ance and lubricating oil contam-
ination.
The tests proved that even en-
gines running at speeds as high
as 1,000 rpm provide enough time
for complete combustion. This
means that a diesel engine will
be able to run on any kind of
liquid fuel if designed according
to requirements.
Extensive lubricating-oil con-
tamination tests have shown that
there is of course an increase of
lube-oil contamination when
changing from gas oil to lighter
intermediate fuels but even bunk-
er fuel of 700 cST viscosity has
not given any additional contami-
nation in the upper load range.
If designed and developed ac-
cording to requirements and
equipped with modern fuel proc-
essing, medium-speed four-stroke
engines are capable of coping
with all liquid fuels to be on the
market for shipping in the future.
Louis Rovs Hansen
B & W Alpha Diesel
A paper on "Alpha Propulsioi
Systems Intermediate Fuel Oi
Recommendations" was presented
by representatives of B&W Al-
pha Diesel Engines. This paper
pointed out that during the past
few years the number of B&W
Alpha Diesel medium-speed en-
gines operating on intermediate
fuels have increased considerably.
An earlier paper of B&W Alpha
predicted that fuel qualities would
deteriorate, resulting in increased
demands on diesel engines and on
the fuel handling systems, and
that fuel prices would continue
to rise, making intermediate fuel
more attractive. Both of these
predictions have come true.
These developments have af-
fected the design of diesel en-
gines, and the safe operation on
intermediate fuels is today a main
design feature of B&W Alpha
Diesel engines.
Also, since that earlier paper,
quite a few changes have taken
place. The specification of the
recommended fuels has been al-
tered, the main idea being not
to specify viscosity as this pa-
rameter only defines the neces-
sary preheating and has nothing
to do with quality. On the other
hand, commercially available
fuels are identified by their vis-
cosity.
The main problem today with
regard to intermediate fuel op-
eration is no longer to make the
engine burn the fuel, but to clean
the oil before it is injected so as
to avoid excessive wear of the
engine.
J.F. Chapuy of S.E.M.T. Piel-
stick spoke on "Heavy Fuels and
PA.6 Ship Propulsion Engines."
As early as 1953, S.E.M.T., using
the alkaline reserves of detergent
oils, showed that in spite of hav-
ing no positive separation be-
tween the combustion chamber
and the crankcase, medium-speed
engines could burn heavy fuel.
Thus, the use of lubricating oils
with a high total base number
has made heavy fuel almost tra-
Jean Francois Chapuy
S.E.M.T. Pielstick
ditional for Pielstick PC type en-
gines since 1960.
However, high-speed engines
running at 1,000 to 1,500 rpm
generally remained out of the
heavy-fuel-burning area, mainly
because of fears of difficulties
with the injection system and
combustion process, and the con-
sequences on engine operation.
The PA.6 model, with its rating
of 400 bhp per cylinder, was in-
vestigated from the beginning to
burn high-viscosity residual fuel.
From the start, good results
were obtained with a four-cylin-
der PA.6 test engine running at
1,000 rpm which had aggregated
over 10,000 hours by November
1979 on several fuels of 3,500 sec.
Redwood No. 1, viscosity of 380
cST at 50°C.
At the present time, over 300
engines of the PA.6 type have
been ordered with more than half
of them already in service. Sixty-
six engines are running in con-
tinuous service on heavy fuel
(out of 44 as main propulsion
units) and have accumulated
roughly one million operating
hours.
G.A. Lustgarten, Sulzer Broth-
ers Limited, described "Recent
Developments on the Sulzer AS25-
Engine." He stated that heavy-
fuel operation is economical for
a high-speed four-cycle engine
like the Sulzer AS25 engine only
if certain requirements concern-
ing maintenance and fuel quality
as well as its treatment are taken
into consideration.
Ernst Yung
Sulzer Diesel
The author also stated that
heavy fuel oils with low impur-
ity level (roughly equivalent to
intermediate fuel IF 30) allow op-
eration close to the economic op-
timum, taking into account fuel
and maintenance costs, plant
availability, etc. Poorer fuel
grades can be used economically
only under very favorable oper-
ating conditions. In general, high-
er total maintenance costs have
to be accepted when burning poor
quality heavy fuels.
Further, the fuel treatment and
lube-oil filtration are exception-
ally important to heavy-fuel op-
eration. Correct layout of the in-
stallation is just as decisive as
the engine design.
If the specified requirements
are met, heavy-fuel operation is
an economically attractive solu-
tion.
Peter Spock
ACBL
R.P. Spock and J.E. Nivin of
American Commercial Barge Line
Company, gave an overview of
"The ACBL Blended Fuel Pro-
gram."
In early 1980, the rapidly in-
creasing price of fuel was ap-
proaching 50 percent of the op-
erating costs for the ACBL fleet
of over 60 vessels. At this point,
management decided that it
should look seriously at various
methods to reduce fuel consump-
tion. As a result of preliminary
discussions concerning blended
fuels, it was decided to call a
meeting to thoroughly discuss
the subject with an oil company,
engine supplier and shipyard rep-
resentatives. This meeting was
held in June 1980 and included
Shell Oil Company, Alco Engine,
ACBL and Jeffboat represent-
atives.
The philosophy of ACBL and
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