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Drum Cooling and Cycle Times

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This topic contains 2 replies, has 2 voices, and was last updated by  Anonymous 11 years ago.

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  • #4317

    Darren Hudema
    Participant

    Hello,

    I’m the unit engineer for a two drum coker currently operating on 20 hour cycles. We make anode grade coke. Our charge rate can range from 8,000 – 10,000 BPD on the 20 hour cycles depending on feed concarbon. We would like to shorten our drum cycles to 18 hours to increase unit throughput. Currently, I believe that our bottleneck is our drum cooling. Our cooling cycle is as follows:
    1 hour slow steam to fractionator
    1 hour fast steam to blowdown (Quench Tower)
    7 hours of cooling water (temperature is 70 – 90 degrees F depending on time of year)
    1 hour to drain drum and turnover to decokers
    Total time -> 10 hours.

    We have a ramping program that increases the cooling water to the drum which I am currently revisiting for furter optimization. Typical cooling water flowrate to the drum once it has reached it’s plateau is usually 13,000 – 15,000 BPD.

    Typically, it takes 5 – 6 hours to decoke the drum and complete the pressure test. This leaves 4 – 5 hours to warmup prior to swing. Our target on the warmup is 600 F on the condensate outlet.

    My question to the group is what are typical cooling times in the industry?
    What effect would reducing our steaming time to 45 minutes each have on coke vcm’s and the cooling time?
    What are typical flowrates for cooling water to the drum?
    What temperature do other Cokers use as a minimum for warmup?

    Thanks,
    Darren

  • #7709

    Anonymous

    Does it take 7 hours to cool your drum because you are pump limited? After the first 2 hours, you should be able to fill the drum quickly without overpressuring the system. . .assuming you have the pump.

  • #5484

    Anonymous

    VCM is mostly dependent on coke drum overhead temperatures and not steaming.

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