Engines for Lower Power Applications

8/6/2019 Engines for Lower Power Applications

http://slidepdf.com/reader/full/engines-for-lower-power-applications 1/3

64 Twenty four7. 1.10

[ IN DETAIL MARIN E ] Twenty our7.

TEXT: R I C K M c A RT H U R |PHOTOS: WÄRTSILÄ

THE ATTRACTIVE OPTION FORLOWER-POWER APPLICATIONS

WÄRTSILÄ IS EXTENDING its product port olio by

introducing two newlow-speed two-strokeengines, the RT-ex35

and the RT-ex40. Bothofer an e cient direct

drive propulsion solutionor a wide range o small

and medium-sized cargovessels such as break-bulk

and bulk carriers, tankersand container eedervessels.

182

180

178

176

174

172

170

168

166

RT-ex Standard

RT-ex Delta

RT-ex Low-load

40% 50% 60% 70% 80% 90% 100%load

b s f c , g / k W

h

Fuel ef ciencyo the RT-ex35 RI (Tier II)

In global terms, the two-stroke engine eetconsists o some , vessels. O these,about are older than years which

means that they are candidates or replacement,and this means new engines. Te number o vessels with two-stroke engines having a poweroutput between kW and 9 kW - therange covered by the R - ex and R - ex- is about , about o the total two-stroke eet.

“When Wärtsilä decided to go into this boresize, market conditions were orecast to be muchbetter, but then came the nancial crisis and

we had to rearrange those expectations,” saysDaniel Schmid, Product Manager, Wärtsilä

Industrial Operations in Switzerland. “Evenso, the 35/40-bore segment still has plenty opotential.”

About 2000 o these 6500 vessels, close to third, are 25 years old or more. “I you calculathat the eet is renewed every 25 years that measome 260 new vessels each year, and that has bethe average rate over the last 12 years,” he say“So there’s a large number o vessels and a loo them are old. Tat’s what makes this marketinteresting.”

“Another aspect is that we expect that themarket or smaller engines will recover soon

which means we’ll be right on time with bothnew engines.”

A 6-cylinder Wärtsilä RT-ex35 withsimple plat orm arrangement.



1.10 Twenty four7. 65

[ IN DETAIL MARIN E ]01. 2010.

RT-ex engines are able to run verystably at very low speeds.

ENGINES WITHATTRACTIVETOTAL COST

OF OWNERSHIP IS A GOOD WAY

TO DESCRIBE THESENEW UNITS

Modularity keeps the price competitiveTe rst order or R - ex3 engines was received

in January 1 when Ningbo Donghai ShippingCo. Ltd signed a contract with YMD or thedelivery o Wärtsilä R - ex common-raildiesel engines or ve new 17, dwt chemicaltankers. Te vessels are being built by the NingboShipyard Group in Fujian, China and willoperate in international trade between the FarEast, the Middle East and Europe. Delivery o the rst engine is scheduled or August 11.

Te R - ex35/40 is a single project whichcovers the development o two engines.“We’re using similar concepts, and one o our development targets is a certain degree o modularity - using the same parts helps in getting

the right quantity and keeping the cost down.‘Engines with attractive total cost o ownerhsip’ would be a good way to describe these new units,as the technology they incorporate ofers realvalue or money,” says Schmid.

Wärtsilä’s cooperation partners in developingthe R - ex35/40 series are Japan’s MitsubishiHeavy Industries Ltd. and China’s YichangMarine Diesel Engine Co., Ltd. (YMD). Wärtsiläand YMD have been investigating small-boreengine markets in China since 2006 as theengines are tailor-made or the Chinese market.

As Wärtsilä does not manu acture two-stroke

engines in-house, R - ex35/40 series engines will be manu actured by the company’s licensees.

Extensive testing at Winterthur Wärtsilä is developing a new common-railsystem optimised or this small-bore engine by adapting our-stroke technologies or two-strokeapplications. In essence, the new Wärtsilä R -

ex system is the best o both worlds. A greatdeal o efort has gone into this and plenty o testing has been required. At the Wärtsilä Diesel

echnology Centre in Winterthur, there’s a testrig simulating the R - ex technology on a R -

ex3 engine. Te results o long-term tests on1 sets o injectors are providing the in ormationnecessary to ensure reliable operation.

