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The Chemistry and Technology of Petroleum
From ac theory, the power factory is recognized as the cosine of the phase angle between the
voltage and current where a pure sine wave form exists for both; it increases with a use in temperature. When an insulating material serves as the dielectric of a condenser the power factor is
an intrinsic property of the dielectric. For practical electrical equipment, low-power factors for
the insulation are of course always desirable; petroleum oils are generally excellent in this respect,
having values of the order of 0.0005, comparable with fused quartz and polystyrene resins. The
power factor of pure hydrocarbons is extremely small. Traces of polar impurities, however, cause a
striking increase. All electrical oils, therefore, are drastically refined and handled with care to avoid
contamination; insoluble oxidation products are particularly undesirable.
10.5.5 stAtIC eleCtrIFICAtIon
Dielectric liquids, particularly light naphtha, may acquire high static charges on flowing through
or being sprayed from metal pipes. The effect seems to be associated with colloidally dispersed
contaminants, such as oxidation products, which can be removed by drastic filtration or adsorption.
Since a considerable fire hazard is involved that a variety of methods have been studied for minimizing the danger.
For large-scale storage, avoidance of surface agitation and the use of floating metal roofs on
tanks are beneficial. High humidity in the surrounding atmosphere is helpful in lowering the static
charge, and radioactive materials have been used to try to induce discharge to ground. A variety
of additives have been found that increase the conductivity of petroleum liquids, thus lowering the
degree of electrification; chromium salts of alkylated salicylic acids and other salts of alkylated
sulfosuccinic acids are employed in low concentrations, say 0.005%.
10.6 OPTICAL PROPERTIES
By optical property is meant the response of petroleum to exposure to electromagnetic radiation
and, in particular, to visible (VIS) light. Such properties, while not often used in the past are not
finding use in environmental cases.
Among their many impacts, oil pollutants modify light fields above and below the water surface.
These modifications are manifested by the attenuation of the light passing through an oiled water
surface by changes in light absorption in the seawater column due to the formation of an emulsion,
and by the scattering of light by particles of such an emulsion. The optical properties of an emulsion
can be described by the attenuation-specific cross-section and the absorption-specific cross-section,
which depend on the optical characteristics of the oil and the seawater, on the size distribution of oil
droplets and on their concentration.
In the case of pollution with fresh crude, the oil undergoes weathering, which alters its properties and, hence, changes in the optical properties of a petroleum-seawater emulsion due to oil
weathering.
10.6.1 reFrACtIve Index
The refractive index (RI) is the ratio of the velocity of light in a vacuum to the velocity of light in
the substance. The measurement of the RI is very simple (ASTM D1218), requires small quantities
of material, and, consequently, has found wide use in the characterization of hydrocarbons and
petroleum samples.
For closely separated fractions of similar molecular weight the values increase in the order paraffin, naphthene, and aromatic. For polycyclic naphthenes and polycyclic aromatics, the RI is usually higher than that of the corresponding monocyclic compounds. For a series of hydrocarbons of
essentially the same type the RI increases with molecular weight, especially in the paraffin series.
The Chemistry and Technology of Petroleum
From ac theory, the power factory is recognized as the cosine of the phase angle between the
voltage and current where a pure sine wave form exists for both; it increases with a use in temperature. When an insulating material serves as the dielectric of a condenser the power factor is
an intrinsic property of the dielectric. For practical electrical equipment, low-power factors for
the insulation are of course always desirable; petroleum oils are generally excellent in this respect,
having values of the order of 0.0005, comparable with fused quartz and polystyrene resins. The
power factor of pure hydrocarbons is extremely small. Traces of polar impurities, however, cause a
striking increase. All electrical oils, therefore, are drastically refined and handled with care to avoid
contamination; insoluble oxidation products are particularly undesirable.
10.5.5 stAtIC eleCtrIFICAtIon
Dielectric liquids, particularly light naphtha, may acquire high static charges on flowing through
or being sprayed from metal pipes. The effect seems to be associated with colloidally dispersed
contaminants, such as oxidation products, which can be removed by drastic filtration or adsorption.
Since a considerable fire hazard is involved that a variety of methods have been studied for minimizing the danger.
For large-scale storage, avoidance of surface agitation and the use of floating metal roofs on
tanks are beneficial. High humidity in the surrounding atmosphere is helpful in lowering the static
charge, and radioactive materials have been used to try to induce discharge to ground. A variety
of additives have been found that increase the conductivity of petroleum liquids, thus lowering the
degree of electrification; chromium salts of alkylated salicylic acids and other salts of alkylated
sulfosuccinic acids are employed in low concentrations, say 0.005%.
10.6 OPTICAL PROPERTIES
By optical property is meant the response of petroleum to exposure to electromagnetic radiation
and, in particular, to visible (VIS) light. Such properties, while not often used in the past are not
finding use in environmental cases.
Among their many impacts, oil pollutants modify light fields above and below the water surface.
These modifications are manifested by the attenuation of the light passing through an oiled water
surface by changes in light absorption in the seawater column due to the formation of an emulsion,
and by the scattering of light by particles of such an emulsion. The optical properties of an emulsion
can be described by the attenuation-specific cross-section and the absorption-specific cross-section,
which depend on the optical characteristics of the oil and the seawater, on the size distribution of oil
droplets and on their concentration.
In the case of pollution with fresh crude, the oil undergoes weathering, which alters its properties and, hence, changes in the optical properties of a petroleum-seawater emulsion due to oil
weathering.
10.6.1 reFrACtIve Index
The refractive index (RI) is the ratio of the velocity of light in a vacuum to the velocity of light in
the substance. The measurement of the RI is very simple (ASTM D1218), requires small quantities
of material, and, consequently, has found wide use in the characterization of hydrocarbons and
petroleum samples.
For closely separated fractions of similar molecular weight the values increase in the order paraffin, naphthene, and aromatic. For polycyclic naphthenes and polycyclic aromatics, the RI is usually higher than that of the corresponding monocyclic compounds. For a series of hydrocarbons of
essentially the same type the RI increases with molecular weight, especially in the paraffin series.