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S70MC-C Mk 7 Project Guide

Two-stroke Engines

This book describes the general technical features of the S70MC-C engine, including

some optional features and/or equipment.

As differences may appear in the individual suppliers extent of delivery, please con-

tact the relevant engine supplier for a confirmation of the actual execution and extent

of delivery.

A List of Updates will be updated continuously. Please ask for the latest issue, to be

sure that your Project Guide is fully up to date.

The list of Updates is also available on the Internet at http:\\www.manbw.dk under

the section Library.

This Project Guide is available on a CD ROM.

2nd Edition

September 1999

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The engine types of the MC programme are

identified by the following letters and figures:

430 100 100 198 19 04

MAN B&W Diesel A/S S70MC-C Project Guide

1.01

Fig. 1.01: Engine type designation

178 34 39-1.0

S 70 MC

Diameter of piston in cm

Stroke/bore ratio

Engine programme

C Compact engine

S Stationary plant

S Super long stroke approximately 4.0

L Long stroke approximately 3.2

K Short stroke approximately 2.8

- C6

Number of cylinders

Design

Concept

C Camshaft controlled

E Electronic controlled (Intelligent Engine)

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Power, Speed and SFOC

S70MC-C

Bore: 700 mm

Stroke: 2800 mm


430 100 100 198 19 05

1.02

Power and speed

LayoutEngine speed Mean effective

pressure

PowerkW

BHP

Number of cylinders

r/min bar 4 5 6 7 8

L1 91 19.0 12420

168801552521100

1863025320

2173529540

2484033760

L2 91 12.2 7940

108009925

135001191016200

1389518900

1588021600

L3 68 19.0 9320

126601165015825

1398018990

1631022155

1864025320

L4 68 12.2 5960

8100

7450

10125

8940

12150

10430

14175

11920

16200

Fuel and lubricating oil consumption

Specific fuel oilconsumption

g/kWhg/BHPh

Lubricating oil consumption

At loadLayout point

With high efficiencyturbocharger

With conventionalturbocharger

System oilApproximate

kg/cyl. 24 hours

Cylinder oilg/kWh

g/BHPh100% 80% 100% 80%

L1 169124 166122 171126 169124

10 1.1-1.6

0.8-1.2

L2 156

115155114

159117

158116

L3 169

124166122

171126

169124

L4 156

115155114

159117

158116

Fig. 1.02: Fuel and lubricating oil consumption

Speed

L2

L1

L3

L4

Power

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Engine Power Range and Fuel Consumption

Engine Power

Thetable contains dataregarding theenginepower,

speed and specific fuel oil consumption of the

S70MC-C.

Engine power is specified in both BHP and kW, in

rounded figures, for each cylinder number and lay-

out points L1, L2, L3 and L4:

L1 designates nominal maximum continuous rating

(nominal MCR), at 100% engine power and 100%

engine speed.

L2, L3 and L4 designate layout points at the other

three cornersof the layout area, chosen for easy ref-

erence. The mean effective pressure is:

L1 L3 L2 L4

bar 19.0 12.2

kp/cm2 19.3 12.4

Overload corresponds to 110% of the power at

MCR, and may be permitted for a limited period of

one hour every 12 hours.

The engine power figures given in the tables remain

valid up to tropical conditions at sea level, ie.:

Tropical conditions:

Blower inlet temperature . . . . . . . . . . . . . . . . 45 C

Blower inlet pressure. . . . . . . . . . . . . . . 1000 mbar

Seawater temperature . . . . . . . . . . . . . . . . . . 32 C

Specific fuel oil consumption (SFOC)

Specific fuel oil consumption values refer to brake

power, and the following reference conditions:

ISO 3046/1-1986:

Blower inlet temperature. . . . . . . . . . . . . . . . . 25C

Blower inlet pressure. . . . . . . . . . . . . . . 1000 mbar

Charge air coolant temperature. . . . . . . . . . . 25 C

Fuel oil lower calorific value. . . . . . . . 42,700 kJ/kg

(10,200 kcal/kg)

Although the engine will develop the power speci-

fied up to tropical ambient conditions, specific fuel

oil consumption varies with ambient conditions and

fuel oil lower calorific value. For calculation of these

changes, see the following pages.

VIT fuel pumps

This engine type is in its basic design not fitted with

the Variable Injection Timing (VIT) fuel pumps, - but

they can optionally (4 35 104) be equipped with VIT

pumps, and in that case they can be optimised be-

tween 85 - 100% of specified MCR (point M), - see

chapter 2.

SFOC guarantee

The figures given in this project guide represent the

values obtained when the engine and turbocharger

arematched witha view toobtaining the lowestpos-

sible SFOC values and fulfilling the IMO NOx emis-

sion limitations.

The Specific Fuel Oil Consumption (SFOC) is guar-

anteed for one engine load (power-speed combina-

tion), this being the one in which the engine is opti-

mised. The guarantee is given witha margin of5%.

As SFOC and NOx are interrelated parameters, an

engine offered without fulfilling the IMO NOx limita-

tions is subject to a tolerance of only 3% of the

SFOC.

Lubricating oil data

Thecylinder oil consumption figuresstated in theta-

bles are valid under normal conditions. During run-

ning-in periods and under special conditions, feed

rates of up to 1.5 times the stated values should be

used.

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430 100 500 198 19 07

1.04

Fig. 1.03: Performance curves for S70MC-C, without VIT fuel pumps

Performance curves

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Description of Engine

Theengines built by our licenseesare inaccordance

with MAN B&W drawings and standards. In a few

cases, some local standards may be applied; how-

ever, all spare parts are interchangeable with MAN

B&W designed parts. Some other components can

differ from MAN B&Ws design because of produc-

tion facilities or the application of local standard

components.

In the following, reference is made to the item num-

bers specified in the Extent of Delivery (EOD)

forms, both for the basic delivery extent and for any

options mentioned.

Bedplate and Main Bearing

The bedplate ismade inone part with the chaindrive

placed at the thrust bearing in the aft end of the en-

gine. The bedplate consists of high, welded, longi-

tudinal girders and welded cross girders with cast

steel bearing supports.

For fitting to the engine seating, long, elastic hold-

ing-down bolts, and hydraulic tightening tools, canbe supplied as an option: 4 82602 and 4 82 635, re-

spectively.

The bedplate is made without taper if mounted on

epoxy chocks (4 82 102), or with taper 1:100, if

mounted on cast iron chocks, option 4 82 101.

The oil pan, which is made of steel plate and is

welded to the bedplate, collects the return oil from

the forced lubricating and cooling oil system. The oil

outlets from the oil pan are normally vertical (4 40

101) and are provided with gratings.

Horizontal outlets at both ends can be arranged as

an option: 4 40 102.

The main bearings consist of thin walled steel shells

lined with bearing metal. The bottom shell can, by

means of special tools, and hydraulic tools for lifting

the crankshaft, be rotated out and in. The shells are

kept in position by a bearing cap.

Thrust Bearing

The chaindrive and the thrust bearing are located in

the aft end. The thrust bearing is of the B&W-Michell

type,and consists,primarily, ofa thrust collar on the

crankshaft, a bearing support, and segments of

steel with white metal. The thrust shaft is thus an in-

tegrated part of the crankshaft.

Thepropeller thrust is transferred through the thrust

collar, the segments, and the bedplate, to the en-

gine seating and end chocks. The thrust bearing is

lubricated by the engines main lubricating oil sys-tem.

Turning Gear and Turning Wheel

The turning wheel has cylindrical teeth and is fitted

to the thrust shaft. The turning wheel is driven by a

pinion on the terminal shaft of the turning gear,

which is mounted on the bedplate.

The turning gear is driven by an electric motor with

built-in gear and chaindrive with brake. The electricmotor is provided with insulation class B and enclo-

sure IP44. The turning gear is equipped with a

blocking device that prevents the main engine from

starting when the turning gear is engaged. Engage-

ment and disengagement of the turning gear is ef-

fectedmanually by anaxial movement of thepinion.

A control device for turning gear, consisting of

starter and manual remote control box, with 15

metres of cable, can be ordered as an option: 4 80

601.

Frame Box

The frame box is of welded design. On the exhaust

side, it is providedwith reliefvalves for eachcylinder

while, on the camhaft side, it is providedwith a large

hinged door for each cylinder.

The crosshead guides are welded on to the frame

box.


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The frame box is attached to the bedplate with

screws. Theframe box, bedplate andcylinder frame

are tightened together by twin stay bolts. The staybolts are made in one part. Two part stay bolts is an

option: 4 30 132.

Cylinder Frame, Cylinder Liner andStuffing Box

The cylinder frame is cast with integrated camshaft

frame and the chain drive located at the aft end. It is

made of cast iron and is attached to the frame box

with screws. The cylinder frame is provided with ac-

cess covers for cleaning the scavenge air space and

for inspection of scavenge ports and piston ringsfrom the camshaft side. Together with the cylinder

liner it forms the scavenge air space.

