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WRTSIL RT-FLEX96C AND WRTSIL RTA96CTECHNOLOGY REVIEW


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12-cylinder Wrtsil RT-ex96C engine giving 68,640 kW (93,360 bhp).

INTRODUCTIONThe Wrtsil RT-ex96C and RTA96C lowspeed marine diesel engines, with a powerrange of 24,000 to 80,080 kW, are tailormade for the economic, reliable propulsion oflarge, fast container liners. They offer clear,substantial benets: High power outputs at optimum shaft

speeds Reliability and proven design Competitive rst cost

Economical fuel consumption over thewhole operating range

Low cylinder oil feed rate Three years between overhauls Low maintenance costs

Full compliance with the NO X emissionregulation of Annexe VI of the MARPOL1973/78 convention.

The Wrtsil RT-ex96C has additionalbenets: Smokeless operation at all running speeds Better fuel economy in the part-load range Lower steady running speeds Reduced maintenance requirements with

simpler engine setting and extendable timebetween overhauls.

The Wrtsil RTA96C two-stroke diesel enginewas introduced in December 1994 to meet

the demand for even higher power outputs topropel the then coming generation of largerand faster container ships. It followed in along line of RTA-series engines with eachgeneration bringing higher power outputs tocater for ever increasing ship sizes.

The RTA96C was readily accepted in themarket. Its reliability was acknowledged veryquickly by the containership operators and ledto a very good reputation, further applications

and repeat orders.The Wrtsil RT-ex96C two-stroke diesel

engine was introduced in 2003 by combiningthe latest common-rail technology for fuelinjection and valve actuation with fully

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Principal parameters of Wrtsil RT-ex96C and RTA96C engines

Bore mm 960

Stroke mm 2500

Output MCR, R1 kW/cyl 5720

bhp/cyl 7780

Speed range, R1-R3 rpm 10292

BMEP at R1 bar 18.6

Pmax bar 145

Mean piston speed at R1 m/s 8.5

Number of cylinders 614*

BSFC: at full load, R1 g/kWh 171

g/bhph 126

* 13- and 14-cylinder engines only in RT-ex version.

Output k

80 000

60 000

50 000

40 000

30 000

20 000

10 000

8 000

6 000

4 000

rev/min

Output bhp

100 000

80 000

60 000

40 000

20 000

10 000

8 000

6 000

60 70 80 90 100 120 140

Engine speed

RTA72U-B

RT-flex84T-DRTA84T-D

RT-flex68-DRTA68-D

RT-flex58T-BRTA58T-B

RTA48T-B

RT-flex96CRTA96C

RT-flex60C-B

RT-flex50-BRTA50-B

RTA52U

RTA62U-B

RT-flex82TRTA82T

RT-flex82CRTA82C

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integrated electronic control and the wellestablished RTA96C engine.

The 14-cylinder RT-ex96C engines extendthe power spectrum of the RTA series up to80,800 kW (108,920 bhp). Thus with wasteheat recovery systems which can add up to 12per cent of engine power, RT-ex96C enginescan meet the propulsion requirements of large,fast containerships from up to around 12,000TEU capacity at service speeds of around 25

knots.


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DEVELOPMENT BACKGROUND Wrtsil has a policy of continuously updatingits engine programme and engine designs toadapt them to the latest market requirementsand to deliver the benets of technicalimprovements. The Wrtsil RT-ex96C andRTA96C engine types are good examples ofthis policy.

When the design of the RTA96C was

introduced in 1994, it was based fully on thewell-established RTA84C to take advantage ofthe wealth of experience in theoretical design,testbed research and operating service fromthe RTA84C and other previous RTA-seriesengines. The rst RTA96C engines enteredservice in 1997.

In 2000, the cylinder power of the RTA96Cwas raised by some four per cent by utilisingpotential already in the design. A 14-cylinder

model was also added to bring the maximum

power up to todays 80,080 kW (108,920bhp). The increased power output was madepossible by the very satisfactory serviceexperience with the engines in service.

Further improvements were subsequentlyachieved by the introduction of various designmeasures to improve piston-running behaviour.These improvements reduce wear rates of

cylinder liners and piston rings, extend timesbetween overhauls and allow reduced cylinderoil feed rates.

A major step forward was achieved whenthe RTA96C was combined with the RT-exelectronically-controlled common-rail technologyfor fuel injection and valve actuation to createthe RT-ex96C engine introduced in 2003. Atthe same time, the decision was taken that the13- and 14-cylinder engines would only be built

in RT-ex form.

