Man B & W Alpha Cylinder Lubrication System; Alpha Adaptive Cylinder Oil Control (Alpha Acc); Working Principle - Man B&W S80ME-C7 Project Manual

MAN B&W
MAN B&W Alpha Cylinder Lubrication System
The MAN B&W Alpha cylinder lubrication system,
see Figs. 9.02.02a and 9.02.02b, is designed to
supply cylinder oil intermittently, e.g. every four
engine revolutions with electronically controlled
timing and dosage at a defined position.
The cylinder lubricating oil is pumped from the
cylinder oil storage tank to the service tank, the
size of which depends on the owner's and the
yard's requirements,  it is normally dimensioned
for minimum two days' cylinder lubricating oil
consumption.
Cylinder lubricating oil is fed to the Alpha cylinder
lubrication system by gravity from the service
tank.
The storage tank and the service tank may alter-
natively be one and the same tank.
The oil fed to the injectors is pressurised by
means of the Alpha Lubricator which is placed
on the HCU and equipped with small multipiston
pumps.
The oil pipes fitted on the engine is shown in Fig.
9.02.04.
The whole system is controlled by the Cylinder
Control Unit (CCU) which controls the injection
frequency on the basis of the enginespeed signal
given by the tacho signal and the fuel index.
Prior to start-up, the cylinders can be prelubric-
ated and, during the runningin period, the opera-
tor can choose to increase the lubricating oil feed
rate to a max. setting of 200%.
The MAN B&W Alpha Cylinder Lubricator is pref-
erably to be controlled in accordance with the Al-
pha ACC (Adaptive Cylinder oil Control) feed rate
system.
The yard supply should be according to the items
shown in Fig. 9.02.02a within the broken line. With
regard to the filter and the small box, plese see
Fig. 9.02.05.
MAN B&W ME/MEC/ME-B/MEGI engines
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.

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.
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.
MAN Diesel
9.02
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