Crude basic composition

Understanding the factors that inhibit the foaming power is of great importance, because it yields a basic knowledge— how the materials produced will perform with respect to foaming. It also serves to predict how individual crude oil compositions would work with different defoamers [301]. 

Fig. 6. Basic schemes for Lurgi gas production, the fundamental technology of which dates back to the era of "artificial" gas. The process shown here (circa early 1970s) permitted selection of various gasifiers and/or changing operating pressures to influence the final crude gas composition, as dictated by the end use and economics. [Lurgi Kt>hie und Mmerabtechnik GmbH. Frankfurt, Germany)...

The composition of crude oil may vary with the location and age of an oil field, and may even be depth dependent within an individual well or reservoir. Crudes are commonly classified according to their respective distillation residue, which reflects the relative contents of three basic hydrocarbon structural types paraffins, naphthenes, and aromatics. About 85% of all crude oils can be classified as either asphalt based, paraffin based, or mixed based. Asphalt-based crudes contain little paraffin wax and an asphaltic residue (predominantly condensed aromatics). Sulfur, oxygen, and nitrogen contents are often relatively higher in asphalt-based crude in comparison with paraffin-based crudes, which contain little to no asphaltic materials. Mixed-based crude contains considerable amounts of both wax and asphalt. Representative crude oils and their respective composition in respect to paraffins, naphthenes, and aromatics are shown in Figure 4.1. 

Petroleum is typically described in terms of its physical properties (such as density and pour point) and chemical composition (such as percent composition of various petroleum hydrocarbons, asphaltenes, and sulfur). Although very complex in makeup, crude can be broken down into four basic classes of petroleum hydrocarbons. Each class is distinguished on the basis of molecular composition. In addition, properties important for characterizing the behavior of petroleum and petroleum products when spilled into waterways or onto land and/or released into the air include flash point, density (read specific gravity and/or API gravity), viscosity, emulsion formation in waterways, and adhesion to soil. 

Introduction of zeolites into catalytic cracking improved the quality of the product and the efficiency of the process. It was estimated that this modification in catalyst composition in the United States alone saved over 200 million barrels of crude oil in 1977. The use of bimetallic catalysts in reforming of naphthas, a basic process for the production of high-octane gasoline and petrochemicals, resulted in great improvement in the catalytic performance of the process, and in considerable extension of catalyst life. New catalytic approaches to the development of synthetic fuels are being unveiled. 

An historical aside may clarify the issues. In the medical tradition that went from the ancients (Hippocrates and Galen) through the Middle Ages until the Enlightenment, physicians basically thought about disease in terms of mechanism. The conventional theory of humors was a crude attempt to describe illness in terms of imbalances in body composition, before the invention of modern chemistry and biochemistry. 

The cracking of naphtha produces most of the world s ethylene. Naphtha is the crude oil fraction boiling Irom about 32°C to 192°C. The composition of naphtha made from crude oil comprises four basic components linear paraffins, branched paraffins, naphthenes (cyclo-paraffins) and aromatics. The relative amount of these in naphtha is dependent on the source crude oil and varies widely. 

An additional major problem with natural membrane systems is that the composition of the one-dimensional unit cell may be unknown because of the presence of proteins of unknown structure and composition. Nevertheless, it is possible to model the electron density profile of a multilamellar system to arrive at a crude model for the distribution of lipids and proteins. The models improve considerably if the lipid composition and lipid stmctures are known. In any case, the basic crystallographic structural method is used The model is refined on the basis of comparisons between the calculated and the experimentally determined intensities through an iterative process. 

The operating conditions for solid-state fermentation for cellulase production are dependent on the strain to be used, the reactor type and the medium composition, but the basic operating procedure remains the same as shown in Fig. 2. The final product can be obtained as crude solid cellulase, liquid cellulase or powder cellulase according to the application. Figure 3 shows a process flowsheet for cellulase production [25]. In the process, wheat bran is used as substrate. Seeds are prepared in a stirred-tank fermentor and then sprayed into the medium by a spray distributor. The fermentation is performed in a shallow-tray fermentor. The temperature and humidity in the fermentor are automatically regulated. After fermentation, cellulase is recovered by water extraction and purified by salt precipitation and ion exchange. The final product is concentrat-... 

The material offered in this chapter is intended to provide some basic insight into the manner in which petroleum lubricants are prepared from crude oil and how the composition of a lubricating fluid thus obtained correlates with its properties. It is only a summary of a subject which would require several volumes for adequate treatment. Particular emphasis will be put on the relations of chemical structures in lubricating oils to classificatory properties and to performance in service. 

The following review presents the chemical demulsifi-cation of W/O emulsions by first introducing crudes and bitumens in terms of the diagenetic diversity and chemistries of their components. Based on the premise that a full appreciation of demulsification must be preceded by an understanding of the basics of the field and laboratory emulsions, we have reviewed demulsifica-tion and some of the characteristics of light crude, heavy oil, and bitumen emulsions researched globally. Thus, in this work the composition and behavior of the natural emulsifiers present in the crudes and some factors responsible for emulsification in the field and laboratory are addressed first. 

Pelroy and Petersen 41) recently demonstrated how complex organic mixtures such as shale oil may produce variable responses in the Ames Salmonella assay depending upon the composition of the chemical mixture. In the presence of the PAH fraction of shale oil, the mutagenicity of dimethylbenzacridine was inhibited by 75% however, in the presence of the basic fraction of shale oil, dimethylbenzacridine mutagenicity was reduced by only 22%. The basic fraction of shale oil contained primarily alkyl-substituted pyridines, anilines, pyrroles, and quinolines. The basic fraction was more mutagenic by itself than any of the other fractions (acidic, neutral, tar, PAH, crude shale oil) tested. 

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