The RT-ex common-rail technology hadbeen introduced rst in the RT-ex58T-Bengine. Service results with this engine, whichentered service in September 2001, wereexcellent, clearly demonstrating that the newRT-ex system offers distinctive operationalbenets which are not possible with camshaftengines. Thus the experience from the

RT-ex58T-B engine type, the RT-ex60Cengine rst built in 2002, and the full-sizedRT-ex58T research engine since June 1998were employed in the development of theRT-ex96C engine.

The rst RT-ex96C engines were shoptested in April 2004 (eight-cylinder engine)and June 2004 (12-cylinder engine). Thesesubsequently entered service in November andDecember 2004 respectively.

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Wrtsil RT-ex96C.

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RT-FLEX: CONCEPT AND BENEFITS The Wrtsil RT-ex system is the result of along project since the 1980s to develop lowspeed marine engines without the constraintsimposed by mechanical drive of fuel injectionpumps and valve actuation pumps but with

far greater exibility in engine setting to reachfuture requirements. The objective is to deliveroperational benets to the shipowners.

The Wrtsil RT-ex96C is basically astandard Wrtsil low-speed two-stroke marinediesel engine, except that, instead of the usualcamshaft and its gear drive, fuel injection pumps,exhaust valve actuator pumps and reversingservomotors, it is equipped with a common-railsystem for fuel injection, exhaust valve actuationand air starting, and full electronic control of these

engine functions.The common-rail injection system operates

with just the same grades of heavy fuel oil asare already standard for Wrtsil low-speedengines.

The RT-ex engines offer a number ofinteresting benets to shipowners and operators: Smokeless operation at all operating speeds Lower steady running speeds, in the range

of 10-15 per cent nominal speed, obtained

smokelessly through sequential shut-off

of injectors while continuing to run on allcylinders

Reduced running costs through lower partload fuel consumption and longer timesbetween overhauls

Reduced maintenance requirements, withsimpler setting of the engine. The asnew running settings are automaticallymaintained

Reduced maintenance costs through precisevolumetric fuel injection control leading toextendable times between overhauls. Thecommon-rail system with its volumetriccontrol gives excellent balance in enginepower developed between cylinders andbetween cycles, with precise injection timing

and equalised thermal loads Reliability is given by long-term testing of

common-rail hardware in component test rigs Higher availability owing to the integrated

monitoring functions High availability also given by the built-in

redundancy, provided by the ample capacityand duplication in the supply pumps, maindelivery pipes, crank-angle sensors, electroniccontrol units and other key elements.

RT-FLEX COMMON-RAIL SYSTEM APPLIED The common rail for fuel injection is a manifoldrunning the length of the engine at just belowthe cylinder cover level. The common rail andother related pipe work are neatly arrangedbeneath the top engine platform and readilyaccessible from above.

The common rail is fed with heated fuel oilat the usual high pressure (nominally 1000bar) ready for injection. The supply unit has anumber of high-pressure pumps running onmulti-lobe cams.

Fuel is delivered from this common railthrough a separate injection control unitfor each engine cylinder to the standardfuel injection valves which are hydraulicallyoperated in the usual way by the high-pressure

fuel oil. The control units, using quick-actingWrtsil rail valves, regulate the timing of fuelinjection, control the volume of fuel injected,and set the shape of the injection pattern.The three fuel injection valves in each cylinder

cover are separately controlled so that,although they normally act in unison, they canalso be programmed to operate separately asnecessary.

The key features of the Wrtsil RT-excommon-rail system are: Precise volumetric control of fuel injection,

with integrated ow-out security Variable injection rate shaping and free

selection of injection pressure Stable pressure levels in common rail and

supply pipes Possibility for independent control and

shutting off of individual fuel injection valves Ideally suited for heavy fuel oil through clear

separation of the fuel oil from the hydraulic

pilot valves Well-proven standard fuel injection valves Proven, high-efciency common-rail fuel

pumps.The RT-ex system also encompasses exhaust

Rail unit at the cylinder top level of the RT-eengine with electronic control units on the front

the rail unit for good access.

valve actuation and starting air control. Theexhaust valves are operated in much the sameway as in existing RTA engines by a hydraulicpushrod but with the actuating energy nowcoming from a servo oil rail at 200 bar pressureThe servo oil is supplied by high-pressure

hydraulic pumps incorporated in the supply unitwith the fuel supply pumps. The electronicallycontrolled actuating unit for each cylinder givesfull exibility in timing for valve opening andclosing.

