Furnace oil is a product of direct distillation of secondary diesel oil fractions. Due to its excellent thermal properties and low cost it is widely used for heating of private houses and industrial buildings.
Classification of furnace oil is based on several criteria According to its viscosity, heat transfer and pour point, the heating oil is divided into:
- light,
- medium,
- heavy.
Light types have a lighter colour, are more liquid and produce more thermal energy. They are often used in industry for refuelling of large generators. Heavy oils are denser and may freeze in containers without additional heating, especially in the cold season.
Preferences of furnace oil:
- low cost,
- absence of unpleasant smell while burning,
- freezing point is less than -28 ° C, which allows using it in the winter.
Furnace fuel is often chosen a domestic heating fuel due to its characteristics. The main characteristics are:
1. Density
Furnace oil is heavier and denser than diesel fuel. This indicator is not regulated by GOST, but it must be indicated for each type. It is calculated at a standard temperature of 20 ° C. The average density index is 930 kg / m3. As the temperature rises, the density decreases, that means that the fuel dilutes.
2. Viscosity
Viscosity is one of the main indicators of the heating oil quality and its operation properties. Furnace oil is more viscous than diesel fuel, so it emits more heat during combustion. The kinematic viscosity of the heating oil is determined at a temperature of 20 ° C and is no more than 8 mm2 / s according to the norms. For comparison, the indicator of diesel fuel is 1.8-5 mm2 / s.
3. Sulfur content
On the base of sulfur content, the fuel oil is divided into sulfureous and low-sulfur. Sulfur content is 1,1% и 0,5% accordingly. In order to preserve the environment, the world’s fuel standards provide a reduction in sulfur content, so the low-sulfur fuel is getting more popular. Also it increases the service life of the heating equipment. Such fuel is produced from petroleum distillates with low sulfur content with additional hydro treatment.
4. Ash content
Ash content is a non-combustible residue of mineral mixtures after complete combustion of fuel. If this indicator is high, it can lead to soot deposition on the walls of the heat generating equipment, which may decrease the heating efficiency. The ash content of the furnace oil is low, about 0.02%, therefore it is excellent for heating.
5. Acidity
Fuel acidity is the percentage of organic and other acidic compounds (naphthenes, phenols, asphaltenes, etc.). A high content of acids causes corrosion of fuel tanks and fuel system parts. Therefore, the GOST standard of the furnace oil acidity is not more than 5 mg KOH / 100 cm3.
6. Cocking.
Cocking depends on the presence of coke residue (coal). The higher the fuel coking ability, the better the corrosion protection of adjacent metals is. Especially at high temperatures, which is typical for thermal equipment. The indicator of furnace oil coking is measured on the base of 10% of the residue and is not more than 0.35%.
7. Water content
Furnace oil may have traces of water content, but not more. Moisture in the fuel worsens its performance and may lead to an interruption of the combustion regime, blocking the fuel supply to the injectors. Besides, a high water content increases the corrosion of fuel system parts.
The indicators of the heating oil are regulated according to TU 38.101656.
