Light fraction

Although distillation and elemental analysis of the fractions provide a good evaluation of the qualities of a crude oil, they are nevertheless insufficient. Indeed, the numerous uses of petroleum demand a detailed molecular analysis. This is true for all distillation fractions, certain crude oils being valued essentially for their light fractions used in motor fuels, others because they make quality lubricating oils and still others because they make excellent base stocks for paving asphalt. 

C for light fractions with boiling points less than 200°C... 

The different cuts obtained are collected their initial and final distillation temperatures are recorded along with their weights and specific gravities. Other physical characteristics are measured for the light fractions octane number, vapor pressure, molecular weight, PONA, weight per cent sulfur, etc., and, for the heavy fractions, the aniline point, specific gravity, viscosity, sulfur content, and asphaltene content, etc. 

Properly speaking, steam cracking is not a refining process. A key petrochemical process, it has the purpose of producing ethylene, propylene, butadiene, butenes and aromatics (BTX) mainly from light fractions of crude oil (LPG, naphthas), but also from heavy fractions hydrotreated or not (paraffinic vacuum distillates, residue from hydrocracking HOC). 

Products of conversion from catalytic cracking are largely olefinic for light fractions and strongly aromatic for the heavy fractions. 

In some cases bacteria may have biodegraded the oil, i.e. destroyed the light fraction. Many shallow accumulations have been altered by this process. An example would be the large heavy oil accumulations in Venezuela. 

Rerunning operations are characterized by large volumes of distillate products and relatively small residue yields. Frequently, the product is withdrawn as a sidestream with undesirable light fractions passing overhead and polymers being withdrawn from the bottom of the tower. Lube rerun stills usually have several sidestreams which permit close control of flash point and viscosity while producing a wide range of stocks. 

The API method is a generalized method that predicts mole fraction of paraffinic, naphthenic, or aromatic compounds for an olefin-Ifee hydrocarbon. The development of the equations is based on dividing the hydrocarbon into two molecular ranges heavy fractions (200 < MW < 600) and light fractions (70 < MW <200). Appendix 7 contains API correlations applicable to the FCC feed. 

Caustic extraction can remove mercaptan sulfur in light fractions, but not higher carbon number mercaptans or other types of sulfur molecules that are in the FCC gasoline. 

It is fruitless to attempt detailed study of a phenomenon whose products are not well identified. It is unfortunately frequently noted in the literature, especially in cases of column chromatography, that fractions are only identified as to the chemical operations which brought them to light. Fractions are identified, for example, only by the solvent used. Speculations as to the composition of the radioactive solutes in such solutions can seldom be really reliable, and the presence of an unexpected radioactive species is in such cases undetectable. It is also important in reading the literature to watch out for cases in which the chemical yields of the carriers have not been measured. Extensive decomposition can often occur on silica gel and alumina columns, especially when photosensitive or moisture sensitive compounds are used. For these reasons much of the information now existing in the literature must be regarded as only exploratory, awaiting the development of better analytical methods for separation, purification, identification and determination of the products —known or expected. 

The gas has a high content of monomers (ethylene and propylene) and other useful hydrocarbons with only some 15% being methane. The feedstock is collected in two stages since the heavy fraction is a wax below about 60 °C. The heavy fraction is typically 60% by weight of the product with the light fraction being 40% by weight. 

As indicated above, the plant consists of a VCC part and a depolymerisation part. Depolymerisation allows for further processing of the residues in the VCC section. The depolymerisation takes place between 350-400 °C. Here, at the same time chlorine is released. Over 80% of the chlorine input will become available as HCl in the light fraction and washed out in a purification process yielding technical HCl. 

From the description above it already can be deduced that this plant can deal with a lot of waste types and hence is rather robust in terms of acceptance criteria. S VZ has experience with treating mixed plastics waste, waste derived fuel (a mixture of plastics, wood and paper), the shredder light fraction of car wrecks, and the plastic fraction from shredded white goods and electronics. SVZ can handle on average 2% chlorine in MPW, with short-term excursions to 6%. The overall chlorine content has to be controlled by a right blend with other waste types. SVZ does not favour a high... 

A PVC-poor light fraction separated from mixed plastic household waste was pyrolysed to yield aromatic oils and heat-providing gas. Target products were benzene, toluene, xylenes, and styrene. Problematic pollutants were... 

The traditional use of SFE involved fractional extraction in which a selected group of oleoresin components is targeted. This technique makes it possible to extract subsequently the volatile oils (light fraction, under milder conditions, 120 bar, 40 C)... 

Particulate organic matter is transitoiy pool between fresh plant residues and humified organic matter (Gregorich and Janzen 1996). Often the term light fraction is used as a synonym for POM (von Lutzow et al. 2007). While POM and LF are similar, they are not equivalent fraction and have different C-, N-, O-alkyl contents (Gregorich et al. 2006). 

Boone RD (1994) Light-fraction soil organic matter origin and contribution to net nitrogen mineralization. Soil Biol Biochem 26 1459-1468... 

Bremer E, Janzen HH, Johnston AM (1994) Sensitivity of total light fraction and mineralizable organic matter to management practices in a Lethbridge soil. Can J Soil Sci 74 131-138... 

Gregorich EG, Drury CF, Ellert BH, Liang BC (1997b) Fertilization effects on physically protected light fraction organic matter. Soil Sci Soc Am J... 

Janzen HH, Campbell CA, Brandt SA, Lafond GP, Townley-Smith L (1992) Light-fraction organic matter in soils from long-term crop rotations. Soil Sci Soc Am J 56 1799-1806... 

Light fraction Undecayed plant and animal tissues and their partial decomposition products that occur within the soil proper and can be recovered by flotation with a liquid of high density... 

The relative concentration of the light fraction, diminished with time in all... 

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