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Emission-Free Sulfur Recovery Unit

Emission-Free Sulfur Recovery Unit

100% sulfur recovery from acid gases

Emission-Free Sulfur Recovery Unit (SRU) is a process that recovers 100% of sulfur from acid gas streams containing hydrogen sulfide. With this proven technology, Air Liquide Engineering & Construction allows clients to benefit from the highest possible recovery rate with around 25% less capital expenditure (CAPEX) than with a traditional SRU including amine wash tail gas treatment.

Recycling for more efficiency

Initially, raw gas is desulfurized in an acid gas removal (AGR) unit, and the resulting acid gas is dispatched to the emission-free SRU. Following the usual Claus or OxyClausTM process, sulfur is then recovered in elemental form. Clients may also choose to feed in gases containing hydrogen sulfide from sour-water strippers. The recovered sulfur is then degassed and can be collected as a sellable product.

In the next step of the process, the Claus tail gas is hydrogenated, cooled, compressed and then sent to the AGR, where it is desulfurized and recycled back to the Claus unit, along with the acid gas. Through this recycling process, a sulfur recovery rate of 100% can be achieved, and sulfur emissions to the atmosphere in the overall complex are significantly reduced.

Air Liquide Engineering & Construction recommends that the emission-free SRU is used in conjunction with OxyClausTM, as this will decrease gas volume, the amount of gas sent to the AGR and the operating cost. The resulting reduced investment cost can be further optimized by a high degree of integration of the SRU with the Air Separation Unit (ASU) and the AGR.


  • Sulfur recovery rate of 100%
  • 25% less CAPEX than with conventional SRU with amine wash tail gas treatment
  • High integration of ASU, SRU and AGR possible reducing the number of equipment

Key figures

  • Capacity: up to 500 tons per day
  • Sulfur recovery: 100%

Emission Free Sulfur Recovery Unit