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Auxiliary Propulsion SystemFor Two-stroke Engine Plants

Add Propulsion Redundancy,Operational Safety and Minimize Risk- in a Very Simple Way

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Extra ma rgins o f sa fety are dicta ted b ythe transportation and handling ofvolatile and flammable liquids andga ses , corros ive chemica ls, a nd simila rhazardous cargoes which may harmthe perso nnel a nd the environment.

Therefore Safety FirstS afety preca utions on b oa rd s hips ha veconstantly been improved throughoutshipping history. Acc ide nts a t se a giverise to such improvements in order to

sec ure the be st po ss ible sa fety for thecrew, the ship, other vessels andinstallations at sea, the environmentand the business a s a whole.

Governments, authorities, classificationsocieties, shipowners and insurancecompa nies a re c hallenging the ma nu-facturers of ships and ships equip-ment to encourage them to improvetheir products in relation to reliabilityand safety. More than ever before,safe transportation of oil products,

toxic chemica ls a nd liq uefied ga ses isa mus t. This kind of trans porta tion isan important and growing business,characterized by high stakes, huge

capital costs, high-value cargoes andrisk ma nag ement. On the other hand,environmental fractions, politicians,the press a nd the public opinion exertan increasing pressure for environ-mental consc iousness and sa fety.

Propulsion RedundancyIn recent years focus has been set onredundancy of propulsion machineryas well as on requirements for arran-gements necessary to restoring andmaintaining availability of the shipspropulsion power and manoeuvringcapability.

In order to meet this demand, MANB &W ha ve d evelope d a new Auxilia ryP ropulsion Sys tem c onsisting of:

Two -stroke propulsion engine CP P ropeller &Control Sys tem Tunnel gea r with two steps El-motor/a lterna tor

- and the Alpha Clutcher

The princ iple of an auxiliaryprop ulsion system

Safety of Highest Priority

Photo : yvind Hagen, St atoil

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Proven ElementsThe low -speed two -stroke eng ine it-self is unique in its simplicity and effici-ency always securing safe operation.

The long la sting know-how a nd pra cti-ca l experience from a vas t number ofdifferent ship types and propulsionapplications form the basis for thevery high me cha nica l q uality of our CPpropellers.

The s upply of a la rge number of c om-plete propulsion packages includingtunnel gear and shaft alternator hasaccumulated good long-term serviceexperience.The d es ign of the Alpha C lutc her isbased on a disconnecting device de-veloped under the name Separexby B urmeister &Wa in in Co penha ge nin 1973.

With the Alpha Clutcher, the mainengine can automatically be clutchedout from the direct-coupled propellershaft, and consequently the propulsi-on pow er is d elivered b y the G enSe tsto the s haft a lterna tor used a s electricmotor, and via the tunnel gear to thepropeller shaft.

Single is SimpleThe MAN B&W Auxilia ry P rop uls ionS ys tem (MAN B&W AP S ys tem ) is avery simple and cost effective alterna-tive to, for insta nce diesel elec tric pro-pulsion systems and maintains all thea dva ntages of a low-speed two-strokeengine pla nt. In rela tion to tw in-screw propulsion installations, the singlescrew configuration is usually prefer-red due to a 10 - 12% higher propul-sion efficiency and last but not least

due to the obvious cost reasons.

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Reduce the Maintenance-stressat Short Stays in HarbourP unctua lity, sho rt sta ys in ha rbour a ndscheduled maintenance of the mainengine must form a synthesis with theships charter. During the stay atquayside, overhaul and maintenancework can be carried out withoutdelaying the sc heduled depa rture.

Increased Propulsion AvailabilityNeces sa ry main engine immob iliza tionor shut downs for, longer lastingscheduled checks and inspectionscan alternatively be dealt with at seaat reduced speed without off-hirejeopa rdizing the s hips trad ing sc heduleor charter.

Sailing in Confined WatersThe MAN B&W AP S ys tem ma kes it

possible for the crew to operate safe-ly a t reduc ed s peed in cha nnels, riversand straits and simultaneously nursethe main engine or related auxiliaryequipment.

Boost the Propulsion PowerAs a measure for observing the shipstransportation schedules, the auxiliarypropulsion system can be suppliedwith the possibility to boost electrical

power to the propeller, in addition tothe main engine power and hence

increase the ships speed whennecessary.

The Alpha Clutcher is forAll Ship TypesBoth safety and economy will benefitfrom this concept and it makes theMAN B&W AP S ys tem a n ob viouschoice for many ship types equippedwith low-speed two-stroke main engi-nes and CP Propellers.

Time for inspections

and overhauls

App. 2708

4327W=2538

620

770

1645

2977 3740 917

6117S=24959921030

D =

4 9 0 0

1 3 8 0

1 2 3 4 5 6 7 80 32313029282726252423222120191817161514131211109

Com pact installation for a 13 500 tdw tanker with a 6S42MC main engine

Maintainability

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Perfect Fit ConnectionTo a lign the two fla nge pa rts for a per-fect fit betw een the cone holes a nd thecones, a ring is pressed against thefla nge s oppo site the c ones . This ring iscontrolled by studs and tightened bynuts on these to the backside of theco nes . Tens ion in the stud s pres se s thecones into the cone holes a nd ensuresa lignme nt of the fla nge s. This ensuresa perfect fit co nnection, which preventshammering in-between the connectionsurfac es like a n ordina ry fitted bo lt.

