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Technology Review
2
3
Technology Review
Introduction 4
Design 5
Chemical Characteristics of the Fuel 6
High-Temperature Corrosion 7
Low-Temperature Corrosion 7
Low NOx Combustion 8
Fuel Injection 9
Piston 10
Piston Ring Set 11
Cylinder Liner and Anti-polishing Ring 12
Connecting Rod and Big End Bearings 13
Cylinder Head 14
Crankshaft and Main Bearings 15
Engine Block and Foundation 16
Camshaft 17
Turbocharging System 17
Cooling Systems 19
Lubricating Oil System 20
Automation System 21
Easy Maintenance 22
This is a summary of Wärtsiläs approach to design and technologyin the Wärtsilä Vasa 32 engine.
Introduction
In the 1970s, the rapid increase in crude oil prices made it highly
economical to use heavy fuel in medium-speed diesel engines.
Consequently, in 1979 the first new-generation engine was launched - the
Wärtsilä Vasa 32 – the real heavy fuel engine.
For the first time in history, heavy fuel operation was as safe and simple
as diesel oil operation. The Wärtsilä Vasa 32 was the real initiator of the
unifuel concept, i.e. the concept of running an engine entirely on heavy
fuel from start to stop. Operators quickly understood the financial
advantages of choosing the most economical fuel available, and within a
decade more than 1,000 Wärtsilä Vasa 32 engines were sold – truly a world
record for an engine of this size.
Ever since launching the heavy fuel era, the Wärtsilä Vasa 32 has
maintained its lead through sustained development. Product development
and vast experience have been the keys to the Wärtsilä Vasa 32’s success as
the real heavy fuel engine.
The latest achievement in this development is the low NOx combustion,
which has been applied to all new Vasa 32 engines.
In addition, the Vasa 32 is now a true multi-fuel engine as well; gas oil,
marine diesel fuel, intermediate fuel, heavy fuel, crude oil and gas – the
Vasa 32 allows you total freedom to select the most economical fuel for
your specific application.
4
Design
Designing a modern diesel engine requires a vast amount of information on
the combustion behaviour and chemical characteristics of various fuels. In
terms of combustion and component performance, heavy fuel is the most
difficult of all fuels. Therefore, the Vasa 32 has been designed to operate
smoothly with the toughest fuel types available: those with poor inginition
and combustion qualities combined with “aggressive” chemical constituents
such as vanadium, sodium and sulphur.
The Wärtsilä Vasa 32 engine offers customers the following core values:
� The experience of a heavy fuel pioneer
� Low NOx emission
� Low operating costs
� State-of-the-art technology
� Fuel versatility
5
Chemical Characteristics of the Fuel
Vanadium, sodium and sulphur are common chemical constituents of many
fuels. When such fuel types are to be used, component temperatures should
be optimised in order to avoid excessive wear. This has been a central
principle in designing the Vasa 32.
6
High temperature corrosion
Correct material temperature
Low temperature corrosion
High-Temperature Corrosion
Metals such as vanadium and sodium are
extremely “aggressive” at high temperatures. This
phenomenon is called high-temperature corrosion.
Fortunately, this can be completely avoided by
ensuring that the surface temperatures of engine
components remain below a critical level, which
is dependent on the melting point of the metals
involved (generally less than 430°C/810°F). In the
Vasa 32, this means controlling the exhaust valve
seat temperature through direct cooling.
Low-Temperature CorrosionA second consideration is that if temperatures fall too low, the sulphur
present may induce low-temperature corrosion, thus damaging the
components. Low-temperature corrosion is known to be caused by
condensation of sulphuric acid and the presence of acidity on component
surfaces. One component typically affected is the cylinder liner, where
temperatures must be significantly higher than normal if low-temperature
corrosion is to be avoided.
7
Low NOx Combustion
To achieve complete combustion three main requirements must be fulfilled:
sufficient oxygen supply in the combustion chamber, sufficiently high
temperatures and sufficiently small fuel droplets. The higher the
temperature and the smaller the fuel droplet, the quicker the fuel will ignite
and burn. However, the way it is burnt has a great effect on thermal
efficiency and exhaust emissions, particularly NOx formation.
