How to improve the properties of marine fuel oil with an onboard fuel oil treatment system?

The properties of marine fuel oil are standardized by ISO 8217, and the quality will be maintained to some extent, but fuel oil will be supplied to the marine engine even if each standardized property is within the standard value. By the time it is essential to improve the properties. 

The following are the property items that can or cannot be improved with a general fuel oil system on board. 

Properties of fuel oil that can be improved	Properties of fuel oil that cannot be improved
Viscosity  Ash  Alumina + Silica  Sludge (Segment (TSP, TSE))  Water (including sodium that can be removed by removing seawater)	Density Sulfur content Vanadium Flash point Pour point Asphaltene Residual carbon Ignition quality (CCAI)

In addition, the following are possible cleaning methods that can be improved with a general inboard fuel oil system. 

1. Temperature control (viscosity) by fuel oil heater 
2. Sedimentation of impurities and separation / removal of water in the settling tank 
3. Remove impurities with a filter, strainer, or other strainer 
4. Remove water, alumina + silica with a purifier 

Although a purifier is an effective cleaning method, it is most important to operate it in an appropriate condition, and generally, the following are effective cleaning methods. 

1. Oil flow
   Fuel consumption + a certain amount is used as the processing amount of the purifier to keep the processing time long and improve efficiency. It is also effective to reduce the processing amount for one unit by operating the purifier in parallel. 
2. Processing temperature
   Heat to the optimum temperature of 98 ℃ to lower the viscosity and increase the processing capacity. 
3. Sludge discharging interval
   Although it cannot be determined unconditionally depending on the properties of fuel oil, the discharge interval should be set appropriately according to the sludge concentration. 
4. Selection of gravity disc
   In the case of purifier operation (oil, water, sludge three-phase separation operation), it is necessary to select an appropriate size for efficient purifier operation. 
5. Sealed water, replacement water amount
   Minimize the loss of water treated by the separated oil (fuel oil) and the sludge side by adjusting the amount of water. 

On the other hand, there are cases where chemical treatment (additives) or additional equipment can be used to address items that cannot be improved by purifier.

Typical additives are sold by various chemical manufacturers such as sludge dispersants, fuel combustion improver, combustion ash modifiers / high temperature corrosion inhibitors, low temperature fluidity improvers, and water separators. 

Regarding the density, the density of oil that can be processed by the purifier is practically up to 991 kg/m3 (at 15 ℃). If the density is higher than this, there is a limit to the gravity disc that can be incorporated into the purifier, and it may be difficult to perform stable operation due to changes in operating conditions (processing temperature, oil flow rate). 

Regarding sulfur content, it is possible to handle fuel oils that exceed the sulfur content regulation value by SOx scrubber, which is a desulfurization device, but non-equipped ships to have fuel oil that exceeds regulation value of sulphur content is a violation. 

* Please refer to the e-mail magazine No. 5 issued by our company for the handling of sulfur content in fuel oil in MARPOL samples and commercial samples. 

 No.5 fuel quality and Sulphur content