fluid catalytic cracking


  • History The first commercial use of catalytic cracking occurred in 1915 when Almer M. McAfee of Gulf Refining Company developed a batch process using aluminium chloride (a
    Friedel–Crafts catalyst known since 1877) to catalytically crack heavy petroleum oils.

  • Three years later, in 1936, Socony-Vacuum converted an older thermal cracking unit in their Paulsboro refinery in New Jersey to a small demonstration unit using the Houdry
    process to catalytically crack 2,000 barrels per day of petroleum oil.

  • Main column[edit] 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.

  • Although the schematic flow diagram above depicts the main fractionator as having only one sidecut stripper and one fuel oil product, many FCC main fractionators have two
    sidecut strippers and produce a light fuel oil and a heavy fuel oil.

  • The feedstock to the FCC conversion process usually is heavy gas oil (HGO), which is that portion of the petroleum (crude oil) that has an initial boiling-point temperature
    of 340 °C (644 °F) or higher, at atmospheric pressure, and that has an average molecular weight that ranges from about 200 to 600 or higher; heavy gas oil also is known as “heavy vacuum gas oil” (HVGO).

  • 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 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.

  • The reactor is a vessel in which the cracked product vapors are: (a) separated from the spent catalyst by flowing through a set of two-stage cyclones within the reactor and
    (b) the spent catalyst flows downward through a steam stripping section to remove any hydrocarbon vapors before the spent catalyst returns to the catalyst regenerator.

  • 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 desirable properties of an FCC catalyst are: • Good stability to high temperature and to steam • High activity • Large pore sizes • Good resistance to attrition • Low
    coke production Structure of aluminosilicate cage in faujasite.

  • [1][2][3] The cracking of petroleum hydrocarbons was originally done by thermal cracking, now virtually replaced by catalytic cracking, which yields greater volumes of high
    octane rating gasoline; and produces by-product gases, with more carbon-carbon double bonds (i.e.

  • Part of that slurry oil is recycled back into the main fractionator above the entry point of the hot reaction product vapors so as to cool and partially condense the reaction
    product vapors as they enter the main fractionator.

  • The steam turbine in the flue gas processing system (shown in the above diagram) is used to drive the regenerator’s combustion air compressor during start-ups of the FCC unit
    until there is sufficient combustion flue gas to take over that task.

  • 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.

  • Economics Oil refineries use fluid catalytic cracking to correct the imbalance between the market demand for gasoline and the excess of heavy, high boiling range products
    resulting from the distillation of crude oil.

  • Some FCC gas recovery units may also separate out some of the ethane and ethylene.

  • Regenerator flue gas[edit] Depending on the choice of FCC design, the combustion in the regenerator of the coke on the spent catalyst may or may not be complete combustion
    to carbon dioxide CO2.

  • In the fluid catalytic cracking process, the HGO feedstock is heated to a high temperature and to a moderate pressure, and then is placed in contact with a hot, powdered catalyst,
    which breaks the long-chain molecules of the high-boiling-point hydrocarbon liquids into short-chain molecules, which then are collected as a vapor.

  • If the expansion of the flue gas does not provide enough power to drive the air compressor, the electric motor–generator provides the needed additional power.

  • Just like Houdry’s fixed-bed reactors, the moving-bed designs were prime examples of good engineering by developing a method of continuously moving the catalyst between the
    reactor and regeneration sections.

  • In 1938, when the success of Houdry’s process had become apparent, Standard Oil of New Jersey resumed the project, hopefully in competition with Houdry, as part of a consortium
    of that include five oil companies (Standard Oil of New Jersey, Standard Oil of Indiana, Anglo-Iranian Oil, Texas Oil and Royal Dutch Shell), two engineering-construction companies (M. W. Kellogg Limited and Universal Oil Products) and a German
    chemical company (I.G.