When the nuts are loosened, thecones and the ring are free to moveand the flanges are free to rotatebeca use the studs a re plac ed outsidethe split diameter.

In the Alpha Clutcher the sta y b olts donot pass inside the cones, but in-betw een them. The cones and thestuds are moved by servo pistons toena ble hydraulic remote co ntrol.

Patented Locking PrincipleInstead of tightening a nut on eachstud, a locking ring locks all conebo lts a t one time. When hyd raulic pres-sure is a dd ed, the studs are stretcheda nd the ring is turned into loc ked po si-tion. The pres sure is then relea sedand the cone bolts are mechanicallyloc ked. To unloc k the c one bo lt c on-nec tion, c lutch-in pres sure ha s to b eadded to be able to turn the lockingring, and after this pressure is addedfor clutching out.

The principle of the locking ring

Auxiliary Propulsion ModeClutching out the Alpha Clutcher isdone remotely from the bridge. Auxili-ary propulsion mode is established inless than two minutes. When clutch-ing in, the Clutcher is remotely con-trolled from a panel in the engineroom.

When o pera ting in a uxilia ry propulsionmode, the shaft alternator is used aselec tric mo tor. This mo tor d eliverspower via the tunnel gear to the pro-peller shaft. When the Alpha Clutcheris clutched out, the main engine isdisconnected from the propeller shaftand stopped. In this mode, however,the Alpha Clucher will transmit thepropeller thrust to the thrust bearingof the main engine.

To ob ta in the be st pos sible p ropulsioneffic ienc y in a uxilia ry propuls ion mod ea t limited electrica l powe r, it is nece s-sa ry to reduce the rate of spe ed of thepropeller to match this limited powerwith the power absorption of the pro-pe ller. Therefo re the tunne l gea r inc or-porates a two-step gearing. Onestep-up ratio for the ordinary propul-sion mode w ith sha ft alterna tor, a nd ala rge r step-do wn ratio for the P TIauxiliary propulsion mode.

The Clutcherhousing

http://clutcher.mpg/http://clutcher.mpg/

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Ordinary Propulsion ModeWhen operating in ordinary propulsionmode, the main engine delivers thepropulsion po w er direc tly to the propel-ler shaft via the clutched-in AlphaClutcher. P TO-pow er is delivered fromthe s ha ft via the flexible c oupling to thetunnel gea rbox and the sha ft alternator.

When switching from auxiliary propul-sion mode, ordinary operation modeis re-es ta blish ed in five minutes . Themain engine and the shaft alternatorhave to be stopped, when the AlphaClutcher is a ctivated for clutching in.

When the ship operates in ordinarypropulsion mode, the Alpha Clutcher

is mechanically locked. No parts aremoving and the Clutcher is not expo-sed to internal wear of any kind. Nohydraulic systems including back-upsystems are required to maintain theClutcher in position. No additionalpow er cons umption.

Easy InstallationThe C lutc her is ea s ily insta lled w ith atrad itiona l hydra ulic shrink-fitted co up-ling to the fore end of the intermediatesha ft through the tunnel ge a r.

The c onnec tion to the intermed ia teshaft at the engine side is made byhydra ulica lly ope rated fit a nd tie bolts.

Alignment InstructionsFor easy alignment of the propulsionplant, alignment calculations are madeand instructions are supplied to theshipya rd. The a lignment instructionsensure the right load distributions onthe stern tube bearings and shaft linebearings. In this connection the Clutc-her is seen as an intermediate shaftintegrated with the C P P ropeller systemand is therefore easy to fit and align.

Clutch Oil SystemLubricating oil and hydraulic operatingoil a re supplied via the Hydra P a ck ta nkunit for the prope ller sy s tem. This ta nkunit is always assembled and factory-tested prior to delivery in order to faci-

lita te the ya rds insta lla tion w ork.

Operating ManualsAn operating manual will provide theoperating crew with a clear guidanceon the redundancy features of thesy ste m. The ma nuals c over a ll deta ilsincluding a general description of thecomplete propulsion system, operat-ing instructions and procedures fordealing with the situations identified inthe class required Failure Mode andEffect Ana lys is , FMEA-repo rt.

Test and TrialsClass approval of the Alpha Clutcherwill be obtained in our workshop priorto delivery. During quay and sea trialsthe functionality of the Alpha Clutcherwill be tested - and the capability ofthe Auxiliary Propulsion System tosecure the right speed and manoeu-vra bility w ill be d emons trated .

RemoteControlSystemThe el-motor/alternator andclutch controlsystem is inte-grated with theCP Propel lerand main engi-ne sys tem.

