WÄRTSILÄ MEDIUM-SPEED ENGINES

POWER RANGE FOR MEDIUM­SPEED ENGINESWÄRTSILÄ

Wärtsilä 34DF

Wärtsilä 50DF

kW 5000 10,000 15,000 20,000 25,000

Wärtsilä 20

Wärtsilä 26

Wärtsilä 32

Wärtsilä 38

Wärtsilä 46

Wärtsilä 46F

Wärtsilä 64

DIESEL ENGINES

DUAL­FUEL ENGINES

Wärtsilä 20DF

The Oasis of the Seas, equipped with six Wärtsilä 46 engines.

The Thetis, equipped with a Wärtsilä 20 engine. The submersible heavy load ship Blue Marlin is equipped with three Wärtsilä 8L32 engines.

2

MEDIUM-SPEED ENGINES

Medium-speed diesel and dual-fuel engines for reliability and total economy .................................3

Compliance with environmental regulations and other standards............4

Main features.........................................4

Engine performance ..............................5

Engine design ........................................6

Engine block......................................6

Crankshaft and bearings.....................6

Connecting rod ..................................7

Cylinder liner and antipolishing ring.....7

Piston & piston rings ..........................8

Cylinder head.....................................8

Multiduct ...........................................9

Camshaft and valve gear ....................9

Operational systems

Fuel injection system........................10

Turbocharging system ......................11

Cooling system ................................12

Lubricating oil system.......................12

Automation system ..........................12

Dual-fuel technology ...........................14

Maintenance features..........................18

Services ..............................................18

The LNG Tanker, GDF-Suez Global Energy is equipped with four Wärtsilä 50DF engines.

The tanker Bitflower is equipped with a Wärtsilä 6L38 engine.

The Naval vessel De Zeven Provincien is equipped with two Wärtsilä 16V26 engines.

MEDIUM-SPEED DIESEL AND DUAL-FUEL ENGINES FOR RELIABILITY AND TOTAL ECONOMY The design of the Wärtsilä medium-speed

engine range is based on the vast amount

of knowledge accumulated over years of

successful operation.

Robust engines and generating sets,

developed from pioneering heavy fuel

technology, have been engineered to provide

unquestionable benefits for the owners and

operators of marine vessels.

These benefits include:

��Proven reliability

��Low emissions

��Low operating costs

��Fuel flexibility

��Integrated system solutions

��All services from spare parts to

reconditioning available from Wärtsilä’s

global network

In shipyard applications, the installation

friendliness, embedded automation system,

and built-on modularized auxiliary systems are

amongst the many added advantages.

Wärtsilä is continuously developing its

portfolio of gas and multi-fuel engines to suit

different marine applications, offshore oil

and gas installations where gaseous fuel is

available from the process, and merchant

vessels operating in environmentally

sensitive areas. Wärtsilä engines offer high

efficiency, low exhaust gas emissions, and

safe operation. The innovative multi-fuel

technology allows the flexibility to choose

between gas or liquid fuel. When necessary,

the engines are capable of switching from

one fuel to the other without any interruption

in power generation.

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4

Environmental issues, especially emissions

reduction and fuel consumption, have

become increasingly important in the

shipping sector where enforcement of

environmental regulations, at both global

and local levels, has notably increased. This

puts pressure on the marine industry to

constantly explore new ways of reducing the

environmental impact of ships.

Wärtsilä creates added value for its

customers by providing products, solutions

and services that fulfill their needs and

expectations. The development of high-

quality, reliable, and environmentally

sound solutions and services has come

as a result of long-term collaboration and

continuous interaction with our customers.

We provide service support to ensure

optimal performance throughout the product

lifecycle. The upgrading of installed products

can also extend their service life.

WÄRTSILÄ MEETS THE NEW REQUIREMENTS ON SHIP EMISSIONS The International Maritime Organization (IMO)

has approved amendments to the MARPOL

Annex VI regulations on ship emissions. These

regulations set stricter limits on emissions

of Nitrogen Oxides (NOX) from the engines,

as well as on the sulphur content of the fuel.

The new requirements will enter into force in

various phases during the years 2010–2020.

As regards NOX emissions, Wärtsilä has

already introduced solutions that comply with

these requirements. Wärtsilä engines are

designed for operation on any fuel sulphur

content. As a response to the tightening

Sulfur Oxides (SOX) emissions, Wärtsilä has

developed scrubber technology that allows

exhaust gases to be cleaned to meet the tight

regulations.