The cylinder frame has ducts for piston cooling oil

inlet. The scavenge air receiver, chain drive,

turbocharger, air cooler box and gallery brackets

are located at the cylinder frame. At the bottom of

the cylinder frame there is a piston rod stuffing box,

which is provided with sealing rings for scavenge

air, and with oil scraper rings which prevent oil from

coming up into the scavenge air space.

Drains from the scavenge air space and the piston

rod stuffingbox are located at the bottom of the cyl-

inder frame.

The cylinder liner is made of alloyed cast iron and is

suspended in the cylinder frame with a low-situated

flange. The top op the cylinder liner is bore-cooled

and, just below a short cooling jacket is fitted. The

cylinder liner has scavenge ports and drilled holes

for cylinder lubrication.

The camshaft is embedded in bearing shells lined

with white metal in the camshaft frame.

Cylinder Cover

The cylinder cover is of forged steel, made in onepiece, and has bores for cooling water. It has a cen-

tral bore for the exhaust valve and bores for fuel

valves, safety valve, starting valve and indicator

valve.

The cylinder cover is attached to the cylinder frame

with 8 studs andnuts tightenedby hydraulic jacks.

Exhaust Valve and Valve Gear

The exhaust valve consists of a valve housing and a

valve spindle. The valve housing is of cast iron andarranged for water cooling. The housing is provided

with a bottom piece of steel with a flame hardened

seat. The bottom piece is water cooled. The spindle

is made of Nimonic. The housing is provided with a

spindle guide.

The exhaust valve is tightened to the cylinder cover

with studs and nuts. The exhaust valve is opened

hydraulically and closed bymeansofairpressure. In

operation, the valve spindle slowly rotates, driven

by the exhaust gas actingonsmall vanes fixed tothe

spindle. The hydraulic system consists of a pistonpump mounted on the roller guide housing, a

high-pressure pipe, and a working cylinder on the

exhaust valve. The piston pump is activated by a

cam on the camshaft.

Air seal ing of the exhaust valve spindle guide is

provided.

Fuel Valves, Starting Valve,Safety Valve and Indicator Valve

Each cylinder cover is equipped with two fuel

valves, one starting valve, one safety valve, and one

indicator valve. The opening of the fuel valves is

controlled by the fuel oil high pressure created by

the fuelpumps,and the valve isclosed bya spring.

An automatic vent slide allows circulation of fuel oil

through the valve and high pressure pipes, and pre-

vents thecompression chamberfrom being filledup

with fuel oil in the event that the valve spindle is

sticking when the engine is stopped. Oil from the

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ventslide and other drains is led away ina closed sys-

tem.

The starting valve is opened by control air from the

starting air distributor and is closed by a spring.

The safety valve is spring-loaded.

Indicator Drive

In its basic execution, the engine is fitted with an in-

dicator drive.

The indicator drive consists of a cam fitted on the

camshaft and a spring-loaded spindle with rollerwhich moves up and down, corresponding to the

movement of the piston within the engine cylinder.

At the top, the spindle has an eye to which the indi-

cator cord is fastened after the indicator has been

mounted on the indicator valve.

Crankshaft

The crankshaft is of the semi-built type. The

semi-built type is made from forged or cast steel

throws. The crankshaft incorporates the thrustshaft.

At the aft end, the crankshaft is provided with a

flange for the turning wheel and for coupling to the

intermediate shaft.

At the front end, the crankshaft is fitted with a flange

for the fitting of a tuning wheel and/or counter-

weights for balancing purposes, if needed. The

flange can also be used for a power take-off, if so

desired.The power take-off canbe supplied at extra

cost,

option: 4 85 000.

Coupling bolts and nuts for joining the crankshaft

togetherwiththe intermediate shaft arenotnormally

supplied. These can be ordered as an option: 4 30

602.

Axial Vibration Damper

The engine is fitted with an axial vibration damper,which is mounted on the fore end of the crankshaft.

The damper consists of a piston and a split-type

housing located forward of the foremost main bear-

ing.The piston is madeasan integratedcollaronthe

main journal, and the housing is fixed to the main

bearing support. A mechanical device for check of

the functioning of the vibration damper is fitted.

5 and 6 cylinder engines are equipped with an axial

vibration monitor (4 31 117).

Plants equipped with Power Take Off at the fore end

arealso to be equipped with the axial vibration mon-itor, option: 4 31 116.

Connecting Rod

The connecting rod is made of forged or cast steel

and provided with bearing caps for the crosshead

and crankpin bearings.

The crosshead and crankpin bearing caps are se-

cured to the connecting rod by studs and nuts

which are tightened by hydraulic jacks.

The crosshead bearing consists of a set of

thin-walled steel shells, lined with bearing metal.

The crosshead bearing cap is in one piece, with an

angular cut-out for the piston rod.

The crankpin bearing is provided with thin-walled

steel shells, lined with bearing metal. Lub. oil is sup-

plied through ducts in the crosshead and connect-

ing rod.

Piston, Piston Rod and Crosshead

The piston consists of a piston crown and piston

skirt. The piston crown is made of heat-resistant

steel and has four r ing grooves which are

hard-chrome plated on both the upper and lower

surfaces of the grooves. The piston crown is with

high topland, i.e. the distance between the piston

top and the upper piston ring has been increased.


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The upper piston ring is a CPR type (Controlled

Pressure Relief) whereas theother three piston rings

arewithanoblique cut. The uppermost piston ring ishigher than the lower ones. The piston skirtis ofcast

iron.

The piston rod is of forged steel and is sur-

face-hardened on the running surface for the stuff-

ing box. The piston rod is connected to the

crosshead with four screws. The piston rod has a

central bore which, in conjunction with a cooling oil

pipe, forms the inlet and outlet for cooling oil.

The crosshead is of forged steel and is provided

with cast steel guide shoes with white metal on the

running surface.

The telescopic pipe for oil inlet and the pipe for oil

outlet are mounted on the guide shoes.

Fuel Pump and Fuel OilHigh-Pressure Pipes

The engine is provided with one fuel pump for each

cylinder. The fuel pump consists of a pump housing

of nodular cast iron, a centrally placed pump barrel,

and plunger of nitrated steel. In order to prevent fueloil from being mixed with the lubricating oil, the

pump actuator is provided with a sealing arrange-

ment.

The pump is activated by the fuel cam, and the vol-

ume injected is controlled by turning the plunger by

means ofa toothed rackconnectedto theregulating

mechanism.

In the basicdesign the adjustment of the pump lead

is effected by inserting shims between the top cover

and the pump housing.

As an option: (4 35 104) the engine can be fitted with

fuel pumps with Variable Injection Timing (VIT) for

optimised fuel economy at part load. The VIT princi-

ple uses the fuel regulating shaft position as the

controlling parameter.

The roller guide housing is provided with a manual

lifting device (4 35 130) which, during turning of the

engine, can lift the roller guide free of the cam.

The fuel oil pumps are provided with a puncture

valve, which prevents high pressure from building

up during normal stopping and shut down.

The fuel oil high-pressure pipes are equipped with

protective hoses and are neither heated nor insu-

lated.

Camshaft and Cams

The camshaft is made in one or two pieces depend-

ing on the number of cylinders, with fuel cams, ex-

haust cams, indicator cams, thrust disc and chain

wheel shrunk onto the shaft.

The exhaust cams and fuel cams are of steel, with a

hardened roller race. They can be adjusted and dis-

mantled hydraulically.

Chain Drive

The camshaft is driven from the crankshaft by two

chains. The chain wheel is bolted on to the side of

the thrust collar. The chain drive is provided with a

chain tightener and guide bars to support the long

chain lengths.

Reversing

Reversing of the engine takes place by means of an

angular displaceable roller in thedrivingmechanism

for the fuel pump of each engine cylinder. The re-

versing mechanism is activated and controlled by

compressed air supplied to the engine.

The exhaust valve gear is not reversible.

2nd order Moment Compensators

These are relevant only for 4, 5 or 6-cylinder en-

gines, and can be mounted either on the aft end or

on both fore end and aft end.

The aft-end compensator consists of balance

weights built into the camshaft chain drive,

option: 4 31 203.

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The fore-end compensator consists of balance

weights driven from the fore end of the crankshaft,

option: 4 31 213.

Tuning Wheel/Torsional VibrationDamper

A tuning wheel, option: 4 31 101 or torsional vibra-

tion damper, option: 4 31105 is to be ordered sepa-

rately based upon the final torsional vibration calcu-

lations. All shaft and propeller data are to be

forwarded by the yard to the engine builder, see

chapter 7.

Governor

The engine is to be provided with an electronic/me-

chanical governor of a make approved by MAN

B&W Diesel A/S, i.e.:

Lyngs- Marine A/S

type EGS 2000. . . . . . . . . . . . . . . option: 4 65 172

Kongsberg Norcontrol Automation A/S

type DGS 8800e . . . . . . . . . . . . . option: 4 65 174

NABCO Ltd.

