Treating Ultra-Sour Gas - Two-Stage Absorption for Acid Gas and Mercaptan Removal

Treating Ultra-Sour Gas - Two-Stage Absorption for Acid Gas and Mercaptan Removal


Growing gas demand, combined with declining conventional sweet gas reserves, necessitates ultra-sour gas development. Development of these ultra-sour reserves encounters many technical challenges that were previously met with conservatism due to limited operational experience, leading to greater facility costs and, in some cases, lower gas treating efficiency.

This technology directly responds to the gas market’s need for improved ultra-sour gas treatment to meet gas demand. Conventional acid gas removal systems operating at low-pressure require molecular sieves or other purification systems downstream to remove mercaptans. This approach is much more capital intensive, increasing both the capital and operating costs of a facility.

Fluor’s practical solution addresses safety by removing acid gas to safe levels through initial low-pressure treatment in an absorber column. Once sufficient acid gas is removed, a high-pressure absorber column follows to remove mercaptans. The solvent used for this system is the same solvent used in Fluor's Improved Econamine℠ Process.

Fluor’s two-stage process mitigates the safety risks associated with ultra-sour gas processing, while achieving more than 90% total mercaptan removal efficiency and practically complete removal of other unwanted components (H2S, CO2 and COS).

Client Benefits

This innovation has numerous benefits to customers building ultra-sour gas treatment facilities over conventional methods, including:

  • Improved quality. Significantly higher mercaptan removal compared to low-pressure amine only AGRU systems.
  • Improved safety. Lower safety risks and impacts when compared to high-pressure treatment.
  • Reduced capital and operating costs. Fluor’s two-stage process has the same total equipment count for the AGRU and compression systems as typical low-pressure processing systems, while decreasing the size or possibly eliminating downstream mercaptan treatment equipment.
  • Improved facility reliability. Fluor’s technology can reduce the total equipment count and facility footprint, improving overall reliability and reducing maintenance.

The two-stage absorption technology was recognized by S&P Global Platts as a 2017 Global Energy Award Finalist for the Breakthrough Solution of the Year.

In 2018, the technology was recognized as a finalist for ADIPEC's Breakthrough Research of the Year and was highly commended at the Institution of Chemicals Engineers 2018 Global Awards.

Related Technologies