Winterization Discussion Group Notes10/26/12Facilitated byMarshall 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