Type MG-800. . . . . . . . . . . . . . . . option: 4 65 175Siemens

type SIMOS SPC 55 . . . . . . . . . . option: 4 65 177

The speed setting of the actuator is determined by

an electronic signal from the electronic governor

based on the position of the main engine regulating

handle. The actuator is connected to the fore end of

the engine.

Cylinder Lubricators

The standard cylinder lubricators are both speed

dependent (442111)and loadchange dependent (4

42 120). They are controlled by the engine revolu-

tions, and are mounted on the fore end of the en-

gine.

The lubricators have a built-in capability to adjust

the oil quantity.They are of the Sight Feed Lubrica-

tor type and areprovided witha sight glass for each

lubricating point. The oil is led to the lubricator

through a pipe system from anelevated tank (Yards

supply).

Once adjusted, the lubricators will basically have a

cylinder oil feed rateproportional to theenginerevo-

lutions. No-flow and level alarm devices are in-

cluded. The Load Change Dependent system will

automatically increase the oil feed rate in case of a

sudden change in engine load, for instance during

manoeuvring or rough sea conditions.

The lubricators areequipped with electricheating of

cylinder lubricator.

As an alternative to the speed dependent lubrica-

tor, a speed andmean effectivepressure (MEP) de-pendent lubricator can be fitted , option: 4 42 113

which is frequently used on plantswith controllable

pitch propeller.

Manoeuvring System (prepared forBridge Control)

The engine is provided with a pneumatic/electric

manoeuvring and fuel oil regulating system. The

system transmits orders from the separate ma-

noeuvring console to the engine.

The regulating system makes it possible to start,

stop, and reverse the engine and to control the en-

gine speed. The speed control handle on the ma-

noeuvring console gives a speed-setting signal to

the governor, dependent on the desired number of

revolutions. At a shut down function, the fuel injec-

tion is stopped by activating the puncture valves in

the fuel pumps, independent of the speed control

handles position.

Reversing is effected by moving the speed control

handle from Stop to Start astern position. Con-

trol air then moves the starting air distributor and,

through an air cylinder, the displaceable roller in the

driving mechanism for the fuel pump, to the

Astern position.

Theengine is provided with a side mounted control

console and instrument panel.


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Gallery Arrangement

The engine is provided with gallery brackets, stan-chions, railings and platforms (exclusiveof ladders).

The brackets are placed at such a height that the

best possible overhauling and inspection condi-

tions are achieved. Some main pipes of the engine

are suspended from the gallery brackets, and the

upper gallery platform on the camshaft side is pro-

vided with two overhauling holes for piston.

The engine is prepared for top bracings on the ex-

haust side (4 83 110), or on the camshaft side, op-

tion 4 83 111.

Scavenge Air System

The air intake to the turbocharger takes place direct

from the engine room through the intake silencer of

the turbocharger. From the turbocharger, the air is

led viathe charging airpipe, aircoolerand scavenge

air receiver to the scavenge ports of the cylinder lin-

ers.Thecharging airpipebetween the turbocharger

and the air cooler is provided with a compensator

and is heat insulated on the outside. See chapter

6.09.

Exhaust Turbocharger

The engine can be fitted with MAN B&W (4 59 101)

ABB (4 59 102) or Mitsubishi (4 59 103) turbochargers

arranged on the exhaust side of the engine.

Alternatively, on this engine type the turbocharger

can be located on the aft end, option: 4 59 124, but

only on 4, 5 and 6-cylinder engines.

The turbocharger is provided with:

a) Equipment for water washing of thecompressor side .

b) Equipment for dry cleaning of the turbine side.

c) Water washing on the turbine side is mountedfor the MAN B&W and ABB turbochargers.

The gas outlet can be 15/30/45/60/75/90 from

vertical, away from theengine. See eitherof options

4 59 301-309. The turbocharger is equipped with anelectronic tacho system with pick-ups, converter

and indicator for mounting in the engine control

room.

Scavenge Air Cooler

The engine is fitted with air cooler(s) of the

monoblock type, one per turbocharger for a seawa-

ter cooling system designed for a pressure of up to

2.0-2.5 bar working pressure (4 54 130) or central

cooling with freshwater of maximum 4.5 bar work-

ing pressure, option: 4 54 132. The air cooler is sodesigned that the difference between the scavenge

air temperature and the water inlet temperature (at

the optimising point) can be kept at a maximum of

12C.

The end covers are of coated cast iron (4 54 150), or

alternatively of bronze, option: 4 54 151

The cooler is provided with equipment forcleaning of:

Air side:

Standard showering system (cleaning pumpunit including tank and filter, yard supply)

Water side:

Cleaning brush

Exhaust Gas System

From the exhaust valves, the gas is led to the exhaust

gas receiver where the fluctuating pressure from the

individual cylinders is equalised, and the total volume

of gas led further on to the turbocharger at a constant

pressure.

Compensators are fitted between the exhaust

valves and the receiver, and between the receiver

and the turbocharger.

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The exhaust gas receiver and exhaust pipes are

provided with insulation, covered by galvanized

steel plating.

There is a protective grating between the exhaust

gas receiver and the turbocharger.

After the turbocharger, the gas is led via the exhaust

gas outlet transition piece, option: 4 60 601 and a

compensator, option: 4 60 610 to the external ex-

haust pipe system, which is yards supply. See also

chapter 6.10.

Auxiliary Blower

The engine is provided with two electrically-driven

blowers (4 55 150). The suction side of the blowers

is connected to the scavenge air space after the air

cooler.

Between the air cooler and the scavenge air re-

ceiver, non-return valves are fitted which automati-

cally close when the auxiliary blowers supply the

air.

Both auxiliary blowerswill start operating before the

engine is startedandwill ensuresufficient scavengeair pressure to obtain a safe start.

During operation of the engine, both auxiliary blow-

erswill startautomatically each time the engine load

is reduced to about 30-40%, and they will continue

operating until the load again exceeds approxi-

mately 40-50%.

In cases where one of the auxiliary blowers is out of

service, the other auxiliary blower will automatically

compensate without any manual readjustment of

the valves, thus avoiding any engine load reduction.

This is achieved by the automatically working

non-return valves in the pressure side of the blow-

ers.

The electric motors are of the totally enclosed, fan

cooled, single speed type, with insulation min. class

B and enclosure minimum IP44.

The electrical control panel and starters for two

auxiliary blowers can be delivered as an option:

4 55 650.

Piping Arrangements

The engine is delivered with piping arrangements

for:

Fuel oil

Heating of fuel oil pipesLubricating and piston cooling oil pipes

Cylinder lubricating oil

Lubricating of turbocharger

Cooling water to scavenge air cooler

Jacket and turbocharger cooling water

Cleaning of turbocharger

Fire extinguishing for scavenge air space

Starting air

Control air

Safety air

Oil mist detector

Various drain pipes

All piping arrangements are made of steel piping,

except the control air, safety air and steam heating

of fuel pipes which are made of copper.

The pipes for sea cooling water to the air cooler are

of:

Galvanised steel . . . . . . . . . . . . . . . . . 4 45 130, orThick-walled, galvanised steel, option 4 45 131, or

Aluminium brass, . . . . . . . . . . . option 4 45 132, or

Copper nickel, . . . . . . . . . . . . . . . . option 4 45 133

In the case of central cooling, the pipes for freshwa-

ter to the air cooler are of steel.


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The pipes are providedwith sockets for local instru-

ments, alarm and safety equipment and, further-

more, with a number of sockets for supplementarysignal equipment.

The inlet and return fuel oil pipes (except branch

pipes) are heated with:

Steam tracing . . . . . . . . . . . . . . . . . . . 4 35 110, or

Electrical tracing . . . . . . . . . . . option: 4 35 111, or

Thermal oil tracing . . . . . . . . . . . . option: 4 35 112

The fuel oil drain pipe is heated by jacket cooling

water.

The above heating pipes are normally deliveredwithout insulation, (4 35 120). If the engine is to be

transported as one unit, insulation can be mounted

as an option: 4 35 121.

The engines external pipe connections are in ac-

cordance with DIN and ISO standards:

Sealed, without counterflanges in one end, and

with blank counterflanges and bolts in the other

end of the piping (4 30 201), or

With blank counterflanges and bolts in both endsof the piping, option: 4 30 202, or

With drilled counterflanges and bolts, option:

4 30 203

A fire extinguishing system for the scavenge air box

will be provided, based on:

Steam . . . . . . . . . . . . . . . . . . . . . . . . . 4 55 140, or

Water mist . . . . . . . . . . . . . . . . option: 4 55 142, or

CO2(excluding bottles). . . . . . . . . option: 4 55 143

Starting Air Pipes

The starting air system comprises a main starting

valve, a non-return valve, a bursting disc on the

branch pipe to each cylinder, a starting air distribu-

tor, and a starting valve on each cylinder. The main

starting valve is connected with the manoeuvring

system, which controls the start of the engine. See

also chapter 6.08.

