Properties Of Heavy Fuel Oil 3mz6s

In ships for propulsion by marine diesel engines and for boilers we use heavy fuel oil or residual fuel oil as the source of the combustion. In this article we will discuss properties, storage, transfer, and the need for the purification of heavy fuel oil.

Properties of Heavy Fuel Oil Used In Ships Some of the properties of heavy fuel oil used in ship: 1. Density 2. Specific Gravity 3. Kinematic Viscosity 4. Pour Point 5. Cloud Point 6. Flash Point. 7. Fire Point. 8. Ignition Point. 9. Calorific value. 10. Carbon Residue. 11. Alumina Content. 12. Asphalt Content. 13. Silica Content. 14. Sodium Content. 15. Sulphur Content. 16. Vanadium Content. 17. Compatibility. 18. Cetane Number and Cetane Index. Density: Density is the relationship between mass and volume at a stated temperature, and the SI unit is Kg/m3. This gives value of 800- 1010 kg/m3 for marine fuels. Density is measured over a range of temperatures, usually for convenience, at the temperature at which the fuel is stored. The value is then corrected back by the use of standard tables to a reference temperature, which is usually 15o C The reason that some grades have a density restriction of 991 kg/m3 is that this is the accepted limit for fuel centrifugal purification of the fuel. Density also gives an indication of other fuel characteristics such as specific energy and ignition quality.

Viscosity: Viscosity is a measure of the resistant of a liquid to shear or flow and is measured in centistokes (CST) with a quoted reference temperature. For distillate fuels the reference temperature is 40o C. knowledge of viscosity is necessary for the determination of the heating required for a fuel transfer purpose and the temperature range required for satisfactory injection and combustion at the fuel atomizer. Flash Point: The flash point of the liquid is the lowest temperature at which sufficient vapor is given to produce a flash on application of a flame under specified test conditions. Flash point may be measured as closed or open cup, but for marine fuels the closed cup is used. The test method uses the Pensky-Marten apparatus. The minimum flash point for marine fuels in the machinery space of merchant ship is governed by international legislation and the valve is 60o C. The minimum flash point is to minimize fire risk during normal storage and handling. Pour point: The pour point is the lowest temperature at which a marine fuel oil can be handled without excessive amounts of wax crystals forming out of solution. At a lower temperature the fuel will gel, thereby preventing flow. Cloud point: The cloud point of a distillate fuel is the temperature at which wax starts to crystallize out, and this is seen when the clear fuel become opaque. Carbon Residue: The carbon residue of a fuel is the tendency to form carbon deposits under high temperature condition in an inert atmosphere, and may be expressed as either Conradson carbon residue (CCR) or micro carbon residue (MCR). The maximum limit of carbon residue content in fuel is 22 %.

Water: Normally the level of water in the fuel is very low, since an effort is made by the supplier to deliver the fuel as dry as possible. 0.1% - 0.2 % by volume is typical. Water can come from a number of sources which include tank condensation, leakage of steam used to heating purposes, and tank leakage. The maximum limit of water content in fuel is 1 %. Ash content: The ash content is related to the amount of inorganic material in the fuel. For distillate fuel the ash content is defined as the residue remaining after all the combustible components of the oil have been burned and is negligible. It is the incombustible material which remains after the combustion, which mainly consists of the material such as vanadium, sulphur, silicon, aluminum, nickel, sodium, and iron content present in the fuel. The maximum limit of ash content in the fuel is 0.2% m/m.

Heavy Fuel Oil