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Winterization Discussion Group

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  • #1791

    4 drums coker
    Participant

    Winterization Discussion Group Notes
    10/26/12
    Facilitated by Marshall Douglas, CEDA

    • Freeze protection of decoking equipment
      • Raise drill string to max height
      • Ensure drain successful
      • Blow air, possibly with methanol, into the Kelly hose and drill string
      • Continuously rotate the drill stem drive
      • Hoardings and roughnecks commonly used
        • If >3 sides, must consider as a confined space and use continuous gas monitoring, rigrat
        • Typically done around pumps, finfans, and maintenance jobs (pigging)
        • One site is discontinuing hoarding for 2012-13 winter….
        • Cutting water tank gooseneck should be very large, 24”, to prevent freeze up and sucking in the tank
        • Blowdown finfans freeze prevention
          • Automated steam injection upstream of inlets.  TC based on finfan outlet temp.
          • Routine operator round to check louvers, temperature controls, and roughnecks required
          • Hoarding sheets reused from year to year, rolled down from fans to deck around the outside.
          • Cold air coming down through the finfans can cause freezing.  Monitor temps in the plenum and take corrective actions.
          • Entire blowdown system has a nitrogen blanket system to purge the entire blowdown during extended outages.
          • Consider the use of minimum flow recirculation on the blowdown sour water to prevent freeze up.  Will not prevent freezing of the rundown piping.
          • Water in reflux (1-2%) can freeze during outages, drain during maintenance
            • Methanol added to the frozen line.  Freed in a few hours.
            • During restart, cut off all steam purges to structure valves and other purged valves until the unit circulation temperature is >325C.  Net steam purge calculated to be 20ton/hr
              • Except the switch valve

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