A slow turning valve with actuator can be ordered asan option: 4 50 140.

The starting air distributor regulates the supply of

control air to the starting valves so that they supply

the engine cylinders with starting air in the correct

firing order.

The starting air distributor has one set of starting

cams for Ahead and one set for Astern, as well

as one control valve for each cylinder.

430 100 042 198 19 08


1.12

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430 100 018 198 19 09


1.13

Fig.: 1.04 Engine cross section

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2 Engine Layout and Load Diagrams

Introduction

The effective brake power Pb of a diesel engine is

proportional to the mean effective pressure peand

enginespeedn,i.e.whenusing c asa constant:

Pb= c x pex n

so, for constant mep, the power is proportional to

the speed:

Pb= c x n1 (for constant mep)

When running with a Fixed Pitch Propeller (FPP), the

power may be expressed according to the propeller

law as:

Pb= c x n3 (propeller law)

Thus, for the above examples, the brake power Pbmay be expressed as a power function of the speed

n to the power of i, i.e.:

Pb= c x ni

Fig. 2.01a shows the relationship for the linear func-

tions, y = ax + b, using linear scales.

The power functions Pb= c x ni, see Fig. 2.01b, will

be linear functions when using logarithmic scales.

log (Pb) = i x log (n) + log (c)

Thus, propeller curves will be parallel to lines having

the inclination i = 3, and lines with constant mep will

be parallel to lines with the inclination i = 1.

Therefore, in the Layout Diagrams and Load Dia-

grams for diesel engines, logarithmic scales are

used, making simple diagrams with straight lines.

Propulsion and Engine Running Points

Propeller curve

The relation between power and propeller speedfor

a fixed pitch propeller is as mentioned above de-

scribed by means of the propeller law, i.e. the third

power curve:

Pb= c x n3

, in which:

Pb= engine power for propulsion

n = propeller speed

c = constant

Propeller design point

Normally, estimations of the necessary propeller

power and speed are based on theoretical calcula-

tions for loaded ship, and often experimental tank

tests, both assuming optimum operating condi-

tions, i.e. a cleanhull and good weather. The combi-

nation of speed and power obtained may be called

the ships propeller design point (PD), placed on the


402 000 004 198 19 10

2.01

Fig. 2.01b: Power function curves in logarithmic scales

178 05 40-3.0

Fig. 2.01a: Straight lines in linear scales

178 05 40-3.0

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light running propeller curve6. See Fig. 2.02. On the

other hand, some shipyards, and/orpropellermanu-

facturers sometimes use a propeller design point(PD) that incorporates all or part of the so-called

sea margin described below.

Fouled hull, sea margin and heavy propeller

When the ship has sailed for some time, the hull and

propeller become fouled and the hulls resistance

will increase. Consequently, the ship speed will be

reduced unless the engine delivers more power to

the propeller, i.e. the propeller will be further loaded

and will be heavy running (HR).

As modern vessels with a relatively high service

speed are prepared with very smooth propeller and

hull surfaces, the fouling after sea trial, therefore,

will involve a relatively higherresistanceandthereby

a heavier running propeller.

If, at the same time the weather is bad, with head

winds, the ships resistance may increase com-

pared to operating at calm weather conditions.

When determining the necessary engine power, it is

therefore normal practice to add an extra power

margin, the so-called sea margin, which is tradition-ally about 15% of the propeller design (PD) power.

When determining the necessary engine speed

consideringthe influenceof a heavy running propel-

ler for operating at large extra ship resistance, it is

recommended - compared to the clean hull and

calm weather propeller curve6 - tochoosea heavier

propeller curve 2 forengine layout, andthepropeller

curve for clean hull and calm weather in curve 6 will

be saidto represent a lightrunning (LR) propeller.

Compared to the heavy engine layout curve 2 we

recommend to use a light running of 3.0-7.0% fordesign of the propeller.

Continuous service rating (S)

The Continuous service rating is the power at which

the engine is normally assumed to operate, and

point S is identical to the service propulsion point

(SP) unless a main engine driven shaft generator is

installed.

Engine margin

Besides the sea margin, a so-called engine mar-

gin of some 10% is frequently added. The corre-

sponding point is called the specified MCR for pro-

pulsion (MP), and refers to the fact that the power

for point SP is 10% lower than for point MP. Point

MP is identical to the engines specified MCR point

(M) unless a mainenginedriven shaft generatoris in-

stalled. In such a case, the extra power demand of

the shaft generator must also be considered.

Note:

Light/heavy running, fouling and sea margin are

overlapping terms. Light/heavy running of the pro-

peller refers to hull and propeller deterioration and

heavy weather and, sea margin i.e. extra power to

the propeller, refers to the influence of the wind and

the sea. However, the degree of light running must

be decided upon experience from the actual trade

and hull design.

402 000 004 198 19 10


2.02

Line 2 Propulsion curve, fouled hull and heavyweather (heavy running), recommended for en-gine layout

Line 6 Propulsion curve, clean hull and calm weather(light running), for propeller layout

MP Specified MCR for propulsion

SP Continuous service rating for propulsion

PD Propeller design point

HR Heavy running

LR Light running

Fig. 2.02: Ship propulsion running points and engine layout

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Engine Layout Diagram

An engines layout diagram is limited by two con-

stant mean effective pressure (mep) lines L1-L3and

L2-L4, and by two constantengine speed lines L1-L2

and L3-L4, see Fig. 2.02. The L1point refers to theengines nominal maximum continuous rating.

Within the layout area there is full freedom to select

the engines specified MCR point M which suits the

demandof propeller powerandspeed for theship.

On the horizontal axis the engine speed and on the

verticalaxis the engine power areshown in percent-

age scales. The scales are logarithmic which means

that, in this diagram, power function curves like pro-

peller curves (3rd power), constant mean effective

pressure curves (1st power) and constant shipspeed curves (0.15 to 0.30 power)arestraight lines.

Specified maximum continuous rating (M)

Based on the propulsion and engine running points,

as previously found, the layout diagram of a relevant

main engine may be drawn-in. The specified MCR

point (M) must be inside the limitation lines of the

layout diagram; if it is not, the propeller speed will

have to be changed or another main engine type

must be chosen. Yet, in special cases point M may

be located to the right of the line L1-L2, see Opti-

mising Point below.

Optimising point (O) = specified MCR (M)

for engine without VIT

The engine type is in its basic design not fitted with

VIT fuel pumps, so the specified MCR is the point at

which the engine is optimised point M coincides

with point O.

The optimising point O is the rating at which the

turbocharger is matched, and at which the engine

timing and compression ratio are adjusted.

Optimising point (O) for engine with VIT

The engine can be fitted with VIT fuel pumps, op-

tion: 4 35 104, in order to improve the SFOC.

The optimising point O is placed on line1 of the load

diagram, and the optimised power can be from 85to

100% ofpoint M'spower,when turbocharger(s) and

engine timing are taken into consideration. When

optimising between 93.5% and 100% of point M's

power, overload running will still be possible (110%of M).

The optimisingpoint O is to be placed inside the lay-

out diagram. In fact, the specifiedMCR point M can,

in special cases, be placed outside the layout dia-

gram, but only by exceeding line L1-L2, and of

course, only provided that the optimising point O is

located inside the layout diagram and provided that

the MCR power is not higher than the L1power.

Load Diagram

Definitions

The load diagram, Fig. 2.03, defines the power and

speed limits for continuous as well as overload op-

eration of an installed engine having an optimising

point O and a specified MCR point M that confirms

the ships specification.

Point A is a 100% speed and power reference point

of the load diagram, and is defined as the point on

the propeller curve (line 1), through the optimising

point O, havingthespecified MCRpower. Normally,

point M is equal to point A, but in special cases, for

example if a shaft generator is installed,point M may

be placed to the right of point A on line 7.

The service points of the installed engine incorpo-

rate the engine power required for ship propulsion

and shaft generator, if installed.


402 000 004 198 19 10

2.03

Constant ship speed lines

The constant ship speed linesa

, are shown at thevery top of Fig. 2.02, indicating the power required

at various propeller speeds in order to keep the

same ship speed, provided that, for each ship

speed, the optimum propeller diameter is used, tak-

ing into consideration the total propulsion effi-

ciency.

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Limits for continuous operation

Thecontinuous servicerange is limitedby four lines:

Line 3 and line 9:

Line 3 represents the maximum acceptable speed

for continuous operation, i.e. 105% of A.

If, in special cases, A is located to the right of line

L1-L2, the maximum limit, however, is 105% of L1.

During trial conditions the maximum speed may be

extended to 107% of A, see line 9.

