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Contents

MAN B&W DieselComputerised Engine Application System (CEAS)

Page

Synopsis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

Program Structure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

Description of Computer Programs . . . . . . . . . . . . . . . . . . . . . . . . 5

A. Estimation of ship particulars . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

B. Propeller layout and power prediction . . . . . . . . . . . . . . . . . . . . 5

C1. Selection of main engine. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

C2. Comparison of main engines. . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

D1. Combined layout and load diagram of engine . . . . . . . . . . . . . . 5

D2. Load diagram of engine. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

E. Overhauling and spare parts costs of engine . . . . . . . . . . . . . . . 5

F. Total economy – comparisons of engine room alternatives . . . 5

G. Electrical power and steam consumption of ship . . . . . . . . . . . . 6

H. Auxiliary machinery capacities . . . . . . . . . . . . . . . . . . . . . . . . . . 6

I. Fuel and lube oil consumption and exhaust gas data of engine . 6

J. Heat dissipation of engine – performance data . . . . . . . . . . . . . . 6

K. Utilisation of exhaust gas heat – steam and electricity production . 6

L. Water condensation in air coolers . . . . . . . . . . . . . . . . . . . . . . . . 6

M. Engine noise sources. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

N. Preheating of diesel engine . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

O. Utilisation of jacket cooling water heat – freshwater production 6

P. Starting air system . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

Q. Exhaust gas back pressure . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

Economy Model Used . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

Definition of Net Present Value (NPV). . . . . . . . . . . . . . . . . . . . . . . 7

Example Based on a 2,300-3,300 TEU Containership. . . . . . . . . . . 8

Estimated ship particulars. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

Power prediction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

Main engine selection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

Programs for more detailed information . . . . . . . . . . . . . . . . . . . . . 11

Summary. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14



Synopsis

A marine power engineering project in-volves a lot of parameters that have tobe evaluated in order to find the opti-mum solution. Such a procedure maybe both complex and time-consuming.

Therefore, MAN B&W Diesel has, overthe past couple of decades, developeda comprehensive Computerised Engine Application System, including an inte-

gral speed and power prediction pro-gram for ships, and the correspondingmain engine selection program. Thesystem enables specifications of mainengine solutions for specific ship projects to be processed on the basis of both technical and economical input.

The system facilitates calculations of such parameters as fuel consumption,utilisation of exhaust gas heat, main-tenance costs, etc., involved in projectengineering, and allows an economic

comparison to be made of the variousalternatives.

The computer system comprises a num-ber of integrated sub-programs whichare hierarchically arranged, thus mak-ing them easy to extend and update.

The system will be illustrated by meansof computerised examples.

Introduction

MAN B&W Diesel has developed a

Computerised Engine ApplicationSystem, which facilitates the calcula-tions involved in project engineeringand allows an economic comparisonto be made of various alternatives.

This computer system has been devel-oped on our Company’s main framecomputer, using the MVS/XA operatingsystem. The program language used isFortran 77. Two graphical output sys-tems are used. The one is our owncompany-made system similar to

PLOT 10, and the other is based ongraphical output formatted directly incompatible PRESCRIBE instructions.

The computer system comprises anumber of integrated sub-programswhich are hierarchically arranged, mak-ing them easy to extend and update. All present MC type engines are coveredby the system. The type and calculationlevels of the main programs incorpora-ted in this system are shown in Table 1.

The normal procedure for calculation isto start at a calculation level determinedby the available project data.

If, for instance, the type of main enginehas already been selected, the calcula-tions may start at level D for final deter-mination of engine layout and loaddiagrams. Hereafter, for instance, theexhaust gas and specific fuel consump-tion data may be calculated, if required.

If, on the other hand, the project workhas just commenced, and the final shipdimensions are unknown, calculationshould start at level A, which will providea set of assumed ship dimensionsbased on average ship dimensions forthe specific ship type in question.

A brief description, together with ex-amples of the computer programs, willbe given in the following, based on cal-culations of a containership project

with limited ship data available.

Today also the most important of thecomputer programs like selection of main engine, list of auxiliary machinerycapacities and SFOC/exhaust gas data,are available in a PC-version using Win-dows NT/98.

3

MAN B&W DieselComputerised Engine Application System (CEAS)

Calculation level Name of program

A Estimation of ship particulars(Based on shiptype, design ship speed, deadweight, etc.)

