There are primary and secondary methods of oil processing.
The methods of refining oil and liquid petroleum products are divided into two groups: physical and chemical.
Physical methods of processing consist in the fact that individual hydrocarbons are obtained from oil or oil products, or more often their mixtures based on the difference in their physical properties - boiling point, crystallization temperature, solubility, etc. The so-called direct distillation of oil and oil products, based on the difference in the boiling temperatures of individual fractions of oil, has become the most widespread.
Chemical methods are based on deep chemical destructive transformations that hydrocarbons contained in oil or oil products undergo under the influence of temperature, pressure, and catalysts. Among these methods, various types of cracking have become the most popular.
The equipment used for physical and chemical processing of oil and oil products must provide, firstly, heating to a high temperature and, secondly, separation of the obtained products. For some chemical processing methods involving catalytic processes, contactors are required.
The heating of oil or petroleum products is carried out mainly in tube furnaces, in which the transfer of heat from the heating gases to the material being processed is carried out through the walls of the radiant tubes by radiation from the flame, incandescent gases, as well as from the vault and by convection through the walls of the convection tubes .
Separation of oil refining products is carried out mainly by rectification in different types of rectification columns. Columns with bubbling caps became the most popular. The peculiarity of the rectification columns of oil refining plants is that they are several simple independent columns placed on top of each other with liquid height selection. The liquid enters the evaporation sections located outside the column and is treated with steam in them. At the same time, vapors of low-boiling fractions are obtained, which are returned to the column and a liquid petroleum product, or distillate. Rectification columns work at elevated or atmospheric pressure, as well as under vacuum.
Catalytic processes of oil refineries are carried out in contact devices of various designs. As a rule, the catalyst in these processes loses its activity very quickly, and therefore the contact nodes include contact devices and regenerators. Contact devices and regenerators with a filter layer of a catalyst, a fluidized bed and with a moving catalyst are operated.
In addition to the specified main devices, the installations have heat exchangers, condensers, storage and other devices.
Direct atmospheric-vacuum distillation of oil. Dehydrated oil is subjected to atmospheric-vacuum distillation: the distillation of light fractions (gasoline, kerosene, kerosene, gas oil) is carried out at atmospheric pressure, and the distillation of fuel oil with the separation of oils (spindle, machine, cylinder) is carried out under vacuum. Modern oil distillation plants use the method of one-time heating of processing products in tubular furnaces with subsequent feeding of the heated mass into the rectification column. The column is irrigated with the lightest fraction and several different fractions are selected from it. For more efficient operation, superheated water vapor is supplied to the column, which does not mix with petroleum products and is easily separated.