2007. The plant, which had a heavy oil processing capacity of 3,000 B/D (propylene production capacity of 140,000 tons/year), ran on a trial basis from 2011 to 2014. As a result of these R&D achievements, HS-FCC has started commercial operations overseas in 2018. ENEOS is also involved in the project as a technology licensor, and at present, HS-FCC is being operated as a process that holds the key to heavy oil-to-chemical conversion.