MAN B&W Alpha Lubricator System. Working principleThe pump station supplies the Alpha Lubricators with 40-50 bar oil pressure.The MCU controls the oil by activating a solenoid valve situated on the relevant lubricator.A feedback signal from each lubricator indicates that oil injection has taken place. This is shown by Light Emitting Diodes (LEDs) on intermediate boxes for each cylinder.Timing is based on two signals from the angle encoder, a TDC cyl. 1 marker and a crankshaft position trigger. The Alpha Lubricator system is normally timed to inject cyl. oil into the piston ring pack during the compression stroke. The cylinder lubrication is based on a constant amount of oil being supplied per injection. The specific feed rate is controlled by variation of the injection frequency.The injection frequency is calculated from index and speed, and is normally proportional to the engine MEP. However, a power Mode or RPM Mode is possible.The basic cylinder oil feed rate at MCR (100% is calculated as a correlation between a number of injectors/rpm and the stroke of the lubricators.On the HMI panel, adjustment of lubrication feed rate for individual cylinders is possible between 60% and 200%. Default value is 100%.During normal operation the system is controlled by the MCU. If any failures are detected in the system, a common alarm is activated in the control room. The detailed alarm reference is displayed on the HMI panel.If a critical failure in the MCU is detected, the BCU automatically takes over. An indication lamp ‘BCU in control’ is lit on the panel that contains the HMI panel.
Note that on older installations, the indication lamps can be situated elsewhere.The BCU is based on random timing and RPM Mode. The injection frequency is adjustable on the BCU and is normally, as minimum, set to the basic cylinder oil feed rate for the engine, plus 50%.