Cutting cylinder oil costs without a break in service - Wärtsilä

p [ MARINE / IN DETAIL ]
[ MARINE / IN DETAIL ]
vessel. Wärtsilä’s two-stroke center and the
Wärtsilä services network are thus working
in close co-operation to minimize the
required installation time so that RPLS can
be retrofitted in a ship while on passage and
during a normal port stay. For example,
Wärtsilä in Korea is manufacturing all
pipework and other mechanical parts.
Before dispatching the material to the
vessel, it is prefitted on a dummy in the
Wärtsilä workshop in Noksan, South
Korea, to verify that the work is correct.
RPLS is an independent system with few
connections or interfaces to other systems,
and utilizes the engine’s existing cylinder
liners. Thus preparation and installation
are easy and fast. All equipment, including
prefabricated piping, is supplied with
installation and commissioning work being
undertaken by Wärtsilä service engineers.
To a substantial extent this material
can be installed during the voyage,
thereby considerably reducing the
port time required for fi nishing the
installation and for the commissioning.
Installation of controls, pumps, wiring,
and interface connections to remote and
alarm monitoring systems, is executed
during the voyage. Ample attention is
paid to commissioning, fi ne adjustment
and the running-in of the RPLS in port
and during a confi rmation voyage.
The whole retrofit and commissioning
on the first vessel, the 7500 TEU container
ship “COSCO SHENZHEN” with a 12cylinder
Wärtsilä RTA96C main engine,
could be completed in five steps without
interrupting the vessel’s schedule:
1. Pre-inspection in Hong Kong
on 22 June 2006.
2. First installation trip from Hong
Kong to Yantian during 26–27
August. Installation work continued
in Yantian and during the Pacifi c
crossing to Long Beach (USA),
arriving there on 9 September.
3. The second and fi nal installation
period in Long Beach during 9–
11 September, included pistonrunning
related modifi cations.
4. The commissioning was carried-out
while on passage from Long Beach to
Oakland, where on 13 September the
final inspection was also carried out.
5. Finally, on her ‘maiden’ passage
to China, measurements and
documentation of the RPLS
performance were carried out.
52 indetail
Cylinder oil tank
Alarm
monitoring
system
Filter WECS
Main
bearing
oil
Servo oil
supply unit
Junction
box
Pressure
sensors
Servo oil
overfl ow
Fig 2. – Schematic of the RPLS.
Working principle
The basic principle of the Pulse
Lubricating System is to deliver metered
quantities of cylinder lubricating oil
under pressure at precise timing exactly
into the piston ring package, from
where it is evenly distributed around the
circumference of the cylinder liner.
The RPLS is based on a lubricating
module for each cylinder with a dosage
pump and monitoring electronics,
which delivers pressurized cylinder
lubricating oil to newly developed
lubricators (formerly known as quills)
that fit existing cylinder liners of the
Wärtsilä RTA and RT-flex engine types.
Each lubricating module is equipped
with two separate supply lines – for
cylinder lubricating oil and servo oil.
A separate servo oil supply unit is
needed to drive the lubricating module
for RTA engines, whereas on RT-fl ex
common rail engines, the servo oil is
taken from the servo oil common rail
through a pressure reducing valve.
Once the Wärtsilä Engine Control
System (WECS) switches the 4/2-way
solenoid valve in the lubricating module
Lubricator
ALM-20
Dosage pump
Cylinder
CAN bus
Power supply
Cylinder oil
Servo oil
Servo oil return
to the open position, servo oil fl ows to
the drive side of the central piston of the
dosage pump in the lubricating module.
As the central piston is actuated, it feeds
cylinder lubricating oil from the lubricating
oil supply to the metering ducts, and then
discharges it from the lubricators at high
pressure. The cylinder oil is accurately
supplied at defined positions of the working
piston whose position is constantly detected
by the control system from the reference
signal given by the crank angle sensor. At
the end of the lubrication work cycle, the
directional valve in the lubricating module
directs the servo oil to the return-fl ow
side of the central piston of the dosage
pump, which then returns to its initial
position. The metering chamber is fi lled
again with cylinder lubricating oil to be
ready for the next lubricating cycle.
A separate servo oil supply unit is
provided for RTA engines. It includes two
gear pumps, one supplying the lubricating
module with servo oil taken from the
main engine oil system, with the second
pump as a standby. The oil supply unit
also includes a pressure limiting and safety
valve, pressure gauge, pressure sensor, and