wartsila 20 tr_2004
DESCRIPTION
Wartsila 20 Technology ReviewTRANSCRIPT
Technology review
20
2
3
Technology review
Setting new standards for
economical power production . . . . . . . . . . 4
Design philosophy . . . . . . . . . . . . . . . . 4
IMO NOX compliance . . . . . . . . . . . . . . 6
Piston. . . . . . . . . . . . . . . . . . . . . . . 6
Piston ring set . . . . . . . . . . . . . . . . . . 7
Connecting rod and big end bearings . . . . . . 7
Cylinder liner and anti-polishing ring . . . . . . . 8
Cylinder head. . . . . . . . . . . . . . . . . . . 8
Multiduct . . . . . . . . . . . . . . . . . . . . . 9
Crankshaft and main bearings . . . . . . . . . . 9
Engine block and foundation . . . . . . . . . . 10
Fuel system . . . . . . . . . . . . . . . . . . . 10
Turbocharging system . . . . . . . . . . . . . 11
Cooling systems . . . . . . . . . . . . . . . . 11
Lubricating oil system. . . . . . . . . . . . . . 12
Automation system . . . . . . . . . . . . . . . 12
Application flexibility . . . . . . . . . . . . . . 13
Easy maintenance. . . . . . . . . . . . . . . . 14
Main technical data . . . . . . . . . . . . . . . 15
20
Setting new standards for economical power productionThe WÄRTSILÄ® 20 medium-speed engine offers a
remarkable combination of state-of-the-art design and top
performance in a compact, space-saving package. With its
virtually pipeless, operator-friendly "heavy duty" design,
the engine has started a new era in the development of
medium-speed engines. Where power-to-weight and
power-to-space rations are concerned, the engine is
unmatched in its power range.
The fact that the Wärtsilä 20 has originally been
designed to operate reliably with the poorest quality heavy
fuel, makes Wärtsilä 20 the ultimate in reliable
performance using Light Diesel Oils. Overhaul intervals
up to 24,000 hours and maintenance-friendly desing are
some of the main valuable features that have earned the
Wärtsilä 20 an installed base of more than two thousand
engines since the launch in 1992.
4
Design philosophyThe design of the Wärtsilä 20 engine is based on
Wärtsilä’s heavy fuel know-how and is fully optimized for
today’s flexible manufacturing methods.
The Wärtsilä 20 engine offers customers the following
core values:
� Proven and reliable heavy fuel technology� Cost-effective design� Easy and cost-effective installation� Low operating costs� Low NOX emission� Minimal consumables
5
FPSO Berge Hugin. MST Berge Hugin, Navion Munin and West Navionare all equipped with four Wärtsilä 6L46 main engines and one Wärtsilä9L20 auxiliary engine. Total output per vessel 22,890 kW.
Seismic vessel Geco Bluefin.Auxiliary engines: four Wärtsilä9L20 generating sets.Total output of 6120 kW/rpm.
Tug, Sanergy JayaMain engines:two Wärtsilä 6L20
Container "Contship Italy"Auxiliary engines: three Wärtsilä 6L20 enginesEmergency engine: one Wärtsilä 4L20 engine
Research vessel Scotia. Main engines: three Wärtsilä 9L20, totaloutput 4,455 kW/1000 rpm. Shipyard: Ferguson ShipbuildersLtd. Shipowner: Fisheries Research Services
IMO NOX complianceGenerally diesel engines have less harmful emissions
(CO2, CO etc.) than many other power sources. The
standard engine can easily meet the NOX level set by IMO
(International Maritime Organisation), in Annex VI to
MARPOL 73/78. To show compliance, the engine is
certified according to the NOX Technical Code, and
delivered with an EIAPP (Engine International Air
Pollution Prevention) Statement of Compliance. The
certification process includes NOX measurements,
marking of components that are affecting NOX formation
and a Technical File that is delivered with the engine.
All major classification societies are on behalf of the flag
state granting the EIAPP Statement of Compliance for the
Wärtsilä 20 engine family.
If lower NOX levels are required, the engine can be
equipped with a Compact SCR catalyst, which can reduce
NOX by up to 95%, down to a level < 1 g/kWh.
PistonPistons are of the low-friction, composite type with steel
top and nodular cast iron skirt. Based on a track record of
more than twenty years, this is the superior concept for
highly rated heavy fuel engines. The design itself is of
course tailored for an engine of this size and includes a
number of innovative solutions. Experience has shown
that nodular cast iron is the best piston material for
modern diesel engines which operate with high pressures
and temperatures in the combustion chamber. Low
friction is obtained by Wärtsilä’s patented skirt lubrication
system.