As well as ensuring compliance with the IMOier II regulations, Wärtsilä’s R - ex technology also allows optimisation o the engine tuning

or reliable, economical and stable operationat part load. Key to this is the act that theengine’s injection and the exhaust valves areelectronically rather than mechanically driven.Power to operate the valves comes rom the servooil system, but the timing can be varied to save

uel and control emissions.“Compared to Standard uning, Delta tuning

ofers bene ts i engine loading is below 90%,”says Schmid. “Te Low-Load tuning option



66 Twenty four7. 1.10

[ IN DETAIL MARIN E ] Twenty our7.

ofers optimum uel per ormance at 55-70%loading. In both, there is no signi cant increase

in emissions. Tis is a huge bene t o R - extechnology and provides complete exibility toship operators.”

Lowest possible auxiliary powerconsumption

Another central concept in the R - ex /series engines is that o achieving the lowestpossible auxiliary power consumption. Ratherthan employing electrically-driven units whichrequire auxiliary gensets to provide their motivepower, the supply units are mechanically driven.

Both the pumps which pressurise the uel up to1 bar and the servo oil pumps which provideoil at a pressure o 3 bar to control the exhaust

valves and other items are driven directly by themain engine through a gearbox. Wärtsilä is also applying its UNIC control

system to a two-stroke engine or the rsttime in R - ex35/40 series engines. aking theopportunity presented by the merging o our-stroke and two-stroke technology, a controlplat orm based on the one already widely usedin our-stroke installations is being constructed

or two-stroke equipment. Tere are multiplebene ts. “One is spare part handling,” saysSchmid. “Te our-stroke sector is also world-

wide, and we’ll be using the same electronicmodules or the control system.”

Other bene ts include the user inter ace -the “look and eel” o the engine control systemor operators. “Merging our-stroke and two-

stroke technology and combining this into theUNIC plat orm means that potentially the typeo engine you’re handling won’t matter,” saysSchmid. UNIC communicates directly with theship’s machinery control system and allows ullintegration into propulsion packages (PROPAC).“Our ocus is on delivering a user- riendly inter ace which allows crews to understand theirengines easily and act quickly when necessary.”

The RT-ex35 common-rail systems Wärtsilä R - lex engines have uelectronically-controlled systems or u

injection, valve operation, starting and cylindelubrication. Fuel oil and servo oil are deliveredat regulated pressures to common-rail pipesarranged in a rail unit along the side o thecylinders.

Heated uel oil is delivered ready or injecat pressures up to 1000 bar. Servo oil is drawn

rom the engine lubrication system and deliverat pressures up to 300 bar. Both uel oil andservo oil pumps are mounted at the a t end othe engine and are driven through gearing romthe cranksha t.

Flexibility and environmental compliance

Precise control o injection, optimised injectiopressures, optimised valve timing, and shuttinof individual injectors at low speeds means thR - ex engines are able to run very stably at velow speeds, slower than camsha t-type engine

R - ex35 engines are ully compliant witthe IMO ier II exhaust-emissions regulationsset out in Annex VI o the MARPOL 73/78convention. Te exibility provided the R -

ex system acilitates compliance with NOXregulations and delivers smokeless operation all engine speeds.

Attractive total cost of ownershipThe Wärtsilä RT-ex35 is a low-speed two-stroke crosshead-type marine diesel engine withuniow scavenging. Designed from the outset with an electronically-controlled common-rail system for fuel injection and valve actuation, it has a 350 mm cylinder bore and a pistonstroke of 1550 mm. Built with 5-8 cylinders in-line, it provides maximum continuous poweroutputs between 3475 and 6960 kW at 142 to 167 rpm.

Key benets of the Wärtsilä RT-ex35 include:Optimum t to shipHigh reliabilityFive years’ operation between overhaulsEconomical uel consumption overthe whole operating range

Low total cost o ownership

Low cylinder oil consumptionLow ancillary power requirementsLow exhaust gas emissionsCapable o extremely low,stable running speeds

Maintenance riendly design.

THE LOWEST POSSIBLEAUXILIARY POWER CONSUMPTION IS ACENTRAL CONCEPT

Turbocharging system o the RT-ex35

Supply pump unitRT-ex35 rail unit

Documents

Engines for Lower Power Applications