All functions in the RT-ex system arecontrolled and monitored through theintegrated Wrtsil WECS-9520 electroniccontrol system. This is a modular system withseparate microprocessor control units for each

cylinder, and overall control and supervisionby duplicated microprocessor control units.The latter provide the usual interface for theelectronic governor and the shipboard remotecontrol and alarm systems.

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RT-FLEX:REAL IN-SERVICE

FUEL ECONOMYWhereas Wrtsil RTA-series engineshave excellent fuel consumption ingeneral, the RT-ex system enables furtherimprovements to be achieved in the partload range. This is because of the freedomallowed by the RT-ex system in selectingoptimum injection pressure, fuel injectiontiming and exhaust valve timing at all engineloads or speeds, while ensuring efcient

combustion at all times, even during deadslow running.

Similar freedom in exhaust valvetiming allows the RT-ex system to keepcombustion air excess high by earlier valveclosing as the load/speed is reduced. This isnot only advantageous for fuel consumptionbut also limits component temperatures,which would normally increase at low load.Lower turbocharger efciencies at part load

normally result in low excess combustion airwith xed valve timing. Another important contribution to fuel

economy of the RT-ex96C engines is thecapability to adapt easily the injection timingto various fuel properties having a poorcombustion behaviour.

DELTA TUNING: A FUEL EFFICIENCY ALTERNATIVE Through their exibility in engine setting,

RT-ex engines also have an alternative fuelconsumption curve as standard to give lowerBSFC (brake specic fuel consumption) inwhat is for many ships the main operatingrange. Through Delta Tuning, the BSFC islowered in the mid- and low-load operatingrange at less than 90 per cent engine power.The consequent increase in NO Xin thatoperating range is compensated by reducingNO X emissions in the high load range. With

both BSFC curves, the engines comply withthe NO X regulation of the MARPOL 73/78convention.

The new alternative BSFC curve for RT-ex96C engines given by Delta Tuning compared woriginal BSFC curves. All curves shown are for engines complying with the IMO NOX regulation.

Smoke emission measurements for RT-ex96C engines compared with theRTA96C engines, both using marine diesel oil.

RT-FLEX: CLEANER IN THE ENVIRONMENT Exhaust gas emissions have become animportant aspect of marine diesel engines. AllWrtsil RTA and RT-ex engines comply withthe NO X emissions limit of Annex VI of theMARPOL 73/78 convention as standard.

RT-ex engines, however, come

comfortably below this NO X limit by virtue oftheir extremely wide exibility in optimisingthe fuel injection and exhaust valveprocesses.

The most visible benet of RT-ex enginesis, of course, their smokeless operation at allship speeds. The superior combustion withthe common-rail system is largely becausethe fuel injection pressure is maintained atthe optimum level irrespective of engine

speed. In addition, at very low speeds,individual fuel injectors are selectively shutoff and the exhaust valve timing adapted tohelp to keep smoke emissions below thevisible limit.

Yet the environmental benets ofRT-ex engines need not be restricted bythe current state-of-the-art. As all settingsand adjustments within the combustionand scavenging processes are madeelectronically, future adaptations will

be possible simply through changes insoftware, which could be readily retrottedto existing RT-ex engines.

A major reduction in all exhaustemissions, including CO2, can be obtainedwith RT-ex96C engines by combining theengine with a high-efciency waste heatrecovery plant (see page 20).

As well as investigating the scope ofpossibilities of the RT-ex system, Wrtsil

is carrying out a long-term researchprogramme to develop techniques forfurther reducing exhaust emissions,including NO X, SO Xand CO2, in both RTAand RT-ex engines.

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12-cylinder Wrtsil RTA96C engine giving 68,640 kW.

RTA96C:THE TRADITIONAL CAMSHAFT ARRANGEMENT The Wrtsil RTA96C retains the traditional,mechanical camshaft arrangement for fuelinjection pumps and valve drives.

The camshaft-driven fuel injection pumpsare of the well-proven double-valve controlledtype that has been traditional in Wrtsil low

speed engines. Injection timing is controlledby separate suction and spill valves regulatedthrough eccentrics on hydraulically-actuatedlay shafts. Consequently, great exibility intiming is possible through the variable fuelinjection timing (VIT) system for improved partload fuel consumption, and for the fuel qualitysetting (FQS) lever to adjust the injection timingaccording to the fuel oil quality.

