Hydrocarbons release from

The reasons for performing a source test differ. The test might be necessary for one or more of the following reasons (1) To obtain data concerning the emissions for an emission inventory or to identify a predominant source in the area. An example of this would be determination of the hydrocarbon release from a new type of organic solvent used in a degreasing tank. 

Fogelqvist E, Tanhua T (1995) Iodinated C1-C4 Hydrocarbons Released from Ice Algae in Antarctica. In Grimvall A, de Leer EWB (eds) Naturally-Produced Organohalogens. Kluwer, Dordrecht, p 295... 

Kross, B. 1988. Experimental investigations of the molecular migration of C1-C6 hydrocarbons. Kinetics of hydrocarbon release from source rocks. In Mattavelli, L. Novelli, L, (eds) Advances in Organic Geochemistry 1987. Organic Geochemistry, 13, 513-523. 

The detection of CO2 with a TCD requires that the gases coming out of the cell be fully oxidized, in order to transform CO and other hydrocarbons released from the catalysts into CO2. Since the technique involves the separation of gases in a GC column, its disadvantages are that it is a noncontinous analysis and that it misses the fine structure, the peak height and its temperature. Besides, the... 

Another synthesis of a bridged hydrocarbon takes advantage of high elearon release from the /wra-position of phenolate anions, which may be used to transform the phenol moiety into a substituted cross-conjugated cyciohexadienone system (S. Masamune, 1961, 1964). 

Vented risers should be provided on most cooling towers to release only light hydrocarbon leakage from the cooling water before the spray header. No ignition or source of spark should be within 30 m of the vented riser. 

Many hydrocarbon flames are luminous because of the incandescent carbon particles formed in the flames. Under certain conditions, these particles are released from the luminous flames as smoke. Smoke from hydrocarbons is usually formed when the system is fuel rich, either overall or locally. 

Forests can act as sources of some of the trace gases in the atmosphere, such as hydrocarbons, hydrogen sulfide, NO, and NH3. Forests have been identified as emitters of terpene hydrocarbons. In 1960, Went (10) estimated that hydrocarbon releases to the atmosphere were on the order of 108 tons per year. Later work by Rasmussen (11) suggested that the release of terpenes from forest systems is 2 x 10 tons of reactive materials per year on a global basis. This is several times the anthropogenic input. Yet, it is important to remember that forest emissions are much more widely dispersed and less concentrated than anthropogenic emissions. Table 8-2 shows terpene emissions from different types of forest systems in the United States. 

Onboard Refueling Vapor Recovery (OR ) regulations were fust proposed m 1987 but were met with a litany of technical and safety issues that delayed the requirement. The 1990 CAA amendments required the implementation of ORVR and the EPA regulation requires passenger cars to first have the systems starting in 1998. The ORVR test will be performed in a SHED and will require that not more than 0.2 grams of hydrocarbon vapor per gallon of dispensed fuel be released from the vehicle. 

They are effective as a means of removing heavy hydrocarbon vapors from emergency release streams, thus minimizing condensation problems in downstream equipment. 

Physical solvent processes have a high affinity for heavy hydrocarbons. If the namral gas stream is rich in C3+ hydrocarbons, then the use of a physical solvent process may result in a significant loss of the heavier molecular weight hydrocarbons. These hydrocarbons are lost because they a c released from the solvent with the acid gases and cannot be economically recovered. 

Most sulfur compounds can be removed from petroleum streams through hydrotreatment processes, where hydrogen sulfide is produced and the corresponding hydrocarbon released. Hydrogen sulfide is then absorbed in a suitable absorbent and recovered as sulfur (Chapter 4). 

When crude oil is refined, some of the processes yield additional gaseous products. The C3 and C4 constituents differ from those released from crude oil or from NGLs, which are saturated hydrocarbons. Refinery gases are high in unsaturates, e.g. propane (propylene) and butane (butylenes). These unsaturated hydrocarbons are a valuable source of chemical process intermediates and enjoy a large market alongside naphtha. 

In a comprehensive study of trichloroethylene emission sources from industry conducted for EPA, the major source was degreasing operations, which eventually release most of the trichloroethylene used in this application to the atmosphere (EPA 1985e). Degreasing operations represented the largest source category of trichloroethylene emissions in 1983, accounting for about 91% of total trichloroethylene emissions. Other emission sources include relatively minor releases from trichloroethylene manufacture, manufacture of other chemicals (similar chlorinated hydrocarbons and polyvinyl chloride), and solvent evaporation losses from adhesives, paints, coatings, and miscellaneous uses. 

The site of pheromone production in flies and cockroaches that utilize hydrocarbons is similar to that of the moths. Oenocyte cells produce the hydrocarbon pheromone which is transported by lipophorin in the hemolymph to epidermal cells throughout the body for release from the cuticular surface in general [20,21]. 

Hydrocarbon formation involves the removal of one carbon from an acyl-CoA to produce a one carbon shorter hydrocarbon. The mechanism behind this transformation is controversial. It has been suggested that it is either a decarbonylation or a decarboxylation reaction. The decarbonylation reaction involves reduction to an aldehyde intermediate and then decarbonylation to the hydrocarbon and releasing carbon monoxide without the requirement of oxygen or other cofactors [88,89]. In contrast, other work has shown that acyl-CoA is reduced to an aldehyde intermediate and then decarboxylated to the hydrocarbon, releasing carbon dioxide [90]. This reaction requires oxygen and NADPH and is apparently catalyzed by a cytochrome P450 [91]. Whether or not a decarbonylation reaction or a decarboxylation reaction produces hydrocarbons in insects awaits further research on the specific enzymes involved. 

---