On February 15, 2016, Refinerlink.com posted a blog article by Steve Pagani titled The Forgotten Areas of an Oil Refinery. The article offers tips on understanding several of the vulnerable areas in an oil refinery. One of those areas mentioned is the Sulfur Plant.
Understand your acid gas and sour water balances. Too often, knee jerk reactions are made when acid gas and sour water capacities are pushed to the limit. It’s important to know where the sources of each are and which ones can be trimmed back most efficiently.
If you operate close to SRU incinerator emission constraints, take a quick look at sulfur recovery in your Claus reactors. There are some refiners who operate reactor outlets well above the dew point buffer temp, thus resulting in lower sulfur conversion.
How well are your tail gas analyzers calibrated? The sulfur conversion reaction is an equilibrium reaction that requires a fine balance of H2S and SO2. Skewed analyzer readings can reduce sulfur recovery.
Most of the safety concerns in sulfur plants are focused around H2S awareness. While this is justifiable, many tend to forget about the hazards of molten sulfur exposure during startups and unit upsets. Simple devises such as Sultraps can be installed to improve SRU personnel safety.
I agree with all these points and would like to add two more:
- Last condensers are often operated at a higher temperature to avoid ammonia salt formation. But ammonia should have been destroyed at the Reaction Furnace so the last condenser can be operated at 125C (257F) to maximize the recovery.
- Know how your process behaves (e.g. COS, CS2 and H2 formation, hydrolysis efficiency and contaminants destruction) through annual performance evaluation. This will give you an idea on how your plant should be operated.