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The cylinder lube oil consum ption rep-resents a large expenditure for an en-gine operating w ith the nom inal guidingfeed rate and, especially for the largebore engines, even a 0.1 g/bhph re-duction in the cylinder oil dosage repre-sents a significant yearly saving for theow ner. C ylinder lubrication is thereforean im portant developm ent them e w iththe aim of reducing the cylinder lube oildosage w hile m aintaining a satisfactorypiston ring/liner w ear rate and m ain-

taining or im proving the tim e betw eenoverhauls. R educed lube oil consum p-tion also has a positive im pact on theenvironm entas em issions w illbe low er.

The cylinder oil m ust be injected intothe cylinder at the exact position andtim e w here the effect is optim al, w hich

is not alw ays possible w ith the conven-tional lubricators of today. M AN B &WD iesel A/S therefore initiated the devel-opm ent of the new electronic system ,the so-called Alpha Lubrication Sys-tem show n in Fig. 1.

The developm ent w ork for the newsystem w as started in 1997, and theprototype entered service on an M ANB &W type 7S35M C engine in 1998.Since then the system has been

fine-tuned on M AN B &W s 4T50M X re-search engine, and service tests w ereextended to cover several K90M C en-gines. The first large bore engine w iththe new lubricator fitted as standard, a12K90M C engine, w as tested in K oreain S eptem ber 1999 w ith very satisfac-tory results, and the system has now

been in service on a num ber of enginesforup to 20,000 hours,w ith good results.

The system is now standard on allM AN B &W tw o-stroke engines w ith adiam eter bigger than 600 m m and is anoption on the sm aller engines. The sys-tem has been ordered for m ore than100 engines,and 30 sets are in service.

The new lubricating system is based onthe principle of injecting a specific vol-

um e of oil into the cylinder, via a num -ber of injectors, for every four (or everyfive, six, etc.) revolutions. Furtherm ore,the precise tim ing ensures that all cylin-der oil is delivered directly onto the pis-ton ring pack w here it is needed. Thiscan be seen in Fig. 2, w hich show s thepressure m easured in the oilinjector

1

To o ther

cylinders

Cylinderliner

Cylinderliner

Accumu-lator

Lubric a tor Lubrica tor

Accumu-lator

Lubricator

Cy linde r oilservice ta nk

P ump station

withstand-by pumps

Master control unit and backup control unit

HMI panel

Lubricator

To ot hercylinders

To ot hercylinders

Solenoid

valve

Solenoid

valve

Solenoid

valve

Solenoid

valve

Feed-back

sensor

Feed-back

sensor

Feed-back

sensor

Tachosignal

Indexsignal

Alarmsystem

Slow-downsystem

Cy linde r lub.oil pipes

Electricalconnections

Fig. 1 : Principle of Alpha Lubricator System

Lubricator System for Cutting the CylinderOil Bill and Reducing Emissions onMAN B&W Two-Stroke Engines

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during a cycle w ith lube oil injection asw ell as during a cycle w ithout lube oilinjection. The passage of the four pis-ton rings is clearly seen in the pressuresignal for the cycle w ithout lube oil in-jection, and the precision of the new lu-bricator is obvious.

The lubricator itself, Fig. 3, has a sm allpiston for each lubricator quill in thecylinderliner,and the pow erforinjectingthe oilcom es from the system pressure,

supplied by a pum p station. A com m onrail system is used on the driving side,butthe injection side has a high-pressurepositive displacem entsystem ,thus givingequalam ounts to each quilland provi-ding the bestp ossible safety m arginagainstclogging ofsingle lubricatorquills.

2

903010

0

80200 5040 7060 100 [m s]

10

15

5O il quill pressure

Lube oilinjection pressure

20

[B ar]

Fig. 2: Injection pattern for Alpha Lubricator System

P

A

TA T

P

Solenoid

valve

Capacitive feedback

sens or for control of

piston movement

C ylinde r lube

oil outlet

Outlets

for cylinder liner

lube oil points

Signal for lubrication

from co ntrol unit

Spacer

for basic setting of

pump s troke

Ad jus ting s c rew Ac tua to r pis to n

Injec tion plungers

45 bar cylinder

lube oil inlet

Fig. 3: Alpha Lub ricator

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For the large bore engines, Fig. 4, eachcylinder has tw o lubricators (each serv-ing five lube oil quills), w hile the sm allbore engines, Fig. 5, (w ith few er lubeoil quills per cylinder) are served by onelubricatorpercylinder.The pum p stationincludes tw o pum ps (one operating,the other on stand-by w ith autom aticstart up).

The com puter unit com prises a m ain

com puter, controlling the norm al oper-ation, a sw itch-over unit and a (sim ple)back-up unit. The injection function iscontrolled by the com putersendingan on/offsignalto a solenoid valve.A

shaft encoder (w hich can be sharedw ith the P M I system , or tim ing systemon the Intelligent Engine) supplies thenecessary tim ing signal.

The am ount of oil injected can be ad-justed autom atically or m anually asrequired,e.g.atload changes,start/stop,atreduced engine load (differentm odesare available), sulphur % in the fuel,tem perature level on liner surface, vari-

ation in cylinderoilBN ,etc.Pre-lubricationbefore startcan be m ade m anually orbea sequence in the bridge m anoeuvringsystem .

Both form arine engines and forenginesfor pow er generation purposes, verylow feed rates have been dem onstrated,w ith oilconsum ption dow n to 0.5 g/bhph.Furtherreductions in w earrates as w ellas in feed rates can be obtained by uti-lising fuel-oil-sulphur-dependent lubri-cation, a principle for w hich M AN B &Whas applied for a patent.

3

Fig. 4: 12K98MC-C w ith Alpha Lubricator

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4

Fig. 5: 7S50MC-C with Alpha Lubricator

M AN B &W D iesel A/STeglholm sgade 41

D K-2450 C openhagen SVTelephone: +45 33 85 11 00Telex: 16592 m anbw dkTelefax: +45 33 85 10 30m anbw @ m anbw.dk

w w w .m anbw .dk

C opyright M AN B &W D iesel A/S

R eproduction perm ittedprovided source is given.

M AN B &W D iesel A/SR eg. N o: 39 66 13 14

August 2001P.384-01.08