B Propeller layout and power prediction

C1 Selection of main engine

C2 Comparison of main engines

D1 Combined layout and load diagram of engine

D2 Load diagram of engine

E Overhauling and spare parts costs of engine

F Total economy – comparisons of engine room alternatives

G Electrical power and steam consumption of ship

H Auxiliary machinery capacities

I Fuel and lube oil consumption and exhaust gas data of engine

J Heat dissipation of engine – performance data

K Utilisation of exhaust gas heat – steam and electricity production

L Water condensation in air coolers

M Engine noise sources

N Preheating of diesel engine

O Utilisation of jacket cooling water heat – freshwater production

P Starting air system

Q Exhaust gas back pressure

Table 1: Type and calculation levels of programs



Program Structure

The software for the technical part of the computer system consists of about400 program modules, which arewidely integrated and interconnected.

The two programs, A and B, are inde-pendent programs, more or less sepa-rate from the rest of the system,whereas the remaining programs arefully integrated and interconnected.

Fig. 1 shows the hierarchically arrangedprogram structure of the system. Thehorizontal bars incorporate program

modules for general use, whereas theprograms in the vertical columns incor-porate program modules used only bythe program in question, designatedby the letter at the top of the verticalcolumn.

The larger the number of horizontalbars below the program, the more com-prehensive is the program. Thus, the‘total economy program’ (F) placedat the very top of the system involves the

use of almost all sub-programs, where-as the ‘noise program’ (M) at the bottomof the system uses only a few sub-programs.

The program is a dynamic systemwhich will never stop growing andwhich is continuously being updatedwith new and/or improved information.

Data for new engines will be entered,but it will still be possible to find andcalculate data for old engine types.

The engine power units used may beeither BHP or kW.

4

II Shaft generator data

lV Main engine performance data

I General

V El/ heat consumption data

Vl El/heat production data

VII Economy

III Main engine basic data

W a t e r c o n d e n s a t i o n i n a i r c o o l e r s

L a y o u t a n d l o a d d i a g

r a m

U t i l i s

a t i o n o f e x h a u s t g a s h e a t

H e a t d i s s i p a t i o

n – p e r f o r m a n c e d a t a

S F O C / e x h a u s t

g a s / l u b . o i l / T C S

U t i l i s

a t i o n o f j a c k e t c o o l i n g w a t e r h e a t

P r o p e l l e r l a y o u t a n d p o w e r p r e

d i c t i o n

E s t i m a t i o n o f s h i p p a r t i c u l a r s

O v e r h a u l i n g a n d s p a

r e p a r t s c o s t s

P r e h e a t i n g o f d i e s e l

e n g i n e

N o i s e s o u r c e s

S t a r t i n g a i r s y s t e m

S e l e c t i o n / c o m p a r i s o n o f m a i n e n g i n

e s

T o t a l e c o n o m y

A u x i l i a r y m a c h i n e r y c a p a c i t i e s

E l e c t r i c a l

p o w e r a n d s t e a m c o n s u m p t i o n

E x h a u s t g a s b a

c k p r e s s u r e

LI

K

J

G

O

B A

ED NM P

C F

H Q

Fig.1: Programs and program structure



Description ofComputer Programs

A. Estimation of ship particulars

The minimum input data required is thetype of ship (for instance tanker, bulkcarrier, container vessel, etc.), the designship speed (knots) and deadweight (dwt)referred to the corresponding propellerdesign draught.

With this information, the program esti-mates the relevant ship particulars, bothempirically and by theoretical formulas. The more input data, the more accuratethe ship’s particulars can be estimated.

B. Propeller layoutandpower prediction

When the ship’s main particulars havebeen estimated (or are known), thepower prediction program can be used

to estimate the required propulsionpower at the design ship speed. Thisprogram also indicates the optimumpitch/diameter ratio and propeller speedfor a given propeller diameter.

The power prediction calculations arecarried out using either the ‘Harvald’ or the‘Holtrop & Mennen’ power predictionmethod. The estimation of the propellerdata is performed using WageningenB-Series propellers.

The polynomials used are described in

‘International Shipbuilding Progress’, Vol. 22, July 1975.

The ship’s propeller speed and propul-sion power prediction in the design pointafter incorporating sea and engine mar-gins and a light propeller running factorcan be used to find the required refer-ence MCR propulsion power and propel-ler speed which, in turn, may be used asinput for our engine selection program.

C1. Selection of main engine

The applicable engine types are selectedfrom the MC engine programme basedon a required reference MCR propulsion

point and a permissible propellerspeed range and constant shipspeed factor ‘α’. If a shaft generatoris installed, the corresponding extrapower needed from the main enginehas to be considered, too.