GAS ENGINES HIGHLIGHTED Wärtsilä has a multifaceted gas engine

strategy, and can provide gas engines

for vessels. Being at the forefront of

technological developments gives Wärtsilä

many opportunities arising from the tightening

environmental regulations. Shipping can

reduce its carbon footprint through ship

design, efficient engines, and optimal

propulsion solutions.

MAIN FEATURES Wärtsilä engines offer outstanding power-

to-weight and power-to-space ratios in their

power range. They have bore sizes from 200 to

640 mm and different cylinder configurations

to cover a power range from 0.5 MW to

20 MW and are capable of using various fuels.

Wärtsilä 4-stroke engines comply with both

IMO Tier I and IMO Tier II emission legislation

without secondary purification systems.

Full advantage is taken of the proven

solutions developed in earlier Wärtsilä engines,

while new features and customer benefits

have been added. Reliability and total economy

are the guiding principles, although emission

control options and installation friendliness are

strongly emphasized.

�� Cylinder power from 185 kW to 2150 kW

�� Nominal speed from 500 to 1000 rpm

�� Multi-fuel operation capability

�� High thermal efficiency and low emissions

�� High reliability and low maintenance costs

�� Low exhaust gas emissions

�� Fuel economy throughout the entire engine

operational range

�� Embedded automation system including

speed control

0

2

4

6

8

10

12

14

16

18

20

0 200 400 600 800

Engine speed, rpm

1000 1200 1400 1600

IMO Tier I, 2000

IMO Tier II, 2011

IMO Tier III, 2016 in emission control areas

NOx emissions, g/kWh

COMPLIANCE WITH ENVIRONMENTAL REGULATIONS AND OTHER STANDARDS

ENGINE PERFORMANCE

Wärtsilä 4-stroke engines utilize the latest

developments in turbo-charging technology, which

enables Miller valve timing and the Variable Inlet

Valve Closing (VIC) system to be employed.

At full-load operation, early closure of the

inlet valves enables a low effective compression

ratio, and as a result, comparatively low

temperatures at the end of the compression

stroke. The charge air, being both somewhat

expanded and cooled on its way through the

receiver into the cylinders, has a low global

temperature that is still high enough to

guarantee reliable and stable ignition of the

fuel/air mixture in the combustion chamber.

This contributes to the creation of favourable

conditions for an environmentally friendly

combustion process.

In Wärtsilä engines, these advantageous

initial conditions are combined with a higher

engine speed and a high expansion ratio,

i.e. with design parameters that make the

combustion chamber expand quickly when

the combustion process has started. Due to

the quick expansion of the combustion gases,

high temperatures that are most critical to the

formation of intensive NOX within the combustion

chamber are rapidly abated. This combination

creates a combustion process that is not only

environmentally friendly, but also extremely

efficient as the high expansion ratio produces

the conditions needed for efficient utilization of

the heat energy released by combustion at the

beginning of the power stroke.

However, it is not only the choice of the

compression/expansion ratio that makes

Wärtsilä engines highly efficient. All versions

of the engine are equipped with fuel injection

systems that allow adjustment of the injection

characteristics to the prevailing load conditions.

The advanced common-rail fuel injection

system offers the freedom to control and fine-

tune the injection process. This enables full use

of the engine’s loading potential over a wide

power range in order to achieve optimum fuel

economy. Similarly, this freedom offered by the

flexible fuel injection equipment can be utilized

to adjust the engine to the existing limitations

of exhaust gas emissions, to minimize smoke

formation. Thermal load and mechanical stress

levels are kept within the safety margins

established by Wärtsilä over decades of engine

development.

5

ENGINE DESIGN ENGINE BLOCK Nodular cast iron is the natural choice for

engine blocks today because of its strength

and stiffness properties. Wärtsilä engine mono-

block designs are based on modern foundry

technology to integrate most oil and water

channels, as well as the charge air receiver.

The result is a virtually pipe-free engine with a

clean outer exterior.

Resilient mounting, available as an option,

is required in many application types. The

engine block has been designed especially for

this purpose. Integrated channels designed

with this in mind serve a double purpose.

CRANKSHAFT AND BEARINGS The latest advances in combustion

development require a crank gear that can

operate reliably at high cylinder pressures.

The crankshaft must be robust and the

specific bearing loads kept at a safe level.

