Download - DetNorskeVeritas
8/4/2019 DetNorskeVeritas
http://slidepdf.com/reader/full/detnorskeveritas 1/29
Slide 1
INTERTANKO,ATHENS 13th April
PROPULSION ALTERNATIVES, LNG
By
Wilhelm Magelssen
Associate Members Committee
8/4/2019 DetNorskeVeritas
http://slidepdf.com/reader/full/detnorskeveritas 2/29
Slide 2
Propulsion power for LNG carriers
20,000
30,000
40,000
125,000 150,000 175,000 200,000
Size (m3)
Engine Power (kW)
21 knots
20 knots
19 knots
Source: MAN B&W
8/4/2019 DetNorskeVeritas
http://slidepdf.com/reader/full/detnorskeveritas 3/29
Slide 3
Thermal efficiencies
35
30
40
25
50
45
Medium speeddiesel engine
20
Capacity (MW)501 10
55
Thermal efficiencies %
Gas turbine
Combined cyclegas turbine
Steam turbine
Low speed diesel engine
5
LNG carrier
Source: MAN B&W
8/4/2019 DetNorskeVeritas
http://slidepdf.com/reader/full/detnorskeveritas 4/29
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)
8/4/2019 DetNorskeVeritas
http://slidepdf.com/reader/full/detnorskeveritas 5/29
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 auxiliariesDiesel engine propulsion:
• One re-liquefaction unit + one oxidizer
Gas turbine propulsion:• One oxidizer with redundant auxiliaries
8/4/2019 DetNorskeVeritas
http://slidepdf.com/reader/full/detnorskeveritas 6/29
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
8/4/2019 DetNorskeVeritas
http://slidepdf.com/reader/full/detnorskeveritas 7/29
Slide 7
Steam Turbine Propulsion - Simplified
Furnace
Condensate
pumps
MainCondenser
Red gear
H.P
L.PShaft
Feedpumps
Deareator
Super-heater
EconomiserFlue gas uptake
Downcomers
Boiler casing
Water wall
8/4/2019 DetNorskeVeritas
http://slidepdf.com/reader/full/detnorskeveritas 8/29
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 IGCCode 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 lowpressure gas engines only
8/4/2019 DetNorskeVeritas
http://slidepdf.com/reader/full/detnorskeveritas 9/29
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
8/4/2019 DetNorskeVeritas
http://slidepdf.com/reader/full/detnorskeveritas 10/29
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 ondetecting 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
8/4/2019 DetNorskeVeritas
http://slidepdf.com/reader/full/detnorskeveritas 11/29
Slide 11
ESD protected engine rooms
• Because of the shut-down requirement for an
ESD Protected engine room, the power
generation for propulsion and manoeuvring
must be divided between two or more enginerooms independent of each other
8/4/2019 DetNorskeVeritas
http://slidepdf.com/reader/full/detnorskeveritas 12/29
Slide 12
Dual Mode Gas/Diesel Engines
8/4/2019 DetNorskeVeritas
http://slidepdf.com/reader/full/detnorskeveritas 13/29
Slide 13
ESD protected engine rooms
8/4/2019 DetNorskeVeritas
http://slidepdf.com/reader/full/detnorskeveritas 14/29
Slide 14
Diesel engines + Re-liquefaction
BOG FEED
VENT
TO TANKS
2 3
1 E
COOLING
WATER
-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
R E S E R V O I R
BY-PASS
SUCTION THROTTLE
N I T R
O G E N
RECYCLING
8/4/2019 DetNorskeVeritas
http://slidepdf.com/reader/full/detnorskeveritas 15/29
Slide 15
Re-liquefaction plant for LNG boil-off
• At present there is experiences only from oneshipboard LNG re-liquefaction plant (NYK)
• Power consumption is high (3,5-5,0 MW)
• For LNG cargo tanks with permitted filling ratioof 99.5% (spherical) overfill protection
arrangements should be considered
8/4/2019 DetNorskeVeritas
http://slidepdf.com/reader/full/detnorskeveritas 16/29
Slide 16
LNG carrier with oxidizer
8/4/2019 DetNorskeVeritas
http://slidepdf.com/reader/full/detnorskeveritas 17/29
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
8/4/2019 DetNorskeVeritas
http://slidepdf.com/reader/full/detnorskeveritas 18/29
Slide 18
Gas Turbines
• Rolls Royce MT30
– 36 MW flat rated @26C
– 42% thermal efficiency
– 201 g/kWhr on gas
– Dual fuel capable
8/4/2019 DetNorskeVeritas
http://slidepdf.com/reader/full/detnorskeveritas 19/29
Slide 19
Cargo
Tank
Steam Turbine Propulsion – Engine Room Arr’t
8/4/2019 DetNorskeVeritas
http://slidepdf.com/reader/full/detnorskeveritas 20/29
Slide 20
Cargo
Tank
Gas Engines/Electric Propulsion – Engine Room Arr’t
+
~
~
Reduced length
8/4/2019 DetNorskeVeritas
http://slidepdf.com/reader/full/detnorskeveritas 21/29
Slide 21
General Arrangement – Gas Turbines
8/4/2019 DetNorskeVeritas
http://slidepdf.com/reader/full/detnorskeveritas 22/29
Slide 22
Gas emissions from LNG carriers
Fuel NOx SOx CO2
Steam turbineHFO +
LNG200 2.400 180.000
Low speeddiesel
+ re-liquefaction
HFO 3.950 1.800 120.000
Dual fuel
electricLNG only 240 0 100.000
Gas turbines and
COGESLNG only 850 0 108.000
Source: ALSTOM Emissions: Tonnes / year / ship
8/4/2019 DetNorskeVeritas
http://slidepdf.com/reader/full/detnorskeveritas 23/29
Slide 23
Economics of LNG Re-liquefaction and
Slow Speed Diesel Propulsion
• Low Fuel Consumption for Propulsion, but powerrequired 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, inthe order of 3-5 MW at max. load
E i f D l F l G /Di l E i /G
8/4/2019 DetNorskeVeritas
http://slidepdf.com/reader/full/detnorskeveritas 24/29
Slide 24
Economics of Dual Fuel Gas/Diesel Engines/Gas
Turbines and Electric propulsion
•Electric Propulsion Plants Require Higher InitialCosts
• 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 PlantsIncrease With Higher Fuel Oil Price
8/4/2019 DetNorskeVeritas
http://slidepdf.com/reader/full/detnorskeveritas 25/29
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 toaccommodate 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
8/4/2019 DetNorskeVeritas
http://slidepdf.com/reader/full/detnorskeveritas 26/29
Slide 26
Offshore re-gasification and discharge
8/4/2019 DetNorskeVeritas
http://slidepdf.com/reader/full/detnorskeveritas 27/29
Slide 27
Experienced personnel, - a serious challenge !
.. insufficient supply of
competent people may
have a knock-on effect onother shipping sectors ?
8/4/2019 DetNorskeVeritas
http://slidepdf.com/reader/full/detnorskeveritas 28/29
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?