Parsons-Beavon process

Selectox Also called BSR/Selectox. A process for converting hydrogen sulfide in refinery gases to elemental sulfur. The gases are passed over a fixed bed of a proprietary catalyst (Selectox 33) at 160 to 370°C. Claimed to be better than the Claus process in several respects. Often used in conjunction with the Beavon process. Developed by the Union Oil Company of California and the Ralph M. Parsons Company, and first operated in 1978. Thirteen units were operating in 1996. 

The Beavon Sulfur Removal (BSR) process was developed jointly by the Parsons Coip. of Pasadena, California, and the Union Oil Company of Califoinia (now Unocal Corporation of Los Angeles, California). The term Beavon process refers to a group of processes utilized for the removal of residual sulfur compounds from Claus plant tail gases. This family of processes has in common an initial hydrogenation and hydrolysis unit to convert all residual sulfur compounds to H2S. Individual processes within this family differ from each other in the technology used to remove the H2S from the Claus tail gas stream. Process improvements and operating experience have been reported by Andrews and Kouzel (1974). Fenton et al. (1975), Beavon and Brocoff (1976), and Kouzel et al. (1977). 

Beavon Also called BSR [Beavon Sulfur Removal], A process for removing residual sulfur compounds from the effluent gases from the Claus process. Usually used in conjunction with other processes. Catalytic hydrogenation over a cobalt-molybdena catalyst converts carbonyl sulfide, carbon disulfide, and other organic sulfur compounds to hydrogen sulfide, which is then removed by the Stretford process. A variation (BSR/MDEA), intended for small plants, uses preliminary scrubbing with methyl diethanolamine. Developed by the Ralph M. Parsons Company and Union Oil Company of California in 1971. More than 100 plants were operating in 2000. See also SCOT. 

Like the Scot process, the BSR BEAVON Sulfur Removal Process) developed by R.M. Parsons Cie. and Union Oil Company of California hydrogenates all sulfur components of the Claus tailgases to H2S. The H2S is then removed in a Stretford unit (see Sect. 2.3.3) to obtain elemental sulfur. The clean offgases from the Stretford unit contain less than 200ppm residual sulfur and less than 5 ppm H2S. 

Several processes have been developed based on the oxidation approach, but, with some exceptions, such as the Linde Clintox process (Heisel and Marold, 1992) these have not been commercial successes because of the complexity of SO2 recovery processes and their comparatively low SO2 removal efficiencies. Hydrogen sulfide, on the other hand, can be removed at very high efficiency by a number of processes, including the selective amine processes discussed in Chapter 2. Processes that involve the conversion of Claus plant tail gas sulfur compounds to H2S and the removal of this H2S are discussed in the following sections. Processes reviewed include Parson s Beavon Sulfur Removal (BSR) process. Shell s SCOT process, FB and D Technologies Sulften process, the TPA Resulf process, and the Exxon Flexsorb SE Plus process. 

Figure 8-29. Beavon sulfur removal process plant. Courtesy The Parsons Corp.

Unocal Science and Technology Div. and the Ralph M. Parsons Co., 1994, Beavon-others in Gas Processes 94, Hydro. Process., April, p. 72. 

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