Sulfur Recovery

SmartSulf® - AdvaSulf™ Suite

SmartSulf® fundamental principle consists in removing the heat produced by the exothermic Claus reaction directly in the catalyst bed, by means of proprietary cooled reactors, rather than being removed by condensation in a downstream heat exchanger.

This technology relies on two important features:

• Increased thermodynamic conversion of the Claus reactions thanks to the embedded heat exchanger.
• Sub-dewpoint Claus process that improves the overall Sulfur Removal by absorbing liquid elemental sulfur on the catalyst.

This technology uses a combination of Axens titanium-based and alumina catalysts, in order to deal with residual COS and CS₂ species and at the same time reach outstanding H₂S conversion performances.

The CAPEX/OPEX of this technology is comparable to that of a conventional Claus unit and offers an easy operability and potential for: retrofit in a small footprint, increase of conversion capacity and efficiency of existing sulfur recovery units.

SmartSulf® + Polishing

SmartSulf® process can be also adapted to 99.9+% sulfur removal when more stringent emission regulations are required. This solution consists in adding a Polishing Section downstream of the Thermal Oxidizer (Incinerator).

This upgrade allows to achieve Word Bank Specifications (150 mg/Nm³ SO₂ emission) with a fraction of the capital investment and plot plan area needed by the conventional Amine based TGTU.

Water Treatment Package can be integrated depending on on-site facilities for treatment of effluent with dissolved salts from polishing.

SmartSulf® Direct Oxydation / DO

SmartSulf® process could be adapted, by removing the Reaction Furnace, in order to treat lean acid gas (0.5<H₂S<15% vol.). This process is called SmartSulf® Direct Oxidation (DO) and it allows to produce, by means of air injection and catalytic reactions, a commercial grade liquid sulfur without having any effluent to be disposed of.

SmartSulf® DO can be designed in order to deal with a wide range of lean acid gas composition and with an overall Sulfur Recovery from 90% up to 99%.

Typical applications are desulfurization of lean acid gases, Light Hydrocarbon streams, Biogas, Shale gas, Gasification.

Claus

The Claus conventional process allows a sulfur recovery between 95 and 98% by converting H₂S present in feed gas streams and recover it as elemental liquid Sulfur. The process is based on the Claus reaction that is composed of two steps, a first thermal stage and a second catalytic stage.

The thermal stage, carried out in the Reaction Furnace, consists in the partial oxidation of H₂S to generate Sulfur dioxide (SO₂), which will then react with the remaining hydrogen sulfide (H₂S) to produce Sulfur in the catalytic stages.

Alumina is the main catalyst used in the Claus process, where the formation of sulfur occurs at the surface of heterogeneous (solid) catalysts. In addition, TiO₂ based catalyst is largely used in the bottom of the first Claus reactor to better convert COS and CS₂ and further reduce sulfur emissions out of stack. The most suitable catalyst configuration to match the required performances and Catalyst Life Span is selected from Axens large SRU Catalyst Portfolio, on a case by case basis.

Sultimate™ - AdvaSulf™ Suite

Axens offers Sultimate™, a Tail Gas Treatment (TGT) technology in sulfur recovery processing that uses conventional or proprietary amine based solvent, featuring the highest sulfur recovery achievable: typically 99.9+%.

The catalyst filled within the TGT Hydrogenation (Reduction) Reactor is one of its best feature. Axens CoMo catalyst has the best performance available on the market at low temperature, allowing drastic OPEX reduction while maintaining high activity during long run duration.

SweetSulf™

SweetSulf™ is a redox process developed for high-pressure natural gas, medium pressure fuel gas or low-pressure acid gas applications. Its specific solid sulfur removal technology overcomes the foaming/plugging problems experienced with other types of redox processes.

• Reaction: Sour Gas is contacted with an aqueous redox solution which extracts the H₂S and converts it into solid elemental sulfur.
• Gas separation: Treated gas, free of H₂S (H₂S specification down to < 1 ppmv is achievable), is separated from the redox solution.
• Solid separation: Solid sulfur is filtered under pressure on a cartridge filter which can be regenerated on stream.
• Re-Oxidation: The redox solution is depressurized and re-oxidized by contact with air.