For the engines selected, the programcalculates the relative difference inestimated worldwide engine price,fuel and lubricating oil, and mainte-nance costs, together with the diffe-

rence in electrical power costs of themain-engine-dependent pumps. Bymeans of the ‘Net Present Value’method, including investment andoperating costs, the engines selectedare evaluated in terms of economyand given priority, with the most at-tractive engine being the one withthe lowest total costs for a given costcalculation period.

Regarding definition of the Net Pres-ent Value (NPV) method, please refer

to the section below ‘Economy ModelUsed’ .

As stated above, the calculation maybe made with or without a shaft gen-erator being incorporated.

C2. Comparison of main engines

Based on a given service rating need-ed for a required ship speed, this pro-gram calculates and compares theoperating costs of the main engines

in question. The Net Present Valuemethod is also used in this program.For unregistered engines (competingtwo-stroke or four-stroke types) thestroke/bore, SFOC, lube oil consump-tion data, etc., are needed.

D1. Combined layout and loaddiagram of engine

This program calculates and drawsup a combined layout/load diagram

in % of the nominal MCR power as afunction of speed (%), showing thelayout and operation limitation linesof the specified engine. Propeller linesand engine operation lines that con-

sider possible shaft generator powerare also drawn.

D2. Load diagram of engine

This program draws up a separate loaddiagram in terms of BHP or kW as func-tion of r/min showing the limitation linesfor operation of the specified engine.Propeller and engine operation lines,including possible shaft generator

power, are also drawn.

E. Overhauling and spare partscosts of engine

The average maintenance costs foroverhauls are calculated based on theoverhauling times and intervals used. Also the average spare parts expensesare estimated and included in the totalmaintenance expenses.

Two different types of maintenancecalculations and corresponding reportscan be generated:

• Average annual maintenance costsfor a long time in operation

• Maintenance costs for a given time inoperation.

F. Total economy – comparisons ofengine room alternatives

This program calculates the overall fueland lubricating oil expenses for variousalternatives of engine room installations.

Many engine room configurations, con-sisting of different combinations of mainengine and electrical power producers,such as diesel generators, turbo gener-ators and main engine driven genera-tors, simultaneously in operation atsea, may be considered and used asengine room alternatives. The calcu-lated alternatives will be compared with

each other by means of the Net Present Value method, see the section regard-ing ‘Economy Model Used’, below.

5



A calculation of several alternatives of each engine room configuration can beworked out with different main engines,different optimising points, differentelectrical power producers, exhaustgas boilers, etc.

Furthermore, but only for a few enginetypes, it is possible to choose a TurboCompound System (TCS) either con-nected to the crankshaft for PowerTake-In (TCS/PTI), or for the produc-

tion of extra power for PowerTake-Off (TCS/PTO). In the latter case,it is also possible to connect the TCSeither to a separate electrical generatoror to an electrical generator driven, forexample, by an auxiliary diesel engineor a turbo generator, and make calcu-lations accordingly.

G. Electrical power and steamconsumption of ship

A detailed calculation of all the ex-pected typical electrical power andsteam consumers valid for a bulk car-rier or a tanker can be carried out forthe ambient temperature condition inquestion. The main-engine-relatedelectrical power and steam consump-tion figures are specially calculated onthe basis of the relevant engine dataand auxiliary machinery capacities,whereas the remaining ship-dependentconsumption figures are empirical.

H. Auxiliary machinery capacities

If a diesel engine has been rated insuch a way that the actual availablerating has been changed, compared toa nominal-rated engine, the necessarycapacities of pumps and coolers maybe calculated on the basis of the givenengine layout. This calculation refers totropical ambient conditions and may bebased on either seawater cooling or acentral cooling water system. If the en-gine is equipped with a separate cam-

shaft lubricating oil system or islow-NOx optimised, this will be includedin the calculations. The use of conven-tional or high efficiency turbocharger,

the make and/or type and numbers arealso included.

I. Fuel and lube oil consumptionand exhaust gas data of engine

Information regarding the use of conven-tional or high efficiency turbochargers,the Turbo Compound System (TCS), if installed, the specified MCR and opti-mised points, the requested running

points, and the ambient conditions, willbe sufficient to calculate the relevantspecific fuel and lubricating oil consump-tions, the exhaust gas amount and tem-perature after the turbochargers, as wellas the TCS power.

J. Heat dissipation ofengine – performance data

This program calculates the actualheat dissipation and other general

performance data of the main engine inquestion. A special calculation optionmay also, in percentage figures, relateengine shaft power and heat dissipationlosses to 100% fuel energy consump-tion (Sankey diagram).