This is achieved by careful optimization of the

crankshaft’s throw dimensions and fillets. The

specific bearing loads are conservative and

the cylinder spacing, which is important to

the overall length of the engine, is minimized.

Besides low bearing loads, the other crucial

factor for safe bearing operation is oil film

thickness. Ample oil film thickness in the main

bearings is ensured by optimal balancing of the

rotational masses and, in the big end bearing,

by ungrooved bearing surfaces in the critical

areas. All the factors needed for a free choice

of the most appropriate bearing material are

present..

The main features of the crankshaft and

bearings design are:

��Clean steel technology to minimize the

amount of slag forming elements, and to

guarantee superior material properties

��A crankshaft line assembled from three

elements: the crankshaft, gear and end

piece. The crankshaft itself is forged in one

piece

��Each throw is fully balanced individually for

safe bearing function

��Main bearing temperature monitoring

��Patented crankpin bearing temperature

monitoring

��Modest bearing loads thanks to generous

bearing dimensions.

CONNECTING ROD The three-piece connecting rod is of the

marine type used in Wärtsilä engines having

a cylinder power of more than 400 kW, where

the combustion forces are distributed over

a maximum bearing area, and the relative

movements between mating surfaces are

minimized. The connecting rod is optimized for

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both strength and weight. The shank is fully

machined. The three-piece design simplifies

piston overhauling, as this can be carried out

without touching the big end bearing. The big

end bearing can also be inspected without

removing the piston.

The two-piece design is used for smaller

engines having a cylinder power of less than

400 kW. The design offers the maximum pin

diameter while still making it possible to pull

the connecting rod through the cylinder liner.

The main features of the connecting rod

design are:

��Two/three-piece type design depending on

engine size

��Hydraulically tightened bolts

��Both strength and weight are optimized

��Easy maintenance

CYLINDER LINER AND ANTIPOLISHING RING The cylinder liner is designed to have the

stiffness needed to withstand both pretension

forces and combustion pressures with virtually

no deformation. This gives the best cylinder

function and ensures good basics for the

tightness of the cylinder head gasket. The

temperature is controlled by optimizing the

cooling water flow in the upper part of the

collar to achieve a low thermal load, and to

avoid sulphuric acid corrosion.

The liner is made of wear-resistant material

developed from a dedicated and long-term

R&D programme. To eliminate the risk of bore

polishing, the liner is provided with an anti-

polishing ring on 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 on any

position of the piston. The absence of contact

between the liner and piston top land deposits

eliminates the risk of bore polishing. Nor can

oil be scraped upwards by the piston. This

significantly reduces liner wear and keeps the

lube oil consumption stable for long periods of

time.

The main features of the cylinder liner

design are:

��Centrifugal casting with high strength and

good wear resistance

��Cooling of the bore for optimum wall

temperatures

��High-collar technology to ensure good

cylinder head gasket tightness

��Anti-polishing ring removes deposits from

the piston top land, ensuring proper cylinder

function, no bore polishing, stable lube oil

consumption, and low wear to the liner.

7

PISTON & PISTON RINGS For years, the outstanding piston concept

for highly rated heavy fuel engines has been

a rigid composite piston with a steel crown

and nodular cast-iron skirt. More than twenty

years of experience has fine-tuned this

concept. When it comes to reliability, there is

no real alternative today for modern engines

with high cylinder pressures and combustion

temperatures.

Wärtsilä’s patented skirt lubrication

minimizes frictional losses, and ensures the

appropriate lubrication of both piston rings and

the piston skirt. In Wärtsilä’s three-ring concept

each ring has a specific task. The rings are

dimensioned and profiled for consistent

performance throughout their operating lives.

To avoid carbon deposits in the ring

grooves of a heavy fuel engine, the pressure

balance above and below each ring is crucial.

Experience has shown that this effect is most

likely achieved with a three-ring pack. Finally,

it is well known that most frictional losses in

a reciprocating combustion engine originate

from the rings. Thus a three-ring pack is the

obvious choice in this respect, too. The piston

ring package and ring grooves are optimized

for long life by a special wear-resistant coating

and groove treatment.

The main features of the piston design are:

��A two-piece composite structure

��A steel crown and nodular cast-iron skirt

��Two compression rings and one oil scraper

ring, which in combination with a pressure

lubricated piston skirt, achieve low friction

and high seizure resistance

��Optimized piston ring groove temperature to

prevent cold corrosion.