Wärtsilä has developed a low NOx combustion process which reduces
the NOx level up to 50% without compromising on thermal efficiency.
The standard version of the low NOx Vasa 32 can already meet the
requirement for NOx level proposed by IMO for ships operating globally.
Regional requirements in marine as well and land-based applications
might require further reductions and for that purpose Wärtsilä has
developed optional NOx control techniques as follows:
� Direct water injection into the combustion space. This method can be
used on any kind of fuel and has a potential of 50% NOx reduction.
� SCR techniques are used on all fuels when 80-90% NOx cleaning is
required. Thanks to the low NOx combustion the SCR can be designed
very compact and requires a space smaller than a conventional silencer.
The low NOx combustion
technology is based on the
following:
� A higher combustion air
temperature at injection
start that drastically reduces
the ignition delay
� A retarded injection start
and shorter injection period
that makes combustion take
place at the optimal point
with respect to efficiency
� Improved fuel atomization
� Modified combustion space
for improved mixing
8
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
er p
ress
ure
Cyl
ind
er p
ress
ure
-90 -90-60 -60-30 -300 030 3060 6090 90120 120
Vasa 32 Low NOx combustion
Fuel Injection
Wärtsilä has developed a special monoblock injection
pump to withstand the high pressures involved in fuel
injection. This assures good atomization of the fuel
and allows for the short injection period necessary in
the low NOx combustion concept.
The pump is equipped with
a constant-pressure relief valve
system, which makes it
possible to avoid cavitation at
low load and secondary
injection at higher loads. The
plunger also has an
anti-cavitation helix geometry.
The fuel injection nozzle has
rounded inner edges on the
nozzle holes. This optimal
hydraulic shape counteracts the
erosion/cavitation phenomena seen in conventional
nozzles. This design has resulted in outstanding
nozzle performance.
The plunger is equipped with wear-resistant
coating and a teflon ring to minimize lacquer build
up.
9
-20 -10 0 10 20 30 °CATDC
-20 -10 0 10 20 30 °CATDC
Inje
cti
on p
ress
ure
Needle
lif
t
-20 -10 0 10 20 30 °CATDC
-20 -10 0 10 20 30 °CATDC
Inje
cti
on p
ress
ure
Needle
lif
t
Conventional injection Low NOx injection
Piston
Pistons are of the low-friction, composite type with steel top and nodular
cast iron skirt. Based on a track record of more than ten 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.
10
Piston Ring Set
The two compression rings and the oil control rings are located in the
crown. This three-ring concept has proved its efficiency in the Wärtsilä 20
and Wärtsilä 46 engines. In a three-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.
11
Spec. Cr
Cr
Cr
Cylinder Liner and Anti-polishing Ring
The 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 obtained by optimized location of 36 vertical cooling water
bores in 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.
12
Connecting Rod and Big End Bearings
The connecting rod is designed for optimum bearing performance. It’s a
three-piece design, where combustion forces are distributed over a
maximum bearing area and where the relative movements between mating
surfaces are minimized.
Piston overhauling is possible without touching the big end bearing and
the big end bearing can be inspected without removing the piston.
The three-piece design also reduces the piston overhauling height.
The big end bearing housing is hydraulically tightened, resulting in a
distortion-free bore for the corrosion-resistant precision bearing.
13
Cylinder Head
Four-screw cylinder head technology was introduced by Wärtsilä Diesel
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 sufficiently
low exhaust valve temperature.
Exhaust as well as inlet valves are fitted with rotators for even thermal
and mechanical load.
14
Crankshaft and Main Bearings
The crankshaft is forged in one piece and equipped with separately
mounted counterweights on every crankweb providing high balancing
level.
The main bearings are of precision type with corrosion resistant bearing
materials, which withstand the corrosive environment existing in heavy fuel
engines.