6
20
18
16
14
12
10
8
60 500 1000 1500 2000N
OX
emis
sio
ns,w
eig
hted
(g/k
Wh)
Rated engine speed (rpm)
IMO global marine NO legislationX
Low NO combustionX
Low NOx design
Engine maximum firing pressure
Pressure riseinduced fromcombustion
Conventional design
Engine maximum firing pressure
Pressure riseinduced fromcombustion
Pressure riseinduced fromcompression
Pressure riseinduced fromcompression
TDC TDC
Cyl
ind
erp
ress
ure
Cyl
ind
erp
ress
ure
-90 -90-60 -60-30 -300 030 3060 6090 90120 120
Wärtsilä 20 Fuel: Marine diesel oil
Piston ring setThe two compression rings and the oil control ring are
located in the crown. This three-ring concept has proved
its efficiency in the Wärtsilä 46 engine. In a three-ring
pack every ring is dimensioned and profiled for the task it
has to perform. It is also well-known that most of the
frictional loss in a reciprocating combustion engine
originates from the piston rings. Thus a three-ring pack is
considered optimal with respect to both function and
efficiency. For maximum wear resistance the top ring
features a special wear-resistant coating.
Connecting rod and big endbearingsThe “stepped split line” design used in the Wärtsilä Vasa
22 and 32 for many years now offers the maximum pin
diameter while still making it possible to pull the
connecting rod through the cylinder liner. The advantage
over the conventional straight, oblique split line is an
increase in pin diameter of at least 15%. This is of vital
importance in a modern engine designed for high
combustion pressures.
When an engine type is designed for both in-line and
V-version the big end bearing width is often a
compromise between the bearing load and overall length
of the V-version. As the Wärtsilä 20 is designed as an
in-line engine only, no compromises are necessary. A
direct consequence is superior oil film thickness and low
oil film pressure. The bearing material used in this engine
can withstand cylinder pressures of well over 200 bar.
The non-grooved upper half of the big end bearing in the
Wärtsilä 20 also helps to maximize the oil film thickness.
7
Spec. Cr
Cr
Cr
Cylinder liner andanti-polishing ringThe cylinder liner is designed for minimum deformation
thanks to its own stiffness and support from the engine
block. It is equally important to adjust the inner wall
temperature to a level just above the sulphuric acid dew
point. This is done by creating an increased tangential
cooling water flow velocity just below the liner collar.
The liner is made of wear-resistant material developed
through a dedicated R&D programme lasting several
years. To eliminate the risk of bore polishing, the liner is
provided with an anti-polishing ring at the upper part.
The purpose of this ring is to limit the carbon deposits
built up on the piston top land to a thickness small
enough to prevent contact between the inner liner wall
and the deposits at any position of the piston. This
mechanism is the source of the “bore- polishing” which
causes local liner wear and increased lube oil
consumption.
Cylinder headFour-screw cylinder head technology was introduced by
Wärtsilä more than 20 years ago. Especially at cylinder
pressures of 200 bar it has proved its superiority when it
comes to liner roundness and dynamic behaviour. In
addition to easier maintenance and reliability it provides a
lot of freedom in employing the most efficient channel
configuration.
A distributed water flow pattern is used for proper cooling
of the exhaust valves and cylinder head flame plate.
This minimizes the thermal stress levels and guarantees a
sufficient low exhaust valve temperature.
8
MultiductA multifunctional duct is connected to the cylinder head.
The functions of this multiduct are as follows:
� Air transfer from air receiver to cylinder head
� Introduction of an initial swirl to the inlet air foroptimal part load combustion
� Exhaust transfer to exhaust system
� Cooling water transfer from cylinder head to returnchannel in the engine block
� Insulation/cooling of the exhaust transfer duct� Support for exhaust system including insulation
Crankshaft and main bearingsWith increasing cylinder pressures and engine output the
crankshaft dimensions will necessarily increase. This goes
hand in hand with the larger bearing surfaces required to
keep the specific bearing loads at an acceptable level.
Thanks to careful optimization of the crankshaft design, the
Wärtsilä 20 has actually reduced bearing loads. In other
words, the material is used in the most favourable way in
terms of both bearing load and crankshaft stress. Low
bearing load and optimized balancing of the rotating masses
ensure ample oil film thicknesses at all loads and speeds. In
the past, corrosion took a heavy toll on bearings in trunk
engines operating on heavy fuel. This is now history, as
corrosive resistant bearing materials are available.
9
Exhaust gas Cooling water Charge air
Engine block and foundationThe engine block has been designed for maximum overall
stiffness and local stiffness around the upper part of the
cylinder liner. As a consequence of the general design
philosophy of component integration, it contains a
number of cast-in or machined water and oil channels.