CYLINDER HEAD The cylinder head design features high

reliability and easy maintenance. A stiff cone- /

box-like design can cope with high combustion

pressures, and is essential for obtaining both

liner roundness and even contact between the

exhaust valves and their seats. Wärtsilä’s vast

global experience of heavy fuel operation has

contributed greatly to the efficient design and

development of exhaust valves.

The basic criterion in exhaust valve design

is having the correct temperature. This is

achieved through optimized cooling and closed

seat ring technology, which extend the life of

the valves and seats.

The cylinder head design is based on the

four-screw concept developed and used by

Wärtsilä for many years. A four-screw cylinder

head design also provides the possibility

for having inlet and exhaust ports with a

minimum of flow losses. The port design

has been optimized using a combination of

computational fluid dynamics analysis and full-

scale flow measurements.

The main features of the cylinder head design

are:

��Four cylinder head screws only, giving

space for flow-efficient ports

��Inlet and exhaust gas ports that are on the

same side

��The height and rigid design, which ensure

even and sufficient surface pressure on the

cylinder head gasket

��A bore-cooled flame plate for optimum

temperature distribution

��Two inlet valves and two exhaust gas

valves, all with valve rotators.

8

MULTI-DUCT A multifunctional duct is connected to the

cylinder head. The functions of this multi-duct

are as follows:

��Air transfer from air receiver to cylinder head

��Introduction of an initial swirl to the inlet air

for optimal part load combustion

��Exhaust transfer to the exhaust system

��Cooling water transfer from the cylinder

head to the return channel in the engine

block

��Insulation/cooling of the exhaust transfer

duct

��Support for the exhaust system, including

insulation

CAMSHAFT AND VALVE GEAR The engine is available with either traditional

mechanical valve actuation, or variable inlet

valve closing actuation.

The camshaft is built of single cylinder

sections with integrated cams. The camshaft

sections are connected through separate

bearing journals, which make it possible to

remove the shaft sections sideways from the

camshaft compartment.

The valve follower is of the roller tappet

type, where the roller profile is slightly

convex for good load distribution. The valve

mechanism includes rocker arms working on

yokes guided by pins.

Both exhaust and inlet valves are equipped

with valve rotators to ensure a safe valve and

seat function. The rotation means that the

temperature distribution and wear to the valves

is even, and that the sealing surface is kept

free of deposits.

The main features of the camshaft and valve

design are:

��Each cylinder section of the camshaft is

forged in one piece with integrated cams

��Separate bearing journals

��The valve follower is of the roller tappet type

��Traditional valve actuation

��Variable Inlet Valve Closing (VIC) for

IMO Tier II compliance.

The VIC system is designed to improve the

engine’s partial load performance by enabling

alternative inlet valve closing timings. The

major advantages are a reduction in visible

smoke, load application improvement, and

thermal load reduction. The variation of inlet

valve closing timing is achieved through the

addition of a hydraulic chamber between

the inlet valve tappet and the push rod.

Adjustability of the inlet valve movement is

achieved by controlling the oil flow into and out

the hydraulic chamber.

The main features of the VIC system are:

��Inlet valve closing timing that can be

adjusted

��With VIC employed, the inlet valve is open

longer

As compared to the standard valve train, the

VIC system comprises the following additional

parts:

��Pressure accumulator

��Piston and oil supply

��Non-return valve

9

OPERATIONAL SYSTEMS FUEL INJECTION SYSTEM The patented Wärtsilä multi-housing principle

ensures outstanding safety of the low-pressure

fuel system. The fuel line consists of channels

drilled in cast parts, which are clamped firmly

to the engine block. For easy assembly and

disassembly, these parts are connected to

each other using slide connections.

Wärtsilä 4-stroke engines are available

with three alternative fuel injection systems

depending on configuration: a conventional

fuel injection system, with either single- or

twin plunger injection pumps, and common-

rail fuel injection. High injection pressures

giving low smoke emissions characterize all

three systems. The common-rail technology

in particular, enables operation at any load

without visible smoke.

An unmatched level of safety is achieved

through housing both the entire low-pressure

and high-pressure systems in a fully covered

compartment.

Common-rail technology offers almost

unlimited possibilities to adjust the fuel

injection process to the prevailing engine

operating conditions, fuel characteristics,

and to achieve emission levels. The main

components of the common-rail injection

system that are designed especially for

Wärtsilä engines are the high-pressure pumps,

the balance accumulators, the fuel injection

valves, and the built-on control oil pump. The

control oil is engine oil with additional filtration.

