Overview. Used marine fuel oil, depending on the method of their preparation is subdivided into two types – distillate and heavy. Distillate fuels are composed of light fractions obtained by distillation in plants for oil refining, are characterized by low viscosity, v = 3 h-6 mm2 / s, so do not need to be heated before it enters the engines or boilers. Heavy fuels are mixtures consisting of residues oil and distillates. Depending on the ratio of light and heavy components of the viscosity of heavy fuels, like others their performance varies widely. In Russia, the quality of fuels is regulated state standards and specifications Abroad quality fuels specifications determined firms supplying the British (BS 2869: 1967) and American (A5> TM-D975 and D396-67). Began in the 70's, and increasingly distributed the process of engaging in the production of fuel products recycling of oil demanded the revision of existing standards and specifications, the expansion of the limit values of quality and attract additional indicators (such as the aluminum content, stability and compatibility of fuels, etc.).
Distillate fuel. Due to limited resources and high cost of distillate price in Class distillate diesel fuel in Russia at approximately 1.7 times the price of heavy fuels. While ensuring the ship heavy fuel causes premature repair of marine diesel engines. Consumption of diesel fuel ships the Navy is only 6-12% of the total fuel burned. Its mainly used to support medium-and high-speed diesel engines, which either by design or because of unsuitability of (no shipping unit for heating fuel) can not be transferred to the heavier grades. In dg diesel fuel used exclusively during the maneuver and to flushing the fuel system, before stopping. The domestic industry produces marine fuel in accordance with gost 305-82 by mixing fractions of the direct distillation of sulfur oils, hydrotreated and dewaxing, with a catalytic gasoil.
The presence of a catalytic gas oil, reduce operating fuel properties, in particular increasing its propensity to deposits. Fuels produce four grades: A, 3, ap, A that the sulfur is divided into two subgroups: with S%, with S == 0,21 – 0,5%. The content of mercaptan sulfur in the sulfur of both subgroups is limited to 0.01%. As a substitute for diesel fuel in ships of sea and river fleet wide using gas-turbine fuel (GOST 10433-75). Fuel obtained as a byproduct in the process of delayed coking unit in the development of petroleum coke, the necessary metallurgical industry. Gas Turbine Fuel tg and tgvk have a higher density and viscosity, but not so high that they had to be heated before use. For these fuels have higher sulfur content (1 and 2.5% respectively) and for that should be paid attention by themselves, they contain up to 25% tar. This leads to their low stability, manifested by heating and mixing with other fuels. Since 1988, the oil industry began to supply the navy ship low-viscosity oil designed to replace diesel and gas turbine fuels. This fuel is produced by mixing the distillate of secondary processes (coking, thermal and catalytic cracking) from the diesel fraction with a high end boiling point, taken from the atmospheric and vacuum columns. Compared with diesel fuel to it impose less stringent requirements (allowed twice high viscosity-11 mm2 / s, the sulfur content of up to 1.5%, lower tsch – not less than 40).