K. Utilisation of exhaust gas heat –steam and electricity production

The steam production from an exhaustgas boiler can be calculated on the ba-sis of the previously calculated exhaust

gas amounts and temperatures, or onthe basis of special exhaust gas dataprovided.

The size of the exhaust gas boiler is de-termined by the pinch point temperature. A low pinch point temperature corre-sponds to a large boiler. The boiler maybe of either the single or dual pressuretype, with/without preheater and super-heater sections.

It is also possible to calculate the elec-

trical power production obtainable byutilising the available steam from theexhaust gas boiler to operate a steamdriven turbo generator.

L. Water condensation in air coolers

This program calculates the theoreticalamount of condensed water in thescavenge air coolers, based on the rel-ative humidity of the intake air. The cor-responding amount of water expectedto be separated by the water mistcatcher is also stated.

M. Engine noise sources

On the basis of theoretical values andactual measurements, this programcalculates the sound levels in octavebands of the following engine-relatednoise sources, which are typical for ourtwo-stroke engines:

• Exhaust gas noise (gas pulsations)

• Air-borne noise (engine room noise)

• Structure-borne noise excitation(vibration in engine feet).

N. Preheating of diesel engine

The jacket water preheater size to berecommended is calculated on the basisof the requested temperature increaseand preheating time, or vice versa.

O. Utilisation of jacket coolingwater heat – freshwater production

The jacket cooling water heat that canbe recovered is calculated, and the cor-responding freshwater amount that canbe produced by means of a freshwatergenerator of the low pressure vacuumevaporation type is found. Several effectstages may be used, and calculationsmay also be carried out for specialheating media available.

P. Starting air system

On the basis of theoretical values andactual measurements, this programcalculates the starting air consumptionand the pressure after a number of successive engine starts.

6



The program may be used for threedifferent purposes:

1. Dimensioning of starting airreceiver and compressor

2. Calculating the number of possiblestarts for a given receiver size andthe initial pressure

3. Evaluating starting air consumptionbased on pressure measurements.

Q. Exhaust gas back pressure

Based upon detailed information of thepipings and components (exhaust gasboiler, silencer, spark arrester, etc.) inthe exhaust gas system, the programcalculates the exhaust gas back pres-sure in the piping and just after theturbocharger(s). The back pressureafter the turbocharger(s) may be com-pared to the recommended design

back pressure (300 mm WC) and po-tential modifications of the pipe systemwill be recommended.

Economy Model Used

For the purpose of making economicalevaluations of alternative projects, theNet Present Value method is used. Thismethod is preferred because, indepen-dent of the payback time, it comparesthe total gain after a certain number of years in operation, and thus – besidesthe annual operating costs – also incor-porates the influence of the size of theinvestment costs.

Definition of Net Present Value (NPV)

The Net Present Value method is usedin order to get an evaluation of the pro-fitability of investing an extra amount of initial capital in an alternative projectcompared to the basic project.

It is assumed that the alternative project necessitates an extra investment of Co at the project start, and that this in-

vestment gives an annual saving on thefuel, lubricating oil and maintenancecost bills equal to So, based on today’sprices, see Fig. 2.

To determine the annual savings ob-tainable during the subsequent years‘n’, So must be corrected for inflation,i.e. Sn = So x (1+i)n, in which ‘i’ is infla-tion and ‘n’ is number of years afterinvestment.

To put these savings in relation to Co,Sn must be calculated back into to-day’s prices at the discount rate ‘d’,assuming that the discount rate isequal to the interest rate for financing

‘r’, as normally done in the shippingtrade, i.e. Sn /(1+d)n = Sn /(1+r)n .

As d = r, the investment cost after nyears Cn = Co x (1+r)n calculated backto today’s price level is still equal to Co.

The Net Present Value is then definedas shown in Equation 1.

For the alternative project, the NPVn

shows, compared to the basic project,how much extra money you will have

in your pocket, i.e. the accumulatedsavings obtained by making the extrainvestment in today’s prices after ‘n’ years.

In our computer programs, the curvesfor the alternative projects show NPVas a function of years after investment. The intersection point with the abscissa(basic project) is the alternative project’s real payback time compared tothe basic project.

