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Tarry Drum Discussion Group

Home Forums Conferences 2012 Canada Tarry Drum Discussion Group

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    4 drums coker
    Participant

    Tarry Drum Discussion Group Notes
    10/26/2012
    Facilitators:  Jennifer Stiglitz, Husky Energy & Evan Hyde, Coking.com

    • Verify hydraulic cart can handle the hydraulic load before deheading a tarry drum.  One site tested the hydraulics and some hoses failed. 
    • Move hydraulic controls away from the line of fire – this should be done in the base case but for sure when dealing with a tarry drum. 
    • Opening the top head before draining can be risky due to boil over risk but it is done because the drum vents are very small, 3-4”.  They are installing larger vent lines, 14”.
    • How do you determine if a tarry drum exists
      • Define site specific process conditions based on experience
        • Lieberman target  = if not >790F for more than 1 hour, then tarry.
      • When can you go back into the drum?
      • Extended steaming experiences
        • 12hrs+ of velocity steam, no burners in heater
        • 12-24hrs of superheated steam.  Must consider impacts to convection and heater outlet piping.
        • Establishing steam and/or quench ASAP after an event is critical to preventing an unquenched drum scenario.
        • Consider the use of double quench or soaking if a tarry drum occurred, especially near the end of cycle to ensure adequate cooling throughout.  Unreacted resid could have plugged channels.  Extended steam strip as well.
        • Drain plugging risk increases with tarry drums.  Slide valves mitigate this problem to a certain degree.  Common drain headers could plug and lead to issues with the entire unit.
          • If a large amount of water is in the drum with the drain plugged on a manual system, consider the use of a sump pump used from the top head to remove some water.  Verify tar level using drill stem.
          • Use of the drilling water has been used to stir up the drum
          • The coke bed could be “cooked” more using very high recycle (50%+ if possible).  Increased mass rates at COT will drive tarry material more towards a solid coke bed.  Tried successfully at one location.
          • One site had alternate drain nozzles on the drum cone, 4 total.  Contributes to additional drum stress but useful in upset conditions.  They are debating using the same design on a new plant but slide valves are an alternative drain as well.
          • Use of chemical cleaning agents, RTI quickturn, has been tried to dissolve some oils before draining the drum.  Results unclear.
          • Short Drum definitions
            • Site 1 = <6 hrs on 16hr cycle
            • Site 2 = <6hrs on 20hr cycle
            • Site 3 = <4hrs on 12hr cycle
            • Other opinions, <3hrs
            • Use extra antifoam if going back into a drum after feeding unreacted resid.

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