Treating · Gas Plant
Sulphur Recovery Unit
A Claus unit that turns the hydrogen sulphide in the acid gas into liquid elemental sulphur, usually followed by tail gas treatment.
What it does
A furnace burns about one third of the H2S to SO2, which then reacts with the rest of the H2S over catalyst beds to form sulphur, condensed after each stage. Two catalytic stages recover about 94 to 96 percent; tail gas treatment and incineration take overall control to about 99.8 percent or more.
Basics
| Furnace | About 980 to 1,540 °C |
| Catalytic stages | Usually 2, sometimes 3, at about 200 to 315 °C |
| Recovery, 2 stages | About 94 to 96 % |
| With tail gas treatment | About 99.8 % or more |
Common failures
- Wrong air to acid gas ratio in the furnace, which lowers recovery and raises SO2 emissions
Troubleshooting
- Symptom
- Recovery drops and stack SO2 rises
- Likely cause
- Air demand control off or catalyst fouled
- What to check
- Check the tail gas analyzer and air ratio, then catalyst condition