The system’s high-pressure pumps are

camshaft-driven and amply dimensioned for

supplying fuel to two cylinders. Each pump is

connected to a fuel accumulator that evens

out the pressure and feeds the two cylinders.

The accumulators are connected to each other

through double-walled pipes, a detail that

both guarantees continuously even pressure

in all accumulators, and that allows the engine

to operate with one or two disconnected

high-pressure pumps, should this ever be

necessary.

From the accumulators, fuel is supplied

at the required pressure into the cylinders

through injection valves controlled by electro-

hydraulic actuators. The individual, and

therefore cylinder-specific, control of injection

timing and duration is an important feature that

is made possible by this injection equipment.

One significant safety detail is that the

injection valves are designed to ensure that the

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injection nozzles are totally unloaded between

injection periods. This feature eliminates the

risk of unintended fuel supply into the cylinders

caused, for example, by incomplete closure of

the nozzle needle at the end of injection.

The twin-pump system, likewise, offers the

possibility to optimize the prevailing engine

operating conditions, fuel characteristics and

emission levels, thanks to twin plunger pump

elements. One plunger controls the quantity

of fuel while the other controls the injection

timing.

TURBOCHARGING SYSTEM Turbocharger technology has undergone

intense design and performance development

in recent years, resulting in higher performance

and greater reliability. Only the best available

charger technology is used on Wärtsilä

engines.

The main features of the turbocharging

system are:

��One-stage turbocharging

��An oil-cooled turbocharger with plain

bearings lubricated by engine oil

��A two-stage charge air cooler depending on

engine configuration

��An LT water bypass valve for charge air

temperature control

��The charge air receiver is integrated into

the engine block

��A water mist catcher as a standard option

��Air and exhaust waste gate functions for

best engine performance, depending on

engine configuration

��A single-pipe exhaust gas system (SPEX)

or pulse charging, depending on engine

configuration

The SPEX system is designed for minimum

flow losses on both the exhaust and air sides.

The charging systems are designed to give

high efficiency and good load acceptance.

SPEX is designed for best possible full-load

performance. SPEX, combined with the

exhaust waste gate and air bypass, meets

the established low load performance of

pulse charging. With its unique design, the

load acceptance is close to that of pulse

charging. Non-cooled chargers, with inboard

plain bearings lubricated by the engine’s lube

oil system, are used. The end result is that

intervals between overhauls are reduced, as is

maintenance.

11

Cen

trifu

gal

 filt

er

Lubricating oil cooler

Charge air cooler LT

LT pump

Charge air cooler HT

Cyl.

HT pump

Heat recovery

Pre­heater

HT stand­by pump

PRINCIPLE LAYOUT OF THE COOLING SYSTEM.

Central cooler

LT stand­by pump

Oil pump

System oil tank

Dry oil sump

Oil cooler Automatic filter

Electric stand­by oil pump

Electric pre­lube oil pump

Suction strainer

PRINCIPLE LAYOUT OF THE LUBRICATING SYSTEM.�

COOLING SYSTEM The cooling system on the engine is split

into two separate circuits: high-temperature

(HT) and low-temperature (LT). The cylinder

liner, the cylinder head, and the first stage

in the charge air cooler are all connected to

the HT circuit. The lubricating oil cooler and

the second stage in the charge air cooler are

connected to the LT circuit.

The amount of water passing through the

LT stage in the charge air cooler is controlled

by a thermostatic valve. This maintains the

desired intake air temperature, regardless of

load level or variations in the cooling water

temperature. Engine-driven pumps and built-

on thermostatic valves are standard. As an

option, the engine is also available without

built-on pumps and thermostatic valves.

LUBRICATING OIL SYSTEM The engine is available with a complete built-

on lube oil system that offers the following

features:

��An engine-driven main lube oil pump (screw

type) with built-in safety valve

��A pressure regulating valve that keeps the

pressure before the main bearings at a

constant level

��A lubricating oil module, including lube oil

cooler, filter and thermostatic valves

��The lube oil filtration is based on a full flow

automatic back-flushing filter. This requires

a minimum of maintenance and needs no

disposable filter cartridges

��A centrifugal filter connected to the back-

flushing line of the automatic filter. This

enables wear particles from the system to

be extracted

��An electric motor driven pre-lubricating

pump, depending on engine configuration

��The oil sump is either a wet or dry type,

depending on engine configuration. A

separate system oil tank is needed for the

dry sump

��Connections for stand-by auxiliaries.

