Recovery of hydrogen sulfide

B. Wilks, M. E. Rezac, Properties of rubbery polymers for the recovery of hydrogen sulfide from gasification gases, J. Appl. Polym. Sci., 85, 2436—2444 (2002). 

Operational changes or equipment modifications that result in enhanced propylene recovery in an FCCU absorber-stripper will inevitably increase hydrogen sulfide recovery. Moreover, the percent recovery of hydrogen sulfide from sour fuel gas may be an order of magnitude greater than the increased percent recovery of propylene from fuel gas. 

Natural Gasoline. Even though gas desulfurization as by the use of monoethanolamine or other agents (see Table 22-4 and Fig. 20-18) is practiced for the removal and/or recovery of hydrogen sulfide from the gas, it is still necessary to sweeten the liquid products and to dry the propane. With especially sour products, the system indicated by M. H Rahmes (see Fig, 10-7) is extensively used. If the mercaptan content... 

The recovery of hydrogen sulfide from natural and refinery gases, and its conversion into sulfur or sulfuric acid, is being conducted extenavely. In Wyoming oil and gas fields alone, the available sulfur is estimated to be 5,678,400 long tons (1950), in Arkansas sour gas fields (1942) at least 1,500,000 long tons, and in the Permian Basin of West Texas and southeastern New Mexico a daily production of at least 400 long tons (1950). 

Purification of refinery gases by elimination of hydrogen sulfide as well as Claus units for sulfur recovery began to make their appearance. 

Certain of the above reactions are of practical importance. The oxidation of hydrogen sulfide in a flame is one means for producing the sulfur dioxide required for a sulfuric acid plant. Oxidation of hydrogen sulfide by sulfur dioxide is the basis of the Claus process for sulfur recovery. The Claus reaction can also take place under mil der conditions in the presence of water, which catalyzes the reaction. However, the oxidation of hydrogen sulfide by sulfur dioxide in water is a complex process leading to the formation of sulfur and polythionic acids, the mixture known as Wackenroeder s Hquid (105). 

The practical importance of the higher sulfanes relates to their formation in sour-gas wells from sulfur and hydrogen sulfide under pressure and their subsequent decomposition which causes well plugging (134). The formation of high sulfanes in the recovery of sulfur by the Claus process also may lead to persistance of traces of hydrogen sulfide in the sulfur thus produced (100). Quantitative deteanination of H2S and H2S in Claus process sulfur requires the use of a catalyst, eg, PbS, to accelerate the breakdown of H2S (135). 

The amount of combustion ait is tightly controlled to maximize sulfur recovery, ie, maintaining the appropriate reaction stoichiometry of 2 1 hydrogen sulfide to sulfur dioxide throughout downstream reactors. Typically, sulfur recoveries of up to 97% can be achieved (7). The recovery is heavily dependent on the concentration of hydrogen sulfide and contaminants, especially ammonia and heavy hydrocarbons, ia the feed to the Claus unit. 

A derivative of the Claus process is the Recycle Selectox process, developed by Parsons and Unocal and Hcensed through UOP. Once-Thm Selectox is suitable for very lean acid gas streams (1—5 mol % hydrogen sulfide), which cannot be effectively processed in a Claus unit. As shown in Figure 9, the process is similar to a standard Claus plant, except that the thermal combustor and waste heat boiler have been replaced with a catalytic reactor. The Selectox catalyst promotes the selective oxidation of hydrogen sulfide to sulfur dioxide, ie, hydrocarbons in the feed are not oxidized. These plants typically employ two Claus catalytic stages downstream of the Selectox reactor, to achieve an overall sulfur recovery of 90—95%. 

Methods of Purification. Although carbon dioxide produced and recovered by the methods outlined above has a high purity, it may contain traces of hydrogen sulfide and sulfur dioxide, which cause a slight odor or taste. The fermentation gas recovery processes include a purification stage, but carbon dioxide recovered by other methods must be further purified before it is acceptable for beverage, dry ice, or other uses. The most commonly used purification methods are treatments with potassium permanganate, potassium dichromate, or active carbon. 

A disadvantage of the hydrocarbon—sulfur process is the formation of one mole of hydrogen sulfide by-product for every two atoms of hydrogen in the hydrocarbon. Technology for efficient recovery of sulfur values in hydrogen sulfide became commercially available at about the same time that the methane—sulfur process was developed. With an efficient Claus sulfur recovery unit, the hydrocarbon—sulfur process is economically attractive. 

Currently, sulfur is mainly produced by the partial oxidation of hydrogen sulfide through the Claus process. The major sources of hydrogen sulfide are natural gas and petroleum refinery streams treatment operations. It has been estimated that 90-95% of the world s recovered sulfur is produced through the Claus process. Typical sulfur recovery ranges from 90% for a lean acid gas feed to 97% for a rich acid gas feed. ... 

Puacz et al. (1995) developed a catalytic method, based on the iodine-azide reaction, for the determination of hydrogen sulfide in human whole blood. The method involves the generation of hydrogen sulfide in an evolution-absorption apparatus. In addition, the method allows for the determination of sulfide in blood without interference from other sulfur compounds in blood. A detection limit of 4 g/dm3 and a percent recovery of 98-102% were achieved. Although the accuracy and precision of the catalytic method are comparable to those of the ion-selective electrode method, the catalytic method is simpler, faster, and would be advantageous in serial analysis. 

Petroleum refining also produces substantial amounts of carbon dioxide, which with hydrogen sulfide, corrode refining equipment, harm catalysts, pollute the atmosphere, and prevent the use of hydrocarbon components in petrochemical manufacture. When the amount of hydrogen sulfide is high, it may be removed from a gas stream and converted to sulfur or sulfuric acid. Some natural gases contain sufficient carbon dioxide to warrant recovery as dry ice. 

Kiuchi, H., Nakamura, T., Eunaki, K., Tanaka, T. 1982. Recovery of hydrogen from hydrogen sulfide with metals and metal sulfides. Int J Hydrogen Energy 7 477 82. 

Because of the presence of hydrogen sulfide in Jay field crude oil, complex facilities, including oil stabilization, gas sweetening, and sulfur-recovery units, were required to produce salable oil and gas. To initiate field production and to provide extended well tests, a small 2.000-B/D facility was installed initially. As development drilling proceeded, 6.S00- and 12,000-B/D modules were built when and where needed. By using the modular-facility design concept, the field producing capacity was more than 00,000 B/D within 2V4 years of discovery. 

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