When using heavy fuel oil of poor combustion properties in Diesel engines,
there may appear phenomena that cause problems in their operation. Among
these problems, the most well known are Scuffing
and Liner Lacquering, which arise especially when
running at full load.
A heavy fuel oil with poor properties of
combustibility (of high density, high C.C.A.I., etc.) tends to take more
time to burn than a fuel oil of higher quality.
Due to the prolonged time of combustion of
the heavy fuel oil in the engine’s combustion chamber, the flame can come
into contact with the cylinder wall and burn its protective film of
lubrication oil. This can cause a process of abrasion or wear on the
surfaces involved: cylinder liners and piston rings.
This phenomenon is termed scuffing
and is characterised by the appearance of marks,
abrasions, or scratches on these surfaces.
A heavy fuel oil containing a high
quantity of polyaromatic hydrocarbons or higher percentages of asphaltenes
and resins produces combustion residues with unburned particles able to
adhere to the grooves of the cylinder liner that are designed to ensure the
movement and distribution of lubrication oil.
The accumulation of these
resinous-asphaltenic adhered substances forms a sort of coat of
varnish or lacquer on the cylinder liner, a phenomenon known as liner
Because of this, less lubrication oil is
found between the surfaces in contact on the cylinder liner and the piston,
and a greater quantity of oil reaches the combustion chamber and is
burned.This causes increased consumption of lubrication oil,
but only in most extreme cases does it cause damage to the engine.
of heavy fuel oil with high-quality additives, such as
beco F1/ASF and “rb bertomeu” beco F1-Ship,
specifically formulated for Diesel engines in Cogeneration Plants and in
marine vessels respectively, helps to minimise occurrences of these
phenomena. A common experience is that the regular use of these
additives (in addition to the main benefits of saving fuel,
reducing corrosion and fuel oil sludge, etc.) causes consumption of
lubricant oil to decrease by around 15-20 %, which is further
evidence of their properties as improvers of combustion for asphaltenes and
other heavy hydrocarbons.