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Applications
The EUROCLAUS® process has been developed to recover elemental sulfur from H2S containing gases originating from gas treating plants such as alkanolamine units or physical solvent plants. The EUROCLAUS® process is an improvement of the SUPERCLAUS® process. Yields up to 99.7% overall sulfur recovery without any further tail gas clean up are possible.

Description
The EUROCLAUS® process consists of a thermal stage followed by three or four catalytic reaction stages with sulfur removed between stages by condensers. Two first two or three reactors are filled with standard Claus catalyst while the last reactor is filled with the selective oxidation catalyst. In the thermal stage, the acid gas is burned with a substoichiometric amount of controlled combustion air such that the tail gas leaving the last Claus reactor contains typically 0.8 to 1.0 vol.% of H2S and 100-200 ppmv SO2. This low SO2 content is obtained with a hydrogenation catalyst which converts SO2 to H2S in the bottom of the last Claus reactor. The SUPERCLAUS® catalyst in the final reactor oxidizes the H2S to sulfur at an efficiency of more than 85%. A total sulfur recovery efficiency up to 99.3% can be obtained with three reactor stages and up to 99.7% with four stages.

The acid gas feed from the Amine Regenerator and from the Sour Water Stripper are introduced to the main burner. The air to the main burner is supplied by a combustion air blower. The air to the burner and combustion chamber is exactly sufficient for the complete oxidation of all hydrocarbons and ammonia present in the feed gases and to burn as much H2S as required to obtain the correct H2S/SO2 ratio. To remove the heat generated in the burner and combustion chamber, the gas passes through a tube bundle located in a waste heat boiler. The gas is cooled, thereby generating steam. Further cooling is done in a condenser generating steam. The process gas stream from the condenser is heated in the first reheater to obtain the optimum temperature for the catalytic conversion. In the reactor, the H2S and SO2 react over the catalyst, forming sulfur and H2O until equilibrium is reached. The effluent gas from the first reactor goes to the first sulfur condenser. The process gas is cooled here and the released heat is used to generate steam. The process gas stream from the condenser is heated in the second reheater to obtain the optimum temperature for the catalytic conversion. The gas from the condenser is heated in the second reheater to obtain the optimum temperature for the catalytic conversion. The bottom layer of hydrogenation catalyst makes sure that almost all SO2 in the gas is converted to H2S for optimum recovery results. The effluent gas from the second reactor goes to the second sulfur condenser. The process gas is cooled here and the released heat is used to generate steam. The tail gas from the final condenser and the vent gas from the sulfur pit gas contain residual H2S and other sulfur compounds, which cannot be released directly to the atmosphere. These gases are therefore thermally incinerated to convert residual H2S an Preheated oxidation air from the main air blower is injected into the process gas leaving the last Claus reactor. The gas is heated in the reheater and process gas and oxidation air are well mixed before entering the SUPERCLAUS® reactor. H2S is selectively oxidized into sulfur in the SUPERCLAUS® reactor. The reactor contains a special selective oxidation catalyst. The air is supplied in excess in order to maintain oxidizing conditions in the reactor to prevent sulfiding of the catalyst. The gas leaving the SUPERCLAUS® reactor passes to the SUPERCLAUS® condenser. In order to condensate as much sulfur vapor as possible, the SUPERCLAUS® condenser operates at a low temperature.
Operating Conditions
Three main principles are applied in operating the EUROCLAUS® process:
  • Operating the Claus plant with excess H2S to suppress the SO2 content in the Claus tail gas.
  • Selective reduction of SO2 in the Claus process gas by means of a catalyst with hydrogenating properties.
  • Selective oxidation of the remaining H2S in the Claus tail gas by means of special catalyst which efficiently converts the remaining H2S in the presence of water vapor and excess oxygen to elemental sulfur only.
Other operating features, which apply to Jacobs Comprimo's Claus process also apply to the EUROCLAUS® process. These include NH3 destruction up to 30 vol.%, the capability to process small amounts of heavy hydrocarbons and aromatics up to 2 vol.%, turndown ratios of 100-15%. Producing 99.9% pure bright yellow sulfur.

Features
  • Application in both new and existing plants.
  • The SUPERCLAUS® catalyst as applied in the SUPERCLAUS® process.
  • A final Claus reactor also containing hydrogenation catalyst.
  • Long catalyst lifetime up (over 5 years)
  • Sulfur recovery up to 99.7%.
  • Reduction of SO2 emissions by up to 90%.
  • Simple continuous operation.
  • Low additional investment costs.
  • NH3 destruction.
  • Capability to combust heavy hydrocarbon and aromatics.
  • High turndown.
  • High reliability - less than 1% unscheduled shutdown time.


    • References
    Since the first commercial demonstration of the EUROCLAUS® process in 2000, more than 15 plants are in operation or under construction.

    Licensor
    Jacobs Nederland B.V., Leiden, The Netherlands.
     

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