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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
Wärtsilä 2-stroke / D.Antonopoulos 3 © Wärtsilä
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
Wärtsilä 2-stroke / D.Antonopoulos 4 © Wärtsilä
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
Wärtsilä 2-stroke / D.Antonopoulos 5 © Wärtsilä
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
Wärtsilä 2-stroke / D.Antonopoulos 6 © Wärtsilä
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 2-stroke / D.Antonopoulos 7 © Wärtsilä
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
Wärtsilä 2-stroke / D.Antonopoulos 10 © Wärtsilä
Tanker vessel emissions compared to other vessel types
Source: EU, DG Environment, 2008
Wärtsilä 2-stroke / D.Antonopoulos 11 © Wärtsilä
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
Wärtsilä 2-stroke / D.Antonopoulos 12 © Wärtsilä
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)
DFC (MT/day) (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
Main engine EEDI (15.6 knots)
DFC (MT/day) (15.6 knots)
EEDI (15.0 knots)
DFC (MT/day) (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
Main engine EEDI (16.1 knots)
DFC (MT/day) (16.1 knots)
EEDI (15.5 knots)
DFC (MT/day) (15.5 knots)
7RT-flex84T-D 2.592 101.8 2.291 86.0
7X82 2.479 97.0 2.190 81.8
Wärtsilä 2-stroke / D.Antonopoulos 13 © Wärtsilä
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.
Wärtsilä 2-stroke / D.Antonopoulos 14 © Wärtsilä
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)
Wärtsilä 2-stroke / D.Antonopoulos 15 © Wärtsilä
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