that time some shipowners found
it advantageous to use interme-
diate fuels (IFO) on their auxil-
iary engines.
Since then the number of en-
gines equipped for IFO operation
has increased every year, and at
the present time about 80 percent
of Bergen's annual engine pro-
duction is sold for IFO opera-
tion. There are today approxi-
mately 320 Bergen Diesel engines,
totaling 2,700 cylinder units, com-
missioned for IFO operation.
The majority of the 210 gen-
erating engines and a fairly large
number of the propulsion engines
which are in operation worldwide
have to accept the wide variety
of fuel qualities available.
Experience has shown that, pro-
vided Bergen's recommendations
for fuel treatment, engine tem-
peratures and load levels are met,
overhaul times and wear figures
generally did not alter signifi-
cantly compared to marine diesel
fuel operation.
Representatives of B&W Diesel,
Inc. presented a paper on "The
Low-Speed Diesel and the Future
Energy Scenario." The authors
spoke of the current B&W Diesel
engine program which is based
on the all-fabricated design which
was introduced with their K-GF
engines in 1973. Because of the
oil crisis in 1973 and the subse-
quent demand for increased pro-
pulsion efficiency, B&W decided
to develop a slower running ver-
sion of this series.
Due to the uniflow scavenging
system of the B&W engine, the
slower turning of the propeller
could be obtained for the same
output by increasing the stroke
of the engine.
With the introduction of con-
stant-pressure turbocharging in
1978 and the improved turbo-
charging efficiency, the exhaust-
valve timing was modified such
that, at the same maximum cyl-
inder pressure and at the same
mean indicated pressure, a more
favorable cylinder process was
obtained. An increase in thermal
efficiency and a lower thermal load
was obtained.
This led B&W to the next log-
ical step, which was that of fur-
ther utilizing the built-in power
reserve by increasing the mean
effective pressure by 12 percent
and the speed by three percent.
At the same time, the maximum
cylinder pressure was increased
by about five percent.
B&W two-stroke engines have
in principle been designed to burn
all commercial grades of heavy
fuel, limited by only a few guid-
ing parameters, mainly related to
the handling of the fuel oils.
B&W has systematically inves-
tigated for the past three years
the effect of such so-called future
fuels on a test engine, a two-
stroke crosshead uniflow-scav-
enged engine and in fact, found
indication that such fuels will not
cause appreciable difficulties.
Hugo Fiedler, Krupp MaK Mas-
chinenbau GmbH, spoke on the
November 15, 1981
"Prospects of Medium Speed
Four-Stroke Diesel Engines in
View of Future Fuel Problems."
This paper reports on investiga-
tions by Krupp MaK in the low-
quality fuel field. Prospects for
lowering of fuel consumption and
possibilities of maintaining low
maintenance costs in spite of in-
creasing difficulties are discussed.
The general feeling has been
that high engine speed might re-
sult in difficulties in burning
heavier and less combustible fuel
components on account of less
time for combustion. Consequent-
ly, Krupp MaK looked for various
fuels representing future param-
eters as close as possible and in-
vestigated the influences on com-
bustion and thermodynamics, de-
posits on the combustion chamber
and neighboring area as well as
on the general engine perform-
Hugo Fiedler
Krupp MaK Diesel
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