Alpha Adaptive Cylinder Oil Control (Alpha Acc); Working Principle; Basic And Minimum Setting With Alpha Acc - Man B&W S50MC-C8-TII Project Manual

MAN B&W

Alpha Adaptive Cylinder Oil Control (Alpha ACC)

It is a wellknown fact that the actual need for
cylinder oil quantity varies with the operational
conditions such as load and fuel oil quality. Con-
sequently, in order to perform the optimal lubrica-
tion – costeffectively as well as technically – the
cylinder lubricating oil dosage should follow such
operational variations accordingly.
The Alpha lubricating system offers the possibility
of saving a considerable amount of cylinder lubri-
cating oil per year and, at the same time, to obtain
a safer and more predictable cylinder condition.
The name of the algorithm which controls the
cylinder oil dosage proportional to the sulphur
content in the fuel is Alpha Adaptive Cylinder oil
Control, Alpha ACC.

Working principle

The basic feed rate control should be adjusted in
relation to the actual fuel quality and amount be-
ing burnt at any given time. The sulphur percent-
age is a good indicator in relation to wear, and an
oil dosage proportional to the sulphur level will
give the best overall cylinder condition.
The following two criteria determine the control:
•
The cylinder oil dosage shall be proportional to
the sulphur percentage in the fuel
•
The cylinder oil dosage shall be proportional to
the engine load (i.e. the amount of fuel entering
the cylinders).
The implementation of the above two criteria will
lead to an optimal cylinder oil dosage, proportion-
al to the amount of sulphur entering the cylinders.
MAN B&W S50MC6, S50MCC7/8, S46MC-C7/8, S42MC7,
S35MC7, L35MC6, S26MC6

Basic and minimum setting with Alpha ACC

The recommendations are valid for all plants,
whether controllable pitch or fixed pitch propellers
are used.
Safe and very lubricatingeconomical control after
running-in is obtained with a basic setting accord-
ing to the formula:
Basic lubricating oil setting = 0,26 g/kWh x S%
with a minimum setting of 0,60 g/kWh, i.e. the
setting should be kept constant from about 2.3%
sulphur and downwards.
Absolute dosage (g/kWh)
1.40
1.30
1.20
1.10
1.00
0.90
0.80
0.70
0.60
0.50
0.40
0.30
0.20
0.10
0.00
0 0.5
Fig 9.02.01: Cylinder lubricating oil dosage with Alpha
ACC at all loads (BN 70 cylinder oil) after running-in
Due to the sulphur dependency, the average cyl-
inder oil dosages rely on the sulphur distribution
in worldwide fuel bunkers. Based on deliveries all
over the world, the resulting yearly specific cylin-
der oil dosage is close to 0.7 g/kWh.
Further information on cylinder oil as a function of
fuel oil sulphur content and alkalinity of lubricating
oil is available from MAN Diesel.
MAN Diesel
1 1.5 2 2.5
9.02
Page 2 of 5
3 3.5 4
Sulphur %
178 61 184.0
198 76 15-6.0