The a utomatic P TI sta rt-up s eq uence

includes, eg interlocks for main engi-ne s topped , C lutcher in c lutched-outpos ition, el-moto r/a lterna tor c lutche dout, gearing in the tunnel gear chan-ged to the P TI step -down ratio, pro-peller pitch adjusted to zero-position.And then follows the transformer-startof the el-motor and the clutching in atthe tunnel gear. In auxiliary propulsionmode the pow er abs orption of the CPPropeller is controlled to stay withinthe load range of the el-motor. Allelectrical circuits of the control system

are monitored by the alarm system.

Factory test of the Hyd ra Pack tank unit with p ump s, filters,

therm ostatic valve, cooler, servo valves and instrum entation

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Alpha Clutcher Range for Two-stroke MC Engines

Four Clutcher series - CB1 to CB4 -have been designed to match auxiliarypropulsion systems for two-strokeengine plants up to and including the60-bo re MC se ries . This eng ine ra ngecorresponds to the pow er rang e of theMAN B&W CP P rope llers, w hich a ga incovers a wide ra nge of modern chemi-ca l, ga s a nd product ta nker designs.

TYP E CB 1 CB 2 C B 3 CB 4Dimensions mmLeng ht [L] 1445 1635 1830 2160Dia meter [D] 1185 1340 1500 1770Weight* [ton] 14 20 29 44ENG INE C ylinder vers ionsS 26MC 4-12L35MC 4-12S 35MC 4-10 11-12L42MC 4-7 8-10 10-12S 42MC 4-5 6-7 8-12S 46MC-C 4 5 6-8L50MC 4 5-6 7-8S 50MC 4-5 6-8

S 50MC-C 4 5-7 8L60MC 4-5 6-8L60MC-C 4 5-8S 60MC 4 5-7S 60MC-C 4 5-6

* App rox weight incl intermed iate shaft

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Significant Advantages

The Auxilia ry P ropuls ion S ys tem w ithAlpha Clutcher mea ns:

Cos t-efficient propulsion redunda ncy S imple, reliab le and proven techno-

logy Sa fe operat ion and quick change of

propulsion mo de Full integration with the CP P ropel-

ler system Easy handling and installation at

shipyards No s eparate thrust transmitting

founda tion req uired No static hydraulic or electric pow er

consumption Maintenance free No prac t ica l wear Free of bac k-las h

For a very wide range of typical pro-duct tankers, gas tankers and chemi-cal tankers the off-hire risk scenarioalone will justify the investment in theAlpha Clutcher system - even withoutadding the value of all the positiveside-effects like, for instance reducedtug related harbour fees and increa-se d ma in eng ine ma inta ina bility.

The Scientific AngleExtensive studies, recently performedby Prof Dr C M Gallin, Gallin MarineConsultants show a clear capital ad-vantage of a single-screw two-strokepropulsion plant with the Alpha Clutc-her Auxiliary Propulsion System - com-

pared to a similar two-stroke propulsi-on system without propulsion redun-dancy on the one hand, and a corre-spo nding twin-sc rew twin-engine two -stroke propulsion system on the other.This sc ientific study w as ba sed on a llcosts in the fields of Safety, Environ-ment and Business related to thecumulative risk for the service life of aproduct tanker with the above threepropulsion plant options.

The c umula tive risk is ca lcula ted from

statistical real life figures, based onaccidents and consequences due tomain engine failures, selected andevaluated from the casualty bank of

Lloyd s Reg iste r in London. The c os tseva luate d a re for insta nce : Va lue ofship and cargo, repair costs, loss ofhire due to repa ir time, los s of hire d ueto waiting time, loss of hire due totowing time and the towing costs.

The 5 th Product- Excellent Project ServicePropulsion know-how, customization,system integration and service is atyour disposal comprising:

Lay-out of engine, tunnel gea r,propeller, piping system etc

Optimizing of propulsion modes S election of the gea r ratios for the

tunnel gear Alignment ana lysis and instructions S trength and vibration ca lculations Arra ngement and insta llation

drawings Instruction books Dimension sketches on disks Pro jec t guides Investment/pay ba ck time

calculations Operat ion and maintenance costs

- and much more due to a strong andflexible too lbo x a va ila ble for suc h pro-ject services.

The Genuine Propulsion PackageS ince 1989, MAN B&W Dies els w orksin Frederiksha vn, Denma rk ha ve ma nu-factured and supplied two-strokeengines of the successful MC-series,toda y up to the 8S 50MC-C e ngine.

The MAN B &W CP propeller p rogram-me has been developed to efficientlymatch the MC-engine series up to the70MC versions .

The Alpha C lutc her is a n integ rate dpart of those propeller systems whichare designed, manufactured and sup-plied by one company taking fullresponsibility for functionality, orderhandling, commissioning, warrantyand after-sales service of the comple-te propulsion system.

Photo:yvind H agen,Statoil

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MAN B&W Diesel A/SAlpha DieselNiels J uels Vej 15DK-9900 Fred eriksha vnDenmarkTelephone + 45 96 20 41 00Telecopy + 45 96 20 40 30e-ma il: a lpha @ma nb w.d khttp//: ww w.ma nbw .dk

653/1.0-GB . Sta tus March 01

Copyright

MAN B &W Dies el A/S , Alpha Dies elReproduction permitted

provided so urce is given .

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