Modern low speed diesel engines for modern efficient ... · Modern low speed diesel engines for modern efficient tanker vessels ... Historical development of engine parameters

Piraeus, 22nd May 2013, International Propeller Club Environmental, Energy, Efficient Management Operation in Shipping

Dionysios Antonopoulos

Wärtsilä Greece, Manager 2-Stroke Technical Services

1 © Wärtsilä

Modern low speed diesel engines for modern efficient tanker vessels – Impact on EEDI

Historical development:

 Gradually higher stroke/bore ratio

 Gradually increased propeller diameter

 Gradually lower rotational speeds (1980s RTA58 127rpm – 1990s RTA62 113rpm – 2000s RTA58T 105rpm)

Historical development of engine parameters

Wärtsilä 2-stroke / D.Antonopoulos 2 © Wärtsilä

Increasing vessel efficiency - Main engine


Main engine Propeller Engine + De-Rating

Aframax 6X62 ~ 7%

Suezmax 6X72 ~ 7%

VLCC 7X82 ~ 5%

Fuel prices Freight rates Environment

  High stroke to bore

  Low rpm (Larger propeller)

  Electronically controlled common rail (Tunings-flexible operation)

  De-rating potential

Modern new low speed engines adapted in modern vessel designs

Gain in daily fuel consumption versus vessels recently delivered with Wärtsilä electronic engines (same design speed and engine cylinder number)

Engine layout


Area of CMCR- selection in the 80ties

Lower specific fuel consumption (BSFC)

Higher propulsive efficiency … depending on prop. diameter

Area of CMCR- selection during 1990 - 2007

Note: Size - Shape of layout field is engine type dependent.

Area of CMCR- selection after 2008

Modern vessel design


Tanker vessel selected design speed expected to be lower compared to previous years. (VLCC 16.1→15.5knots – Suezmax 15.6→15.0knots Aframax 15.3→14.8knots) Lower design speed and increased propeller diameter results in decreased optimum propeller rpm.

Vessel fuel consumption = BSFC x required power Vessel designers must consider also engine BSFC at certain RPM!

Worst BSFC Better BSFC

Propeller diameter limitations


Ballast draught operation – VLCC case study Propeller diameter = 9.7 m Ballast operation

Forward draught = 8.5 m Aft draught = 10.5 m

Propeller diameter = 10.6 m Ballast operation

Forward draught = 8.5 m Aft draught = 11.5 m

Propulsion power penalty for ballast operation with the 10.6 m propeller is about 3.5% due to more trim and more draught

Propeller diameter mainly restricted:

  Vessel design draught

  Ballast draught restrictions

  Hull clearances

  Propeller strength limitations

All owners want minimum sailing in ballast condition


Wärtsilä common rail benefits for modern tankers

  Superior slow steaming operation. Steady and smokeless down to 10 to 12% of MCR- speed. Achieved with unique sequential injection nozzles.

Low load: 2 nozzle operation

Low load: 1 nozzle operation

  Different tuning possibilities for operational flexibility offering superior fuel consumption (for part load and low load operation).

  Thermally balanced cylinders.

  15 years experience in common rail technology (12 years sea service).

Increased total efficiency: Suezmax tanker with W-X72

8 © Wärtsilä Wärtsilä 2-stroke / D.Antonopoulos

* Main engine: 6RT-flex68-D

Particulars – Base design*   Vessel service speed = 15.0knots   CMCR power = 16,800kW at 85rpm   CSR load = 90%   Service power = 15,120kW   Propeller speed at service power = 82.1rpm   Assumed propeller diameter = 8.2m

Particulars – W5/6X72   Vessel service speed = 15.0knots   CMCR power = 16,600kW at 81pm   CSR load = 90%   Service power = 14,940kW   Propeller speed at service power = 78.2rpm   Assumed propeller diameter = 8.5m

