EFFICIENT AFRAMAX DESIGN PROVIDING SOLUTIONS FOR EMISSIONS LEGISLATION (SOX and NOX)

At Wärtsilä, we are passionate about

optimising lifecycle value by offering

precisely what each of our customers need.

We can deliver on this promise because

we provide the only true total offering of

marine products, integrated solutions and

services in the industry – worldwide. We

help our customers find the shorter route

to robust growth and bigger profits through

operational efficiency, environmental

excellence, fuel flexibility and services. Even

though this brochure is just a beginning

to learn why Wärtsilä nowadays powers

one in every three ships worldwide, it still

demonstrates how we are able to customise

our comprehensive offering in order to give

customers a crucial competitive edge. What

can we do for you?

• A single decked, single screw motor ship with

machinery and accommodation located aft

• Double bottom and double shell protection

along cargo area

• Compliant with Common Structural Rules

(CSR) for double hull tankers

• The centre section to be subdivided into

twelve (12) cargo tanks by means of

transverse bulkheads and one longitudinal

bulkhead at the centre line. Slop tanks and

cargo drain tank to be arranged aft of cargo

tanks

• Clean design – HFO tanks in engine room

arranged with cofferdams against outer shell

• Unrestricted ocean services and terminals

compatible with vessel’s dimensions

TANKER FOR CRUDE OIL AND DARK PETROLEUM PRODUCTS

WSD AFRAMAXMAIN DATALength over all ..................................253.20 mDeadweight ................................. 117,500 dwtSpeed ............................................ 14.8 knotsOperation range ............................ “Worldwide”Main engine .................................Wärtsilä X62

RESISTANCE AND PROPULSIONDuring design stage hull shapes have been

generated and carefully tested by means of

RANS CFD computations.

The purpose has been to minimise hull

resistance and maximise propulsive efficiency of

the vessel keeping constrains of deadweight and

cargo capacity to the upper limit.

During optimisation stage wave profiles,

pressure distribution and flow lines along the

hull have been carefully analysed. Necessary

modifications have been done showing

sufficient improvement in the forward and aft

parts of the hull.

Finally cylindrical bow design showed

improved performance for variable operational

draughts and also during rough weather

conditions still having high deadweight and

cargo capacity kept.

Propulsion of the vessel has been

optimised by the adaptation of the modern

high performance electronically-controlled

2-stroke long-stroke / low-speed Wärtsilä X62

engine. The new engine offers high propulsion

efficiency in a unique combination of low

engine revolutions and an engine design with

a minimum physical width. This benefit results

in a slimmer aft body design leading to further

propulsion efficiency improvements. When

comparing the new Wärtsilä X62 to currently

available main engine options, a gain of

approximately 7% in efficiency can be achieved.

Thanks to the optimised engine parameters,

the required propulsion power for the same

vessel speed for the specific vessel can

be achieved with one cylinder less (6 cyl)

compared to previous generation main

engine options. With a propeller diameter of

7600 mm, including a sea margin of 15%

and an engine margin of 10%, Power (Pb) of

14,400 kW at 92 rpm is required.

A 7 cylinder is a solution for even higher

efficiency due to the lower rpm and higher de-

rating potential that can be achieved. Power

(Pb) of 14,150 kW at 83 rpm is required with

a propeller diameter of 7900 mm, including

a sea margin of 15% and an engine margin

of 10%.

The achieved EEDI value is below the

requirements of Phase 1 (Jan 2015–Dec

2019). Further reduction can be achieved with

waste heat recovery, power take-off devices.

During optimisation stage vessel’s hull form was considerably improved providing lower resistance with higher propulsion efficiency together with the increased deadweight and cargo capacity.

Aframax tanker (previous generation

main engine)

Aframax tanker (Wärtsilä X62 main engine)

Propeller diameter 7200mm 7600mm 7900mm

Number of cylinders for main engine 7 cylinders 6 cylinders 7 cylinders

Efficiency gain due to larger propeller Reference ~ 4% ~ 5%

Efficiency gain due to higher engine internal efficiency Reference ~ 1% ~ 1%

Efficiency gain due to de-rating potential Reference Equal to reference ~ 1%

Total efficiency gain ~ 5% ~ 7%

Daily fuel consumption at CSR (approx MT/day) 53.5 50.9 49.5CSR = Continuous Service Rating / LCV of MDO = 42,700kJ/kg

Wärtsilä X62 – High performance 2-stroke main engine – Electronically-controlled common-rail – Extra long stroke – Low rpm.

SOLUTIONS FOR NOX AND SOX EMISSIONSIn order to achieve compliance with both the

IMO Tier III NOX standards and the requirements

for SOX control, aftertreatment solutions such as

SCR and Scrubber have been selected. In the

main engine the SCR unit is placed before the

turbocharger turbine and the Scrubber unit is

placed on the funnel. The equipment are tuned

together with the main and auxiliary engines for

operation in the complete load range.

AFRAMAX CASE STUDY – OPERATION IN ECAA case is shown of an Aframax tanker with a

route between Galveston (US) to Rotterdam

(NL). Assuming the North America and the

European ECA`s, the percentage of the time

spend in ECA`s per roundtrip corresponds to

approximately 35% including harbour time.