The above limits may in general be extended to

105%, and during trial conditions to 107%, of thenominal L1speed of the engine, provided the tor-

sional vibration conditions permit.

The overspeed set-point is 109% of the speed in A,

however, it may be moved to 109% of the nominal

speedin L1, provided that torsional vibration condi-

tions permit.

Running above 100% of the nominal L1speed at a

load lower than about 65% specified MCR is, how-

ever, to be avoided for extended periods. Only

plants with controllable pitch propellers can reachthis light running area.

Line 4:

Represents the limit at which an ample air supply is

available for combustion and imposes a limitation

on themaximum combinationof torqueandspeed.

Line 5:

Represents the maximum mean effective pressure

level (mep), which can be accepted for continuous

operation.

Line 7:

Represents the maximum power for continuous

operation.

402 000 004 198 19 10


Fig. 2.03b: Engine load diagram for engine with VIT

2.04

178 05 42-7.3

Fig. 2.03a: Engine load diagram for engine without VIT

A 100% reference pointM Specified MCR pointO Optimising point

Line 1 Propeller curve through optimising point (i = 3)(engine layout curve)

Line 2 Propeller curve, fouled hull and heavy weather heavy running (i = 3)

Line 3 Speed limitLine 4 Torque/speed limit (i = 2)Line 5 Mean effective pressure limit (i = 1)Line 6 Propeller curve, clean hull and calm weather

light running (i = 3), for propeller layoutLine 7 Power limit for continuous running (i = 0)Line 8 Overload limitLine 9 Speed limit at sea trial

Point M to be located on line 7 (normally in point A)

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Limits for overload operation

The overload service range is limited as follows:

Line 8:

Represents the overload operation limitations.

The area between lines 4, 5,7 and the heavy dashed

line 8 is available for overload running for limitedpe-

riods only (1 hour per 12 hours).

Recommendation

Continuous operation without limitations is allowed

only within the area limited by lines 4, 5, 7 and 3 ofthe load diagram, except for CP propeller plants

mentioned in the previous section.

The area between lines 4 and 1 is available for oper-

ation in shallow waters, heavy weather and during

acceleration, i.e. for non-steady operation without

any strict time limitation.

After some time in operation, the ships hull and pro-

peller will be fouled, resulting in heavier running of

the propeller, i.e. the propeller curvewill move to the

left from line 6 towards line 2, and extra power is re-quired for propulsion in order to keep the ships

speed.

In calm weather conditions, the extent of heavy run-

ning of the propeller will indicate the need for clean-

ing the hull and possibly polishing the propeller.

Once the specified MCR (and the optimising point)

has been chosen, the capacities of the auxiliary

equipment will be adapted to the specified MCR,

and the turbocharger etc. will be matched to the op-

timised power.

If the specified MCR (and/or the optimising point) is

to be increased later on, this may involve a change

of the pump and cooler capacities, retiming of the

engine, change of the fuel valve nozzles, adjusting

of the cylinder liner cooling, as well as rematching of

the turbochargeror even a change to a larger size of

turbocharger. In some cases it can also require

larger dimensions of the piping systems.

It is therefore of utmost importance to consider, al-

ready at theprojectstage, if thespecificationshould

be prepared for a later power increase. This is to beindicatedin item 4 02010of the ExtentofDelivery.

Examples of the use of the Load Diagram

In the following are some examples illustrating the

flexibility of the layout and load diagrams and the

significant influence of the choice of the optimising

point O.

The upper diagrams of the examples show engines

withoutVIT fuel pumps, i.e. point A = O, the lower

diagrams show engines with VIT fuel pumps forwhich the optimising point O is normally different

from the specified MCR point M as this can improve

the SFOC at part load running.

Example 1 shows how to place the load diagram for

an engine without shaft generator coupled to a fixed

pitch propeller.

In example 2 are diagrams for the same configura-

tion, here with the optimising point to the left of the

heavy running propeller curve (2) obtaining an extra

engine margin for heavy running.

Example3 shows the same layout for anenginewith

fixed pitch propeller (example 1), but with a shaft

generator.

Example 4 shows a special case with a shaft genera-

tor. In this case the shaft generator is cut off, and the

GenSets used when the engine runs at specified

MCR. This makes it possible to choose a smaller en-

gine with a lower power output.

Example5 shows diagrams for anenginecoupled to

a controllable pitch propeller, with or without a shaft

generator.

Example 6 shows where to place the optimising

point for an engine coupled to a controllable pitch

propeller.

For a project, the layout diagram shown in Fig. 2.10

may be used for construction of the actual load dia-

gram.


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2.05

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For engines without VIT, the optimising point O will

have the same power as point M and its propeller

curve 1 for engine layout will normally be selected

on the engine service curve 2 (for fouled hull and

heavy weather), as shown in the upper diagram of

Fig. 2.04a.

For engines withVIT,the optimisingpoint O and its pro-

peller curve 1 will normally be selected on the engine

service curve 2, see the lower diagram of Fig. 2.04a.

Point A is then found at the intersection between pro-

pellercurve1 (2) and the constantpower curve through

M, line 7. In this case point A is equal to point M.


402 000 004 198 18 57

2.06

Example 1:

Normal running conditions. Engine coupled to fixed pitch propeller (FPP) and without shaft generator

M Specified MCR of engine Point A of load diagram is found:S Continuous service rating of engine Line 1 Propeller curve through optimising point (O) is

equal to line 2O Optimising point of engineA Reference point of load diagram Line 7 Constant power line through specified MCR (M)MP Specified MCR for propulsion Point A Intersection between line 1 and 7

SP Continuous service rating of propulsion

Fig. 2.04a: Example 1, Layout diagram for normal running

conditions, engine with FPP, without shaft generator

Fig. 2.04b: Example 1, Load diagram for normal running


With VIT

Without VIT

178 05 44-0.6

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Once point A has been found in the layout diagram,

the load diagram can be drawn, as shown in Fig.

2.04b and hence the actual load limitation lines of the

diesel engine may be found by using the inclinations

fromtheconstruction lines andthe%-figures stated.

A similar example 2 is shown in Fig. 2.05. In this

case, the optimising point O has been selected

more to the left than in example1, obtaining anextra

engine margin for heavy running operation in heavy

weather conditions. In principle, the light running

margin has been increased for this case.


402 000 004 198 19 10

2.07

Example 2:

Special running conditions. Engine coupled to fixed pitch propeller (FPP) and without shaft generator

M Specified MCR of engine Point A of load diagram is found:S Continuous service rating of engine Line 1 Propeller curve through optimising point (O)

is equal to line 2O Optimising point of engineA Reference point of load diagram Line 7 Constant power line through specified MCR (M)MP Specified MCR for propulsion Point A Intersection between line 1 and 7


Fig. 2.05a: Example 2, Layout diagram for special running


178 39 23-1.0

Fig. 2.05b: Example 2, Load diagram for special running


178 15 46-4.6

With VIT

Without VIT

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In example 3 a shaft generator (SG) is installed, and

thereforethe servicepower of the engine also has to

incorporate the extra shaft power required for the

shaft generators electrical power production.

In Fig. 2.06a, the engine service curve shown for

heavy running incorporates this extra power.

The optimising point O will be chosen on the engine

service curve as shown, but can, by an approxima-

tion, be located on curve 1, through point M.

Point A is then found in the same way as in example

1, and the load diagram can be drawn as shown in

Fig. 2.06b.

402 000 004 198 19 10


2.08

Example 3:

Normal running conditions. Engine coupled to fixed pitch propeller (FPP) and with shaft generator

M Specified MCR of engine Point A of load diagram is found:

S Continuous service rating of engine Line 1 Propeller curve through optimising point (O)

O Optimising point of engine Line 7 Constant power line through specified MCR (M)

A=O Reference point of load diagram Point A Intersection between line 1 and 7



SG Shaft generator power

Fig. 2.06a: Example 3, Layout diagram for normal running


Fig. 2.06b: Example 3, Load diagram for normal running

conditions, engine with FPP, with shaft generator

178 39 25-5.1

178 05 48-8.6

With VIT

Without VIT

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402 000 004 198 19 10

Example 4:

Special running conditions. Engine coupled to fixed pitch propeller (FPP) and with shaft generator

2.09

M Specified MCR of engine Point A of load diagram is found:

S Continuous service rating of engine Line 1 Propeller curve through optimising point (O) orpoint S

O Optimising point of engine Point A Intersection between line 1 and line L1- L3

A Reference point of load diagram Point M Located on constant power line 7 through

point A. (A = O if the engine is without VIT)

and with MP's speed.



SG Shaft generator

See text on next page.

Fig. 2.07a: Example 4. Layout diagram for special running

conditions, engine with FPP, with shaft generatorFig. 2.07b: Example 4. Load diagram for special running

conditions, engine with FPP, with shaft generator

178 06 35-1.6

178 39 28-0.1

With VIT

Without VIT

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Example 4:

Also in this special case, a shaft generator is in-stalled but, compared to Example 3, this case has a

specified MCR for propulsion, MP, placed at the top

of the layout diagram, see Fig. 2.07a.