7

S2

S3

S4

Co

S /(1+d)n

n

S1

C /(1+d)n

nC = C x (1+r)n o

n

S = S x (1+i)n o

n

Fig. 2: Definition of Net Present Value (NPV)

So

Savings at project start

Sn

Savings the n’th year afterinvestment

Co

Extra investment at projectstart

n Number of years afterinvestment

i Rate of inflation

rRate of interest forfinancing

d = r Discount rate

Equation 1: NPVS

(1 d)C

(1+r)

(1 d)n

n=1

n

n

n O

n

n=+

− ×+

=∑ S1+ i

1+ rC

n=1

n

O

n

O∑

−



Example Based on a 2,300 -3,300 TEU Containership

For the purpose of giving an impres-sion of the large number of calculationpossibil ities of the ‘ComputerisedEngine Application System’, a container-ship project in the initial design phasewill be used as an example.

By means of our ship particulars andpower prediction programmes, the

required propulsion power has beencalculated and, on this basis, a mainengine selection has been performed.

Estimated ship particulars

The input values used in order to esti-mate the ship particulars are:

• Type of ship: Containership

• Deadweight at design draught:39,000 tons(at scantling draught 43,000 tons)

• Speed at design draught:22.0 knots.

The above-mentioned figures and esti-mated ship particulars, see Fig. 3, areused as input data for the power pre-diction.

Power prediction

The power prediction calculations arevalid for loaded ship on trial trip condi-tions, i.e. for calm weather and cleanhull and 22.0 knots, without any sea orengine margin and light running factorincorporated. Data have been calcu-lated by means of the Harvald method.

The power/speed requirement for thesingle screw containership with anassumed 5-bladed propeller with themaximum possible diameter of 7.6metres, is calculated to be 17,488 kW at98.0 r/min, see Fig. 4, and corre-sponds to the propeller design pointPD shown in Fig. 5 and placed on thelight running propeller curve 6.

When in this case incorporating a 15%sea margin, a 15% engine margin, and

5% light running of the propeller, thecorresponding reference service andMCR propulsion points, SP and MP forheavy running are found, see Fig. 5:

• SP (85% MCR):20,111 kW and 97.8 r/min

• MP (100% MCR):23,660 kW and 103.2 r/min.

8

r/min

kW

18,000

22,000

20,000

12,000

16,000

10,000

14,000

100

80

90

20 21 2319 22

Trial condition, loaded ship

Trial condition, loaded ship

20 21 2319 22

knots

Propeller speed

Power prediction

Ship speed

Shaft power

Fig. 4: Prediction of the power and speed requirement for the propeller design point of a single screw containership, having a7.6 metre propeller diameter with 5 blades and sailing 22 knots

Input data

Type of shipDesign ship speedDeadweight at design draughtdraughtLength between perpendicularsBreadth on waterline

Container22.00

39,000230.0032.20

knotstonsmm

Estimated ship particulars

Length on waterline

Design draughtDisplacement (volume)

Block coefficient (based on Lpp)Midship section coefficientLongitudinal prismatic coefficientFineness (length displacement) ratioBreadth-draught ratioBreadth-length ratio

Transverse bulb areaLCB, longitudinal centre of buoyancy(+forward Lpp/2)Immersed midship section area

237.00

11.1052,600

0.6400.9790.6386.2782.9010.137

30.0-1.70

350.0

m

mm3

m2

%

m2

Fig.3: Estimated ship particulars of a 2,300 TEU (15t) - 3,300 TEU(empty) container vessel



Power

97.8 r/min

Engine speed6

20,111 kW

17,488 kW

23,660 kW

98.0 r/min

103.2 r/min

Sea margin(15% of PD)

LR = 5%

Engine margin(15%of MP)

SP

PD

MP

2

Main engine selection

As a basis for our main engine selec-

tion program, we have used thereference propulsion MCR point (MP)stated above, i.e. 23,660 kW at 103.2r/min, assuming that the propeller dia-meter layout permits an MCR propellerspeed in the 91.0-120.0 r/min range.

In the upper speed range of 103.2-120.0r/min, we use the constant ship speedfactor α = + 0.17 (reduced propellerdiameter), and in the lower range of 91.0-103.2 r/min, we use α = – 0.17(increased propeller pitch).

α expresses the change in power ‘P’with changes in propeller speed ‘n’ asfollows: P = Pref. x (n/nref. ) α.

As the engine is not equipped with ashaft generator, the engine’s specifiedMCR (M) is equal to the propulsionMCR (MP).

Fig. 6 shows the speed and powerranges of the required specified MCRpoint, together with the superimposeddiagrams for all engine types, i.e. the

entire layout area for the MC program-me in a power/speed diagram.

