Sulfolin process

The Sulfolin process solution contains organic nitrogen compounds in addition to vanadium. The process was developed by SASOL South Africa and Linde AG. It is a new process with limited data available in the literature, although reduced by-product salt make rates have been claimed (Dalrymple 1989). 

Perox Process, 762 Takahax Process, 765 Stretford Process, 769 Hiperion Process, 794 Sulfolin Process, 797 Unisulf Process, 802... 

The Sulfolin process is an aqueous phase oxidative H2S removal process closely related to the Stretford technology. It was developed by Linde AG for gas streams having a relatively low hydrogen sulfide concentration. The first conunercial application of the Sulfolin process was in 1985 at the Sasol II sulfur recovery plant in Secunda, South Africa. The unit consisted of one train designed for 171,000 scfm (275,000 Nm /hr) of feed gas and 110 metric TPD of sulfur production (Heisel and Marold, 1987). 

Primary Reactions. The basic chemistry used in the Sulfolin process parallels that employed in Stretford solutions, except for the use of an organic nitrogen vanadium promoter instead of the ADA oxygen carrier (Heisel and Maiold, 1987). 

After oxidation of H2S to elemental sulfur, the reduced vanadium (V +) must be reoxidized. As in the Stretford process, direct oxidation with air would be too slow for a viable commercial process. In the Stretford process the ADA redox cycle produces hydrogen peroxide, which rapidly oxidizes vanadium to V. In the Sulfolin process the oxidation rate is accelerated by the addition of a promoter, which increases the reactivity of the reduced vanadium. The promoter is described as an organic nitrogen compound, but the exact composition is proprietary. 

The SASOLI sulfur recovery plant initially used a conventional Stretford unit to desulfurize Rectisol regeneration off-gas. Operational problems in the SASOL I Stretford plant led to a decision to switch to the Sulfolin process in the SASOL I, SASOL II, and SASOL in plants. The following problems were encountered in SASOL I with the Stretford process ... 

Another application of the Sulfolin process is at the Rheinbraun AG HTW coal gasification plant near Cologne, West Germany (Heisel, 1989). The raw synthesis gas is purified in various steps, and eventually the H2S, and part of the CO2, are removed in a non-selective Rectisol wash. The H2S/CO2 stream from the Rectisol unit is treated using the Sulfolin process. 

Gas streams with large flow rates and high H2S concentrations are usually treated with a conventional absorption process followed by the Claus process. Typically, the Sulfolin process is best suited for a gas feed containing less than 5 tpd sulfur as H2S. The ranges of economical choices between the Sulfolin process and the amine absorption + Claus sy.stem. based on operating and investment costs, are shown in Figure 9-28 (Heisel and Marold, 1987). 

Design parameters that tend to make the Sulfolin process less attractive economically include (Heisel and Marold, 1987) ... 

Typical utility requirements per metric ton of sulfur for the Sulfolin process are given in Table 9-15 (Heisel et al.. 1990). 

Sulfolin A process for removing sulfur compounds from hydrocarbons, similar to the Stretford process, but including vanadium and an organic nitrogen compound in the... 

SASOL [Suid-Afrikaans Sintetiese OLie] Not a process but a large coal gasification complex in South Africa, operated by the South African Oil and Gas Corporation. It first operated in 1955 but took several years to be fully commissioned. A Lurgi fixed-bed gasification unit is used for the primary process. Downstream processes include the following ones, described under their respective names Arge, Fischer-Tropsch, Rectisol, Sulfolin, Synthol. 

Several liquid redox processes have been developed for smaller-scale (ca. 0.25-20 t sulfur day ) applications, achieving 99.9-t- % recovery. For example, SuIFerox and ARI-LO-CAT use complexed Fe species to oxidize absorbed H2S in acidic solutions, and Stretford, Unisulf, and Sulfolin use vanadium (V) in slightly alkaline solutions as the oxidant for absorbed HS ions. Atmospheric oxygen is the ultimate oxidant in all such processes, as it reoxidizes the reduced form of the dissolved metal species, the concentrations of which are not so limited as that of dissolved oxygen ... 

The section closes with a discussion of three new processes introduced in the 1980s they include the Unisulf, Sulfolin, and Hiperion processes. Unisulf and Sulfolin are vanadium-based processes that were designed to minimize or eliminate the need for spent solution... 

The process flow diagram for a typical Sulfolin plant is shown in Figure 9-27. The process consists of a. scnibbing cycle and a sulfur/liquor separation stage. The H2S-contain-ing feed gas enters the scrubber and is contacted by downflowing scrubbing liquor. The rich. solution then passes into a reaction tank in which the oxidation of hydrosulfide to elemental sulfur, which started in the absorber, is completed. 

Hgure 9-27. Typical Sulfolin plant process flow diagram. Weber etal., 198. Reprinted with permission from Linde Reports on Science end Technology... 

Weber, Bucki, and Hofer, 1988, Sulfolin-Development of an Oxidative Hydrogen Sulphide Scrubbing Process, Linde Reports on Science and Technology, Vol. 44. 

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