Sulfur quality

The SulFerox process converts hydrogen sulfide into elemental sulfur, which is separated from the slurry by filtration. Sulfur quality can be influenced by contaminants in the gas stream. However, filtration, followed by melting, can usually provide a yellow sulfur product with less than 100 ppmw of iron, 500 ppmw of ash, and 1,000 ppmw of carbon. A comparison between Claus-produced sulfur and the filtercake and molten sulfur produced in the SulFerox process is shown in Table 9-26 (Van Kleeck and Morisse-Amold, 1990). As indicated earlier, direct melting without concentration of the sulfur slurry is usually not a viable process option due to contamination of the molten sulfur and high chemical losses caused by thermal degradation. 

Comparison Between SulFerox and Claus Sulfur Quality... 

Sulfur is the heteroatom most frequently found in crude oils (see Table 1.5). Sulfur concentrations can range from 0.1 to more than 8 weight percent moreover, this content is correlated with the gravity of the crude oil and, therefore, its quality (light or heavy). 

The determination of the elemental composition of a petroleum cut is of prime importance because it provides a quick means of finding out the quality of a given cut or determining the efficiency of a refining process. In fact, the quality of a cut generally increases with the H/C ratio and in all cases, with a decrease in hetero-element (nitrogen, sulfur, and metals) content. 

Hydrocracking makes very good quality diesel fuels concerning the cetane number, cold behavior, stability, and sulfur content. However this type of stock is only available in limited quantities since the process is still not widely used owing essentially to its high cost. 

In France there are four categories of heavy fuels whose specifications are given in Table 5.19 the different product qualities are distinguished essentially by the viscosity, equal to or less than 110 mm /s at SOT for No. 1 fuel oil, equal to or greater than 110 mm /s for No. 2 fuel oil, and by the sulfur content varying from 4 wt. % (No. 2 fuel oil) to 1 wt. % (No. 2 TBTS - very low sulfur content fuel oil). 

It is noteworthy, however, that traces of sulfur can have beneficial effects on the anti-wear resistance of fuel injection pumps. It is thus undesirable to reduce the sulfur content to extremely low values unless additives having lubricating qualities are added. Independently from total sulfur content, the presence of mercaptans that are particularly aggressive towards certain metal or synthetic parts is strictly controlled. The mercaptan content is thereby limited to 0.002% (20 ppm) maximum. The analysis is performed chemically in accordance to the NF M 07-022 or ASTM D 3227 procedures. 

The coking process produces electrode quality coke from vacuum residues of good quality (low metal and sulfur contents) or coke for fuel in the case of heavy crude or vacuum residue conversion having high impurity levels. 

Problems sulfur and nitrogen transferred to the products (and coke) Solutions feed hydrotreating, reduction of S, N, Conradson carbon, metals Results higher quality products reduction in pollution better yields of valuable products reduced post-treatment... 

Heavy residue conversion is linked to the demand for high quality diesel motor fuel (aromatics content 10%, cetane number 55) as well as to the demand for production of light fuel-oil having very low sulfur, nitrogen and metal contents. 

A technical quality anhydride, assay about 97% maximum, often contains color bodies, heavy metals, phosphoms, and sulfur compounds. 

LPC Product Quality. Table 10 gives approximate analyses of several LPC products. Amino acid analyses of LPC products have been pubhshed including those from alfalfa, wheat leaf, barley, and lupin (101) soybean, sugar beet, and tobacco (102) Pro-Xan LPC products (100,103) and for a variety of other crop plants (104,105). The composition of LPCs varies widely depending on the raw materials and processes used. Amino acid profiles are generally satisfactory except for low sulfur amino acid contents, ie, cystine and methionine. 

National Ambient Air Quality Standards. Under the Clean Air Act, six criterion pollutants, ie, pollutants of special concern, have been estabhshed by the EPA sulfur oxides (SO ), particulates, carbon monoxide (CO), nitrogen oxides (NO ), o2one (photochemical oxidants), and lead. National Ambient Air QuaUty Standards (NAAQS) were developed by EPA based on threshold levels of air pollution below which no adverse effects could be experienced on human health or the environment. 