9

50 120 250200160140100807060

L42

L35

S26

L80

S35

K90

S80

S90-C

L60

S80-C

S60-C

70

60

50

40

30

20

15

6

4

1

10

8

100

BHP kWx 1000

Power

60

80

108

2

5

3

40

30

15

20

L50

S42

L70

K98

K80-C

K90-C

S50

S60

L90-C

S70

S46-CS5

0-C

K98-C

2

S70-C

Speed

r/min

= -0.17

Ref. MCR power : 23,660 kW (PRef. MCR speed : 103.2 r/min (n

Minimum speed: 91.0 r/min

Specified engine MCR (M)

rr

ef.ef

)

. )

Maximum speed: 120.0 r/min

Constant ship (lower/upper)speed factor : -0.17/+0.17

M Constant ship speed lines= 0.17

Fig.6: Selection of main engine from the MC engine programme 1998-1999

Ship propulsion running points and engine layout

2

6

MP:SP:

PD:LR:

Heavy propeller curve – fouled hulland heavy weather, for engine layout

Light propeller curve – clean hull andcalm weather, for propeller layout

Specified propulsion MCR pointService propulsion point

Propeller design pointLight running factor

NB: Logarithmic speed and power scales

Fig. 5: Sea and engine margins together with light running factor used for layout of main engine



The basic economical data used to-gether with the required engine data isas follows:

• Limitation of engine/propeller speed:91-120 r/min

• Limitation of cylinder numbers: 6-8

• Reference specified engine MCRpower (M) 23,660 kW at 103.2 r/min

• Optimising point (O) (engine match-

ing point): 93.5% of specified MCR

• Engine power in service:85% of specified engine MCR

• Normal sea service per year:300 days/year (7,200 hours/year)

• Lower calorific value of fuel:40,200 kJ/kg

• Price of fuel oil: 100 USD/t

• Price of cylinder oil: 1,300 USD/t

• Price of lube oil: 1,000 USD/t

• Hourly wages for overhaul:

45 USD/hour

• Rate of interest: 6% p.a.

• Rate of inflation: 3% p.a.

• Rate of exchange: 6.5 DKK/USD

• Required cost calculation period:12 years

• Selected engines:7K80MC-C and 8S70MC-C.

The main engine types – with option 1as the best one, i.e. having the lowesttotal (investment and operating) costs

in terms of net present value after 12years – are found and evaluated withregard to economy by using 85% MCRas the service power, and the abovestated economy figures.

10

45

50

110

70

100

90

80

70

60

55

Layout/load diagram

7K80MC-C High efficiency turbocharger

(Nominal engine MCR (L1):Specified engine MCR (M):Optimising point (O):Engine service point (S):

Engine speed, % of nominal MCR speed

40

75 80 85 90 95 100 105 11063

M

S0

5

38

4 1

26

Engine shaft power, % of nominal MCR power

25,270 kW and 104.0 r/min)23,660 kW and 103.2 r/min22,122 kW and 100.9 r /min20,111 kW and 97.8 r/min

FIg. 8: Combined layout and load diagram for the selected 7K80MC-C engine

-200

0

1,400

Opt. 2

10 128 16 1814 22204 62

-400

1,200

1,000

800

600

400

200

Years after investment

Opt. 1

Opt. 5

Running point in service:

85.0% Ref. MCR propeller power

20,111 kW at 97.8 r/min1000 USD

Opt. 3

Option 1: 7K80MC-C

Option 2: 8S70MC-C

Option 3: 8K80MC-C

Option 4: 6K90MC-C

Option 5: 7L80MC

Opt. 4

Economy of selected main engines

Total costs(NPV)

Fig. 7: Total operating and investment costs of the selected mainengines ordered in NPV priority after 12 years in operation



The result of the total costs (NPV)calculations, shown in graphical formin Fig. 7, gives preference to the7K80MC-C and 8S70MC-C engines.

The layout/load diagram for the7K80MC-C engine is shown in Fig. 8.

In Fig. 7 the option 2 curve for 8S70MC-Cindicates that – compared to option 1for 7K80MC-C – the investment needed

is about 400,000 USD lower, and thatafter about 5 years in service this lowerinvestment has been ‘eaten up’ by thehigher operating costs.

Programs for moredetailed information

By means of the remaining programsD–Q, more detailed investigations canbe made, such as calculations of themaintenance costs, program E, andthe SFOC as a function of the engineshaft power, program I. Also the ex-haust gas heat utilisation possibilitieswill normally be investigated, and the

obtainable steam production from theexhaust gas boiler will be comparedwith the steam consumption of theship, program K. Investigations

regarding selection of electrical powerproducers (Total Economy) may alsooften be useful, program F.

