Fuel oil (possibly from Arabic مازوت - - 'scum') - a liquid product of dark brown color, a residue after separation of gasoline, kerosene and gas oil fractions from crude oil or its second-generation products boiling at up to 350-360°C.
Fuel-oil is a mix of hydrocarbons (with a molecular weight of 400 to 1000), petroleum resins (with a molecular weight of 500-3000 and more), asphaltenes, carbenes, carboides and organic compounds containing metals (V, Ni, Fe, Mg , Na, Ca). Physical and chemical properties of fuel-oil depend on the chemical composition of the original oil and the degree of stripping distillate fractions, and are characterized by the following data: viscosity of 8-80 mm²/s (at 100°C), density of 0,89-1 g/cm³ (at 20°C) pour point of 10-40°C, sulfur content of 0,5-3,5%, ash 0,3%, the lower calorific value of 39,4-40,7 MJ/mol.
Fuel-oils are used as fuel for steam boilers, boiler plants and industrial furnaces, for the production of marine fuel, heavy engine fuel for crosshead diesel engines, and bunker fuel. Fuel-oil yield makes about 50% of the feed oil based on the original weight. Due to the necessity of its further processing, oil is subjected to further treatment on an increasing scale, stripping distillates boiling in the range of 350-420, 350-460, 350-500 and 420-500°C in vacuum. Vacuum distillates are used as a raw material for production of motor fuels by catalytic cracking, hydrocracking - it is also used to produce distilled lubricants. Vacuum distillation residue is used for processing in the thermal cracking and coking units, in the production of residual lubricating oils and tar, then converted into bitumen.
The approximate component composition of commercial fuel oil may include:
- Fuel-oil from atmospheric distillation of crude oil;
- Vacuum gas-oils;
- Extracts from grease production;
- Kerosene-gas oil fractions (virgin and second-generation);
- Heavy gas-oils from catalytic cracking and coking;
- Visbreaking residue;
- Heavy pyrolysis resin.
The main consumers of fuel-oil are industry, navy and housing and utility services.