AUTOMATION SYSTEM Wärtsilä engines can be equipped with a

modular embedded automation system, the

Wärtsilä Unified Controls – UNIC, which is

available in three different versions. The basic

functionality is the same in all versions, but

the functionality can be easily expanded to

cover different applications. UNIC C1 and

UNIC C2 are versions applicable for engines

with conventional fuel injection, whereas UNIC

C3 additionally includes fuel injection control

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LDU

LCP

ESM

MCM

CCM CCM

IOM

PDM

Ethernet

Hardwired connections

Loadsh. CAN

UNIC

for engines with common-rail fuel injection.

UNIC C3 automation is also used in gas

engines.

The Wärtsilä UNIC is a flexible and fully

scalable control system for large reciprocating

diesel and gas engines.

The UNIC system is designed to fulfill the

long lifetime expectations for large marine

diesel and gas engines operating in the

toughest of conditions. The system is based

on a high degree of commonalities and

standard interfaces, covering different engine

sizes and fuel systems in a modular way.

A modular, standardized interface provides

an easily reusable design for off-engine

automation systems. It allows, for example,

diesel engines to be converted to dual fuel or

common rail with a minimum of modifications.

Thanks to the pre-tested configuration,

minimal commissioning or installation work

is needed before the engine or generating

set is operational. The critical parts of the

UNIC system are either redundant or very

fault-tolerant to guarantee high safety and

availability in all circumstances. In particular,

parts like the communication and power supply

are fully redundant to allow single failures

without interruptions in engine operation.

The electronic control enables the engine to

be adapted to different operating conditions.

The main features of the UNIC system are:

��A complete engine safety system

��Local monitoring

��Speed control with load sharing

��Fuel injection

��Timing control and knock detection

��Alarm signal acquisition

AUTOMATION SYSTEM COMPONENTS

ESM Engine Safety Module

MCM Main Control Module

TCM Thermocouple Module

IOM Input Output Module

PDM Power Distribution Module

LCP Local Control Panel

LDU Local Display Unit

CCM Cylinder Control Module

��Start/stop sequencing and load reduction

request

��System diagnostics and a fieldbus interface

applicable to each engine’s configuration.

13

BMEP

 (bar

) Mis

firin

g

Ther

mal

 effi

cien

cy (%

)

NO(g

/kW

h)X

Air/fuel ratio

0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0 2.2

Knocking

2.62.4

Operating window

45%

2 g/kWh

14

THE LEAN-BURN CONCEPT The Wärtsilä dual-fuel technology operates

on the lean-burn principle: the mixture of air

and gas in the cylinder has more air than

is needed for complete combustion. Lean

combustion reduces peak temperatures

and therefore NOX emissions. Efficiency

is increased and higher output is reached

while avoiding knocking.

Combustion of the lean air-fuel mixture

is initiated by injecting a small amount of

LFO (pilot fuel) into the cylinder. The pilot

fuel is ignited in a conventional diesel

process, providing a high-energy ignition

source for the main charge. To obtain the

best efficiency and lowest emissions, every

cylinder is individually controlled to ensure

operation at the correct air-fuel ratio and

with the correct amount and timing of pilot

fuel injection.

Wärtsilä has developed a special

electronic control system to cope with

the demanding task of controlling the

combustion in each cylinder, and to ensure

optimal performance in terms of efficiency

and emissions under all conditions by

keeping each cylinder within the operating

window. Stable and well-controlled

combustion also contributes to less

mechanical and thermal load on the engine

components.

DUAL-FUEL TECHNOLOGY

FUEL SYSTEM The fuel system of the Wärtsilä dual-fuel engine

has been divided into three: for gas, for liquid fuel,

and for a separate pilot fuel system. The Wärtsilä

dual-fuel engine is started in diesel mode using

both main diesel and pilot fuel. Gas admission

is activated when combustion is stable in all

cylinders. When running the engine in gas mode,

the pilot fuel amounts to less than 1% of full-load

fuel consumption. The amount of pilot fuel is

controlled by the engine control system. When

running the engine in liquid fuel mode the pilot is

also in use to ensure nozzle cooling.

