Conversion · Refining
Delayed Coker
A unit that heats the heaviest residue and lets it crack in large drums, leaving solid petroleum coke and lighter liquids and gas.
What it does
Turns the bottom of the barrel into products. The heater brings the residue to cracking temperature and the drums give it time to crack; when one drum is full the flow switches to the other, and the full drum is cooled with water and cut out with high pressure water. It is a key unit for heavy crude and oil sands bitumen.
Basics
| Feed | Vacuum residue |
| Heater outlet | About 480 to 510 °C (900 to 950 °F), 25 to 30 psi |
| Drum | Coke held about 24 hours |
| Decoking | High pressure water cutter |
| Products | Coke, gas oils, naphtha, gas |
Common failures
- Hot coke or steam released if a drum is opened before it is fully cooled
Troubleshooting
- Symptom
- Furnace run length shortening
- Likely cause
- Coke laying down in the heater tubes
- What to check
- Check water or steam injection to the tubes and plan a decoke