The valve-controlled fuel injection pump,

in comparison with a helix type, has a plungerwith a signicantly greater sealing length.The higher volumetric efciency reduces thetorque in the camshaft. Additionally, injectionfrom a valve-controlled pump is far more

stable at very low loads and rotational shaftspeeds down to 15 per cent of the ratedspeed are achieved. Valve control also hasbenets of less deterioration of timing overthe years owing to less wear and to freedomfrom cavitation.

The camshaft is assembled from a numberof segments, one for each pump housing. Thesegments are connected through SKF sleevecouplings. Each segment has an integralhydraulic reversing servomotor located withinthe pump housing.

The camshaft drive uses the wellproven arrangement of gear wheelshoused in a double column locatedat the driving end in the centre of

the engine, depending upon numberof cylinders. There are three gearwheels in the camshaft drive. The main gearwheel on the crankshaft is in one piece andange-mounted.

Fuel injection pump with double control valves.

Pump housing with fuel injection pumps andexhaust-valve actuator pumps.

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Three views of principal elements in the engine structure:bedplate (top left), column (top right) and cylinder jacket (above).

ENGINE STRUCTURE

Wrtsil RT-ex96C and RTA96C engines havea well-proven type of structure, with a gondola

type bedplate surmounted by very rigid, Ashaped double-walled columns and cylinderblocks, all secured by pre-tensioned vertical tierods. The whole structure is very sturdy with lowstresses and high stiffness. Both bedplate andcolumns are welded fabrications which are alsodesigned for minimum machining.

A high structural rigidity is of majorimportance for the todays two-stroke engineslong stroke. Accordingly the design is based on

extensive stress and deformation calculationscarried out by using a full three-dimensionalnite-element computer model for differentcolumn designs to verify the optimum frameconguration.

The cylinder jacket is assembled fromindividual cast-iron cylinder blocks, bolted

together to form a rigid whole. The supply unitin RT-ex engines, or the fuel pump blocksin RTA engines, are carried on supports onone side of the column and the scavengeair receiver on the other side of the cylinder

jacket. Access to the piston under-side isnormally from the supply unit side, but is alsopossible from the receiver side of the engine,to allow for maintenance of the piston rodgland and also for inspecting piston rings.

The tilting-pad thrust bearing is integratedin the bedplate. Owing to the use of gearwheels for the supply unit drive, the thrustbearing can be very short and very stiff, andcan be carried in a closed, rigid housing.

Finite-element model of the engine structure for computeranalysis comprising the gondola type bedplate, weldedbox-type columns and individual cast-iron cylinder blocks.

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Lowering the crankshaft into the bedplate.

RUNNING GEARThe running gear comprises the crankshaft,connecting rods, pistons and piston rods,together with their associated bearings andpiston rod glands.

The crankshaft is semi-built comprisingcombined crank pin/web elements forged froma solid ingot and the journal pins then shrunkinto the crank web.

The main bearings have white metal shells.The main bearing caps are held down by twopairs of elastic holding down studs.

A better understanding of the main bearingloads is obtained with todays nite-elementanalysis and elasto-hydrodynamic calculationtechniques as they take into account thestructure around the bearing and vibrationof the shaft. The FE model comprises thecomplete shaft and its bearings together

with the surrounding structure. Boundaryconditions, including the crankshaft stiffness,can thus be fed into the bearing calculation.

The crosshead bearing is designed to thesame principles as for all other RTA and RT-ex

engines. It also features a full-width lower halfbearing. The crosshead bearings have thinwalled shells of white metal for a high loadbearing capacity. Wrtsil low-speed enginesretain the use of a separate elevated-pressurelubricating oil supply to the crosshead. Itprovides hydrostatic lubrication which liftsthe crosshead pin off the shell during every

revolution to ensure that sufcient oil lmthickness is maintained under the gas load.This has proved crucial to long-term bearingsecurity.

Extensive development work has beenput into the piston rod gland because ofits importance in keeping crankcase oilconsumption down to a reasonable level andmaintaining the quality of the system oil.

Todays RTA and RT-ex engines employ an

improved design of piston rod gland with gastight top scraper rings, and large drain areasand channels. Hardened piston rods are nowstandard to ensure long-term stability in thegland behaviour.

