Crude fractionation

A key process in the production of gasoline, catalytic reforming is used to increase the octane number of light crude fractions having high paraffin and naphthene contents (C7-C8-C9) by converting them to aromatics. 

Vor-zerkleinerung, /. preliminary crushing, -zerlegung, /. preliminary decomposition crude fractionation. 

Crude fraction Boiling point, °F (melting point) Approximate chemical composition Uses... 

Sulfur in crude oils is mainly present in the form of organosulfur compounds. Hydrogen sulfide is the only important inorganic sulfur compound found in crude oil. Its presence, however, is harmful because of its corrosive nature. Organosulfur compounds may generally be classified as acidic and non-acidic. Acidic sulfur compounds are the thiols (mercap-tans). Thiophene, sulfides, and disulfides are examples of non-acidic sulfur compounds found in crude fractions. Extensive research has been carried out to identify some sulfur compounds in a narrow light petroleum fraction.Examples of some sulfur compounds from the two types are ... 

As noted above, whole-cell MALDI-TOF MS was intended for rapid taxonomic identification of bacteria. Neither the analysis of specific targeted bacterial proteins, nor the discovery of new proteins, was envisioned as a routine application for which whole cells would be used. An unknown or target protein might not have the abundance or proton affinity to facilitate its detection from such a complex mixture containing literally thousands of other proteins. Thus, for many applications, the analysis of proteins from chromatographically separated fractions remains a more productive approach. From a historical perspective, whole-cell MALDI is a logical extension of MALDI analysis of isolated cellular proteins. After all, purified proteins can be obtained from bacteria after different levels of purification. Differences in method often reflect how much purification is done prior to analysis. With whole-cell MALDI the answer is literally none. Some methods attempt to combine the benefits of the rapid whole cell approach with a minimal level of sample preparation, often based on the analysis of crude fractions rather... 

It is not normally prudent to employ biospecific affinity chromatography as an initial purification step, as various enzymatic activities present in the crude fractions may modify or degrade the expensive affinity gels. However, it should be utilized as early as possible in the purification procedure in order to accrue the full benefit afforded by its high specificity. 

Neural Networks using Genetic Algorithm for On-Line Property Estimation of Crude Fractionator Products. 

The partition of different lipids between two immiscible solvents (countercurrent distribution) is useful for crude fractionation of lipid classes with greatly differing polarities. Repeated extractions in a carefully chosen solvent pair increase the effectiveness of the separation but in practice mixtures of lipids are still found in each fraction. A petroleum ether-ethanol-water system can be used to remove polar contaminants (into the alcoholic phase) when interest lies in the subsequent analysis of neutral glycerides, which may be recovered from the ether phase. Carbon... 

In the initial experiments, we resolved reticulocyte lysates on DEAE-cellulose into two crude fractions Fraction 1, which contained proteins not adsorbed to the resin, and Fraction 2, which contained all proteins adsorbed to the resin and eluted with high salt. The original aim of this fractionation was to get rid of hemoglobin, which was known to be in Fraction 1, while most non-hemoglobin proteins of reticulocytes were known to be in Fraction 2. We found that neither fraction was active by itself, but ATP-dependent protein degradation could be reconstituted by combination of the two fractions [13]. The active component in Fraction 1 was a small, heat-stable protein we have exploited its stability to heat treatment for its purification to near homogeneity. We termed this protein at that time APF-1, for ATP-dependent Proteolysis Factor 1 [13]. The identity of APF-1 with ubiquitin was established later by Wilkinson et al. [14], subsequent to the discovery in my laboratory of its covalent ligation to protein substrates, as described below. 

On February 23, 1999, a flash fire occurred at the Tosco Avon, California refinery killing four workers and critically injuring one other. The accident occurred while a critical piping repair job was underway on the crude fractionation unit. A small naphtha leak had been reported on February 10, but almost two weeks had lapsed while workers attempted to isolate the circuit and physically remove a corroded section of line. The unit remained in production while this work was taking place. 

Figure 3 Crude fractionation (crude distillation, three stages). An atmospheric fractionating stage produces lighter oils. An initial vacuum stage produces lube oils. A second vacuum stage fractionates bottoms from the other stages to produce asphalt and catalytic cracker feed. (From Ref. 5.)...