  • That step was implemented by advent of the moving-bed process known as the Thermofor Catalytic Cracking (TCC) process which used a bucket conveyor-elevator to move the catalyst
    from the regeneration kiln to the separate reactor section.

  • The combustion flue gas (containing CO and CO2) at 715 °C and at a pressure of 2.41 bar is routed through a secondary catalyst separator containing swirl tubes designed to
    remove 70 to 90 percent of the particulates in the flue gas leaving the regenerator.

  • Fluid Catalytic Cracking (FCC) is the conversion process used in petroleum refineries to convert the high-boiling point, high-molecular weight hydrocarbon fractions of petroleum
    (crude oils) into gasoline, alkene gases, and other petroleum products.

  • The combustion air flow is controlled so as to provide the desired ratio of carbon monoxide (CO) to carbon dioxide for each specific FCC design.

  • [9][10] The design and operation of an FCC unit is largely dependent upon the chemical and physical properties of the catalyst.

  • In the US, fluid catalytic cracking is more common because the demand for gasoline is higher.

  • Licensing the process to other companies also began and by 1940 there were 14 Houdry units in operation processing 140,000 barrels per day.

  • If the flue gas expansion provides more power than needed to drive the air compressor, then the electric motor–generator converts the excess power into electric power and
    exports it to the refinery’s electrical system.

  • [3] The expanded flue gas is then routed through a steam-generating boiler (referred to as a CO boiler) where the carbon monoxide in the flue gas is burned as fuel to provide
    steam for use in the refinery as well as to comply with any applicable environmental regulatory limits on carbon monoxide emissions.

  • [12][13][14] Chemical engineering professors Warren K. Lewis and Edwin R. Gilliland of the Massachusetts Institute of Technology (MIT) suggested to the CRA researchers that
    a low velocity gas flow through a powder might “lift” it enough to cause it to flow in a manner similar to a liquid.

  • The Houdry process at that time used reactors with a fixed bed of catalyst and was a semi-batch operation involving multiple reactors with some of the reactors in operation
    while other reactors were in various stages of regenerating the catalyst.

  • There are two different configurations for an FCC unit: the “stacked” type where the reactor and the catalyst regenerator are contained in two separate vessels, with the reactor
    above the regenerator, with a skirt between these vessels allowing the regenerator off-gas piping to connect to the top of the regenerator vessel, and the “side-by-side” type where the reactor and catalyst regenerator are in two separate vessels.

  • In the cracking process carbon is also produced which gets deposited on the catalyst (catalyst coke).

  • [12][13][14] By 1938, when the Houdry process was publicly announced, Socony-Vacuum had eight additional units under construction.

  • Then a full-scale commercial TCC unit processing 10,000 barrels per day began operation in 1943 at the Beaumont, Texas refinery of Magnolia Oil Company, an affiliate of Socony-Vacuum.

  • Since the cracking reactions produce some carbonaceous material (referred to as catalyst coke) that deposits on the catalyst and very quickly reduces the catalyst reactivity,
    the catalyst is regenerated by burning off the deposited coke with air blown into the regenerator.

  • 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.

  • The clarified slurry oil or decant oil is withdrawn from the top of slurry settler for use elsewhere in the refinery, as a heavy fuel oil blending component, or as carbon
    black feedstock.

  • As of 2006, FCC units were in operation at 400 petroleum refineries worldwide, and about one-third of the crude oil refined in those refineries is processed in an FCC to produce
    high-octane gasoline and fuel oils.

  • It is said that the Houdry and TCC units were a major factor in the winning of World War II by supplying the high-octane gasoline needed by the air forces of Great Britain
    and the United States for the more efficient higher compression ratio engines of the Spitfire and the Mustang.

  • The combustion of the coke is exothermic and it produces a large amount of heat that is partially absorbed by the regenerated catalyst and provides the heat required for the
    vaporization of the feedstock and the endothermic cracking reactions that take place in the catalyst riser.