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Piston, piston rod and gland box. Crosshead pins with guide shoes.

with crankshaft distortion

without crankshaft distortion

Lo a d v e c t or

Load diagrams for main bearing with and without crankshaft distortion taken Finite-element analysis of the crank throw of the RT-ex96Cinto account. under full dynamic loading.

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Bore-cooled pistons from the underside.

Cooling oil spray nozzles at top of piston rod.

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COMBUSTION CHAMBER The combustion chamber in todays dieselengine has a major inuence on the enginesreliability. Careful attention is needed for thelayout of the fuel injection spray pattern toachieve moderate surface temperatures and to

avoid carbon deposits. At Wrtsil, optimisation of fuel injectionis carried out rst by the use of moderncalculation tools, such as CFD (computeriseduid dynamics) analysis. The calculated resultsare then conrmed on the rst test engines.

The modern calculation tools wereinvaluable with the RTA96C which has arather shallow combustion chamber owing toits comparatively short stroke/bore ratio, andcare was needed with the large quantity of fuel

injected to avoid impingement on componentsurfaces.

The well-proven bore-cooling principle isalso employed in all the combustion chambercomponents to control their temperatures, aswell as thermal strains and mechanical stresses.

The solid forged steel, bore-cooled cylindercover is secured by eight elastic studs. It isequipped with a single, central exhaust valvein Nimonic 80A which is housed in a bolted

on valve cage. The engines have three fuelinjection valves symmetrically distributed inthe cylinder cover. Anti-corrosion cladding isapplied to the cylinder covers downstream ofthe injection nozzles to protect the cylinder

covers from hot corrosive or erosive attack.The pistons comprise a forged steel crown

with a short skirt. Combined jet-shaker oilcooling of the piston crown provides optimumcooling performance. It gives very moderate

temperatures on the piston crown with a fairlyeven temperature distribution right across thecrown surface. No coatings are necessary.

The cylinder liner is also bore cooled. Itssurface temperatures are optimised for goodpiston-running behaviour.

PISTON-RUNNINGBEHAVIOURToday the time between overhaul (TBO) oflow-speed marine diesel engines is largelydetermined by the piston-running behaviourand its effect on the wear of piston ringsand cylinder liners. For this reason, WrtsilRT-ex96C and RTA96C engines nowincorporate a package of design measures thatenable the TBO of the cylinder components,including piston ring renewal, to be extended toat least three years, while allowing the further

reduction of cylinder lubricating oil feed rate.The standard design measures applied tonewly-built RT-ex96C and RTA96C enginesfor improved piston-running behaviour nowinclude:

Liner of the appropriate material, withsufcient hard phase

Careful turning of the liner running surfaceand plateau honing of the liner over the fulllength of the running surface

Optimised surface temperatures on thecylinder liner without any insulation orinsulating tubes

Chromium-ceramic coated, pre-proledpiston rings in all piston grooves

Anti-Polishing Ring (APR) with doubleacting scraper edges at the top of thecylinder liner

Increased thickness of chromium layer inthe piston-ring grooves

Two bronze rubbing bands on short pistonskirt

Load-dependent accumulator lubricatingsystem for cylinder lubrication.

A key element good piston-running is thesurface nish of the cylinder liner. Carefulmachining and plateau honing gives theliner an ideal running surface for the pistonrings, together with an optimum surfacemicrostructure.

The Anti-Polishing Ring (APR) prevents

the build up of deposits on the top land of thepiston which can damage the oil lm on theliner and cause bore polishing. The APR has asmaller clearance with the piston crown, andtwo scraper edges for greater cleaning effect.

Fully bore-cooled combustion chamber. Analysis of fuel distribution and injection trajectories in thecylinder. Colours indicate concentration with blue/green for thestoichiometric mixture. No combustion calculated.

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The Anti-Polishing Ring (APR) for RTA96C and RT-ex96C engines has ageometry with two edges to clean the piston top land during both the upstrokes of the piston.

Piston of an RTA96C engine after testing at 110 per cent load. The pistonceramic rings in all grooves and two bronze rubbing bands in the short s

It is important that the liner walltemperature is optimised over the pistonstroke. The use of chromium-ceramic coatedpiston rings in all grooves allows lower linertemperatures which are now achieved without

mid-stroke insulation.Whilst trying to avoid corrosive wear

by optimising liner wall temperatures, it isnecessary to take out as much water aspossible from the scavenge air. Thus, theunderslung scavenge air receiver combinedwith highly-efcient vane-type waterseparators tted after the air cooler and theeffective water drainage arrangements areabsolutely essential for good piston running.