This involves that the intendedspecified MCR of the

engineMwill beplaced outsidethe top of the layout

diagram.

One solution could be to choose a larger diesel

engine with an extra cylinder, but another and

cheaper solution is to reduce the electrical power

production of the shaft generator when running in

the upper propulsion power range.

In choosing the latter solution, the required speci-

fied MCR power can be reduced from point M to

point M asshown inFig. 2.07a.Therefore, whenrun-ning in the upper propulsion power range, a diesel

generator has to take over all or part of the electrical

power production.

However, such a situation will seldom occur, as

ships are rather infrequently running in the upper

propulsion power range.

Point A, having the highest possible power, is

then found at the intersection of line L1-L3with

line 1, see Fig. 2.07a, and the corresponding load

diagram is drawn in Fig. 2.07b. Point M is found

on line 7 at MPs speed.

402 000 004 198 19 10


2.10

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Fig. 2.08 shows two examples: on the left diagrams

for anengine without VIT fuel pumps (A = O = M), onthe right, for anenginewithVIT fuelpumps (A= M).

Layout diagram - without shaft generator

If a controllable pitch propeller (CPP) is applied, the

combinator curve (of the propeller) will normally be

selected for loaded ship including sea margin.

The combinator curve may for a given propeller speed

haveagivenpropellerpitch,and thismay beheavy run-

ning in heavy weather like for a fixed pitch propeller.

Therefore it is recommended to use a light running

combinator curve as shown in Fig. 2.08 to obtain an

increased operation margin of the diesel engine in

heavyweather to the limit indicated bycurves 4 and5.

Layout diagram - with shaft generator

The hatched area in Fig. 2.08 shows the recom-

mended speed range between 100% and 96.7% of

the specified MCR speed for an engine with shaft

generator running at constant speed.

The service point S can be located at any point

within the hatched area.

The procedure shown in examples 3 and 4 for en-

gines with FPP can also be applied here for engineswith CPP running with a combinator curve.

Theoptimising point O for engines withVIT may be

chosen on the propeller curve through point A = M

with an optimised power from 85 to 100% of the

specified MCR as mentioned before in the section

dealing with optimising point O.

Load diagram

Therefore, when the engines specified MCR point

(M) has been chosen including engine margin, sea

margin and the power for a shaft generator, if in-stalled, point M may be used as point A of the load

diagram, which can then be drawn.

The position of the combinator curve ensures the

maximum load range within the permitted speed

range for engine operation, and it still leaves a rea-

sonable margin to the limit indicated by curves 4

and 5.

Example 6 will give a more detailed description of

how to run constant speed with a CP propeller.


402 000 004 198 19 10

Example 5:

Engine coupled to controllable pitch propeller (CPP) with or without shaft generator

M Specified MCR of engine O Optimising point of engine

S Continuous service rating of engine A Reference point of load diagram

Fig. 2.08: Example 5: Engine with Controllable Pitch Propeller (CPP), with or without shaft generator

2.11

With VITWithout VIT

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Example 6: Engines with VIT fuel pumps

running at constant speed with controllable

pitch propeller (CPP)

Fig. 2.09a Constant speed curve through M, nor-

mal and correct location of the optimising point O

Irrespective of whether the engine is operating on a

propeller curve or on a constant speed curve

through M, the optimising point O must be located

on the propeller curve through the specified MCR

point M or, in special cases, to the left of point M.

The reason is that the propeller curve 1 through the

optimising point O is the layout curve of the engine,

and the intersection between curve 1 and the maxi-mum power line 7 through point M is equal to 100%

power and 100%speed, point A of the load diagram

- in this case A=M.

In Fig. 2.09a the optimising point O has been placed

correctly, and the step-up gear and the shaft gener-

ator, if installed, may be synchronised on the con-

stant speed curve through M.

Fig. 2.09b: Constant speed curve through M,

wrong positionof optimising point O

If the engine has been service-optimised in point O

ona constantspeedcurvethrough point M, then the

specified MCR point M would be placed outside the

load diagram, and this is not permissible.

Fig. 2.09c: Recommended constant speed run-

ning curve, lower than speed M

In this case it is assumed that a shaft generator, if in-

stalled, is synchronisedat a lower constant main en-

gine speed (for example with speed equal to O or

lower) at which improved CP propeller efficiency isobtained for part load running.

In this layout example where an improved CP pro-

peller efficiency is obtained during extended peri-

ods of part load running, the step-up gear and the

shaft generator have to be designed for the ap-

plied lower constant engine speed.

402 000 004 198 19 10


2.12

Fig. 2.09: Running at constant speed with CPP

Fig. 2.09 a: Normal procedure

Constant speed servicecurve through M

Constant speed servicecurve through M

Fig. 2.09 b: Wrong procedure

Logarithmic scales

M: Specified MCRO: Optimised pointA: 100% power and speed of load

diagram (normally A=M)

Fig. 2.09 c: Recommended procedure

Constant speed servicecurve with a speed lowerthan M

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402 000 004 198 19 10

Fig. 2.10: Diagram for actual project

178 06 86-5.0

2.13

Fig. 2.10 contains a layout diagram that can be used for con-struction of the load diagram for an actual project, using the%-figures stated and the inclinations of the lines.

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Specific Fuel Oil Consumption

High efficiency/conventional turbochargers

The high efficiency turbochargeris applied to the

engine in the basicdesign with the view to obtaining

the lowest possible Specific Fuel Oil Consumption

(SFOC) values.

With aconventional turbochargerthe amount of air

required forcombustion purposes can, however, be

adjusted to provide a higher exhaust gas tempera-

ture, if this is needed for the exhaust gas boiler. The

matching of the engine and the turbocharging sys-

tem is then modified, thus increasing the exhaustgas temperature by 20 C.

This modificationwill lead toa 7-8%reduction in the

exhaust gas amount, and involve an SFOC penalty

of up to 2 g/BHPh.

So this engine is available in two versions with re-

spect to the SFOC, see Fig. 2.11.

(A) With conventional turbocharger,

option: 4 59 107

(B) With high efficiency turbocharger,

option: 4 59 104

The calculationof the expected specific fuel oil con-

sumption (SFOC) can be carried out by means of

Fig. 2.12 for fixed pitch propeller and 2.13 for con-

trollable pitch propeller, constant speed. Through-

out the whole load area the SFOC of the engine de-

pends on where the optimising point O is chosen.

SFOC at reference conditions

The SFOC is based on the reference ambient condi-

tions stated in ISO 3046/1-1986:

1,000 mbar ambient air pressure

25 C ambient air temperature

25 C scavenge air coolant temperature

and is related to a fuel oil with a lower calorific value

of 10,200 kcal/kg (42,700 kJ/kg).

For lower calorific values andforambient conditions

that are different from the ISO reference conditions,

the SFOC will be adjusted according to the conver-

sion factors in the below table provided that the

maximum combustion pressure (Pmax) is adjustedto the nominal value (left column), or if the Pmaxis

notre-adjustedto thenominal value (rightcolumn).

WithPmaxadjusted

WithoutPmaxadjusted

Parameter Condition changeSFOCchange

SFOCchange

Scav. air coolanttemperature per 10 C rise + 0.60% + 0.41%

Blower inlettemperature per 10 C rise

+ 0.20% + 0.71%

Blower inletpressure per 10 mbar rise - 0.02% - 0.05%

Fuel oil lowercalorific value

rise 1%(42,700 kJ/kg)

-1.00% - 1.00%

With for instance 1 C increase of the scavenge air

coolant temperature, a corresponding 1 C in-

crease of the scavenge air temperature will occur

and involves an SFOC increase of 0.06% if Pmaxis

adjusted.

402 000 004 198 19 10


Fig. 2.11: Example of part load SFOC curves for the two

engine versions

2.14

178 15 22-9.0

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SFOC guarantee

The SFOC guarantee refers to the above ISO refer-ence conditions and lower calorific value, and is

guaranteed for the power-speed combination in

which the engine is optimised (O) and fulfilling the

IMO NOxemission limitations.

The SFOC guarantee is given with a margin of 5%.

As SFOC and NOxare interrelated paramaters, an

engine offered without fulfilling the IMO NOxlimita-

tions only has a tolerance of 3% of the SFOC.

Without/with VIT fuel pumps

This engine type is in its basic design fitted with fuel

pumps without Variable Injection Timing (VIT), so

the optimising point "O" has then to be at the speci-

fied MCR power "M".

VIT fuel pumps can, however, be fitted as an option:

4 35104,and in that case they can be optimised be-

tween 85-100% of the specifiedMCR, point "M", as

for the other large MC engine types.