GAS SUPPLY The natural gas is supplied to the engine

through a gas valve unit. The gas is first filtered

to ensure a clean supply. The gas pressure

is controlled by a valve located in the valve

station. The gas pressure is dependent on

engine load. At full load the pressure before

the engine is 3.5 bar (g) for LHV 36 MJ/m3.

For lower LHV the pressure has to be

increased. The system includes the necessary

shut-off and venting valves to ensure a safe

and trouble-free gas supply.

On the engine, the gas is supplied through

large common-rail pipes running along the

engine. Each cylinder then has an individual

feed pipe to the gas admission valve on the

cylinder head.

Gas piping in marine installations is of

double wall design as standard.

LIQUID FUEL OIL SUPPLY The fuel oil supply on the engine is divided into

two separate systems: pilot fuel and back-up

fuel oil system.

The pilot fuel is elevated to the required

pressure by a pump unit. This includes

duplex filters, pressure regulator and an

engine-driven radial piston-type pump. The

high-pressure pilot fuel is then distributed

through a common-rail pipe to the injection

valves at each cylinder. Pilot fuel is injected at

approximately 900 bar pressure and the timing

and duration are electronically controlled. The

pilot fuel system is separated from the back-up

fuel system with separate connections on the

engine. The back-up fuel system is fed to a

normal camshaft-driven injection pump. From

the injection pump, the high-pressure fuel goes

to a spring-loaded injection valve of standard

design for a diesel engine.

INJECTION VALVE The Wärtsilä dual-fuel has a twin-needle

injection valve. The larger needle is used in

back-up mode for LFO or HFO operation and

the smaller for pilot fuel oil when the engine

is running in gas mode and also in back-up

fuel operation to ensure nozzle cooling. Pilot

15

injection is electronically controlled and the

main diesel injection is hydromechanically

controlled. The individually controlled solenoid

valve allows optimum timing and duration of

pilot fuel injection into every cylinder when

the engine is running in gas mode. Since NOX

formation depends greatly on the amount of

pilot fuel, this design ensures very low NOX

formation while still employing a stable and

reliable ignition source for the lean air-gas

mixture in the combustion chamber.

FUEL INJECTION PUMPS FOR LIQUID FUEL OPERATION INJECTION VALVES

M

PILOT FUEL PUMP UNIT

BOOSTER PUMP UNIT

CO

MM

ON

RA

IL

FO

R H

IGH

PR

ES

SU

RE

PIL

OT

FU

EL

RE

TU

RN

FU

EL

RETURN FUEL

PILOT FUEL TANK LFO

PR

ES

SU

RE

PR

ES

SU

RE

PRESSURE

BOOSTER PUMP UNIT

MAIN FUEL TANK LFO or HFO

Control system

GAS ADMISSION VALVE Gas is admitted to the cylinders just before

the air inlet valve. The gas admission valves

are electronically actuated and controlled by

the engine control system to give exactly the

correct amount of gas to each cylinder. In this

way, the combustion in each cylinder can be

fully and individually controlled. Since the valve

can be timed independently of the inlet valves,

the cylinder can be scavenged without risk of

gas being fed directly to the exhaust system.

Independent gas admission ensures the

correct air-fuel ratio and optimal operating

point with respect to efficiency and emissions.

It also enables reliable performance without

shutdowns, knocking or misfiring. The gas

admission valves have a short stroke and

specially selected materials, thus providing low

wear and long maintenance intervals.

INJECTION PUMP The Wärtsilä dual-fuel engine utilizes the well-

proven monoblock injection pump developed

by Wärtsilä. This pump withstands the high

pressures involved in fuel injection and has

a constant-pressure relief valve to avoid

cavitation. The fuel pump is ready for operation

at all times and will switch over from gas to

fuel oil if necessary. The plunger is equipped

with a wear-resistant coating.

PILOT PUMP The pilot fuel pump is engine-driven. It receives

the signal for correct outgoing fuel pressure

from the engine control unit and independently

sets and maintains the pressure at the required

level. It transmits the prevailing fuel pressure to

the engine control system.

High-pressure fuel is delivered to each

injection valve through a common-rail pipe,

which acts as a pressure accumulator and

damper against pressure pulses in the system.

The fuel system has a double wall design with

alarm for leakage.

