Operation
0710−1/A1
Winterthur Gas & Diesel Ltd.
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3.7 Acid Number
Fuels with high acid numbers have caused damage to fuel injection systems. Most
fuels have a low acid number, which is not dangerous, but an acid number above
2.5 mg KOH/g, can cause problems. Some naphthenic fuels can have an acid
number of more than 2.5 mg KOH/g, but still be permitted. Only a full laboratory
analysis can find the strong acid number.
3.8 Sediment, Carbon and Asphaltenes
High quantities of sediment, carbon and asphaltenes decrease the ignition and
combustion quality of the fuel and increase wear and damage to engine components.
Asphaltenes also have an effect on the stability of mixed fuels and can cause too
much sludge in the separators and filters. If the mixed fuel is not stable, particles can
collect on the bottom of the tank.
To keep risks to a minimum, make sure that bunkers from different suppliers and
sources are not mixed in the storage tanks on board. Also be careful when HFO is
mixed on board to decrease the viscosity. Paraffinic distillate, when added to an HFO
of low stability reserve, can cause the asphaltenes to collect, which causes heavy
sludge.
HFO can contain up to 14% asphaltenes and will not cause ignition and combustion
problems in 2-stroke engines if the fuel preparation equipment is adjusted correctly.
3.9 Pour Point
The operation temperature of the fuel must be kept between approximately 5_C to
10_C above the pour point to make sure that the fuel can flow easily.
3.10 Water
The separator and the correct configuration of drains in the settling and service tanks
is used to decrease the water quantity in the fuel. A complete removal of water is
highly recommended to decrease the quantity of hydrophilic cat fines and sodium in
the fuel. Sodium is not a natural oil component, but diesel engine fuel often has sea
water contamination, which has sodium. 1.0% sea water in the fuel is related to 100
ppm sodium.
To get a good separation effect, the flow rate and temperature of the fuel must be
adjusted in relation to the viscosity. For high-viscosity fuels the separation
temperature must be increased, although the flow rate must be decreased in relation
to the nominal capacity of the separator. For the recommended data to operate the
separator, refer to the instruction manual.
3.11 Ash and Trace Metals
Fuels with a low content of ash, vanadium, sodium, aluminium, silicon, calcium,
phosphorous and zinc are recommended. These materials can increase mechanical
wear and high-temperature corrosion, and can abrase particles in the turbocharger,
exhaust system and boilers.
3.11.1 Vanadium and Sodium
Sodium compounds decrease the melting point of vanadium oxide and sulphate salts,
specially when the vanadium to sodium ratio is 3:1. High sodium quantities (as well as
lithium and potassium) at the engine inlet can damage the turbocharger, exhaust
system and boilers. Ash modifiers can correct the effect of high-temperature corrosion
and particles.
2017−08
Diesel Engine Fuels
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