Furthermore, the camshaft bearings are housed directly in
the engine block as is the camshaft gear train at the
flywheel end of the engine. Thanks to its overall stiffness,
easy-to-install, four point support is standard for the
engine. To allow the most flexible common base plate
arrangement independent of the alternator make, the
alternator is fitted with an adjustable mounting pad
arrangement. For resilient mounting simple structure and
effective isolation is provided by separate engine feet.
Fuel systemThe low pressure fuel system is an integrated part of the
injection pump. This is realized with a multihousing,
which contains the following:
� the single cylinder injection pump
� a fuel supply line along the whole engine
� the fuel return lines from each pump
� the pneumatic overspeed trip device� guiding for the valve tappets
This arrangement represents the ultimate in safe fuel
systems. Moreover, the high pressure fuel line is also fully
enclosed with an alarm for possible leakages and all fuel
carrying parts are housed in a fully covered compartment,
i.e. a hotbox. The high pressure side is designed for a 2000
bar injection pressure while the pressure utilized is around
10
1500 bar. The pump element itself features a method to
eliminate cavitation erosion. The fuel injection valve is
designed for uncooled nozzles and the nozzles are
heat-treated for low wear and high heat resistance. All this
ensures easy maintenance and long lifetimes. The Wärtsilä
20 can of course start, stop and operate over the whole
load range using heavy fuel.
Turbocharging systemThe Wärtsilä 20 engine is designed for applications where
the most demanding load pick-up and prolonged
operation on low loads are required. This means that all
cylinder configurations of the engine are equipped with an
optimized pulse system.
Cooling systems
High temperature (HT) cooling system
The system is totally integrated with the various engine
components; virtually no pipes are used. Supply and
return channels are cast into the engine block while the
pump cover and turbocharger support hold the
connections between the pump and engine block.
The system temperature is kept at a high level, about
95°C, for safe ignition/combustion of low quality heavy
fuels at low loads. An additional advantage is maximum
heat recovery and total efficiency. An engine-driven pump
of the cassette type is standard.
Low temperature (LT) cooling system
This system is also fully integrated with the engine
components, i.e. engine block, pump cover, air and lube
oil cooler housings. An engine-driven pump of the same
type as for the HT-system is standard.
11
3-pulse
Pulse converter
Lubricating oil systemAll Wärtsilä 20 engines are equipped with a complete lube
oil system, i.e. an engine-driven main pump, electrically
driven prelubricating pump, cooler, full flow filter and
centrifugal filter. Pressure regulation and safety valves are
integrated into engine driven pump fitted at the free end
of the engine where also prelubricating pump with electric
motor is fitted. Filter, cooler and thermostatic valves are
built up in a module located at the engine rearside.
The lube oil filtration is based on an automatic
back-flushing filter requiring a minimum of maintenance.
The filter elements are made of seamless sleeve fabric with
high temperature resistance. An overhaul interval of one
year is recommended. The expected lifetime is four years.
A special feature is the centrifugal filter, connected to the
back-flushing line of the automatic filter. This provides
the means for extraction wear particles from the system.
Automation systemMaking the electronic connections to the external system
usually involves a lot of work. The Wärtsilä 20 is made for
easy plug-in connection of sensors to prefabricated cabling
modules.
The following functions are incorporated in the
automation system:
� Instrumentation for local reading of engine andturbocharger speed, exhaust temperature after eachcylinder and after the turbocharger and an operatinghour counter
� Electronic boards for speed measuring and charge airtemperature control
� Plug-in connectors for connection to the externalcontrol system
12
FilterCooler Pump
Primingpump
Lube oil system
The main cabinet is firmly mounted on the engine to
isolate it from engine vibrations. There is a battery of
pressure switches and a manometer panel near the cabinet
for operating convenience.
A more advanced electronic control unit with capability
for direct bus-connection will be provided for shipyards
that want to make use of the latest ship automation
technology.
Application flexibilityWärtsilä 20 is suitable for wide range of applications in
various respects. Different fuels from lowest viscosity of
1,8cSt up to 730cSt HFO (at 50ºC) can be used and
optimised engine performance is provided by standard
engine specifications for constant and variable speed
applications.
Flexibility in engine support arrangements allows
optimised rigid or flexible foundation for wide range of
application types in marine and land based power
solutions. Easy and cost effective installation is provided
by minimised application work due to on-built auxiliary
equipment with low positioned interface connections.
Suitability for small engine rooms is supported by low
installation height and by standard options with
turbocharger at free end and also at driving end for 6-, 8-
and 9-cylinder engines.
13
Easy maintenanceEfficient maintenance is incorporated in the engine
design. Hydraulics are used for pretensioning the
cylinder head screws, connecting rod screws and main
bearing screws. Access to the injection pumps is
excellent thanks to limited piping in the hotbox, where
the pumps are housed. An injection pump element is
easy to replace without removing the multihousing.
