Petroleum oil is a multicomponent mixture of the hydrocarbons and heteroatomic compounds, which consists of thousands of components and boils in a wide range of temperatures (30…700оС). It is not possible to split it to separate compounds by the usual methods. Petroleum oil and its products are split by distillation into fractions (distills), every such fraction is simpler mixture and boils in narrow range of temperatures in comparison to raw petroleum oil. Petroleum oil and its fractions are characterized not by the boiling temperature, but by the limits of the start and the end of boiling.
As a result of atmosphere distillation of the petroleum oils are received the fractions, which boils at temperatures from 30 to 350-360 °С, the mazut is received as residue. From the fractions, which boils below 360 °С, are usually obtained fuels (gasoline, jet fuels and diesel fuel), raw materials for petrochemical synthesis (benzene, ethylbenzene, xylene, ethylene, butadiene), solvents etc. The general fractions are next:
- Gasoline fraction, which boils in range from 40 to 200 °С, contains hydrocarbons from С5Н12 to С11Н24. By further distillation of this fraction can be obtained gasoline (Tboil – 40-70 °С), petrol (Tboil – 70-120 °С) – aviation petrol, automobile petrol etc.
- Ligroin fraction, collects from 150 to 250 °С, contains hydrocarbons from С8Н18 to С14Н30. Ligroin is used like a fuel for tractors. Most part of ligroin is usually recycled into petrol.
- Kerosene fraction contains hydrocarbons from С12Н26 to С18Н38 with boiling temperature from 180 to 300 °С. Kerosene after refining is usually used as fuel for tractors, reactive airplanes and rockets.
- Gasoil fraction (Tboil > 275 °С), in other words it is called diesel fuels
- The residue after the distillation of petroleum oil – mazut – contains hydrocarbons with big quantity of atoms of carbon (up to many dozens) in one molecule. Mazut can also be separated for fractions by the process of rectification under low pressure, to avoid decomposition. As a result straw oil (diesel fuel), lubricating oils (auto-tractor, aviation, industrial etc.), Vaseline (technical Vaseline is used for lubricating of metal goods with the purpose of the avoidance them from corrosion. Purified Vaseline is used as basis for cosmetic facilities and in medicine). From some sorts of petroleum oil paraffin is received (for the production of matches, candles etc.). Goudron remains after distillation of volatile matters from the mazut. Goudron is widely applicated in road building. In addition to recycling of mazut as lubricating oils, it is also used as a liquid fuel in boiler installations.
With the usage of the rectification column SARGAS the petroleum oil can be distilled for the standard fractions (kerosene, petroleum, diesel, mazut etc.) or any other number of fractions. Also it is possible to extract fraction of solvents. In basic packaging the rectification column is equivalent to 8 theoretical plates, the reflux number is possible to set during the process over the range from 1/14 to 14. At the same time accuracy of rectification with the reflux number 2 fits or even better than requirements of State Standards for petroleum oil fractions.
