# Direct Selective Oxidation of Hydrogen Sulfide: Laboratory, Pilot and Industrial Tests
## 22 Facility for the Purification of Gases Caused by Blowing-off Sour Crude Oil  
Strict limitations for the hydrogen sulfide content in oil for pipeline transport have been in place in Russia since 2002. Herewith, the mass fraction of hydrogen sulfide is limited to within 20-100 ppmv (GOST P 51858-2002. Oil. General technical conditions). When purifying 200 g of oil an hour, about 0.1 t of H\({}_{2}\)S, or, on a yearly basis, 800 t of H\({}_{2}\)S, are generated. This is particularly relevant because of the short period of transition (2019-2020) regarding technical regulations put in place by the Eurasian Economic Union \"Regarding the safety of oil prepared for transportation or use\" (TR EAES 045/2017), limiting hydrogen sulfide levels to 20 ppmv. The blowing-off process of H\({}_{2}\)S with purified gas (mainline natural gas) is used for oils from the fields in the Volga Ural oil and gas province (Nurlatskoye, Aznakaevskoye, and Aznakaevskoye) with hydrogen sulfide levels up to 600 ppmv. In this case, a H\({}_{2}\)S-enriched hydrocarbon flow is formed which then undergoes amine treatment. Meanwhile, the concentrated hydrogen sulfide should be disposed of using the most reasonable method. To this end, the Boreskov Institute of Catalysis SB RAS, in collaboration with specialists from JSC SHESHMAOIL and JSC VNIIUS, constructed an industrial unit (Table 4). The unit is scheduled to be used on an industrial basis in 2021 [159]. Minirefineries and GPPs or plants with a capacity of recycled hydrocarbon sulfurous raw materials of up to 3 million tons of oil per year for refineries and up to 80 million m\({}^{3}\) gas per year for GPPs are worthy of special consideration. Such enterprises are becoming rather \begin{table}
\begin{tabular}{c c} \hline \# & **Parameters** & **Value** \\ \hline
1 & Acid gas flow rate after amine unite to the direct oxidation unit, nm\({}^{3}\)/hour & to 110 \\
2 & H\({}_{2}\)S concentration in acid gas, vol. \% & 75–90 \\
3 & Diameter of the fluidized bed reactor, m & 0.52 \\
4 & Catalyst loading, kg & 185 \\
5 & Sulfur yield, tons/hour & 0.13 \\ \hline \end{tabular}
\end{table} 
Table 4: Main characteristics of the installation for the removal of H\({}_{2}\)S from gases originating from the blowing off of sour crude oil, designed for JSC SHESHMAOIL. Figure 25: Sulfur produced at the Bavly gas shop of PJSC Tatneft. numerous in the CIS countries. Their main goal is to localize the production of high-quality motor fuels in regions which are distant from large oil and gas processing centers. The low capacity of such production does not allow the creation of full-size hydrogen sulfide utilization units based on the Claus process, and the hydrogen sulfide formed as a result of the primary processing processes is usually burned off. To solve this issue, at the JSC Condensate (Republic of Kazakhstan), an installation for hydrogen sulfide removal with sulfur production was built. Investors recognized the compact direct oxidation plant as the most rational way to solve the problem from a technical and economical viewpoint. The installation has successfully passed commissioning and is ready to begin permanent operations. At present, a plant which will use the hydrogen sulfide formed in the hydrocracking process is being created at the Ust-Luga Complex of PJSC NOVATEK. The technology was selected as a result of a vote, as it proved to be superior to those proposed by other licensers. The acid gas flow rate to the direct oxidation unit after the amine unit is about 170 nm\({}^{3}\)/h. The present status of the technology is as follows:  
* The basic design of the technology has been finalized. * The design and working documentation have been presented. * The various apparatus units have been fabricated (Figure 26);
* The block of the plant has been delivered to the customer (Figure 27);
* The technology achieves the direct catalytic oxidation of hydrogen sulfide via the use of acid gases. It is an alternative to the Claus process (MTU-0.5 Mini Plant, Republic of Kazakhstan). Figure 27: Cooling Block. 23.