Sulfur equivalent

It is common to express the sulfur content of a stream in terms of sulfur equivalent. This assumes that all of the hydrogen 

According to this reaction, 1 mole of hydrogen sulfide is converted to one mole of S. 

First you must determine the number of moles of hydrogen sulfide in the gas stream, as discussed earlier. Therefore to obtain the molar flow rate of H2S in the gas stream, multiply the flow rate by the molar equivalent given above and then multiply by the mole fraction H2S in the stream. 

Q - flow rate at standard or normal conditions F - the factor given earlier to convert the standard flow rate into a molar flow rate yH s - mole fraction H2S in the gas 

From the chemical reaction, one mole of H2S produces one mole of S. Therefore  

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The 1990 Amendments to the U.S. Clean Air Act require a 50% reduction of sulfur dioxide emissions by the year 2000. Electric power stations are beheved to be the source of 70% of all sulfur dioxide emissions (see Power generation). As of the mid-1990s, no utiUties were recovering commercial quantities of elemental sulfur ia the United States. Two projects had been aimounced Tampa Electric Company s plan to recover 75,000—90,000 metric tons of sulfuric acid (25,000—30,000 metric tons sulfur equivalent) aimuaHy at its power plant ia Polk County, Elorida, and a full-scale sulfur recovery system to be iastaHed at PSl Energy s Wabash River generating station ia Terre Haute, Indiana. Completed ia 1995, the Terre Haute plant should recover about 14,000 t/yr of elemental sulfur. 

A number of zinc selenium complexes have now been characterized, with particular interest in the formation of zinc selenide semiconductors and quantum dots. In many cases analogous structures to those observed with thiol or thiolates are recorded. 77Se NMR is frequently used in characterization, and comparison with the sulfur equivalent is relevant. Zinc selenium compounds are of particular interest as precursors for metal/selenide materials and their relevance as models for selenocysteine-containing metalloproteins. 

Carbon disulfide, the all sulfur equivalent of isothiocyanates, was found to react with benzimidazole 127 very rapidly under microwave irradiation to produce 128 <00TL5857>. 

Over the six years from 1973 to 1978, sulfur production capability on a global basis increased from about 48 million long tons (sulfur equivalent) to about 55 million tons per year (2.8% per year). Since world sulfur demand has historically averaged well above 3 percent per year, the gap between demand and supply narrowed noticeably. It should not be surprising, therefore, that recently sulfur prices have begun to increase. 

The reverse is true for the production of recovered sulfur - from refineries, sour gas operations, and smelters. Overall, the total, sulfur supply from all sources amounted to about 1.9 million long tons of sulfur equivalent in 1978, representing a substantial decline since 1974, when production was 2.4 million tons. 

By far, the greatest surplus will exist in the mid-continent and Intermountain regions of the U.S., where the current area surplus will rise from about 2.8 million long tons per year of sulfur equivalent to about 7.2 million tons per year by 1990. These supply/ demand historical relationships and projections are summarized for each country and for North America in Table IV. 

NORTH AMERICAN SULFUR OUTLOOK PAST AND PROJECTED SUPPLY/DEMAND BALANCE, 1970-1990 (In millions of long tons of sulfur equivalent)... 

Millions of Long Ions Sulfur Equivalent Prices, Alberta... 

The mechanism of the Wittig reaction of phosphoranes with carbonyl compounds has fascinated chemists and remains a matter of discussion. Though the sulfur equivalent is very much less used, this reaction is known... 

Halides are readily converted into alcohols and phenols (and their sulfur equivalents) by several different methods. The preparation of alcohols from all sources has been reviewed previously210. 

TABLE 25.3 U.S. Production and Consumption of Sulfur in all Forms in 2003 (Million Metric Tons, Sulfur Equivalent)... 

Once removed from the raw gas, the question arises as to what should be done with the acid gas. If there is a large amount of acid gas, it may be economical to build a Claus-type sulfur plant to convert the hydrogen sulfide into the more benign elemental sulfur. Once the H2S has been converted to sulfur, the leftover carbon dioxide is emitted to the atmosphere. Claus plants can be quite efficient, but even so, they also emit significant amounts of sulfur compounds. For example, a Claus plant processing 10 MMSCFD of H2S and converting 99.9% of the H2S into elemental sulfur (which is only possible with the addition of a tail gas clean up unit) emits the equivalent of 0.01 MMSCFD or approximately 0.4 ton/day of sulfur into the atmosphere. Note that there is more discussion of standard volumes and sulfur equivalents later in this chapter. 

An acid gas stream of 1 MMCSFD is 75% H2S. What is the sulfur equivalent for this stream ... 

As well as this variety of oxidation states, sulfur shows a sometimes surprising versatility in function. Simple S(II) compounds are good nucleophiles as you would expect from the high-energy nonbonding lone pairs (3sp rather than the 2sp of oxygen). A mixture of a thiol (RSH, the sulfur equivalent of an alcohol) and NaOH reacts with an alkyl halide to give the sulfide alone by nucleophilic attack of RS-. 

The sulfur at the center of mustard gas is an excellent nucleophile, and chloride is a decent leaving group. Sulfur can do in internal nucleophilic subsitution to make a reactive sulfonium salt and the sulfur equivalent of an epoxide. gj.y j-gactive —... 

Note In I he case of nitrogen and sulfur compounds F and M are given in the mass of species and not in nitrogen or sulfur equivalents... 

Basis 100 long tons/day sulfur equivalent in process gas. b Dry basis at 60°F. and 14.7 psig. c S02 volume 1.46 M SCFM (standard cubic ft/min). d Includes reductant as 100% CH4. 

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