INTERTANKO,ATHENS 13th April

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INTERTANKO,ATHENS 13th April

• PROPULSION ALTERNATIVES, LNG
• By
• Wilhelm Magelssen
• Associate Members Committee

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Propulsion power for LNG carriers
Engine Power (kW)
21 knots
40,000
20 knots
19 knots
30,000
20,000
Size (m3)
125,000
150,000
175,000
200,000
Source MAN BW
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Thermal efficiencies
Source MAN BW
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Handling of boil-off gas

• Use as fuel in boilers
• Accumulation during voyage
• Use as fuel in gas engines
• Use as fuel in gas turbines
• Re-liquefaction
• Burn in oxidizer (incinerator)

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Means for disposal of boil-off gas

• Steam turbine propulsion
• Two boilers main and auxiliary condenser
• Gas engine propulsion
• One oxidizer with redundant auxiliaries
• Diesel engine propulsion
• One re-liquefaction unit one oxidizer
• Gas turbine propulsion
• One oxidizer with redundant auxiliaries

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Propulsion alternatives for LNG carriers

• Steam turbine/dual fuel steam boilers
• Dual fuel high pressure gas/diesel engine
• Dual mode low pressure gas/diesel engines
• Low pressure gas engines and diesel engines
• Gas turbine combined gas turbines/diesel
  engines
• Diesel engine/boil-off re-liquefaction

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Steam Turbine Propulsion - Simplified
Economiser
Flue gas uptake
Super-heater
Downcomers
Deareator
Furnace
Boiler casing
Water wall
Red gear
H.P
Shaft
Feed pumps
L.P
Main Condenser
Condensate pumps
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DNV Rules for gas fuelled engine installations

• The Rules define two concepts for safety against
  gas hazards in machinery spaces
• Inherently gas safe machinery space
• The two-barrier concept as known from the IGC
  Code with an additional requirement for fitting
  excess flow shut-off in the gas supply
• ESD protected machinery space
• Single wall gas piping accepted. Applicable for
  low pressure gas engines only

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Gas engines - piping

• Low pressure gas engines have gas supply piping
  which is difficult to arrange with complete
  jacketing
• There are no low pressure gas engines on the
  market at present having fully jacketed gas
  piping. However,Wärtsilä, is claiming that they
  are in the position in the near future

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ESD Rule conditions (Emergency Shut Down)

• Conditions for acceptance of ESD protected
  machinery space
• Gas supply pressure to be lt 10 bar
• Automatic de-energising of all sources of
  ignition on detecting of low concentration of gas
  and shut-off of gas supply to the engine room
• Automatic shut-off of gas supply on loss of
  engine room ventilation, detection of fire or
  excess gas flow

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ESD protected engine rooms

• Because of the shut-down requirement for anESD
  Protected engine room, the power generation for
  propulsion and manoeuvring must be divided
  between two or more engine rooms independent of
  each other

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Dual Mode Gas/Diesel Engines
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ESD protected engine rooms
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Diesel engines Re-liquefaction
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Re-liquefaction plant for LNG boil-off

• At present there is experiences only from one
  shipboard LNG re-liquefaction plant (NYK)
• Power consumption is high (3,5-5,0 MW)
• For LNG cargo tanks with permitted filling ratio
  of 99.5 (spherical) overfill protection
  arrangements should be considered

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LNG carrier with oxidizer
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Coastal LNG carrier Pioneer Knutsen

• delivered 2004, 1100 m3 cargo carrying
  capacity
• 2 x engines for gas fuel only 2 diesel
  engines , - diesel electric propulsion
• 2 pods for main propulsion
• redundant propulsion

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Gas Turbines

• Rolls Royce MT30
• 36 MW flat rated _at_26?C
• 42 thermal efficiency
• 201 g/kWhr on gas
• Dual fuel capable

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Steam Turbine Propulsion Engine Room Arrt
Cargo Tank
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Gas Engines/Electric Propulsion Engine Room
Arrt

Cargo Tank


Reduced length
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General Arrangement Gas Turbines
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Gas emissions from LNG carriers
Fuel NOx SOx CO2
Steam turbine HFO LNG 200 2.400 180.000
Low speed diesel re-liquefaction HFO 3.950 1.800 120.000
Dual fuel electric LNG only 240 0 100.000
Gas turbines and COGES LNG only 850 0 108.000
Source ALSTOM
Emissions Tonnes / year / ship
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Economics of LNG Re-liquefaction andSlow Speed
Diesel Propulsion

• Low Fuel Consumption for Propulsion, but power
  required by the re-liquefaction plant adds
  another 10 20 tons of heavy fuel oil
• Unknown Initial Cost for the Re-liquefaction
  Plant, but Assumed to be Significant
• High Power Requirements for Re-liquefaction, in
  the order of 3-5 MW at max. load

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Economics of Dual Fuel Gas/Diesel Engines/Gas
Turbines and Electric propulsion

• Electric Propulsion Plants Require Higher Initial
  Costs
• Gas/Diesel Engine Plants Have Lower Fuel
  Consumption - Thermal Efficiency 42-44 v.s.
  31-33 for Steam Propulsion
• Gas/Diesel Engines Have Higher Maintenance Costs
• Fuel Cost Savings for Gas/Diesel Plants Increase
  With Higher Fuel Oil Price

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LNG carrier propulsion - Conclusion

• The traditional steam turbine propulsion has
  served LNG carriers well for over 30 years
• Future operating modes will require flexibility
  and efficient propulsion plants able to
  accommodate different ship speeds
• Operating economy and environmental issues have
  to be considered carefully when selecting
  propulsion power plant
• Safety and redundancy are important features
  required from the propulsion power plant

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Offshore re-gasification and discharge
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Experienced personnel, - a serious challenge !
.. insufficient supply of competent people may
have a knock-on effect on other shipping sectors ?
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LNG Trade in cold Climate

• Cold climate Is this the future environment for
  LNG carriers? What kind of impact will this have
  on the Propulsion system?

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End of Presentation
Thank you!