15
Engine Block and Foundation
The engine block is cast in one piece with an integrated air receiver; it
features increased rigidity, simplicity and cleanness. The engine has an
underslung crankshaft. This design renders the engine block very stiff,
providing excellent conditions for main bearing performance. For special
applications, the engine block can be installed directly on resilient
mountings. A stiff engine block is a prerequisite for this type of installation.
16
Camshaft
The camshaft is built of single
cylinder sections with integrated
cams. The cam lobes are of a
harmonic design, featuring soft
acceleration changes and
vibration-free performance of the
tappet roller.
Turbocharging SystemThe output range of the Vasa 32 is attractive for a wide range of application
types, each having their specific requirements for load response, low load
or high load operational capability and thermal efficiency.
For this reason the Vasa 32 is fitted with an application-optimized
turbocharging system. This means pulse charging for most marine
applications and emergency gensets. SPEX is suitable for base load power
plant applications operating on high load.
For increased waste heat recovery from the charge air there is a
two-stage cooler fitted. The turbocharger is equipped with water cleaning
devices for in-operation cleaning of both the turbine and the compressor
side.
17
SPEX
3-PULSE
Cooling Systems
Correct cylinder temperatures are as important for complete combustion as
good fuel atomization. Low compression temperatures are critical, especially
at low loads. For this reason Wärtsilä Vasa 32 engines operating over a wide
load range are equipped with a load-dependent cooling water system. The
charge air is heated at low loads for optimal combustion and cooled at high
loads for the highest fuel efficiency. The system is totally automatic, with a
dual-setting thermostatic valve which controls the cooling of the charge air
and lubricating oil at high loads. At low loads, the cooling water is
recirculated so that the charge air is preheated with the waste heat from the
lube oil cooling system.
The engine can be equipped with mounted-on pumps for both low
temperature and high temperature cooling systems.
18
Engine
62–70 °C73–80 °C
Charge aircooler
Lube oilcooler
Exp.0.7–1.5 bar
Exp.0.7–1.5 bar
35–45 °C65–70 °C
LTCcentralcooler
93–97 °C
HTCcentralcooler
Engine
Pre-heater
Lubricating Oil System
� The Vasa 32 can be equipped with either a dry or wet oil sump.
� The oil pump can be either engine-driven or electrically driven
� The oil is filtered through a full flow paper cartridge filter which can be
mounted on the in-line engines.
� Automatic luboil filter is available as an option.
� A centrifugal filter is mounted in by-pass, thereby acting as an indicator
for excessive dirt in the lube oil.
� For the purpose of running in, provision has been made for mounting
special running-in filters in front of each main bearing.
19
Automation System
The Vasa 32 is normally equipped with a conventional control
system for start, stop, alarm, shutdown speed control and
monitoring.
For customers who want to make use of the latest
automation technology the advanced automation system WECS
with provision for direct bus connection can be supplied. WECS
has been exclusively developed for use with diesel engines. The
hardware is designed for extreme operating environments and
the system consists entirely of engine mounted computers.
The principal features of WECS are as follows:
� Instrumentation for local reading of engine and turbocharger speed,
exhaust gas temperatures and other temperatures and pressures.
� A distributed computer system for signal processing of all monitoring and
alarm sensors.
� A safety system for start, stop, automatic shutdown and start-up
interruption.
� Data communication with external monitoring/alarm system.
20
SensorsConnected to SMU or DCU
Control CabinetMCU - Main Control UnitRM - Relay Module
Modbus RTUTo external systems
CAN busFor internal communication
SMUSensorMultiplexingUnit
DCUDistributed Control Unit
Easy Maintenance
For ease of maintenance, the engine block has large
openings to the crank case and to the camshaft. All bolts
requiring high tension are hydraulically tightened, and
hydraulics are extensively used for many other operations
as well.
Since the main bearing caps are relatively heavy, each
bearing cap is equipped with a permanently fitted hydraulic
jack for easy manoeuvring of the cap. The complete
assembly is built around the lube oil feed pipe. During
delivery test runs, a running-in filter is installed to prevent the bearings from
being scratched by any particles left in the piping system.
To facilitate servicing, all fuel pipes are left free of insulating material.