  • The hot catalyst (at about 715 °C) leaving the regenerator flows into a catalyst withdrawal well where any entrained combustion flue gases are allowed to escape and flow back
    into the upper part to the regenerator.

  • For that reason, FCC units are often referred to as being ‘heat balanced’.

  • The flow of spent catalyst to the regenerator is regulated by a slide valve in the spent catalyst line.

  • In 1931, the Vacuum Oil Company merged with Standard Oil of New York (Socony) to form the Socony-Vacuum Oil Company.

  • The terminology light and heavy in this context refers to the product boiling ranges, with light products having a lower boiling range than heavy products.

  • In 1933, Houdry and Socony-Vacuum joined with Sun Oil Company in developing the Houdry process.


Works Cited

[‘1. James H. Gary; Glenn E. Handwerk (2001). Petroleum Refining: Technology and Economics (4th ed.). CRC Press. ISBN 0-8247-0482-7.
2. ^ Jump up to:a b c d James. G. Speight (2006). The Chemistry and Technology of Petroleum (4th ed.). CRC Press.
ISBN 0-8493-9067-2.
3. ^ Jump up to:a b c d e f Reza Sadeghbeigi (2000). Fluid Catalytic Cracking Handbook (2nd ed.). Gulf Publishing. ISBN 0-88415-289-8.
4. ^ Jump up to:a b c d David S.J. Jones and Peter P. Pujado (Editors) (2006). Handbook
of Petroleum Processing (First ed.). Springer. ISBN 1-4020-2819-9. {{cite book}}: |author= has generic name (help)
5. ^ U.S. Downstream Processing of Fresh Feed Input by Catalytic Cracking Units Archived 2008-09-28 at the Wayback Machine (Energy
Information Administration, U.S. Dept. of Energy)
6. ^ Editorial Staff (November 2002). “Refining Processes 2002”. Hydrocarbon Processing: 108–112. ISSN 0887-0284.
7. ^ Fluid Catalytic Cracking
8. ^ Alex C. Hoffmann; Lewis E. Stein (2002). Gas
Cyclones and Swirl Tubes:Principles, Design and Operation (1st ed.). Springer. ISBN 3-540-43326-0.
9. ^ Jump up to:a b Jessica Elzea Kogel, Nikhil C. Trivedi, James M. Barber and Stanley T. Krukowsk (Editors) (2006). Industrial Minerals & Rocks:
Commodities, Markets and Uses (Seventh ed.). Society of Mining, Metallurgy and Exploration. ISBN 0-87335-233-5. {{cite book}}: |author= has generic name (help)
10. ^ Jump up to:a b Wen-Ching Yang (2003). Handbook of Fluidization and Fluid Particle
Systems. CRC Press. ISBN 0-8247-0259-X.
11. ^ Pioneer of Catalytic Cracking: Almer McAfee at Gulf Oil Archived 2008-04-18 at the Wayback Machine (North American Catalysis Society website)
12. ^ Jump up to:a b c d e Tim Palucka (Winter 2005). “The
Wizard of Octane: Eugene Houdry”. Invention & Technology. 20 (3). Archived from the original on 2008-06-02. Retrieved 2008-05-10.
13. ^ Jump up to:a b c d e Amos A. Avidan, Michael Edwards and Hartley Owen (Mobil Research and Development) (January
8, 1990). “Innovative Improvements Highlight FCC’s Past and Future”. Oil & Gas Journal. 88 (2).
14. ^ Jump up to:a b c d e “Houdry Process for Catalytic Cracking”. American Chemical Society. Archived from the original on January 12, 2013. Retrieved
April 27, 2012.
15. ^ Eger Murphree and the Four Horsemen: FCC, Fluid Catalytic Cracking Archived 2008-04-18 at the Wayback Machine (North American Catalysis Society website)
Photo credit: https://www.flickr.com/photos/jenny-pics/3150964108/’]