By the installation and operation of scrubbers,

savings to the order of 7% can be achieved

per roundtrip. In the case of an increased time

spend in ECA savings will be even higher. Fuel

costs include the operation of the auxiliary

engines but the consumption of auxiliary boilers

during port stay has not been taken into account.

The alternative with SCR is Tier III compliant.

ASSUMPTIONSHFO price: .....................................650 USD/tonneMGO price: ....................................975 USD/tonneUrea price: .....................................240 USD/tonneCaustic soda price: .........................235 USD/tonne

SCR (Selective Catalyst Reactor) Scrubber (Funnel positioned)

Oper

atin

g tim

e pe

r rou

ndtr

ip (%

)

50

45

40

35

30

25

20

15

10

5

0Harbour 12.5 knots

(reduced speed)14.8 knots(ballast)

14.8 knots(loaded)

Outside ECA

Inside ECA

Cons

umab

le c

osts

per

roun

dtrip

(kUS

D) 1000

800

600

400

200

0Wärtsilä 7X62

(Tier II)Wärtsilä 7X62

(SCR & scrubber, Tier III)

100.0%93.2%

NaOHUreaMGOHFO

1200

Operating profile per roundtrip (Galveston – Rotterdam).

Comparison of consumable costs per roundtrip of the different alternatives.

Daily fuel consumption vs vessel speed Design Draught / LCV-42,700kJ/kg / Delta Tuning (Part load)

10.815.0

20.0

25.929.0

31.7

36.3

40.6

45.8

52.4

0.0

10.0

20.0

30.0

40.0

50.0

60.0

8.0 9.0 10.0 11.0 12.0 13.0 14.0 15.0 16.0Vessel speed (knots)

Fuel

con

sum

ptio

n (M

T/da

y)

WÄRTSILÄ EQUIPMENT • Main engine (Wärtsilä X62 –

electronically-controlled common-rail) • Auxiliary engines/generators

(Wärtsilä genset 20) • Integrated scrubber

(Main engine+Auxiliary engines+Auxiliary boilers)

• Selective catalyst reactors • Automation • Fixed pitch propeller, seals and

bearings • Ballast water treatment • Oily water separator • Inert gas systems

WÄRTSILÄ® is a registered trademark. Copyright © 2012 Wärtsilä Corporation.

WARTSILA.COM

MAIN DIMENSIONSLength over all, approx. .........................253.20 mLength between PP ...............................244.60 mBreadth moulded ....................................44.00 mDepth moulded, approx. ..........................21.30 mDesign draught .......................................13.60 mScantling draught ....................................15.20 mGross tonnage, approx. .........................65,000 GTDeadweight, D = 15.20 m ................ 117,500 dwt

SPEED

Speed, d = 13.6 m, approx. ..................14.8 knotsCruising range ....................................14,700 nm

CAPACITIES

Cargo tanks, approx. ..........................134,250 m³Slop tanks, approx. ..................................3020 m³Ballast water tanks, approx. ..................39,600 m³HFO, storage, serv., approx. .....................3115 m³MDO, approx. ...........................................520 m³Lub. Oil, approx. ........................................250 m³ME cylinder oil, approx. ...............................50 m³Fresh water tanks, approx. .......................2000 m³Urea, approx. ............................................310 m³Caustic soda, approx. ................................370 m³

PROPULSION PLANT

• 1x2-stroke Wärtsilä X62 § 6 cyl CMCR 14 400 kW at 92 rpm FP-propeller, Æ 7 600 mm or

• § 7 cyl CMCR 14 150 kW at 83 rpm FP-propeller, Æ 7 900 mm

DECK’S EQUIPMENT

• One Free-fall motor lifesaving boat for 40 persons• Four inflatable rafts for each 20 persons• One inflatable raft for 6 persons• One Rescue boat

SHIP EQUIPMENT

• One balanced semi spade rudder• One el.-hydraulic steering gear

DECK’S MACHINERY

• Two separate combined windlass/mooring winches, main deck fwd.

• Two mooring winches, main deck, fwd area• Two mooring winches, main deck forward of

accommodation block• Three mooring winches, main deck aft.

AUXILIARY ENGINE PLANT• Three auxiliary diesel generator sets• Wärtsilä 875W6L20, 875 kWe, 900 rpm• One emergency / harbour generator set

E-PLANTPower .....................................3 AC, 440 V, 60 Hz

ACCOMMODATION• 32 persons fully air-conditioned

CLASSIFICATION• DNV Tanker for Oil, ESP, CSR

PLUS, NAUTICUS (Newbuilding), BIS, TMON, E0, NAUT-AW, COAT-1, SPM, OPP-F, CCO, VCS-2, CLEAN

EMISSIONS• Compliance CO2 – EEDI value 3.59 (7 cyl engine)

(Below Phase 1, Jan 2015–Dec 2019)• Compliance NOX – IMO Tier III (SCR)• Compliance SOX – 0.1% sulphur limit (Scrubber)

(IMO / USA / Europe – SOX legislation) or low sulphur fuel/distillates

SP

-EN

-DB

AC

2156

10 /

08.

2012

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