Load-dependent cylinder lubrication isprovided by the well-proven Wrtsil multilevel accumulator system which deliversthe timely quantity of lubricating oil for goodpiston-running. The lubricating oil feed rate

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is controlled according to the engine loadand can also be adjusted according to enginecondition. The system allows feed rates downto 1.1 g/kWh, though a lower feed rate of 0.9g/kWh is possible after analysis of engine

performance by a Wrtsil service engineer.The new Pulse Jet Lubrication System is

also being introduced on RT-ex96C engines.This electronically-timed, load-dependentcylinder lubrication system ensures optimumdistribution of cylinder lubricating oil on therunning surface of the cylinder liner. Cylinderlubricating oil is sprayed as multiple jets onto the liner surface from a single row of quillsaround the liner, each quill having multiple

nozzle holes. The feed rate and timing areelectronically controlled at the lubricator pump.There is thus full exibility in the setting of thelubricator timing point, and volumetric meteringensures constant spray patterns across the

engine load range. The dosage is preciselyregulated even for low feed rates.

TURBOCHARGING ANSCAVENGE AIR SYSTThe RT-ex96C and RTA96C engines areuniow scavenged with air inlet ports in thelower part of the cylinder and a single, centraexhaust valve in the cylinder cover. Scavengeair is delivered by a constant-pressureturbocharging system with one or morehigh-efciency exhaust gas turbochargersdepending on the numbers of cylinders. For

starting and during slow-running, the scavengeair delivery is augmented by electrically-drivenauxiliary blowers.

The scavenge air receiver is of anunderslung design with integral non-return
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Air cooler

Location ofwater separator

Arrangements for transmitting propeller thrust to the engine seatings forthe RT-ex96C and RTA96C engines. The inset shows the thrust sleeve fothe thrust bolts.

Side stopper

Thrust

Scavenge air ow from the turbocharger throughthe horizontal scavenge air cooler and the verticallymounted water separator, exiting left to the enginecylinders.

INSTALLATION ARRANGEMENTS aps, air cooler, water separator and theauxiliary blowers. The turbochargers aremounted on the scavenge air receiver whichalso carries the xed foot for the exhaustmanifold.

Immediately after the horizontal air cooler,the scavenge air is swung round 180 degreesto the engine cylinders, in the processpassing through the vertically-arranged waterseparator. The highly-efcient water separatorcomprises a row of vanes which divert the airow and collect the water. There are ampledrainage provisions to remove completelythe condensed water collected at the bottomof the separator. This arrangement provides

the effective separation of condensed waterfrom the stream of scavenge air which isimperative for satisfactory piston-runningbehaviour.

Wrtsil low-speed engines have specicdesign features that help to facilitateshipboard installation.

The engine layout elds give the shipdesigner ample freedom to match the

engine to the optimum propeller for the ship.The engines have simple seating

arrangements with a modest number ofholding down bolts and side stoppers.For example, a 12-cylinder RT-ex96C orRTA96C requires 14 side stoppers. No endstoppers or thrust brackets are needed asthrust transmission is provided by ttedbolts or thrust sleeves which are applied to anumber of the holding-down bolts. The holes

in the tank top for the thrust sleeves canbe made by drilling or even ame cutting.

After alignment of the bedplate, epoxy resinchocking material is poured around thethrust sleeves.

All ancillaries, such as pumps and tankcapacities, and their arrangement are optimisedto reduce the installation and operating costs.The number of pipe connections on the enginethat must be connected by the shipyard are

minimised. The engines electrical powerrequirement for the ancillary services is alsokept down to a minimum.

A standard all-electric interface isemployed for engine management systems- known as DENIS (Diesel Engine InterfaceSpecication) - to meet all needs for control,monitoring, safety and alarm warningfunctions. This matches remote controlsystems and ship control systems from a

number of approved suppliers.The engine is equipped with an integrated

axial detuner at the free end of the crankshaft. An axial detuner monitoring system developedby Wrtsil is standard equipment.

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Schematic of a typical waste heat recovery plant for containershipsin the 7000-9000 TEU range.

M

G

G

G

G

Main engine

Exhaust gaseconomiser Ship service steam

Ship service power

Aux. engines

Steam turbine

Power turbine

Turbogenerator set for the high-efciency waste heat recovery plant, withthe exhaust-gas power turbine on the left, the generator on the right, andthe steam turbine to the right of centre.