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LFOGas HFO

liquid fuel to gas 100 %

LFOGas HFO

gas to liquid fuel

Instant ~0,5 h ~0,1 h

~0,5 h

*

~80%

Exhaust waste­gate Load

Speed

P I

T

TC

P

Exhaust

Air

Engine control system

In the dual-fuel solution the twin injection nozzles are used also for HFO operation. The LFO pilot is in use also during the HFO operation. * The time needed to reach full load on gas depends on the duration of HFO-mode operation.

“INSTANT” CHANGE OVER FROM GAS TO LIQUID FUEL MODE WITH THE DUAL-FUEL SOLUTION

OPERATION MODE TRANSFER The engine can be switched automatically

from liquid fuel oil to gas operation at loads

below 80% of the full load. Transfer takes place

automatically after the operator’s command

without load changes. During switchover, which

lasts about one minute, the fuel oil is gradually

substituted by gas.

In the event of for instance a gas supply

interruption, the engine converts from gas to

liquid fuel operation at any load instantaneously

and automatically. Futhermore, the separate

liquid fuel system makes it possible to switch

over from LFO to HFO without power reduction.

The pilot fuel is in operation at liquid fuel mode to

ensure nozzle cooling. The pilot fuel consumption

is less than 1% of full load fuel consumption.

Switching over to LFO from HFO operation can

also be done without load reduction. From LFO

to gas operation, the switch can be made as

described above. This operation flexibility is the

real advantage of the dual-fuel system.

AIR-FUEL RATIO CONTROL The correct air-fuel ratio under any operating

conditions is essential to optimum performance

and emissions. For this function, Wärtsilä dual-

fuel engines are equipped with an exhaust gas

waste-gate valve.

Part of the exhaust gases bypasses the

turbocharger through the waste-gate valve. The

valve adjusts the air-fuel ratio to the correct value

independent of the varying site conditions under

high engine loads.

17

MAINTENANCE FEATURES During design and development, engine

manufacturers typically emphasize ease of

maintenance by including tooling and easy

access in the basic design, and by providing

easy-to-understand instructions.

Wärtsilä´s maintenance principle is

substantiated by the following:

��A cylinder head with four fixing studs and

simultaneous hydraulic tightening of all four

studs

��Uniform one-cylinder camshaft pieces

��Slip-on fittings wherever possible

��Exhaust gas system insulation using easy-

to remove panels on an engine mounted

frame

��A hydraulic jack for the overhaul of the main

bearing where applicable

��A three-piece connecting rod in bigger

engines, allowing inspection of the big end

bearing without removal of the piston, and

piston overhaul without dismantling the big

end bearing

��Weight-optimized and user-friendly

maintenance tools

SERVICES Several customers have recognized us as

their preferred service supplier to ensure the

availability and cost-efficient operation of their

installations. They benefit from having their

entire power system fully serviced by one

global supplier. Wärtsilä Services provides full

service throughout the product lifecycle for

both marine and power plant customers, and is

constantly developing its network worldwide.

Additionally we are continually broadening

our range of services by adding valuable

products and specialist services to our

portfolio. In this way we also support

equipment onboard your vessel or at your

installation and in our numerous workshops

around the globe and in key ports, regardless

of equipment make.

We offer lifecycle efficiency solutions in the

following services product lines:

��Engine Services

��Propulsion Services

��Electrical & Automation Services

��Boiler Services

��Operations & Management Services

��Training Services

��Environmental Services

These services cover everything from basic

support with parts, field service and technical

support to service agreements and condition

based maintenance; from installation and

commissioning, performance optimization,

including upgrades and conversions, to

environmental solutions, technical information

and online support.

The choice available to you extends from

parts and maintenance services to a variety

of comprehensive, customized long-term

service agreements, including performance

and operations & management agreements.

Our Services organization currently features

more than 11,000 dedicated professionals in

70 countries.

Wärtsilä adds value to your business at

every stage in the lifecycle of your installations.

With us as your service partner, you receive

many measurable benefits such as availability

and performance, productivity gains and

cost benefits. Above all, peace of mind in

the knowledge that your installation is being

serviced by the most experienced partner you

could have – Wärtsilä.

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Wärtsilä is a global leader in complete lifecycle power solutions for the marine

and energy markets. By emphasising technological innovation and total

efficiency, Wärtsilä maximises the environmental and economic performance

of the vessels and power plants of its customers. Wärtsilä is listed on the

NASDAQ OMX Helsinki, Finland.

WÄRTSILÄ® is a registered trademark. Copyright © 2010 Wärtsilä Corporation.