HIGH DENSITY

Density is defined as the mass per unit volume and expressed in kg/m3 in SI units. This is one of the important bunker properties. Marine fuel oils have a linear density/temperature relationship, as opposed to water for example, and decreases with increasing temperature at a rate of about 0.66 kg/m3 per degree celsius rise.

Significance

1. Quantity calculation
2. Seperability of water and solids – to select the optimum size of gravity disc for purification
3. Specific energy calculation
4. Calculated Carbon Aromaticity Index (CCAI) – measures the ignition quality (increased index number causes an increase in ignition delay)

HIGH POUR POINT

The pour point is the lowest temperature at which a marine fuel can be handled without excessive amounts of wax crystals forming out of solution. At 3 degree C below pour point temperature, the fuel will become gel thereby preventing flow under its own weight. So more viscous fuels need to heated up to maintain their pumpability.

HIGH WATER CONTENT

Significance

1. Wet sludge
2. Corrosion (specially sea water)
3. Possible ignition interference
4. Displacement of fuel quantity
5. Specific energy calculation (heat loss)

Saline water in the emulsified state has a particular affinity for highly cracked fuels and heavy sludging can be experienced during purification. Water can cause cavitations in pump suction, corrosion and disturbed atomization during combustion, ignition retarded and cylinder liner lube oil film diluted. Water is separated by gravity separation in the fuel tanks and by centrifugal purification in purifiers.

 

Reference

“SHIP SAFETY AND ENVIRONMENTAL PROTECTION” BY GAUTAM SEN