Maintenance costs. The maintenancecosts calculated, including manhoursfor overhaul and spare part costs, arebased on data given individually for eachcomponent (spare part), i.e.

• overhauls:

time between overhauls andmanhours per overhaul

• spare parts:lifetime and repair kit price.

11

40

Fuel consumption

7K80MC-C high efficiency turbocharger

(Nominal engine MCR: 25,270 kW and 104.0 r/min)Specified engine MCR: 23,660 kW and 103.2 r/min

Running with fixed pitch propeller.(Propeller curve through specifiedMCR point)

Engine shaft power % SMCR

50 60 70 80 90 100 11030

171

170

173

172

167

Alt. 1

169

168

175

174

Optimising points

176

Alt. 1) 100.0% SMCR Alt. 2) 93.5% SMCR

Alt. 3) 90.0% SMCR

Alt. 3

g/kWh

Alt. 2

SFOC

177

Fig. 10: Expected SFOC at part load running at ISO ambient condi-tion ( LCV= 42,700 kJ/kg) valid for three different optimising points

5.0

yearshours

7K80MC-C SMCR: 23,660 kW x 103.2 r/min

Specific cumulative average maintenance costs

4.0

6.0

0.0

1.0

3.0

8.0

7.0

9.0

2.0

1072,000

15108,000

20144,000

5

36,000

Maintenance costs

00

USD/kW/year Time span

Time in service

Fig. 9: Expected maintenance costs per year the 7K80MC-C engine has been in service



Fig. 9 shows the maintenance costs in

USD/kW/year as a function of the timethe engine has been in service. In thefirst years in service, the maintenancecosts are relatively low, but will increasegradually until they become ‘constant’ af-ter some 10-12 years, at which time theyare influenced by the renewal of heavyand costly components such as pistonsand cylinder liners.

Fuel consumption. If the diesel engine isnormally running in service at part load,the fuel consumption may be some-what lower if the engine is ‘service’

optimised (matched) for a lower powerthan the specified MCR. Fig. 10 showsthe effect of this. On the other hand,if the engine is normally running in

service in the high power range, the

‘service’ optimising will have a negativeeffect.

Exhaust gas boiler. Furthermore, theannual running costs for the ship maybe reduced by utilising the waste heatof the main engine. The necessary sat-urated steam for heating services maythus be produced by means of an ex-haust gas boiler that recovers the heatcontent of the main engine’s exhaustgas.

Fig. 11a shows a calculated tempera-

ture/heat transfer diagram indicatingthe equivalent dimensions of an ex-haust gas boiler with evaporator andpreheater sections, and the upper

curve in Fig. 11b shows the corre-

sponding steam production and ship’srequirements valid at ISO ambient tem-perature conditions (25 °C). In wintertime (10 °C), the exhaust gas tempera-ture will be lower, and the correspondingsteam production will be reduced,whereas the steam consumption willincrease, meaning that the oil firedboiler may occasionally have to start upto supplement the steam production,see the lower curve of Fig. 11b.

Electrical power producers. The totaleconomy program may be demon-

strated by means of a simple exampleregarding the choice of electrical powerproducers. For this purpose we havechosen three different engine room

12

250

200

150

100

Exhaust gas boiler layout

7K80MC-C high efficiency turbocharger

(Nominal engine MCR:Specified engineMCR:Optimising point :Service point :

P point temperature: 25 Cincho

1,600800 2,0001,200 2,400400

50

0

7 bar abs

Tempe-rature

B

C

Heat transfer

Exhaust gasboiler sections:

B. Evaporator

C. Preheater

E x h a u s t g a s

Ambient air

O

C

kW

0

Steam/water

25,270 kW and 104.0 r/min)23,660kW and 103.2 r/min22,122 kW and 100.9 r/min20,111 kW and 97.8 r/min

Fig. 11a: Temperature/heat transfer diagram of an exhaust gas boiler at ISO ambient conditions and 85% specified engine MCR

1,000

4,000

3,000

2,000

Engine shaft power

0

Steam consumption

Extra steamneeded

1,000

0

2,000

Steam consumption

Total steamproduction

Surplus steam

50 60 70 80 90 100 11040

50 60 70 80 90 100 11040

Total steamproductionWinter ambient conditions (10

oC)

Steam/water

kg/h

ISO ambient conditions (25oC)

Steam production

kg/h

Surplus steam

% spec. MCR

Fig. 11b: Steam production at ISO and winter ambient conditions



alternatives – each having the selected7K80MC-C installed as the main engine. The three electrical power producer(in operation) alternatives are:

1. a 1,400 kW diesel generator (DG)operating on marine diesel oil (MDO)

2. a 1,400 kW diesel generator (DG)operating on heavy fuel oil (HFO)

3. a 1,400 kW main engine driven fre-quency controlled shaft generator(SG)

all with the main engine operating onheavy fuel oil (HFO), see Table 2.

