INTRODUCTION
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. Consequently, in order to perform the optimal lubrication 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 lubricating 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 being burnt at any given time. The sulphur percentage 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, proportional to the amount of sulphur entering the cylinders.
BASIC LUBRICATING OIL SETTING :-
• Bore 60 and above = 0.20 g/kWh x S%
• Bore 50 and below = 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 3% (bore 60 and above) and 2.3% (bore 50 and below) sulphur and downwards.
Due to the sulphur dependency, the average cylinder oil dosages rely on the sulphur distribution in worldwide fuel bunkers. Based on deliveries all over the world, the resulting yearly specific cylinder oil dosage is close to 0.65 g/kWh (bore 60 and above) and 0.7 g/kWh (bore 50 and above).