Wärtsilä Unveils New Cylinder Lubricating System

Wärtsilä Corporation has introduced a new, electronically-controlled cylinder lubricating system to meet the demand for lower cylinder oil feed rates: the Pulse Lubricating System (PLS). Developed for application in Wärtsilä RTA and RT-flex low-speed marine diesel engines, it delivers reduced cylinder oil consumption without compromising piston-running reliability. The Pulse Lubricating System makes it possible to reduce the cylinder oil feed rate compared with the existing accumulator system through an improved distribution of cylinder lubricating oil to the cylinder liner, and the fully flexible, precise timing of oil delivery.

The guide feed rate for Wärtsilä RTA and RT-flex engines equipped with the Pulse Lubricating System as original equipment is 0.7 g/kWh of cylinder lubricating oil. Thus the cost savings achievable with the Pulse Lubrication System are significant. In the case of a 12-cylinder Wärtsilä RT-flex96C engine of 68,640 kW maximum continuous output, running at 85 per cent load for 7000 hours a year with cylinder oil costing US$ 1700/tonne, the reduction from the guide feed rate of 1.1 g/kWh (0.8 g/bhph) with the existing accumulator system to the new guide feed rate of 0.7 g/kWh (0.5 g/bhph) can generate cost savings of more than US$ 270,000 a year. This corresponds to a cost saving of about 36 per cent for cylinder lubricating oil. The key feature of the Pulse Lubricating System is that it delivers accurately metered, load-dependent quantities of lubricating oil to the cylinder liner running surface at the precise timing required. Electronic control ensures the accurate dosage and timing, with full flexibility in settings. The cylinder lubricating oil is sprayed as a pulse of multiple jets on to the liner surface from a single row of lubricators arranged around the liner, each lubricator having a number of nozzle holes. The oil jet sprays ensure better distribution of the oil over the liner running surface than with the existing accumulator system. There is no atomisation and no loss of lubricating oil to the scavenge air.

Cylinder oil is delivered under pressure to the lubricators by a newly-developed dosage pump which is powered by pressurised servo oil drawn from the engine's system oil. The feed rate and timing are electronically controlled through a solenoid valve at the lubricator pump. There is full flexibility in the setting of the lubricator timing point, and volumetric metering ensures constant spray patterns across the engine's load range. The dosage is precisely regulated even for low feed rates.

The Pulse Lubricating System is available from January 2007 for newly-built Wärtsilä RT-flex96C, RTA96C, RT-flex84T-D and RTA84T-D engines. Additional engine types will be added to these in 2007. The new RT-flex82C, RTA82C, RT-flex82T and RTA82T engine types will be equipped with the Pulse Lubricating System from the beginning.

The Pulse Lubricating System is available now for retrofitting to RT-flex96C and RTA96C engines, and for RT-flex84T-D and RTA84T-D engines from January 2007, with additional engine types to be added during 2007.