Engines with VIT fuel pumps can be part-load opti-mised between 85-100% (normally at 93.5%) of the

specified MCR.

To facilitate the graphic calculationof SFOC we use

the same diagram 1 for guidance in both cases, the

location of the optimising point is the only differ-

ence.

The exact SFOC calculated by our computer pro-

gram will in the part load area from approx. 60-95%

give a slightly improved SFOC compared to engines

without VIT fuel pumps.

Examples of graphic calculation ofSFOC

Diagram 1 in figs. 2.12 and 2.13 valid for fixed pitch

propeller and constant speed, respectively, shows

the reduction inSFOC, relative to the SFOC atnomi-

nal rated MCR L1.

The solid lines are valid at 100, 80 and 50% of the

optimised power (O).

The optimising point O is drawn into the above-

mentioned Diagram 1. A straight line along the

constant mep curves (parallel to L1-L3) is drawn

through the optimising point O. The line intersec-

tions of the solid lines and the oblique lines indi-cate the reduction in specific fuel oil consumption

at 100%, 80% and 50% of the optimised power,

related to the SFOC stated for the nominal MCR

(L1) rating at the actually available engine version.

The SFOC curve for an engine with conventional

turbocharger is identical to that for an engine with

high efficiency turbocharger, but located at 2

g/BHPh higher level.

In Fig. 2.14 an example of the calculated SFOC

curves are shown on Diagram 2, valid for two al-ternative engine ratings: O1= 100% M and

O2= 85%M.


402 000 004 198 19 10

2.15

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402 000 004 198 19 10


Data at nominal MCR (L1): S70MC-C Data of optimising point (O)

100% Power:

100% Speed:

Highefficiencyturbocharger:

Conventional turbocharger:

91124126

BHPr/min

g/BHPhg/BHPh

Power: 100% of (O)

Speed: 100% of (O)

SFOC found:

BHP

r/ming/BHPh

Note: Engines without VIT fuel pumps have to be optimised at the specified MCR power 178 43 64-0.0

178 15 92-3.0

Fig. 2.12: SFOC for engine with fixed pitch propeller

178 43 63-9.0

2.16

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402 000 004 198 19 10

2.17

Data at nominal MCR (L1): S70MC-C Data of optimising point (O)

100% Power:

100% Speed:

Highefficiencyturbocharger:Conventional turbocharger:

91

124126

BHPr/min

g/BHPhg/BHPh

Power: 100% of (O)

Speed: 100% of (O)

SFOC found:

BHP

r/min

g/BHPh

Note: Engines without VIT fuel pumps have to be optimised at the specified MCR power

178 15 91-1.0

Fig. 2.13: SFOC for engine with constant speed178 43 63-9.0

178 43 64-0.0

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402 000 004 198 19 10


2.18

Data at nominal MCR (L1): 6S70MC-C Data of optimising point (O) O1 O2

100% Power:

100% Speed:

High efficiency turbocharger:

25,32091

124

BHPr/ming/BHPh

Power: 100%of O

Speed:100%ofO

SFOC found:

21,000 BHP

81.9 r/min

122.1g/BHPh

17,850 BHP

77.4 r/min

119.7 g/BHPh

Note: Engines without VIT fuel pumps have to be optimised at the specified MCR power

178 15 88-8.0

Fig. 2.14: Example of SFOC for 6S70MC-C with fixed pitch propeller, high efficiency turbocharger and VIT fuel pumps

178 43 66-4.0

178 43 67-6.0

O1: Optimised in M

O2: Optimised at 85% of power M

Point 3: is 80% of O2= 0.80 x 85% of M = 68% M

Point 4: is 50% of O2= 0.50 x 85% of M = 42.5% M

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Fuel Consumption at an Arbitrary Load

Once the engine has been optimised in point O,shown on this Fig., the specific fuel oil consumption

in an arbitrary point S1, S2or S3can be estimated

based on the SFOC in points 1" and 2".

These SFOC values can be calculated by using the

graphs in Fig. 2.12 for the propeller curve I and Fig.

2.13 for the constant speed curve II, obtaining the

SFOC in points 1 and 2, respectively.

Then the SFOC for point S1can be calculated as an

interpolation between the SFOC in points 1" and

2", and for point S3as an extrapolation.

The SFOC curve through points S2, to the left ofpoint 1, is symmetrical about point 1, i.e. at speeds

lower than that of point 1, the SFOC will also in-

crease.

The above-mentioned method provides only an ap-

proximate figure. A more precise indication of the

expected SFOC at any load can be calculated by

using our computerprogram.This is a servicewhich

is available to our customers on request.


402 000 004 198 19 10

Fig. 2.15: SFOC at an arbitrary load

178 05 32-0.1

2.19

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Emission Control

IMO NOxlimits, i. e. 0-30% NOxreduction

All MC engines are delivered so as to comply with

the IMO speed dependent NOxlimit, measured ac-

cording to ISO 8178 Test Cycles E2/E3 for Heavy

Duty Diesel Engines.

The primary method of NOxcontrol, i.e. engine ad-

justment and component modification to affect the

engine combustion process directly, enables re-

ductions of up to 30% to be achieved.

The Specific Fuel Oil Consumption (SFOC) and the

NOxare interrelated parameters, and an engine of-

fered with a guaranteed SFOC and also guaranteed

tocomply with the IMO NOx limitationwill be subject

to a 5% fuel consumption tolerance.

30-50% NOxreduction

Water emulsification of the heavy fuel oil is a well

proven primary method. The type of homogenizer is

either ultrasonic or mechanical, using water fromthe freshwater generator and the water mist

catcher. The pressure of the homogenised fuel has

to be increased to prevent the formation of the

steamand cavitation. It may be necessary to modify

some of the engine components such as the fuel

pumps, camshaft, and the engine control system.

Up to 95-98% NOxreduction

This reduction can be achieved by means of sec-

ondary methods, such as the SCR (Selective Cata-

lytic Reduction), which involves an after-treatment

of the exhaust gas.

Plants designed according to this method have

been in service since 1990 on four vessels, using

Haldor Topse catalysts and ammonia as the re-

ducing agent, urea can also be used.

The compact SCR unit can be located separately in

the engine room or horizontally on top of the engine.

The compact SCR reactor is mounted before the

turbocharger(s) in order to have the optimum work-

ing temperature for the catalyst.

More detailed information canbe found in our publi-

cations:

P. 331 Emissions Control, Two-stroke Low-speed

Engines

P. 333 How to deal with Emission Control.

402 000 004 198 19 10


2.20

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3. Turbocharger Choice

Turbocharger Types

The MC engines are designed for the application of

either MAN B&W, ABB or Mitsubishi (MHI) turbochar-

gers, which are matched to comply with the IMO

speed dependent NOxlimit, measured according to

ISO 8178 Test Cycles E2/E3 for Heavy Duty Diesel

Engines.

The engine is normally equipped with one or two

turbochargers located on exhaust side of the en-

gine. 4, 5 and 6-cylinders engines can however be

equipped with one turbocharger on the aft end of the

engine, option: 4 59 124.

In order to clean the turbine blades and the nozzle

ring assembly during operation, the exhaust gas in-

let to the turbocharger(s) is provided with a dry

cleaning system using nut shells and a water wash-

ing system.

The engine power, the SFOC, and the data stated in

the list of capacities, etc. are valid for high efficiency

turbochargers stated in Fig. 3.01a.

The amount of air required for the combustion can,

however be adjusted to provide a higher exhaust

gas temperature, if this is needed for the exhaust

gas boiler. In this case the conventional turbochar-

gers are to be applied, see Fig. 3.01b. The SFOC is

then about 2g/BHPh higher, see section 2.

For other layout points than L1, the size of turbo-

charger may be different, depending on the point at

which the engine is to to be optimised, see the fol-

lowing layout diagrams.

Fig. 3.02 shows the approximate limits for applica-

tion of the MAN B&W turbochargers, Figs. 3.03 and

3.04 for ABB types TPL and VTR, respectively, and

Fig. 3.05 for MHI turbochargers.

