slide 1 intertanko,athens 13th april propulsion alternatives, lng by wilhelm magelssen associate...
TRANSCRIPT
Slide 1
INTERTANKO,ATHENS 13th April
PROPULSION ALTERNATIVES, LNG
By
Wilhelm Magelssen
Associate Members Committee
Slide 2
Propulsion power for LNG carriers
20,000
30,000
40,000
125,000 150,000 175,000 200,000Size (m3)
Engine Power (kW)
21 knots
20 knots
19 knots
Source: MAN B&W
Slide 3
Thermal efficiencies
35
30
40
25
50
45
M edium speeddiesel engine
20
Capacity (M W )501 10
55
Therm al efficiencies %
Gas turbine
Com bined cyclegas turbine
Steam turbine
Low speed diese l engine
5
LNG carrier
Source: MAN B&W
Slide 4
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)
Slide 5
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
Slide 6
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
Slide 7
Steam Turbine Propulsion - Simplified
Furnace
Condensate pumps
Main Condenser
Red gear
H.P
L.PShaftFeed
pumps
Deareator
Super-heater
Economiser Flue gas uptake
Downcomers
Boiler casing
Water wall
Slide 8
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
Slide 9
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
Slide 10
ESD Rule conditions (Emergency Shut Down)
• Conditions for acceptance of ESD protected machinery space:– Gas supply pressure to be < 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
Slide 11
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
Slide 12
Dual Mode Gas/Diesel Engines
Slide 13
ESD protected engine rooms
Slide 14
Diesel engines + Re-liquefaction
BOG FEED
VENT
TO TANK S
2 3
1 E
COOLINGWATER
-200
-100
0
+100
-200
-100
0
+100
-200
-100
0
+100
-200
-100
0
+100
MAX
MIN
-200
-100
0
+100
MAX
MIN
-200
-100
0
+100
-200
-100
0
+100
-200
-100
0
+100
-200
-100
0
+100
RE
SE
RV
OIR
BY -PASS
SUCTION THROTTLE
NIT
RO
GE
N
RECYCLING
Slide 15
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
Slide 16
LNG carrier with oxidizer
Slide 17
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
Slide 18
Gas Turbines
• Rolls Royce MT30
– 36 MW flat rated @26C– 42% thermal efficiency– 201 g/kWhr on gas– Dual fuel capable
Slide 19
CargoTank
Steam Turbine Propulsion – Engine Room Arr’t
Slide 20
CargoTank
Gas Engines/Electric Propulsion – Engine Room Arr’t
+~
~
Reduced length
Slide 21
General Arrangement – Gas Turbines
Slide 22
Gas emissions from LNG carriers
Fuel NOx SOx CO2
Steam turbineHFO + LNG
200 2.400 180.000
Low speed diesel
+ re-liquefactionHFO 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
Slide 23
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
Slide 24
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
Slide 25
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
Slide 26
Offshore re-gasification and discharge
Slide 27
Experienced personnel, - a serious challenge !
.. insufficient supply of competent people may have a knock-on effect on other shipping sectors ?
Slide 28
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?
Slide 29
End of Presentation
Thank you!