Acid gas recovery

Also known as: Gas scrubber, Amine unit, Girbotol

Many of the conversion and hydrotreating units generate refinery gas that contains a mix of H2S and CO2, called acid gas. The acid gas recovery units extract the H2S from the other gas components using an amine solvent. Once separated, the H2S can then be sent to the sulfur plant to recover the sulfur.

How it works

The refinery gas is fed into a vessel and mixed with an alkylamine solution. The amine absorbs the acid gas, leaving a clean refinery gas stream that can be sent to the gas plant. The acid-gas-rich amine stream is sent to a regenerator/separation vessel and heated with steam, causing the dissolved acid gas to come out of the solution so it can be drawn off and sent to the sulfur plant.

There are a number of different alkylamine solvents that can be used. The most common are:

  • Diethanolamine (DEA)
  • Monoethanolamine (MEA)
  • Methyl-Diethanolamine (MDEA)
  • Diisopropanolamine (DIPA)
  • Diglycolamine (DGA)
  • Hot potassium carbonate

Author: Tim Fitzgibbon, Refining Industry Sr. Expert

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