Oil - the liquid from light brown (almost colorless) to dark brown (almost black) color (even though there are examples of emerald-green oil). The average molecular weight of 220-300 g / mol (rare 450-470). Density 0,65-1,05 (0,82-0,95 usually) g / cm ³; oil whose density is lower than 0.83, is called light, 0,831-0,860 - average above .860 - heavy. The density of oil, as well as other hydrocarbons, is strongly dependent on temperature and pressure [9]. It contains a large number of different organic substances and therefore not characterized by a boiling point, and the initial boiling point of liquid hydrocarbons (typically> 28 ° C, at least ≥ 100 ° C in the case of heavy oils) and fractional composition - Out separate fractions, distilled first at atmospheric pressure and then under vacuum in certain temperature range, usually up to 450-500 ° C (boiling over ~ 80% of the sample), at least 560-580 ° C (90-95%). The crystallization temperature of -60 to + 30 ° C; depends primarily on the content of petroleum wax (what it is, the higher the crystallization temperature) and light fractions (the more, the lower the temperature.) Viscosity varies widely (from 1.98 to 265.90 mm ² / s for various oil produced in Russia), determined the fractional composition of oil and its temperature (the higher and higher the number of light ends, the lower the viscosity), and content of resin-asphaltene substances (the more, the viscosity of the above). Specific heat capacity of 1.7-2.1 kJ / (kg ∙ K), specific heat (low) 43,7-46,2 MJ / kg, the dielectric constant of 2.0-2.5, the electric conductivity of the [specific] from 2 ∙ 10-10 to 0,3 ∙ 10-18 ohm-1 ∙ cm-1.
Oil - a flammable liquid, the flash point of - 35 [10] to +121 ° C (depending on the fractional composition and its content of dissolved gases). Oil soluble in organic solvents, in normal circumstances, is insoluble in water, but it can form stable emulsions. The technology to separate oil from water and dissolved salts conduct dehydration and desalting.
The chemical composition
Main article: List of crude oil products
The overall composition
Petroleum is a mixture of about 1,000 individual substances of which the majority - liquids (> 500 substances or usually 80-90% by weight) and heteroatomic organic compounds (4-5%), mainly sulfur (about 250 agents), nitrogen (> 30 substances) and oxygen (85 substances), and organometallic compounds (mainly vanadium and nickel), and the remaining components - dissolved hydrocarbon gases (C1-C4, from tenths to 4%), water (from trace to 10% ), mineral salts (mainly chlorides, 0,1-4000 mg / l or more), solutions of salts of organic acids, etc., mechanical impurities.
hydrocarbon composition
Basically in paraffin oil are (usually 30-35, sometimes 40-50% by volume) and naphthenic (25-75%). To a lesser extent - aromatic compounds (10-20, at least 35%) and mixed or hybrid, structure (eg, paraffin-naphthenic, naphthene-aromatic).
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