Indicative performance of RT-ex96C engines with high-efciency waste heat recovery (WHR) plant*RT-flex96C engine 10 cylinders 12 cylinders 14 cylinders

Reference plant of engine alone:

Engine power, MCR kW 57,200 68,640 80,080

Fuel consumption, g/kWh 171 171 171

Plant combining engine and WHR:Engine power, MCR kW 57,200 68,640 80,080

WHR turbogenerator output, kWe 7040 8450 9860

Overall fuel consumption, g/kWh 158 158 158

* Indicative values based on standard reference conditions and 100 per cent engine power at the R1 rating. Theengines with WHR plant employ Delta Tuning.

WASTE HEAT RECOVERY: FUEL SAVING WITH REDUCED An extended form of high-efciency waste

heat recovery plant has been developed forWrtsil RT-ex96C engines, providing anenvironmentally-clean solution to reducingships fuel consumption. The generatedelectrical power can be about 12 per cent of theengine power, and is employed to assist shippropulsion or for supplying shipboard services.

The generated power thus contributessignicant savings in both fuel costs andoverall exhaust-gas emissions, such as

CO2, NO X, SO X, etc. It is the only technologycommercially available today that reduces bothfuel consumption and exhaust emissions at thesame time.

The waste heat recovery plant follows the

well-established concept of passing the exhaust

gases of the ships main engine through anexhaust-gas economiser to generate steam fora turbine-driven generator. However, the quantityof energy recovered from the exhaust gasesis maximised by adapting the engine to thelower air intake temperatures that are availableby drawing intake air from outside the ship(ambient air) instead of from the ships engineroom. The engine turbochargers are matchedfor the lower air intake temperatures thereby

increasing the exhaust energy. At the same time, todays high-efciency

turbochargers have surplus capacity at theengines upper load range when matched forambient air intake. Thus about 10% of the

engines exhaust gas ow can be branched off

to drive a power turbine which is incorporatedin the turbogenerator package.

The overall result of the new concept isthat the quantity of energy recoverable in anexhaust-gas economiser and in the powerturbine is increased without affecting the air owthrough the engine. There is thus no increase inthe thermal loading of the engine and there isno adverse effect on engine reliability.

Heat is also recovered from the engines

scavenge air and jacket cooling water forfeedwater heating. The scavenge air coolersare designed in such a way that the boiler feewater can be heated close to the evaporationtemperature.

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MAINTENANCEPrimary objectives in the design and

development of Wrtsil low-speed enginesare high reliability and long times betweenoverhauls. Three years between overhauls arenow being achieved by engines to the latestdesign standards. At the same time, their highreliability gives shipowners more freedom toarrange maintenance work within ships sailingschedules.

Yet, as maintenance work is inevitable,particular attention is given to ease of

maintenance by including tooling and easyaccess, and by providing easy-to -understandinstructions.

All major fastenings throughout theengine are hydraulically tightened. For the

RT-ex96C and RTA96C, the dimensions and

weights of these jacks are kept low by theuse of 1500 bar working pressure. Access tothe crankcase continues to be possible fromboth sides of the engine. The handling ofcomponents within the crankcase is facilitatedby ample provision for hanging hoistingequipment.

The Wrtsil RT-ex system is designedto be user friendly, without requiring shipsengineers to have any special additional skills.

The system incorporates its own diagnosticfunctions, and all the critical elements aremade for straightforward replacement. In fact,the knowledge for operation and maintenanceof RT-ex engines can be included in Wrtsils

usual one-week courses for RTA-series

engines available for ships engineers. Trainingtime usually given to the camshaft system, fuelpumps, valve actuating pumps, and reversingservomotors is simply given instead to theRT-ex system.

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SHIP REFERENCES

Wrtsil 9RTA96C Wrtsil 10RTA96C

Wrtsil 10RTA96C

Wrtsil 12RTA96C

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MAIN TECHNICAL DATA

DEFINITIONS: Dimensions and weights: All dimensions are in millimetres and are

not binding. The engine weight is net in metric tonnes (t), without oil

and water, and is not binding. R1, R2, R3, R4 = power/speed ratings at the four corners of the

engine layout eld (see diagram). R1 = engine Maximum Continuous Rating (MCR). Contract-MCR (CMCR) = selected rating point for particular

installation. Any CMCR point can be selected within the enginelayout eld.

