Purification Temperature and Hybrid/ Ultra-low Sulphur Fuels!
It is not clear yet to many when it comes to handling/purification and treatment of ultra low sulphur or the hybrid fuels. This is a special effort by MFAME, working in close association with Alfa Laval and Viswa Lab to address the ever nailing question:
“What is the purification temperature when using hybrid or Ultra Low Sulphur Fuels?”
Here is the answer!
Note that not all marine machinery are designed to operate with hybrid or ultra low sulphur fuels. The design and type approval tests would have been done with heavy and distillate fuels, which are widely used on board ships. This does not mean the hybrid or any other fuel which fall in between the residual or distillate category is fit for use unless the equipment or machinery maker certifies it.
The new ECA fuels introduced to the market has characteristics where the density varies from 790kg/m³ to 910 kg/m³ and the viscosity from 10cSt to 70cSt, with the sulphur limit below or at 0,10%. The common issue is that they should not be mixed with any other oils on-board since this can create unstable fuel mixes.
Some of the oils are based on distillates and have the same qualities as MGO/MDO. Some are residual fuels diluted with lighter oils. Some are taken directly from hydro crackers or other refinery systems. This may make them unstable and it is not recommended to mix with any other fuel unless a stability test is made. Viswa Lab’s onboard Stability/Compatibility test kit may come handy when the ship staff attempts such a test.
Some of the oils will contain cat-fines and it is important they are treated in a separator before Consumption. Separator operation will be no issue in itself other than with separators especially made to operate on high density oils.
It is recommended to take fuel samples every bunkering to make sure to have a full understanding on the fuel properties and secure correct handling and cleaning. The viscosity will be the decider on the separation temperature and we have the following recommendation:
|Viscosity @ 50°C||Storage temp||Separation temp|
|Up to 20cSt||30°C||40°C|
|20 to 30cSt||30°C||50°C|
|30 to 40cSt||10°C above PP||60°C|
|40 to 50cSt||10°C above PP||70°C|
|50 to 70cSt||10°C above PP||80°C|
Major oil suppliers and independent oil supplier are all introducing their own ECA blend and it is important to look at the oil characteristic of each oil to see if it will fit the purpose and handling capabilities of the ship. Some oils might need to be heated during the whole process due to high pour point, and it is important to adjust the separation and storage temperature according to the viscosity.
- Check the purifier operational manual for operating limits. Consult with Alfa Laval or any other purifier maker if you have any questions on operational capability.
- The above limits/range are for guidance only. Test the fuels before using them. If any fuel related query, do not hesitate to contact Viswa Lab.
We thank Alfa Laval and Viswa Lab for sharing their knowledge and experience with us.
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