Toxicity of crude fractions from Prorocentrum concavum. All four crude fractions extracted from concavum (SIU strain 364) (Figure 3b) consistently contained potent toxln(s). The results of mouse bloassay of these fractions are Included in Tables IV. Corresponding dose response curves and LD q s are shown in Figure 4. 

Nakajlma and coworkers (20) reported an ether soluble extract from concavum to be slightly toxic to mice but provided little additional information. Crude fractions containing ciguatoxin obtained from moray eel (Gymnothorax javanicus) and toxlcus from the Pacific were reported to have LD q s of 12.2 mg/kg and 28.1 mg/kg, respectively (37). These compare well with the LD q of 8.3 mg/kg for similarly purified ESAF from concavum. 

Table V. A Comparison of The Four Crude Fractions and Their Respective Toxic Components From Prorocentrum concavum Using Analytical and Preparative TLC.

Analysis of the Mixture of Organic Compounds from the Soil. The crude fractions were analyzed using a LKB-2091 capillary gas chromatograph/mass spectrometer/data analysis system (CGC/MS/DA). The capillary column used was a J W DB-1, 60 m x 0.32 mm, connected directly to Ae ion source of the mass spectrometer. Up to 1.0 tfL of a solution of the sample in an appropriate solvent was injected directly onto the column at 40 °C, whereupon the column temperature was immediately raised to 100 for 4 min, and programmed to 310 °C at a rate of 10°/min. and held there for 30 min. 

Thin-layer chromatography (75) and sodium dodecylsulfate-(poly)acrylamide gel electrophoresis (SDS-PAGE) are helpful for analyses of the lipid and protein composition, respectively. Size-exclusion chromatography allows estimation of the size distribution of the (proteo)liposomes and crude fractionation of the material as reviewed in Ref. 76. Accurate determinations of size distributions require analyses by static or dynamic... 

Before discussing the various derivatives that have been used, it should be remembered that oligosaccharides are often obtained by chromatography on paper or on cellulose columns, and this may cause them to become contaminated by xylan this may be eliminated by extraction of the crude fractions with hot ethanol.474 For similar reasons, glucose that is really extraneous may be detected in fractions separated by electrophoresis on cellulose acetate.475 Gas-liquid chromatography was used to show the presence in pituitary glyco-... 

The microcrystalline or amorphous waxes separated from the crude fractions boiling above paraffin distillate are predominantly of the naphthene-containing paraffin structure (62, 70). Thus urea adducting of 149° to 165° F. melting point wax (Superla of Indiana) isolated but 15% of adductive material assumed to be normal or terminally branched paraffins. The microcrystalline waxes consist mostly of hydrocarbon with 34 to 60 carbon atoms (70) and have a melting range from 140° to 200° F. (16). 

In addition, residues of corticosteroids can be cleaned up through application of a three-phase liquid-liquid partition system consisting of acetonitrile, hexane, and dichloromethane. Since its inception, this procedure has been used successfully to perform a fast, crude fractionation of tissue components and drugs extracted from tissue homogenates into the aqueous acetonitrile supernatant. Non-... 

From this equation It is evident that the parameters which control the falling velocity of water particle are the droplet else, density difference and viscosity of oil. Application of heat will reduce the oil gravity as well as viscosity. However, heat will cause loss of lighter crude fractions. Thus, adjusting the crude viscosity and gravity hy heat has economic limits. Therefore, the most practical approach would be to attempt to increase the particle size. 

The distillate product would become increasingly contaminated with heavier components. If this were a refinery crude fractionator, we would say that the endpoint of the naphtha overhead product would increase. 

Alternatively, a crude fraction boiling at 160-185° is collected on redistillation, the product which boils at 181-184° is collected (Read and Foster). 

When the mixture contains larger molecules, it is a liquid at normal temperatures and pressures. A typical crude oil contains thousands of different chemical compounds, and trying to separate it into different chemicals is impractical. Therefore, the crude oil normally is separated into crude fractions according to the range of boiling points of the compounds included in each fraction. Table 1-2 gives a list of the typical fractions which are separated from crude oil. 

Following differential sedimentation, proteins may be separated into crude fractions by the addition of increasing amounts of (NH4)2S04. Specific proteins characteristically precipitate in a limited range of salt concentrations. 

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