Oil and natural gases, these unique minerals, are the main sources of hydrocarbons. Crude oil is a complex mixture of hydrocarbons with other compounds. Oil refining produces products that are then applied to all industries, energy, agriculture and household.
Crude oil is separated into its constituent parts by simple, fractional and vacuum distillation. The composition of the fractions obtained in this case depends on the composition of the original crude oil.
Oil refining goes through several stages: fractional distillation, reforming, cracking and sulfur removal.
Fractional distillation is the very first stage of processing, which divides it into fractions: gas, light, medium and fuel oil. Thus, primary oil refining allows you to immediately identify the most valuable fractions.
- The gas fraction is unbranched simple hydrocarbons: butanes, propane and ethane.
- A gasoline or light fraction is a mixture of various light hydrocarbons, including branched and unbranched alkanes.
- Fuel oil remains after distillation of all other lighter fractions.
Further oil refining is carried out using the cracking method. In this case, the splitting of high molecular weight crude oil compounds into smaller ones characteristic of low boiling fractions occurs. This important processing method allows to obtain an additional amount of low boiling oil fractions, the demand for which, especially in gasoline, is extremely high.
- In industry, several types of cracking are used: catalytic, thermal and reforming. During thermal cracking, high molecular weight compounds from heavy oil fractions break down into low molecular weight compounds under the influence of high temperatures. Oil refining by cracking, both thermal and catalytic, provides a mixture of unsaturated and saturated hydrocarbons. Using the octadecane as an example, the cracking process can be described by the formula:
C 18 H 38 -> C 9 H 20 + C 9 H 18
At temperatures up to 1000 ° C, thermal decomposition of high molecular weight oil products occurs, as a result of which mainly light alkenes and aromatic hydrocarbons are obtained .
- Catalytic cracking takes place at relatively low temperatures, while the catalyst is a mixture of alumina and silica. In this case, a mixture of saturated and unsaturated hydrocarbons is also obtained. Oil refining using this method is used to produce high-quality gasoline.
- Reforming changes the structure of molecules or combines them into larger ones. In the process, low-quality low molecular weight oil fractions are converted, in particular, into high-grade gasoline fractions.
Natural and associated gases are a mixture of methane (up to 90% by volume) and its nearest homologues, as well as a small amount of impurities.
The main task of gas processing is the conversion of the saturated hydrocarbons contained therein to non-saturated ones , which can be further used in chemical synthesis.
Thus, the processing of oil and gas allows you to get an extremely large assortment of various petroleum products, from which chemical synthesis yields a huge variety of substances used in various sectors of the country's economy.