Neither is it necessary to remove fuel feed/return pipes
for the simple reason that there are not any. The
multiduct remains on the engine block holding the
exhaust system when the cylinder head is removed.
Neither is it necessary to remove water pipes because
they are integrated with the multiduct. Only two screws
have to be loosened to remove the rocker arms and
bracket. The water pump is easy to replace thanks to
the cassette design. It is even easier to remove the end
cover alone if the impeller has to be changed.
14
15
Main technical data
Cylinder bore . . . . . . . . . . . . . . . . . . . . . . . . 200 mmPiston stroke. . . . . . . . . . . . . . . . . . . . . . . . . 280 mmCylinder output . . . . . . . . . . . . . . . . . . . 130 - 200 kW/cylSpeed . . . . . . . . . . . . . . . . . . . . . . . . 720 - 1000 rpmMean effective pressure . . . . . . . . . . . . . . . 22.5 - 28.0 barPiston speed . . . . . . . . . . . . . . . . . . . . . . 6.7 - 9.3 m/sVoltage . . . . . . . . . . . . . . . . . . . . . . . . . 0.4 – 13.8 kVAlternator efficiency . . . . . . . . . . . . . . . . . . . 0.94 – 0.96Fuel specification:Fuel oil . . . . . . . . . . . . . . . . . . . . . . . . . 730 cSt/50°C
. . . . . . . . . . . . . . . . . . . . . . . . . . . 7200 sR1/100°F
. . . . . . . . . . . . . . . . . ISO 8217, category ISO-F-RMK 55SFOC 188-196 g/kWh at ISO condition ± 5% tolerance
Rated power: Propulsion engines
Enginetype
Output in kW/bhp at 1 000 rpm
C2 -output C3 -output
kW bhp kW bhp
4L205L206L208L209L20
720825
108014401620
9801120147019602200
1200
1800
1630
2450
Principal engine dimensions (mm) and wet weights (tonnes)
Enginetype A* A B* B C* C D
4L205L206L208L209L20
––
325439734261
25102833310837834076
––
152816141614
13481423134814651449
––
158017561756
14831567157917131713
18001800180018001800
E F H K N* Weight*4L205L206L208L209L20
325325325325325
725725624624624
155155155155155
980980980980980
––
589708696
7.27.89.3
11.011.6
For this engine type the dimension B refers to the highest point of the engine.Weight with liquids (wet sump) but without flywheel.*Turbocharger at flywheel end.
Rated power: Generating sets
Enginetype
C2 -output C3 -output
720 rpm/60 Hz
750 rpm/50 Hz
900 rpm/60 Hz
1000 rpm/50 Hz
900 rpm/60 Hz
1000 rpm/50 Hz
Eng.kW
Gen.kW
Eng.kW
Gen.kW
Eng.kW
Gen.kW
Eng.kW
Gen.kW
Eng.kW
Gen.kW
Eng.kW
Gen.kW
4L205L206L208L209L20
520–
78010401170
495–
740990
1110
540–
81010801215
515–
77010251155
680775
102013601530
645735970
12901455
720825
108014401620
685785
102513701540
––
1110–
1665
––
1055–
1580
––
1200–
1800
––
1140–
1710
Principal genset dimensions (mm) and weights (tonnes)
Engine A* H* I L* M Weight*
4L205L206L208L209L20
49105220532560306535
17701920
1770/19201920/20702070/2300
18001800180018001800
23382458
2243/23232474
2524/2574
11681329129913901390
14.015.116.820.723.8
* Values are based on standard alternator, whose type (water or air cooled) and sizeaffects width, length, height and weight. Weight is based on wet sump engine with engineliquids. Gen. output based on generator efficiency of 95%.
Fuel Quality Limits
Range DMX min RML55 max
Viscosity (cSt)Density (kg/m3)CCAICCR (%)Pour point (°C)S (%)V (ppm)
1.8––––––
730101087022305
600
20
W04
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edia
Wärtsilä Finland OyP.O.Box 252,FIN-65101 Vaasa,Finland
Tel. +358 10 709 0000Fax (Ship Power) +358 6 356 7188Fax (Power Plants) +358 6 356 9133
Wärtsilä is The Ship Power Supplier for builders, owners and operators
of vessels and offshore installations. We are the only company with a
global service network to take complete care of customers’ ship
machinery at every lifecycle stage.
Wärtsilä is a leading provider of power plants, operation and lifetime
care services in decentralized power generation.
The Wärtsilä Group includes Imatra Steel, which specializes in special
engineering steels.
For more information visit www.wartsila.com
WÄRTSILÄ ® is a registered trademark. Copyright © 2004 Wärtsilä Corporation.