Fluid catalytic cracking
FCC units are less common in Europe, the Middle East and Africa (EMEA) because those regions have high demand for diesel and kerosene, which can be satisfied with hydrocracking.
The modern FCC units are all continuous processes which operate 24 hours a day for as long as 3 to 5 years between scheduled shutdowns for routine maintenance.
The schematic flow diagram of a typical modern FCC unit in Figure 1 below is based upon the "side-by-side" configuration.
The preheated high-boiling petroleum feedstock (at about 315 to 430 °C) consisting of long-chain hydrocarbon molecules is combined with recycle slurry oil from the bottom of the distillation column and injected into the catalyst riser where it is vaporised and cracked into smaller molecules of vapour by contact and mixing with the very hot powdered catalyst from the regenerator.
[7][6] The reaction product vapors (at 535 °C and a pressure of 1.72 bar) flow from the top of the reactor to the bottom section of the main column (commonly referred to as the main fractionator where feed splitting takes place) where they are distilled into the FCC end products of cracked petroleum naphtha, fuel oil, and offgas.
After further processing for removal of sulfur compounds, the cracked naphtha becomes a high-octane component of the refinery's blended gasolines.
The main fractionator offgas is sent to what is called a gas recovery unit where it is separated into butanes and butylenes, propane and propylene, and lower molecular weight gases (hydrogen, methane, ethylene and ethane).
The bottom product oil from the main fractionator contains residual catalyst particles which were not completely removed by the cyclones in the top of the reactor.
The expansion of flue gas through a turbo-expander provides sufficient power to drive the regenerator's combustion air compressor.
The fluid catalytic cracking process breaks large hydrocarbons by their conversion to carbocations, which undergo myriad rearrangements.
The propylene, butylene and isobutylene are also valuable feedstocks for certain petroleum refining processes that convert them into high-octane gasoline blending components.
[1][2][3][4] FCC units continuously withdraw and replace some of the catalyst in order to maintain a steady level of activity.
[citation needed] The alumina matrix component of an FCC catalyst also contributes to catalytic activity sites.
Supported by the French government, they built a small demonstration plant in 1929 that processed about 60 tons per day of lignite coal.
[15][16][17] Houdry had found that Fuller's earth, a clay mineral containing aluminosilicates, could convert oil derived from the lignite to gasoline.
Because of the economic depression of the early 1930s, Socony-Vacuum was no longer able to support Houdry's work and gave him permission to seek help elsewhere.
In 1937, Sun Oil began operation of a new Houdry unit processing 12,000 barrels per day (1,900 m3/d) at their Marcus Hook refinery in Pennsylvania.
A small semi-commercial demonstration TCC unit was built in Socony-Vacuum's Paulsboro refinery in 1941 and operated successfully, producing 500 barrels per day (79 m3/d).
Then a full-scale commercial TCC unit processing 10,000 barrels per day (1,600 m3/d) began operation in 1943 at the Beaumont, Texas refinery of Magnolia Oil Company, an affiliate of Socony-Vacuum.
By the end of World War II in 1945, the processing capacity of the TCC units in operation was about 300,000 barrels per day (48,000 m3/d).
[15][16][17] Supplies of American aviation gas also negated the deficit of high-octane gasoline for the Red Army Air Force.
This fluid catalytic cracking process had first been investigated in the 1920s by Standard Oil of New Jersey, but research on it was abandoned during the economic depression years of 1929 to 1939.
Based on their work, M. W. Kellogg Company constructed a large pilot plant in the Baton Rouge, Louisiana refinery of the Standard Oil of New Jersey.
Based on the success of the pilot plant, the first commercial fluid catalytic cracking plant (known as the Model I FCC) began processing 13,000 barrels per day (2,100 m3/d) of petroleum oil in the Baton Rouge refinery on May 25, 1942, just four years after the CRA consortium was formed and in the midst of World War II.
