Separation · Refining
Atmospheric Distillation
The first and largest column in the refinery. Hot crude enters near the bottom and separates by boiling point into cuts drawn off at different heights.
What it does
Lightest products rise to the top and heaviest stay at the bottom: gases and naphtha at the top, kerosene and diesel in the middle, gas oil lower and atmospheric residue at the bottom.
Basics
| Pressure | Slightly above atmospheric |
| Main cuts | Gases, naphtha, kerosene, diesel, gas oil, residue |
| Found in | Every refinery |
Common failures
- Corrosion in the overhead system from chlorides carried past the desalter
Troubleshooting
- Symptom
- Cuts off specification
- Likely cause
- Changes in crude feed or column temperature profile
- What to check
- Adjust draw rates and reflux, check feed temperature