Photo: Suezmax tanker

Increased total efficiency: Suezmax tanker with W-X72

Base design W5X72 W6X72 Vessel speed 15.0 knots 15.0 knots 15.0 knots

Service load 90% 90% 90%

CSR power 15,120 kW 14,940 kW 14,940 kW

CSR speed 82.1 rpm 78.2 rpm 78.2 rpm

BSFC at CSR 167.7 g/kWh 162.9 g/kWh 158.1 g/kWh

Daily fuel consumption1 (MDO) 60.85 t 58.41 t 56.68 t

Daily fuel consumption 100% 96.0% 93.2%

Daily fuel consumption1 (HFO) 64.20 t 61.56 t 59.74 t

HFO difference per day - 2.6 t - 4.5 t

Annual HFO cost difference2 - 423,000 US$ - 731,000 US$

9 © Wärtsilä Wärtsilä 2-stroke / D.Antonopoulos

1 LCV of MDO = 42,700kJ/kg / HFO = 40,500kJ/kg 2 HFO price = 650USD/ton, 250 days/year

Reduction in required propulsion power resulting in reduced fuel and cylinder lub oil consumption


Tanker vessel emissions compared to other vessel types

Source: EU, DG Environment, 2008


EEDI for tanker vessels

Source:Lloyd`s Register

A previous generation VLCC with electronic engine has an attained EEDI value of approximately 7% above Phase 1 A previous generation Suezmax with electronic engine has an attained EEDI value of approximately 8% above Phase 1 A previous generation Aframax with electronic engine has an attained EEDI value of approximately 4% below Phase 1


EEDI and fuel consumption–Aframax/Suezmax/VLCC tanker Aframax (112kdwt) – Main engine X62

Main engine EEDI (15.3 knots)

DFC (MT/day) (15.3 knots)

EEDI (14.8 knots)


6RT-flex58T-D 3.601 48.8 3.446 45.1

6X62 3.327 45.0 3.224 42.2

* Mentioned speed refers to design speed at 90% of engine load. Engine margin 10%. DFC - MDO LCV 42,700kJ/kg

Suezmax (155kdwt) – Main engine X72



EEDI (15.0 knots)


6RT-flex68-D 3.495 68.0 3.261 60.9

6X72 3.308 63.9 3.066 56.7

VLCC (300kdwt) – Main engine X82



EEDI (15.5 knots)


7RT-flex84T-D 2.592 101.8 2.291 86.0

7X82 2.479 97.0 2.190 81.8


EEDI and fuel consumption – Natural gas

LNG as fuel – about 20% less CO2 – about 20% reduced EEDI compared to conventional diesel propulsion

2-stroke gas dual fuel engine under development – 2014 pilot project planned. Based on vast experience from 4-stroke gas dual fuel engines. Exceeding 5,000,000 rhrs.


Reducing further fuel consumption/maintenance costs

SOx – Emissions Legislation Current / Future-IMO/EU/US

Solutions   Scrubbers   Distillates   Alternative fuel (Natural gas-DF engine)

NOx – Emissions Legislation Future-IMO Tier III

Solutions   SCR (Selective catalyst reactor)   Exhaust gas recirculation   Natural gas

Waste Heat Recovery

  5-6% power recovery (VLCC)

  4-5% power recovery (Suezmax)

FAST nozzle

  Reduction approx. 1g/kWh

Intelligent Combustion

Monitoring (ICC)

  Reduction up to 2.5g/kWh

Setpoint correction

Newbuilding tanker main engine

  High stroke to bore engine

  Low rpm (Larger propeller)

  Electronically controlled common rail

(Tunings-flexible operation)

  De-rating potential

Total Cost of Ownership (TCO)

  Extended TBOs   Optimized procurement and pricing   Maintenance methods

(flex components-remanufacturing)


Updated portfolio for modern tanker vessels

X35/40

X82

Suezmax Tanker

X72

Aframax Tanker

X62

VLCC Tanker

Small Tanker

Prroduct tanker

RT-flex50 RT-flex58T-D

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Modern low speed diesel engines for modern efficient ... · Modern low speed diesel engines for modern efficient tanker vessels ... Historical development of engine parameters