Air Quality Criteria for Sulfur Oxides, National Air Pollution Control Administration, U.S. Dept, of Health, Education, and Welfare, Washington, D.C.,Jan. 1969, pp. 89-102. 

J. B. Rosenbaum, D. R. George, and L. Crocker, "The Citrate Process for Removing SO2 and Recoveriag Sulfur from Waste Gases," paper presented at the MIME Environmental Quality Conference, Washiagton, D.C., June 7—9,1971. 

J. D. Benson and co-workers. Effects of Gasoline Sulfur on Mass Exhaust Emissions—-Autoj Oil Air Quality Improvement Research Program, SAE 912323, Society of Automotive Engineers, Warrendale, Pa., 1991. 

ERA promulgated the basic set of current ambient air-quality standards in April 1971. The specific regulated pollutants were particulates, sulfur dioxide, photochemical oxidants, hydrocarbons, carbon monoxide, and nitrogen oxides. In 1978, lead was added. Table 25-1 enumerates the present standards. 

Sulfur Corrosion Chromium is the most important material in imparting resistance to sulfidation (formation of smfidic scales similar to oxide scales). The austenitic alloys are generally used because of their superior mechanical properties and fabrication qualities, despite the fact that nickel in the alloy tends to lessen resistance to sulfidation somewhat. 

The quality of steels and alloys depend on content at them alloying elements, oxygen, phosphorus, and sulfur. The presence of harmful admixtures worsens properties of materials that show up in formation of cracks, decline of plasticity and malleability. In this connection great value has operations, which allow in this as result to decrease content of solute oxygen, phosphoms, sulfur - desoxidation, desulfuration, dephosphorization. 

The tetrahydrofurfuryl alcohol available from the Quaker Oats Company, or the Practical grade from the Eastman Kodak Company, has been used. If the material a ailable does not hydrogenate satisfactorily, it may be purified by hydrogenation over Raney nickel at 150 /100-200 atmospheres pressure. A sample of good quality boils at 177-178°/740 mm. and does not become dark-colored when a few milliliters are shaken with 1 drop of concentrated sulfuric acid at room temperature. 

The regenerator has two main functions It restores catalyst activity and supplies heat to crack the feed. The spent catalyst entering the regenerator contains between 0.8-2.5 wt% coke, depending on the quality of the feedstocks. Components of coke are carbon, hydrogen, and trace amounts of sulfur and nitrogen, which burn according to the reactions shown in Table 4-3. 

For any pollutant, air quality criteria may refer to different types of effects. For example. Tables 22-1 through 22-6 list effects on humans, animals, vegetation, materials, and the atmosphere caused by various exposures to sulfur dioxide, particulate matter, nitrogen dioxide, carbon monoxide, ozone, and lead. These data are from fhe Air Quality Criteria for these pollutants published by the U.S. Environmental Protection Agency. 

Sources Air Quality Criteria for Particulate Matter and Sulfur Oxides, final draft, U.S. Environmental Protection Agency, Research Triangle Park, NC, December 1981 Review of the National Ambient Air Quality Standards for Sulfur Oxides Assessment of Scientific and Technical Information, Draft OAQPS Staff Paper, U.S. Environmental Protection Agency, Research Triangle Park, NC, April 1982. 

Some variants of best practicable means are spelled out in the U.S. Clean Air Act of 1977. One is the requirement that best available control technology (BACT) for a specific pollutant be employed on new "major sources" that are to be located in an area that has attained the National Ambient Air Quality Standard (NAAQS) for that pollutant. BACT is also required for pollutants for which there is no NAAQS [e.g., total reduced sulfur (TRS), for which emission limits are specified by a Federal New Source Performance Standard (NSPS)]. BACT must be at least as stringent as NSPS but is determined on a case-by-case basis. 

A determination by the method of Pucher, Vickery, and Leavenworth showed that 26 g. of citric acid remained in the sulfuric acid solution. It is inadvisable to use this solution for another run the accumulation of water and by-products reduces considerably the yield and the quality of the product. 

It IS expected that production of coal-derived pitches, liquids, and chemicals will take on a more important role in the future. This is of some strategic concern to the United States, where the demand for domestic petroleum is greater than the supply. Moreover, the quality of imported petroleum cmdes is declinmg in that they contain increasing amounts of contarmnant metals and sulfur... 

---