HYBRID SULFUR RECOVERY PROCESS FOR NATURAL GAS UPGRADING
This final report describes the objectives, technical approach, results and conclusions for a project funded by the U.S. Department of Energy to test a hybrid sulfur recovery process for natural gas upgrading. The process concept is a configuration of CrystaTech, Inc.'s CrystaSulf{reg_sign} process which utilizes a direct oxidation catalyst upstream of the absorber tower to oxidize a portion of the inlet hydrogen sulfide (H{sub 2}S) to sulfur dioxide (SO{sub 2}) and elemental sulfur. This hybrid configuration of CrystaSulf has been named CrystaSulf-DO and represents a low-cost option for direct treatment of natural gas streams to remove H{sub 2}S in quantities equivalent to 0.2-25 metric tons (LT) of sulfur per day and more. This hybrid process is projected to have lower capital and operating costs than the competing technologies, amine/aqueous iron liquid redox and amine/Claus/tail gas treating, and have a smaller plant footprint, making it well suited to both onshore and offshore applications. CrystaSulf is a nonaqueous sulfur recovery process that removes H{sub 2}S from gas streams and converts it to elemental sulfur. In CrystaSulf, H{sub 2}S in the inlet gas is reacted with SO{sub 2} to make elemental sulfur according to the liquid phase Claus reaction: 2H{sub 2}S + SO{sub 2} {yields} 2H{sub 2}O + 3S. The SO{sub 2} for the reaction can be supplied from external sources by purchasing liquid SO{sub 2} and injecting it into the CrystaSulf solution, or produced internally by converting a portion of the inlet gas H{sub 2}S to SO{sub 2} or by burning a portion of the sulfur produced to make SO{sub 2}. CrystaSulf features high sulfur recovery similar to aqueous-iron liquid redox sulfur recovery processes, but differs from the aqueous processes in that CrystaSulf controls the location where elemental sulfur particles are formed. In the hybrid process, the needed SO{sub 2} is produced by placing a bed of direct oxidation catalyst in the inlet gas stream to oxidize a portion of the inlet H{sub 2}S. Oxidation catalysts may also produce some elemental sulfur under these conditions, which can be removed and recovered prior to the CrystaSulf absorber. The CrystaSulf-DO process can utilize direct oxidation catalyst from many sources. Numerous direct oxidation catalysts are available from many suppliers worldwide. They have been used for H{sub 2}S oxidation to sulfur and/or SO{sub 2} for decades. It was believed at the outset of the project that TDA Research, Inc., a subcontractor, could develop a direct oxidation catalyst that would offer advantages over other commercially available catalysts for this CrystaSulf-DO process application. This project involved the development of several of TDA's candidate proprietary direct oxidation catalysts through laboratory bench-scale testing. These catalysts were shown to be effective for conversion of H{sub 2}S to SO{sub 2} and to elemental sulfur under certain operating conditions. One of these catalysts was subsequently tested on a commercial gas stream in a bench-scale reactor at CrystaTech's pilot plant site in west Texas with good results. However, commercial developments have precluded the use of TDA catalysts in the CrystaSulf-DO process. Nonetheless, this project has advanced direct oxidation catalyst technology for H{sub 2}S control in energy industries and led to several viable paths to commercialization. TDA is commercializing the use of its direct oxidation catalyst technology in conjunction with the SulfaTreat{reg_sign} solid scavenger for natural gas applications and in conjunction with ConocoPhillips and DOE for gasification applications using ConocoPhillips gasification technology. CrystaTech is commercializing its CrystaSulf-DO process in conjunction with Gas Technology Institute for natural gas applications (using direct oxidation catalysts from other commercial sources) and in conjunction with ChevronTexaco and DOE for gasification applications using ChevronTexaco's gasification technology.
- Research Organization:
- CrystaTech, Inc. (US)
- Sponsoring Organization:
- (US)
- DOE Contract Number:
- FC26-99FT40725
- OSTI ID:
- 831077
- Resource Relation:
- Other Information: PBD: 1 Jun 2004
- Country of Publication:
- United States
- Language:
- English
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HYBRID SULFUR RECOVERY PROCESS FOR NATURAL GAS UPGRADING
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