The SubDewPoint MCRCTM-SUPERCLAUS® combi-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. Modern SDP-SUPERCLAUS® plants are able to process H2S/NH3 containing gases as well, originating from Sour Water Strippers, with the objective yield approaching 99.7% overall sulfur recovery without any further tail gas clean-up.
The SDP-SUPERCLAUS® process consists of two well-known processes in series: The sub-dewpoint MCRCTM process followed by the selective oxidation stage of SUPERCLAUS®, with the patented main combustion air control of SUPERCLAUS®. The sub-dewpoint part consists of a thermal stage followed by two or more catalytic reaction stages with sulfur removed between stages by condensers. The first reactor is always operated at normal Claus conditions, the second reactor (MCRCTM) is a sub-dewpoint reactor being regenerated on-line by increased inlet temperature, the third sub-dewpoint reactor operates below the dewpoint of sulfur. These reactors are filled with standard Claus catalyst while the last reactor (the SUPERCLAUS® stage) is filled with proprietary 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 sub-dewpoint reactor contains an increased H2S concentration of typically 0.2 to 0.3 vol.%. Under these conditions, hardly any SO2 leaves the sub-dewpoint part. Because the proprietary catalyst neither oxidizes H2S SO2 and H2O nor reverses the reaction of sulfur and water to H2S and SO2, a total sulfur recovery efficiency of 99.7% can be obtained.
Three main principles are applied in operating the SDP-SUPERCLAUS® process:
- Operating the SDP-Claus part with excess H2S as in the SUPERCLAUS® process to suppress the SO2 content in the SDP-Claus tail gas. This principle makes the recovery of the plant less sensitive to the amount of air supplied than in (conventional) Claus plants
- Operating the last Claus reactor below the sulfur dewpoint to maximize the sulfur recovery.
- Selective oxidation of the remaining H2S in the SDP-Claus tail gas by means of SUPERCLAUS® catalyst, which efficiently converts the remaining H2S in the presence of water vapor and excess oxygen to mainly sulfur.
Other operating features that apply to Jacobs Comprimo's Claus process, are applicable for the SDPMCRC-SUPERCLAUS® process as well. 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% and production of 99.9% pure bright yellow sulfur.
- Application in both new and existing plants.
- The proprietary SUPERCLAUS® catalyst possesses some unique properties
- oxidation of H2S to sulfur is complete
- no sensitivity to water vapor
- further oxidation of SO2 is negligible even in the presence of excess oxygen
- components such as H2, CO and other combustibles are not affected
- the catalyst does not promote the Claus equilibrium reaction
- Long catalyst lifetime up to 10 years.
- Low additional investment costs.
- NH3 destruction capability.
- Capability to combust heavy hydrocarbon and aromatics.
- High turndown.
- High reliability - less than 1% unscheduled shutdown time.
Sulfur Recovery Efficiency
For an acid gas with 90% H2S the expected recoveries are:
3-bed MCRC+SC: 99.5 - 99.6%
Since the first commercial demonstration of the SUPERCLAUS® process in 1988, more than 190 plants with a capacity up to 1165 t/d are in operation or under construction in the first quarter of 2003. Since 1978, 35 MCRC units with a capacity up to 950 t/d have been licensed.
Jacobs Nederland B.V., Leiden, The Netherlands, and Jacobs Canada, Calgary together forming Jacobs Comprimo® Sulfur Solutions.