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Minimum feedrate in FCCU (potential constrains)

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This topic contains 1 reply, has 1 voice, and was last updated by  Anonymous 10 years, 11 months ago.

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  • #2001

    Freddy Martinez

    Dear all,

    My question is related with the potential problems that could appear when the feedrate in a FCCU is reduced to the technical minimum (turn-down) or below.

    – According to your experience, what is the minimum feedrate that can be processed in a FCCU? 60% of nominal feedrate or does anyone operated below this point?
    – Which are the most likely limitations that could appear in this point?
    1. Insufficient gas flow rate to the wet gas comppresor?
    2. Insufficient pressure or delta P in feed nozzles? Problems to obtain a suitable vaporization?
    3. Insufficient coke production to close heat balance?
    4. Insufficient liquid-vapour traffic in the main fractionation?
    5. Any other limitation?

    Thank you very much for your collaboration

    Best regards

  • #4711


    Never operated below 60% of nominal. The problems that we encounter are the ones you have described.
    1) Low flow rate to feed injectors
    2) Low flow rate to the main fractionator
    3) Low flow air blower
    4) Slide Flue gas valve closed too (poor control)
    5) Low flow rate of the slurry and difficult to manage the temperature of the column bottom
    6) Possible loss of catalyst
    Obviously we always try to handle the problems, but have never managed to reduce the technical minimum below 60% of nominal (UOP FCCU side by side 36,000 b / d)

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