The assumed electrical power con-sumption in service is 1,100 kW.

The assumed economical data used isthe same as stated for main engineselection, whereas the assumed tradepattern of the ship, a total of 300 days/ year in normal sea service, has beenstated in more detail, see Table 3.

% PropulsionMCR

100 93.5 85 70

Days/year 10 30 140 120

Table 3: Trade pattern of the ship

13

1,000 USD

-800

Rate of interest/discount %/year: 6.0Rate of inflation %/year: 3.0Fuel oil price (MDO) USD/t: 170Fuel oil price (HFO) USD/t: 100In normal sea service days/year: 300

Years after investment

12 16 20

Alt. 1

4 8

Alt. 1: 7K80MC-C + DG(MDO) Alt. 2: 7K80MC-C + DG(HFO) Alt. 3: 7K80MC-C + SG(HFO)

-600

-400

400

600

800

1,000

1,200

-200

0

200

Total savings (NPV)

Based on a given trade pattern

22

Alt. 2

Alt. 3

10 14 182 6

Economy of electrical power producers

Fig. 13: Total savings in terms of Net Present Value relative to alternative 1

25,270 kW and 104.0 r/min23,627 kW and 101.7 r/min23,691 kW and 104.0 r/min

12,000

kW Engine shaft power 104.0 r/min

14,000

16,000

18,000

20,000

25,000

30,000

10,000

M

0 MP

25,270 kW

8

4 2A

3

5

1

6

70

Engine speed

75 80 85 90 95 10064 105 r/min

2

Load diagram

7K80MC-C High efficiency turbocharger

Specified engine MCR (M):(O):

Propulsion MCR (MP):Optimising point

Fig. 12: Load diagram for 7K80MC-C main engine equipped with a1,400 kW shaft generator

AlternativeMain

engineEl. Producerin operation

Maintenance costsof DG and SGUSD/kW/year

Fuel oilpriceUSD/t

El. producers not in opera-

tion

1

2

3

7K80MC-C

7K80MC-C

7K80MC-C

1 x DG(MDO)

1 x DG (HFO)

1 x SG (HFO)

10

15

1

170

100

100

2 x DG (MDO)

2 x DG (HFO)

2 x DG (HFO)

Table 2: Electrical power production alternatives



For alternatives 1 and 2, the mainengine’s specified MCR power is asshown in Fig. 8, whereas, for alterna-tive 3, the extra shaft generator poweralso has to be incorporated. The MCRmay be found by means of programD2, and the corresponding load diagramis shown in Fig. 12.

The nominal engine speed found foralternative 3 is 104.0 r/min instead of 103.2 r/min, enabling the engine to

produce the maximum shaft poweroutput.

Compared to alternative 1, Fig. 13shows the total savings in terms of netpresent value for alternatives 2 and 3,including the difference in investmentcosts, and the relative savings in totalfuel, lube oil and maintenance costs.

The total savings (NPV) relative to alter-native 1, and shown as a function of years in service after investment, indicate,

based on the assumptions given, thatthe diesel generator and shaft genera-tor alternatives operating on heavy fueloil are the best ones, economy-wise,after about 2.6 - 7.5 years in service.On the other hand, unquantifiableparameters like noise, reliability, etc.,may also have an influence.

Summary

As illustrated in this paper, we have acomprehensive tool at hand to assistour customers, not only in selecting theoptimum main engine and calculatingthe corresponding performance data,but also in selecting the optimum en-gine room configuration. Furthermore,it is possible, and our aim, already atthe initial stage of a project, to assistwith a preliminary determination of ship

particulars and propeller power prediction.

As demonstrated, it is also possible toobtain more detailed main-engine-relatedinformation regarding, for example, thedimensioning of the exhaust gas boiler,silencer and pipe system.

Only with the optimum total engineroom configuration and optimum over-all operation can the owner expect toget the best return on his investment.

The development of this computersystem is one of our contributions tohelping the project engineer, and thusthe owner, in meeting these demands.

computer is ed engine application

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