Separation · Refining
Vacuum Distillation
A wide column that runs below atmospheric pressure and takes the residue from the atmospheric column for a second split.
What it does
Low pressure lowers boiling points, so heavy oil can be distilled without cracking it. It yields vacuum gas oils for the cracking units and a heavy vacuum residue that can feed the coker.
Basics
| Feed | Atmospheric residue |
| Products | Vacuum gas oils, vacuum residue |
| Vacuum | Partly created with steam |
| Found in | More complex refineries |
Common failures
- Loss of vacuum, which lets air into a hot unit and creates a fire hazard
Troubleshooting
- Symptom
- Column pressure rising
- Likely cause
- Steam supply problem or air leaking in
- What to check
- Check the steam that holds the vacuum and find the leak before air reaches hot oil