Natural gas odorants

OT,-methionine propane odorant natural gas odorant components water repeUants prevulcanization inhibitor flocculent... 

J. M. Toth. Natural gas odorization and its techniques. In Proceedings Volume, pages 170-174.49th Annu Appalachian Gas Meas Short Course (Coraopolis, PA, 8/15-8/18), 1989. 

Liquefied natural gas (LNG) is a very clean fuel in that the few impurities present in natural gas (water vapor, hydrogen sulfide, carbon dioxide, particulates and foreign matter, etc.) are removed almost completely when the natural gas is liquefied. Liquefaction also removes most of the hydrocarbons heavier than propane so that the resulting fuel is 95-99% methane with the remainder being primarily ethane with a smaller amount of propane. The liquefaction process is so efficient at removing contaminants that it removes the odorant placed in natural gas for transmission over pipelines (natural gas odorants are primarily mer-captans which contain sulfur and are relatively large molecules). 

Properties Colorless gas natural-gas odor. Noncorrosive. Bp -42.5C, fp -189.9C, density of liquid 0.531 (0C), density of vapor 1.56 (0C), flash p -156F (-105C), autoign temp 874F (467C). Soluble in ether, alcohol slightly soluble in water. An asphyxiant gas. 

Physical Description Colorless gas with a gasoline-like or natural gas odor. [Note Shipped as a liquefied compressed gas. A liquid below 31 °F.] ... 

Precaution Flamm. dangerous fire risk can react vigorously with oxidizing materials Hazardous Decomp. Prods. Heated to decomp, or on contact with acid or acid fumes, emits highly toxic fumes of SOx Uses Odorant to permit detection of gas leaks intermediate bacterial nutrient Manuf./Distrib. Aldrich http //www.sigma-aldrich.com, ChevronPhillips http //www.cpchem.com, Fluka http //www.sigma-aldrich.com. Natural Gas Odorizing Occidental http //www. oxychem. com... 

ChevronPhi 11 i ps http //www. cpchem. com, Fluka http //www.sigma-aldrich.com. Natural Gas Odorizing... 

At one time thiols were named mercaptans Thus CH3CH2SH was called ethyl mercaptan according to this system This nomenclature was abandoned beginning with the 1965 revision of the lUPAC rules but is still sometimes encountered When one encounters a thiol for the first time especially a low molecular weight thiol its most obvious property is its foul odor Ethanethiol is added to natural gas so that leaks can be detected without special equipment—your nose is so sensitive that it can detect less than one part of ethanethiol m 10 000 000 000 parts of arr The odor of thiols weakens... 

The physical properties of the principal constituents of natural gas are Hsted in Table 5. These gases are odorless, but for safety reasons, natural gas is odorized before distribution to provide a distinct odor to warn users of possible gas leaks in equipment. Sulfur-containing compounds such as organic mercaptans, aUphatic sulfides, and cycHc sulfur compounds are effective odorants at low concentrations and are added to natural gas at levels ranging from 4 to 24mg/m. ... 

Another product from kraft black Hquor is dimethyl sulfide. This chemical, which is added to natural gas to give it odor, is also oxidized to produce the versatile solvent, dimethyl sulfoxide (see Sulfoxides). 

Like M( F(7s, S()F(7s can integrate fuel reforming within the fuel cell stack, A prereformer converts a substantial amount of the natural gas using waste heat from the fuel cell, (iornpoiinds containing sulfur (e,g, thiophene, which is cornrnonlv added to natural gas as an odorant) must be removed before the reformer. Typically, a hvdrodesiilfii-rizer combined with a zinc oxide absorber is used. 

Natural gas is eonsidered non-toxie but ean produee an oxygen defieient atmosphere (p. 153). It is odourless (therefore an odorant is added for distribution by pipeline). Its physieal properties are similar to those of methane, i.e. ... 

Observable Characteristics - Physical State (as normally shipped) Liquid Color Colorless Odor Ethereal characteristic sweet, alcoholyc like natural gas. 

Before entering the pipeline, the gas is also adjusted in the field to achieve a uniform heating value of 1,00(1 Btu (British thermal units) per cubic foot. And for safety, because natural gas is odorless and colorless, an odorant is added to provide a distinctive and disagreeable smell that is easy to recognize. 

Metering gas as it enters their systems, LDCs lower it to pressures suitable for their customers and add the familiar odor that identifies natural gas, otherwise odorless, to the consumer. 

The most striking characteristic of thiols is their appalling odor. Skunk scent, for instance, is caused primarily by the simple thiols 3-methyl-1-butanethiol and 2-butene-l-thiol. Volatile thiols such as ethanethiol are also added to natural gas and liquefied propane to serve as an easily detectable warning in case of leaks. 

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