RFCC (Residue Fluid Catalytic Cracking) and FCC (Fluid Catalytic Cracking) units are both used in petroleum refineries for converting heavy hydrocarbon feedstocks into lighter and more valuable products such as gasoline, diesel, and various petrochemicals. While both units perform similar functions, there are some key differences between RFCC and FCC units:
Feedstock: The main difference lies in the type of feedstock each unit processes. FCC units primarily handle vacuum gas oil (VGO) and other lighter fractions derived from crude oil, while RFCC units are designed to process heavier residues, such as atmospheric residue, vacuum residue, or even heavy oils like bitumen.
Catalyst: FCC units use a catalyst that is typically composed of zeolite or other porous materials, which have high activity and selectivity for cracking lighter hydrocarbons. RFCC units, on the other hand, employ a catalyst that is more tolerant to heavier feedstocks and operates at higher temperatures. This catalyst often contains additional metals, such as nickel or vanadium, to promote the cracking of heavier molecules.
Operating conditions: Due to the difference in feedstock, RFCC units typically operate at higher temperatures and pressures compared to FCC units. The higher temperatures help to break down the heavier molecules found in the feedstock.
Product yield: RFCC units are known to produce a higher yield of valuable products, such as gasoline and olefins, compared to FCC units. This is because the heavier feedstock processed in RFCC units contains more complex hydrocarbon structures that can be converted into lighter products.
Coke formation: Both units generate coke as a byproduct, which can cause catalyst deactivation. However, RFCC units generally produce more coke due to the heavier feedstock, requiring more frequent catalyst regeneration or replacement.
Integration: FCC units are often integrated with other refining units, such as a catalytic reformer, to maximize the production of high-octane gasoline. RFCC units are sometimes integrated with delayed coking units to further upgrade heavy residues.
It's worth noting that the specific design and configurations of RFCC and FCC units can vary between refineries, and some refineries may use the terms interchangeably or have hybrid units that combine features of both technologies. The key differences outlined above serve as general differentiating factors between RFCC and FCC units.