Analyse

Raman effect When light of frequency Vo is scattered by molecules of a substance, which have a vibrational frequency of j, the scattered light when analysed spectroscopically has lines of frequency v, where... 

As shown in Table 2.4, atomic absorption is extremely sensitive. It is particularly suited to the analyses of arsenic and lead in gasolines, for sodium in fuel oils (where it is the only reliable method) and for mercury in gas condensates. 

With the accumulation of results obtained from various and complex analyses of narrow cuts (Waterman method), correlations have been found f ctween refractive index, specific gravity and molecular weight on one hand, and percentages of paraffinic, naphthenic and aromatic carbon on the other. 

As the boiling points increase, the cuts become more and more complex and the analytical means must be adapted to the degree of complexity. Tables 3.4 and 3.5 describe the most widely used petroleum product separation scheme and the analyses that are most generally applied. 

Although gas chromatography can give the concentration of each component in a petroleum gas or gasoline sample, the same cannot be said for heavier cuts and one has to be satisfied with analyses by chemical family, by carbon atom distribution, or by representing the sample as a whole by an average molecule. 

For hydrocarbon studies, analyses can be made without prior assumptions, since the carbons not carrying protons can be excited directly, this of course not being the case for hydrogen (e.g., quaternary carbons in alkanes, substituted carbons in aromatic rings). 

It must be emphasized that NMR is first and foremost a tool for structural analysis and, in addition to the petroleum analyses described above, the technique (phosphorus NMR and sometimes nitrogen NMR) is abundantly used in all petrochemical synthesis operations. 

The analyst now has available the complete details of the chemical composition of a gasoline all components are identified and quantified. From these analyses, the sample s physical properties can be calculated by using linear or non-linear models density, vapor pressure, calorific value, octane numbers, carbon and hydrogen content. 

Nevertheless, within the same work group, once the chromatographic procedures are established, SARA analyses are very often performed to characterize heavy feedstocks or to follow their conversion. 

Nevertheless, this type of analysis, usually done by chromatography, is not always justified when taking into account the operator s time. Other quicker analyses are used such as FIA (Fluorescent Indicator Analysis) (see paragraph 3.3.5), which give approximate but usually acceptable proportions of saturated, olefinic, and aromatic hydrocarbons. Another way to characterize the aromatic content is to use the solvent s aniline point the lowest temperature at which equal volumes of the solvent and pure aniline are miscible. 

Composition is normally expressed by a distillation curve, and can be supplemented by compositional analyses such as those for aromatics content. Some physical properties such as density or vapor pressure are often added. The degree of purity is indicated by color or other appropriate test (copper strip corrosion, for example). 

Sometimes analyses are required for particular compounds such as sulfur, chlorine and lead, or for specific components such as mercaptans, hydrogen sulfide, ethers and alcohols. 

The aromaUc extracts are sought mainly tor their solvent power. They are characterized particularly by componential analyses such as the separation according to hydrocarbon family by liquid phase chromatography. 

New analytical methods. From this point of view, the development of instrument technology is emphasized that provides either gains in productivity or quality, or more advanced analyses. 

The determination of properties for each cut enables curves to be obtained for yields and properties as well as curves for iso-properties that are useful in the economic analyses of crude oils. 

Oelert, H.H. (1971) "Entwicklung und Anwendung einer auf IR-NMR Spektroskopie und elemental Analyse beruhenden Strukturgruppenanalyse fiir hohersiedende Kohlenwasserstoffgemische und Mineralolanteile". Z Anal. Chem., Vol. 255, p. 177. 

Analysing the distribution of elements and compounds related to petroleum occurrences... 

The formation cuttings that are ohipped off by the bit travel upward with the mud and are caught and analysed at the surface. This provides information about the lithology and qualitative indications of the porosity. 

If there are hydrocarbons present in the formation that is being drilled, they will show in the cuttings as oil stains, and in the mud as traces of oil or gas. The gas in the mud is continuously monitored by means of a gas detector. This is often a relatively simple device detecting the total combustible gas content. The detector can be supplemented by a gas chromatograph, which analyses the composition of the gas. 

The failure mode of an equipment item describes the reason for the failure, and is often determined by analysing what causes historic failures in the particular item. This is another good reason for keeping records of the performance of equipment. For example, if it is recognised that a pump typically fails due to worn bearings after 8,000 hours in operation, a maintenance strategy may be adopted which replaces the bearings after 7,000 hours if that pump is a critical item. If a spare pump is available as a back-up, then the policy may be to allow the pump to run to failure, but keep a stock of spare parts to allow a quick repair. 

A technique widely used by the industry is Critical Path Analysis (CPA or Network Analysis ) which is a method for systematically analysing the schedule of large projects, so that activities within a project can be phased logically, and dependencies identified. All activities are given a duration and the longest route through the network is known as the critical path. 

More difficult it is to analyse and value the acoustic emission signals which are originated from the casting part and the child mold during the casting process (fig. 6 below). Only an... 

To analyse and evaluate the acoustic emission signals send out from the casting part and the child mold, which means to determine informative characteristic values a conception was realized which contains as well four partial steps (fig. 7, right). 

The last part, following the method to analyse radioscopy and acoustic emission values, will be to correlate the characteristic values of the radioscopic detection of casting defects with extracted characteristic values of the acoustic emission analysis. The correlation between the time based characteristic values of acoustic emission analysis and the defect characterizing radioscopy values did not come to very satisfactory results referring the low frequency measurements. The reason can be found in the... 

The application of load in materials produces internal modifications such as crack growth, local plastic deformation, corrosion and phase changes, which are accompanied by the emission of acoustic waves in materials. These waves therefore contain information on the internal behaviour of the material and can be analysed to obtain this information. The waves are detected by the use of suitable sensors, that converts the surface movements of the material into electric signal. These signals are processed, analysed and recorded by an appropriate instrumentation. 

The vessels will be pressurised up to 1,1 - 1,25 fold of the normal service pressure of the drums, within stress increments of 50 kPa (0,5 bar) and a constant and smooth slope of less than 10 kPa.min . During the complete test the data will be acquired, stored and analysed. 

Afterwards, the vessels were pressurized according a proof test and a burst test with acoustic emission measurements. Acoustic emission data recorded during these tests are analysed in order to determine assessment criteria. The criteria are mainly based on ... 

---