Sulfinol

Sulfinol solvent is a composite solvent, consisting of a mixture of diisopropanolamine (30-45%) or methyl diethanolamine (MDEA), sulfolane (tetrahydrothiophene dioxide) (40-60%), and water (5-15%). The acid gas loading of the Sulfinol solvent is higher and the energy required for its regeneration is lower than those of purely chemical solvents. At the same time it has the advantage over purely physical solvents that severe product specifications can be met more easily and co-absorption of hydrocarbons is relatively low. For selective absorption of hydrogen sulfide (H₂S), carbonyl sulfide (COS) and mercaptans, while co-absorbing only part of the carbon dioxide (CO₂), the Sulfinol-M process is used. Deep removal of CO₂ in LNG plants is another application. Integration of gas treating with the SCOT solvent system is an option.

The Sulfinol Process is depicted in Figure 1. The feed gas is contacted counter-currently in an absorption column with the Sulfinol solvent. The regenerated solvent is introduced at the top of the absorber. The sulfur compounds loaded solvent (rich solvent) is heated by heat exchange with the regenerated solvent and is fed back to the regenerator where it is further heated and freed of the acid gases with steam in the stripper.

The acid gases removed from the solvent in the regenerator are cooled with air or water, so that the major part of the water vapor they contain is condensed. The sour condensate is reintroduced into the system as a reflux. The acid gas is passed to the sulfur recovery plant (Claus plant).

Sulfinol is used in the Buggenum, Netherlands IGCC coal gasification plant as the acid gas removal process.

References/Further Reading

Sulfinol process
James G. Speight, Natural Gas (Second Edition), 2019
Chemical Solvent-Based Processes for Acid Gas Removal In Gasification Applications [PDF] (Feb 1997)
Gasification Technology in Practice IChemE Conference in Milan, Italy

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