459 100 259 198 19 11


3.01

178 45 92-2.0

Fig. 3.01b: Conventional turbochargers, option: 4 59 107

Cyl. MAN B&W ABB ABB MHI

4 1 x NA70/T9 1 xTPL80-B12 1 x VTR714D 1 x MET71SE

5 1 x NA70/T9 1 x TPL85-B11 1 x VTR714D 1 x MET83SE

6 2 x NA57/T9 1 x TPL85-B12 2 x VTR564D 1 x MET83SE

7 2 X NA70/T9 2 x TPL80-B11 2 x VTR714D 1 x MET90SE


Fig. 3.01a: High efficiency turbochargers

Cyl. MAN B&W ABB ABB MHI

4 1 x NA70/T9 1 xTPL80-B11 1 x VTR714D 1 x MET66SD

5 1 x NA70/T9 1 x TPL85-B11 1 x VTR714D 1 x MET83SD

6 1 x NA70/T9 1 x TPL85-B11 2 x VTR564D 1 x MET83SD



178 45 94-0.0

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459 100 259 198 19 11

Fig. 3.02a: Choice of high efficiency turbochargers, make MAN B&W

3.02

178 45 98-8.0

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459 100 259 198 19 11


3.03

Fig. 3.02b: Choice of conventional turbochargers, make MAN B&W, option: 4 59 107

178 44 50-2.0

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459 100 259 198 19 11

3.04

Fig. 3.03a: Choice of high efficiency turbochargers, make ABB, type TPL

178 44 53-8.0

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459 100 259 198 19 11

3.05

Fig. 3.03b: Choice of conventional turbochargers, make ABB, type TPL, option: 4 59 107

178 44 55-1.0

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459 100 259 198 19 11

3.06

Fig. 3.04a: Choice of high efficiency turbochargers, make ABB, type VTR

178 44 58-7.0

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459 100 259 198 19 11

3.07

Fig. 3.04b: Choice of conventional turbochargers, make ABB, type VTR, option: 4 59 107

178 44 59-9.0

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459 100 259 198 19 11

3.08

178 44 62-2.0

Fig. 3.05a: Choice of high efficiency turbochargers, make MHI

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459 100 259 198 19 11

Fig. 3.05b: Choice of conventional turbochargers, make MHI, option: 4 59 107

3.09

178 44 63-4.0

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Cut-Off or By-Pass of Exhaust Gas

The exhaust gas can be cut-off or by-passed theturbochargers using either of the following four sys-

tems.

Turbocharger cut-out system

Option: 4 60 110

This system, Fig. 3.06, is to be investigated case by

case as its application depends on the layout of the

turbocharger(s), can be profitably to introduce on

engines withtwo turbochargersif the engine is to

operate for long periods at low loads of about 50%

of the optimised power or below.

The advantages are:

Reduced SFOC if one turbocharger is cut-out

Reduced heat load on essential engine compo-

nents, due to increased scavenge air pressure.

This results in less maintenance and lower spare

parts requirements

The increased scavenge air pressure permits run-

ning without auxiliary blowers down to 20-30% of

specified MCR, instead of 30-40%, thus saving

electrical power.

The saving in SFOC at 50% of optimised power is

about 1-2 g/BHPh, while larger savings in SFOC are

obtainable at lower loads.


459 100 259 198 19 11

3.10

Fig. 3.06: Position of turbocharger cut-out valves

178 06 93-6.0

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Valve for partical by-pass

Option: 4 60 117

Valve for partical by-pass of the exhaust gas round

the high efficiency turbocharger(s), Fig. 3.07, can be

used in order to obtain improved SFOC at part

loads. For engine loads above 50% of optimised

power, the turbocharger allows part of the exhaust

gas to be by-passed round the turbocharger, giving

an increased exhaust temperature to the exhaust

gas boiler.

At loads below 50% of optimised power, the

by-pass closes automatically and the turbocharger

works under improved conditions with high effi-

ciency. Furthermore, the limit for activating the aux-

iliary blowers decreases correspondingly.

Total by-pass for emergency running

Option: 4 60 119

By-pass of the total amount of exhaust gas round

the turbocharger, Fig. 3.08, is only used for emer-

gency running in case of turbocharger failure.

This enables the engine to run at a higher load than

with a locked rotor under emergency conditions.

The engines exhaust gas receiver will in this case be

fitted with a by-pass flange of the same diameter as

the inlet pipe to the turbocharger. The emergency

pipe is the yards delivery.


459 100 259 198 19 11

Fig. 3.07: Valve for partial by-pass

3.11

Fig. 3.08: Total by-pass of exhaustforemergency running

178 06 69-8.0 178 06 72-1.1

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4 Electricity Production

Introduction

Next to power for propulsion, electricity production

is the largest fuel consumer on board. The electricity

is produced by using one or more of the following

typesofmachinery, eitherrunningaloneor inparallel:

Auxiliary diesel generating sets

Main engine driven generators

Steam driven turbogenerators

Emergency diesel generating sets.

The machinery installed should be selected based

on an economical evaluation of first cost, operating

costs, and the demand of man-hours for mainte-

nance.

In the following, technical information is given re-

garding main engine driven generators (PTO) and

the auxiliary diesel generating sets produced by

MAN B&W.

The possibility of using a turbogenerator driven by

the steamproduced by anexhaust gas boiler can be

evaluated based on the exhaust gas data.

Power Take Off (PTO)

With a generator coupled to a Power Take Off (PTO)

from the main engine, the electricity can be pro-

duced based on the main engines low SFOC and

use of heavy fuel oil. Several standardised PTO sys-

tems are available, see Fig. 4.01 and the designa-

tions on Fig. 4.02:

PTO/RCF

(Power Take Off/Renk Constant Frequency):

Generator giving constant frequency, based on

mechanical-hydraulical speed control.

PTO/CFE

(Power TakeOff/Constant Frequency Electrical):

Generator giving constant frequency, based on

electrical frequency control.

PTO/GCR

(Power Take Off/Gear Constant Ratio):

Generatorcoupled to a constant ratiostep-up gear,

used only for engines running at constant speed.

The DMG/CFE (Direct Mounted Generator/Constant

Frequency Electrical) and the SMG/CFE (Shaft

Mounted Generator/Constant Frequency Electrical)

are special designs within the PTO/CFE group in

whichthegenerator iscoupled directly to themain en-

gine crankshaft and the intermediate shaft, respec-

tively, without a gear. The electrical output of the gen-

erator is controlled by electrical frequency control.

Within each PTO system, several designs are avail-

able, depending on the positioning of the gear:

BW I:

Gear with a vertical generator mounted onto the

fore end of the diesel engine, without any con-

nections to the ship structure.

BW II:

A free-standing gear mounted on the tank top

and connected to the fore end of the diesel en-gine, with a vertical or horizontal generator.

BW III:

A crankshaft gear mounted onto the fore end of

thediesel engine, witha side-mountedgenerator

without any connections to the ship structure.

Onthis type ofengine, special attentionhas tobe

paid to the space requirements for the BWIII sys-

tem if the turbocharger is located on the exhaust

side.

BW IV:

A free-standing step-up gear connected to the

intermediate shaft, with a horizontal generator.

The most popular of the gear based alternatives is

the type designated BW III/RCF for plants with a

fixed pitch propeller (FPP) and the BW IV/GCR for

plants with a controllable pitch propeller (CPP). The

BW III/RCF requires no separate seating in the ship

and only little attention from the shipyard with re-

spect to alignment.


485 600 100 198 19 13

4.01

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485 600 100 198 19 13


4.02

Alternative types and layouts of shaft generators Design Seating Total

efficiency (%)

PT

O/RCF

1a 1b BW I/RCF On engine(vertical generator)

88-91

2a 2b BW II/RCF On tank top 88-91

3a 3b BW III/RCF On engine 88-91

4a 4b BW IV/RCF On tank top 88-91

PTO/CFE

5a 5b DMG/CFE On engine 84-88

6a 6b SMG/CFE On tank top 84-88

PTO

/GCR

7 BW I/GCR On engine(vertical generator)

92

8 BW II/GCR On tank top 92

9 BW III/GCR On engine 92

10 BW IV/GCR On tank top 92

Fig. 4.01: Types of PTO

178 19 66-3.1

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485 600 100 198 19 13

Fig. 4.02: Designation of PTO

4.03

Power take off:

BW III S70-C/RCF 700-60

178 45 49-8.0

50: 50 Hz

60: 60 Hz

kW on generator terminals

RCF: Renk constant frequency unitCFE: Electrically frequency controlled unit

GCR: Step-up gear with constant ratio

Engine type on which it is applied

Layout of PTO: See Fig. 4.01

Make: MAN B&W

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PTO/RCF

Side mounted generator, BWIII/RCF(Fig. 4.01, Alternative 3)

The PTO/RCF generator systems have been devel-

oped in close cooperation with the German gear

manufacturer Renk. A complete package solution is

offered, comprising a flexible coupling, a step-up

gear, an epicyclic, variable-ratio gear with built-in

clutch, hydraulic pump and motor, and a standard

generator, see Fig. 4.03.

For marine engines with controllable pitch propel-

lers running at constant engine speed, the hydraulic

system can be dispensed with, i.e. a PTO/GCR de-sign is normally used.

Fig. 4.03 shows the principles of the PTO/RCF ar-

rangement. As can be seen, a step-up gear box

(called crankshaft gear) with three gear wheels isbolted directly to the frame box of the main engine.

The bearings of the three gear wheels are mounted

inthegear box sothat the weightof the wheelsis not

carried by the crankshaft. In the framebox, between

the crankcase and the gear drive, space is available

for tuning wheel, counterweights, axial vibration

damper, etc.

The first gear wheel is connected to the

s70mcc

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