oil is separated into fractions to obtain the oil in two stages, i.e. petroleum distillation passes through the primary and secondary processing.
process of primary refining
At this stage, the distillation is performed prior dehydration and desalting of crude oil on the special equipment to extract salts and other contaminants that may cause corrosion of the equipment and reduce the quality of petroleum products.Thereafter, the oil contained 3-4 mg salt per liter and not more than 0.1% water.The prepared product is ready for distillation.
Due to the fact that liquid hydrocarbons boiling at a different temperature, this property is used in petroleum refining to isolate its individual fractions at different stages of the boil.Distillation of the oil refineries in the first made it possible to allocate the following fractions, depending on the temperature of petrol (boils at 180 ° C and below), jet fuel (boils at 180-240 ° C) and diesel oil (boiling at 240-350 ° C).From the distillation of crude oil remains oil.
During distillation oil is separated by boiling points into fractions (components).The result is a commodity petroleum products or their components.Distillation of the oil is the initial stage of its processing at specialized plants.
On heating the vapor phase is formed, the composition of which is different from the liquid.The resulting oil distillation fractions are typically not pure product as a mixture of hydrocarbons.Some hydrocarbons can be distinguished only by repeated distillation of petroleum fractions.
straight distillation of crude oil runs
- flash evaporation method (so-called equilibrium distillation) or simple distillation (fractional distillation);
- with and without a rectification;
- using a volatile agent;
- under vacuum and at atmospheric pressure.
equilibrium distillation less clearly separates oil fractions than simple distillation.In the vapor state at the same temperature in the first case moves more oil than in the second.
Fractional distillation of the oil gives the possibility to obtain various fuels (gasoline, diesel fuel and jet fuel), and the raw material (benzene, xylenes, ethylbenzene, ethylene, butadiene, propylene), solvents, and other products.
Next, you have secondary oil refining of the products obtained, the so-called cracking.
secondary refining process
secondary oil refining is carried out by chemical or thermal catalytic cleavage of those products that isolated from it as a result of the primary oil distillation.Thus, a greater quantity of gasoline fractions, as well as raw materials for the production of aromatic hydrocarbons (toluene, benzene, and others).The most common technique is a secondary refining of oil cracking.
cracking process called high-temperature processing of oil and fractions allocated for (mainly) products that have a lower molecular weight.These include motor fuel, lubricating oil and so on. N., The raw material for the petrochemical and chemical industries.The course runs from cracking break CC bonds and the formation of free radicals or carbanions.The gap of the C-C is performed simultaneously with the dehydrogenation, isomerization, and polymerization by condensation of intermediates and starting materials.The latter two processes form a cracked residue, i.e.fraction boiling above 350 ° C and coke.
Distillation of oil cracking method was patented in 1891 by VG Shukhov and S. Gavrilov, then these engineering solutions repeated W. Barton in the construction of the first US plant.
Cracking raw materials is carried out by heating or exposure to high temperature and catalysts.
Cracking allows you to select from the oil more useful components.
