Diesel fuel
Diesel fuel is a liquid product used as a fuel in a diesel internal combustion engine and in a gasoline engine. This type of fuel is obtained from the kerosene-gasoil fractions of direct distillation of crude oil. Diesel fuel is a mixture of alkanes, cycloalkanes and aromatic hydrocarbons and their derivatives. The average molecular weight is 110-230, and the boiling point is 170-380°C.
Distillate low-viscosity fuel oil is used for high-speed and high-viscosity residual fuel oil is used for slow-speed (tractor, marine, stationary, etc.) engines. Distillate fuel consists of hydrotreated kerosene-gasoil fractions of direct distillation and up to 1/5 of gas oils from catcracking and coking. Viscous fuels for low-speed engines are a mixture of fuel oils from the kerosene-gasoil fraction. The calorific value of diesel fuel averages 42624 kJ/kg (10180 kcal/kg).
Main characteristics of diesel fuel that affect its quality
Viscosity and water content
There are so-called winter and summer diesel fuels. The main difference is in the ASTM D 6371 filter limit temperature and ASTM D97 and ASTM D2500 cloud point and pour point specified in the standards for this fuel. The production of winter fuel is more expensive, but without preheating it is impossible to use summer fuel at -10°C, for example. Another problem is the high water content of diesel fuel. Water exfoliates during storage of diesel fuel and collects at the bottom, as the density of diesel fuel is less than 1 kg/l. A water plug in the line completely blocks engine operation. Requirements of the interstate standard GOST 305-82 “Diesel fuel. Technical conditions “regulate the kinematic viscosity at 20 ° C for summer grades in the range of 3.0 ÷ 6.0 cSt, for winter grades 1.8 ÷ 5.0 cSt, for Arctic 1.5 ÷ 4.0 cSt. This standard also requires the absence of water in all fuel grades.
Physical properties:
Summer diesel fuel: Density: no more than 860 kg / m³. Flash point: 62 ° C. Solidification temperature: -5 ° C. It is obtained by mixing straight-run, hydrotreated and secondary hydrocarbon fractions with a boiling point of 180-360 degrees Celsius. An increase in the boiling point temperature leads to increased nozzle coking and smoke.
Winter diesel fuel: Density: no more than 840 kg / m³. Flash point: 40 ° C. Solidification temperature: -35 ° C. It is obtained by mixing straight-run, hydrotreated and secondary hydrocarbon fractions with a boiling point of 180-340 ° C. Similarly, winter diesel fuel is obtained from summer diesel fuel by adding a depressant additive that lowers the pour point of the fuel, but slightly changes the temperature of the maximum filterability. In an artisanal way, up to 20% of TS-1 or KO kerosene is added to summer diesel fuel, while the operational properties remain virtually unchanged.
Arctic diesel fuel: Density: no more than 830 kg / m³. Flash point: 35 ° C. Solidification point: -50 ° C.
