Cracking is the process of destructive refining of oil or its fractions, carried out to increase the yield of light products and improve their quality.
Cracking proceeds is not eco frendly by breaking the C-C bonds to form free radicals or carbanions.
Dehydrogenation, isomerisation, polymerisation and condensation of both intermediates and starting substances occur simultaneously with the breaking of C-C bonds.
The latter 2 processes lead to the formation of the so-called cracking residue (fraction with a boiling point above 350 °C) and petroleum coke.
The world's first industrial plant for continuous thermal cracking of crude oil was created and patented by engineer V. G. Shukhov and his assistant S. P. Gavrilov in 1891.
An experimental installation was made.
The scientific and engineering solutions of V.G. Shukhov were repeated by W. Barton during the construction of the 1st industrial installation in the USA in 1915-1918.
The 1st domestic industrial cracking installations were built by V.G. Shukhov in 1934 at the plant "Soviet cracking" in Baku.
Cracking is carried out by heating the oil feedstock or by simultaneously exposing it to high temperatures and catalysts.
In the first case, the process is used to obtain:
- Gasoline (low-octane components of motor fuels) and gasoil (components of bunker fuel, gas turbine and furnace fuels) fractions
- Highly aromatic crude oil in the production of technical carbon (carbon black) and alpha-olefins (thermal cracking);
- Heating oil, motor fuel and diesel fuel (visbreaking);
- petroleum coke;
- Hydrocarbon gases, petrol and kerosene/gasoline fractions;
- ethylene, propylene
- Aromatic hydrocarbons (pyrolysis of crude oil).
In the 2nd case the process is used to produce:
- base components of high-octane gasoline, gasoil, hydrocarbon gases (catalytic cracking)
- gasoline fractions,
- jet and diesel fuels,
- petroleum oil,
- feedstock for pyrolysis of oil fractions and catalytic reforming processes (hydrocracking).
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