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.