Instead, all fuel-carrying equipment is placed in an insulated, covered space
known as a “hot box”. This drained space is an excellent fire protection
precaution.
� The exhaust system is surrounded by an insulating box resiliently
mounted to prevent any harmful vibration that might affect the insulating
material. Easy access to the piping system is obtained by removing the
insulating panels.
� The camshaft is built of identical cylinder segments bolted to intermediate
bearing pieces. The segments are removed sideways, thus simplifying
camshaft overhauls and eliminating the usual need for axial space for
camshaft overhaul.
� A wide range of special tools and measuring equipment specifically
designed to facilitate service work are also available.
21
Main Technical Data
Cylinder bore 320 mm
Piston stroke 350 mm
Speed 720 - 750 rpm
Mean effective pressure 24.0 - 21.3 bar
Piston speed 8.4 - 8.75 m/s
Fuel specification:Fuel oil 730 cSt/50°C
7 200 sRI/100°FISO 8217, category ISO-F-RMK 55
Natural gas
Rated power: Propulsion engines
Enginetype
*D rating at E rating at720 rpm 750 rpm 720 rpm 750 rpm
kW BHP kW BHP kW BHP kW BHP4R326R328R329R32
12V3216V3218V32
1 4802 2202 9603 3304 4405 9206 660
2 0103 0204 0304 5306 0408 0509 060
1 5002 2503 0003 3754 5006 0006 750
2 0403 0604 0804 5906 1208 1609 180
1 6202 4303 2403 6454 8606 4807 290
2 2003 3004 4104 9606 6108 8109 910
1 6402 4603 2803 6904 9206 5607 380
2 2303 3504 4605 0206 6908 920
10 040
*Available for Gas-Diesel
Principal engine dimensions (mm) and weights (tonnes)Engine type A* A B C D E G
4R326R328R329R32
12V3216V3218V32
4 7885 9196 6126 9416 3237 5188 070
3 9455 0836 1136 6035 6866 8607 420
2 2592 3452 7122 7362 5712 8512 881
1 9811 9932 0342 0342 3102 5852 585
2 5502 5502 5502 5502 3302 3302 330
600600600600600600600
2 5703 5504 5305 0203 9705 0905 650
H I K M N O Weight4R326R328R329R32
12V3216V3218V32
225225225225225225225
950950950950
1 2001 2001 200
1 3501 3501 3501 3501 6001 6001 600
1 0891 0501 1421 1421 2061 2571 257
1 3121 3401 0531 0311 4751 5451 545
----
900900900
20.329.240.544.442.558.061.4
*Turbocharger at flywheel endWeights with liquids (wet sump) but without flywheel.
22
Rated power: Auxiliary engines
Engine typeE rating (max.) at
720 rpm/60 Hz 750 rpm/50 HzEng. kW Gen. kW Eng. kW Gen. kW
4R326R328R329R32
12V3216V3218V32
1 6202 4303 2403 6454 8606 4807 290
1 5602 3303 1103 5004 6706 2207 000
1 6402 4603 2803 6904 9206 5607 380
1 5702 3603 1503 5404 7206 3007 090
Principal genset dimensions (mm) and weights (tonnes)Engine type Length Width Height Weight
4R326R328R329R32
12V3216V3218V32
6 8338 60210 47910 62510 04110 89311 593
2 1402 2902 8902 8903 0603 0603 060
3 6793 7654 3324 3564 2634 5434 573
3649677582
100105
The alternator outputs are calculated for an efficiency of 96 %.
23
A
A*
B
C
D
EF
GH IK
MN
A
A*
B
C
D
EF
GH IK
MN O
Wärtsilä Finland OyP.O.Box 252,FIN-65101 Vaasa, Finland
Tel. +358 10 709 0000Fax Marine Engines +358 6 356 7188Fax Power Plants +358 6 356 9133 W
0106
E/
Bo
ck´s
Off
ice
/F
ram
Wärtsilä Corporation is the leading global ship power supplier and a
major provider of solutions for decentralized power generation and of
supporting services.
In addition Wärtsilä operates a Nordic engineering steel company
and manages substantial share holdings to support the development
of its core business.