BSFC = brake specic fuel consumptions (BSFC). All gures arequoted for fuel of lower caloric value 42.7 MJ/kg, and for ISOstandard reference conditions (ISO 15550 and 3046). The BSFCgures are given with a tolerance of +5%.

Wrtsil RT-ex96C engines have a lower part-load fuelconsumption than the corresponding Wrtsil RTA96C engines.

The values of power in kilowatts and fuel consumption in g/kWhare the standard gures, and discrepancies occur between theseand the corresponding brake horsepower (bhp) values owing to therounding of numbers. For denitive values, please contact Wrtsillocal ofces.

ISO standard reference conditionsTotal barometric pressure at R1 ........................................ 1.0 barSuction air temperature ................................. ..................... 25 C

Relative humidity ..................................................................30%Scavenge air cooling water temperature:- with sea water ................................. ................................ 25 C- with fresh water ............................... ................................ 29 C

MAIN DATA RT-ex96C AND RTA96CCylinder bore 960 mmPiston stroke 2500 mmSpeed 92 - 102 rpmMean effective pressure at R1 18.6 barPiston speed 8.5 m/sFuel specication:Fuel oil 730 cSt/50C

7200 sR1/100F ISO 8217, category ISO-F-RMK 55

RATED POWER: PROPULSION ENGINES

Cyl.

Output in kW/bhp at102 rpm 92 rpm

R1 R2 R3 R4

kW bhp kW bhp kW bhp kW bhp6789

1011121314

34 32040 04045 76051 48057 20062 92068 64074 36080 080

46 680 54 460 62 240 70 020 77 800 85 580 93 360

101 140108 920

24 00028 00032 00036 00040 00044 00048 00052 00056 000

32 64038 08043 52048 96054 40059 84065 28070 72076 160

30 96036 12041 28046 44051 60056 76061 92067 08072 240

42 12049 14056 16063 18070 20077 22084 24091 26098 280

24 00028 00032 00036 00040 00044 00048 00052 00056 000

32 64038 08043 52048 96054 40059 84065 28070 72076 160

BRAKE SPECIFIC FUEL CONSUMPTION (BSFC)g/kWh g/bhph g/kWh g/bhph g/kWh g/bhph g/kWh g/bh

Load 100% 171 126 163 120 171 126 164 121

BMEP, bar 18.6 13.0 18.6 14.4

PRINCIPAL ENGINE DIMENSIONS (MM) AND WEIGHTS (TONNES)Cyl. A

67891011121314

11 56413 24415 83417 51419 19420 87422 55424 23425 914

B C D E F* G I K Weigh4 480 1 800 10 925 5 232 12 950 2 594 723 676 1 1604 480 1 800 10 925 5 232 12 950 2 594 723 676 1 2904 480 1 800 10 925 5 232 12 950 2 594 723 676 1 4704 480 1 800 10 925 5 232 12 950 2 594 723 676 1 6204 480 1 800 10 925 5 232 12 950 2 594 723 676 1 7604 480 1 800 10 925 5 232 12 950 2 594 723 676 1 9104 480 1 800 10 925 5 232 12 950 2 594 723 676 2 0504 480 1 800 10 925 5 232 12 950 2 594 723 676 2 1604 480 1 800 10 925 5 232 12 950 2 594 723 676 2 300

* Standard piston dismantling height, can be reduced with tilted piston withdrawal.

13- and 14-cylinder engines are only available in RT-ex versions, and not RTA versions.

All the above data apply to both RTA96C and RT-ex96C versions. However, there may be differences in weightsthe RT-ex96C.

Wrtsil RT-ex engines are also available with part-load optimisation for lower fuel consumptions.

Power Engine-MCR

Speed

Engine layout field

R4

R3

R2

R1

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Wrtsil Switzerland LtdP.O. Box 414, CH-8401 Winterthur, Switzerlandl Tel. +41 52 262 49 22 l Fax +41 52 262 07 18

0 1

. 2 0 0 7 / B o c

k s O f c e

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Wrtsil enhances the business of its customers by providing them withcomplete lifecycle power solutions. When creating better and environmentallycompatible technologies, Wrtsil focuses on the marine and energy marketswith products and solutions as well as services. Through innovative productsand services, Wrtsil sets out to be the most valued business partner ofall its customers. This is achieved by the dedication of more than 14,000professionals manning 130 Wrtsil locations in close to 70 countries aroundthe world.

WRTSIL is a registered trademark. Copyright 2007 Wrtsil Corporation.

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Wartsila o e Rt Flex96c Rta96c Tr