Question

Give a list of the properties or test by which distillate and blended fuels may be specified or decisions be made on their fitness for use. Name the properties or constituents that may be found in a blended fuel having a high viscosity and high carbon content. Explain how they may cause problems in engine operation. (16)

Answer 1

ISO 8217:2017

List of properties of LSFO and LSMGO

Fuel oil properties are explained below:

1. Viscosity: Measures the fuel's resistance to flow

Viscosity varies inversely with the temperature and can be controlled by heating.

High viscosity directly impacts flow and atomisation.

2. Density @15°C: Calculating quantity (tonne), purifier gravity disc, (Max 991kg/m³),

Density and volume will vary with the temperature.

3. Water: Water contamination reduces lubricity, energy content, and can cause corrosion and deposits. Acceptable limits are typically specified (e.g., max 0.5%). Removal methods include settling, centrifugation, and filtration.

4. Ash: Represents non-combustible inorganic materials. High ash leads to abrasion and fouling. Separators can remove some ash.

5. MCR [Micro Carbon residue]: Indicates the amount of carbon residue left after combustion.

High MCR Indicates significant carbon deposition, leading to fouling of injectors, combustion chambers, and exhaust systems.

6. Sediment: Represents insoluble matter, including asphaltenes, which can cause blockages of filters and fuel oil lines

7. Pour Point: The lowest temperature at which the fuel will flow. A high pour point can cause filter blockages in cold weather.

8. Net Calorific Value: Indicates the fuel's energy content.

9. Flash Point: The lowest temperature at which the fuel vapor ignites. A low flash point poses a fire hazard

10. Acid Number: Indicates fuel acidity, impacting corrosion.

11. Phosphorus, Calcium, Zinc: Indicate the presence of used lubricating oil.

12. Vanadium: Naturally occurring element that forms corrosive deposits at high temperatures.

13. Sodium: A naturally occurring element that, along with vanadium, forms corrosive deposits. Removal methods include draining and purification

14. Sulphur (naturally occurring) Statutory Limits: Naturally occurring and contributes to corrosion (forming sulfuric acid).

15. Aluminium and Silicon (Cat fines): Abrasive particles from the refining process causing wear in the fuel system.

16. Calculated Carbon Aromaticity Index (CCAI): An indicator of ignition quality. High CCAI values can cause ignition delay and knocking.

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