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    Catalytic Cracking

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    tariq fareed
    Catalytic cracking is the most important refinery process for converting heavy oils into gasoline and lighter products. It has replaced thermal cracking because it produces more gasoline with a higher octane rating, fewer heavy fuel oils, and more light gases. The cracking reaction occurs over a catalyst, which becomes deactivated by coke deposits. To maintain activity, the catalyst is continuously regenerated by burning off the coke in a regenerator, then returned to the reactor. The key steps are contact of oil and hot catalyst in the reactor, separation of products from catalyst, removal of remaining oil from catalyst, regeneration of catalyst in the regenerator, and return of regenerated catalyst to the reactor.

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    Catalytic Cracking

    Uploaded by

    tariq fareed
    97 views17 pages
    Catalytic cracking is the most important refinery process for converting heavy oils into gasoline and lighter products. It has replaced thermal cracking because it produces more gasoline with a higher octane rating, fewer heavy fuel oils, and more light gases. The cracking reaction occurs over a catalyst, which becomes deactivated by coke deposits. To maintain activity, the catalyst is continuously regenerated by burning off the coke in a regenerator, then returned to the reactor. The key steps are contact of oil and hot catalyst in the reactor, separation of products from catalyst, removal of remaining oil from catalyst, regeneration of catalyst in the regenerator, and return of regenerated catalyst to the reactor.

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    CATALYTIC CRACKING

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    Catalytic cracking is the most important refinery process for converting heavy oils into gasoline and lighter products. It has replaced thermal cracking because it produces more gasoline with a higher octane rating, fewer heavy fuel oils, and more light gases. The cracking reaction occurs over a catalyst, which becomes deactivated by coke deposits. To maintain activity, the catalyst is continuously regenerated by burning off the coke in a regenerator, then returned to the reactor. The key steps are contact of oil and hot catalyst in the reactor, separation of products from catalyst, removal of remaining oil from catalyst, regeneration of catalyst in the regenerator, and return of regenerated catalyst to the reactor.

    Copyright:

    © All Rights Reserved
    Download as PDF, TXT or read online from Scribd
    Download as pdf or txt
    97 views17 pages

    Catalytic Cracking

    Uploaded by

    tariq fareed
    Catalytic cracking is the most important refinery process for converting heavy oils into gasoline and lighter products. It has replaced thermal cracking because it produces more gasoline with a higher octane rating, fewer heavy fuel oils, and more light gases. The cracking reaction occurs over a catalyst, which becomes deactivated by coke deposits. To maintain activity, the catalyst is continuously regenerated by burning off the coke in a regenerator, then returned to the reactor. The key steps are contact of oil and hot catalyst in the reactor, separation of products from catalyst, removal of remaining oil from catalyst, regeneration of catalyst in the regenerator, and return of regenerated catalyst to the reactor.

    Copyright:

    © All Rights Reserved
    Download as PDF, TXT or read online from Scribd
    Download as pdf or txt
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    The key takeaways are that catalytic cracking is an important refinery process that converts heavy oils into more valuable gasoline and lighter products. It has largely replaced thermal cracking because it produces more gasoline with a higher octane and less heavy fuels and light gases. The cracking reaction is endothermic while the regeneration reaction is exothermic.

    The two main types of catalytic cracking processes are moving-bed units and fluidized-bed units. In moving-bed units, the catalyst falls slowly through the reactor and regenerator by gravity and is returned mechanically to the top. In fluidized-bed units, fine powder catalysts are continuously transported between the reactor and regenerator using the fluidization properties of fine powders.

    Some of the catalysts used in catalytic cracking include acid-treated clays ground into a powder, synthetic silica-alumina catalysts of higher activity in an amorphous form, and crystalline synthetic silica-alumina catalysts called zeolites or molecular sieves.

    UPGARDING PROCESSES:

    CATALYTIC CRACKING
    Catalytic Cracking is the
    most important and widely
    used refinery process for
    converting heavy oils into
    more valuable gasoline &
    lighter products.
    The Catalytic Process has almost
    completely replaced thermal
    cracking because
    more gasoline having a higher
    octane & less heavy fuel oils
    and
    light gases
    are produced.
    Generally
    The light gases produced by
    catalytic cracking contain
    more olefins than those
    produced by thermal
    cracking.
    The cracking process produces carbon
    (coke) which remains on the catalyst
    particle and rapidly lowers its activity.
    To maintain the catalyst activity at a
    useful level, it is necessary to regenerate
    the catalyst by burning off this coke with
    air.
    As a result, the catalyst is continuously
    moved from reactor to regenerator and
    back to reactor.
    The Cracking Reaction is
    endothermic and the Regeneration
    Reaction exothermic.
    Some units are designed to use the
    regeneration heat to supply for the
    reaction and to heat the feed up to
    reaction temperature. These are
    known as ‘‘heat balance’’ units
    .
    Average Reactor Temperatures
    are in the range 900 to 1000 °F
    (480–540 °C), with Oil Feed
    Temperatures from 500 to 800 °F
    (260–425 °C) and Regenerator
    Exit Temperatures for Catalyst
    from 1200 to 1500 °F (650–815
    °C).
    The catalytic-cracking processes in
    use today can all be classified as
    either MOVING-BED or FLUIDIZED-
    BED units.
    There are several modifications
    under each of the classes depending
    upon the designer or builder, but
    within a class the basic operation is
    very similar.
    Moving Bed
    In which the Catalyst was allowed to fall
    slowly by gravity (through the Reactor &
    a Regenerator Vessels) and was returned
    mechanically to the top.
    Fluidized Bed
    Is based on the Fluidization Properties
    of Fine Powders, which enabled the
    catalyst to be transported continuously
    between the Reactor and Regenerator.
    CATALYSTS
    both systems use basically similar catalysts
    but produced in a different form, in the
    shape of BEDS for Moving Bed and FINE
    POWDER for Fluidized Bed.
    Acid treated clays ground to a powder
    Synthetic silica- alumina catalysts of
    higher activity (amorphous)
    Crystalline synthetic silica – alumina
    catalyst called ZEALOTS or MOLECULAR
    SIEVES.
    advantages

    The Process Flows of


    both types of Processes
    are Similar as in the
    Following:
    1) The Hot Oil Feed is contacted with the
    catalyst in either the feed line or the
    reactor.
    2) As the Cracking Reaction Progresses, the
    catalyst is progressively deactivated by the
    formation of coke on the surface of the
    catalyst.
    3) The Catalyst and Hydrocarbon Vapors are
    separated mechanically, and oil
    remaining on the catalyst is removed by
    Steam Stripping before the catalyst enters
    the Regenerator.
    4) The Oil Vapors are taken overhead to
    a Fractionation Tower for separation
    into streams having the desired boiling
    ranges.
    5) The Spent Catalyst flows into the
    Regenerator and is reactivated by
    burning off the coke deposits with air.
    6) The catalyst in some units is
    steam-stripped as it leaves the
    Regenerator to remove adsorbed
    oxygen before the catalyst is
    contacted with the oil feed.
    In addition to the nature of the
    charge stock, the major operating
    variables affecting the conversion
    and product distribution are:
    1) Cracking Temperature,
    2) Catalyst/Oil Ratio,
    3) Space Velocity,
    4) Catalyst Type & Activity, and
    5) Recycle Ratio.
    Fluidized-bed catalytic cracking (FCC)

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