Developing a Next-generation FCC (HS-FCC) Process
HS-FCC (High Severity Fluid Catalytic Cracking) is a process by which heavy oil is broken down efficiently to produce light olefins such as propylene, butylene and other high value-added raw materials for petrochemicals.
In particular among the light olefins, demand for propylene has been on a steady rise, most notably in Asia. Propylene is used to produce petrochemical products, including the common plastic polypropylene. The oil refining sector is expected to supply this important raw material in growing volumes.
The HS-FCC process was developed through joint research with Saudi Arabia, under the leadership of the Japan Cooperation Center Petroleum. With support from the Ministry of Economy, Trade and Industry, we then began work on a semi-commercial plant. This plant, which had a heavy oil processing capacity of 3,000 B/D (propylene production capacity of 140,000 tons/year), was built and operated at our Mizushima Refinery for a period starting in April of 2011.
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
Research aimed at 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 in 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), was run on a trial basis from 2011 to 2014. We are now engaged in various studies toward the goal of commercialization.