Download - CORE DESIGN ISSUES OF LARGE LNG CARRIER
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CORE DESIGN ISSUES OF
LARGE LNG CARRIER
Ho-Chung Kim, Duck-Yull LeeDaewoo Shipbuilding & Marine Engineering Co., Ltd.
Seoul, Koreawww.dsme.co.kr
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Contents
1. Introduction
2. Hydrodynamic Aspect
3. Strength Aspect
4. Propulsion Systems
5. Concluding Remarks
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1. Introduction
Capacity of LNG Carriers
� Late 1999s - up to 138,000 m3
� Since the year 2000 - rapid increase in
size up to 250,000 m3 based on
membrane type
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DSME Large LNG Carriers for New LNG Market
Size 210 K 230 K 250 K
303.0 325.0 333.0
50.0 51.0 55.0
12.0/ 13.6 12.0/ 13.6 12.0/ 13.6
210,000 230,000 250,000
No. of Cargo Tank five (5) five (5) five (5)
Service Speed (kts) 19.5 19.5 19.5
No. of propeller Twin Twin Twin
Propulsion System1) DF electric 2) 2-Stroke diesel3) GT electric
1) DF electric2) 2-Stroke diesel3) GT electric
1) DF electric2) 2-Stroke diesel3) GT electric
LBP (m)
B (m)
Td/ Ts (m)
Cargo Vol. (m3)
1. Introduction
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Investigated Core Design Issues for Large
LNG Carrier
� Optimum hull form development
- Twin/Single propulsion
� Strength assessment
- Sloshing
- ULS, Buckling
- Fatigue ---
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1. Introduction
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� Alternative propulsion systems
- Steam turbine propulsion, conventional
- Electric propulsion, dual fuel engines
- Slow speed diesel engines + reliquefaction
plant
- Electric propulsion, gas turbine
1. Introduction
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Characteristics & Design Requirements
� Ship/shore compatibility
� Cargo tank arrangement
� Hydrodynamic performances
2. Hydrodynamic Aspect
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2. Hydrodynamic Aspect
� Hull form generation
� CFD analysis
� Model tests
� Performance evaluation
� Next design spiral for improvement
Hull Form Optimization Technology
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2. Hydrodynamic Aspect
Forebody Hull Forms
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InitialDevelopedImproved
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2. Hydrodynamic Aspect
Bulbous Bow Shapes
F.P.
Load Waterline
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InitialDevelopedImproved
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Developed
Initial
ImprovedEstimated wave patterns
[Full load condition]
2. Hydrodynamic Aspect
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Estimated wave profiles
[Full load condition]
2. Hydrodynamic Aspect
Developed
Initial
Developed
Improved
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Developed
Improved
Observed Waves
2. Hydrodynamic Aspect
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2. Hydrodynamic Aspect
Aftbody Hull Forms
Single skeg Twin skeg
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Actual modelCFD
Virtual model
2. Hydrodynamic Aspect
Aftbody Optimization
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Single skeg Twin skeg
Aftbody Models for Comparative Tests
2. Hydrodynamic Aspect
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Model Test Results for Speed Performance [twin/single, Full load]
Speed power curves [design draft]
Approx. 9%
Single skeg
Twin skeg
Ship Speed in Knots
Required p
ower
20,000
16 17 18 19 20 21
40,000
19.5
knots
2. Hydrodynamic Aspect
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2. Hydrodynamic Aspect
Model Test Results for Manoeuvring Performance [twin/single, Full load]
-500 0 15001000
Y
1000
500
0
-500
-1000
500
X
Angle
30
0
-10
-20
10
20
-3035030025020015010050
Time
Angle
30
0
-10
-20
10
20
-30
35030025020015010050Time
40
50
-40
10/10 Zig-zag Manoeuvre
20/20 Zig-zag Manoeuvre
Turning Manoeuvre
Single skeg Twin skeg
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Yaw Checking Ability – 10/10 Zig-zag
IMO limit
Single screw ships tested at SSPA
Twin-skeg ships tested at SSPA
Single skeg
Twin skeg
Yaw checking ability - 10/10 Zig-zag
0
10
20
5 10 20 30 40
Lpp / V [sec]
1st
Overs
hoot angle [deg]
2. Hydrodynamic Aspect
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Yaw Checking Ability – 10/10 Zig-zag
5
10
20
30
40
5 10 20 30 40
Lpp / V [sec]
2nd
Overs
hoot angle [deg]
IMO limit
Single screw ships tested at SSPA
Twin-skeg ships tested at SSPA
Single skeg
Twin skeg
2. Hydrodynamic Aspect
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Yaw Checking Ability – 20/20 Zig-zag versus Tactical Diameter
IMO limit
Single screw ships tested at SSPA
Twin-skeg ships tested at SSPA
Single skeg
Twin skeg
2. Hydrodynamic Aspect
5
10
15
20
25
30
35
40
45
1 1.5 2 2.5 3 3.5 4 4.5 5 5.5
Tactical diameter / Lpp [-]
1st
overs
hoot [d
eg]
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Turning Ability
IMO limit
Single screw ships tested at SSPA
Twin-skeg ships tested at SSPA
Single skeg
Twin skeg
Turning ability
1
2
3
4
5
1 2 3 4 5
Tactical diameter / Ship length [-]
Advance
/ S
hip
length
[-]
2. Hydrodynamic Aspect
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Spiral Tests
IMO limit
Single screw ships tested at SSPA
Twin-skeg ships tested at SSPA
Single skeg
Twin skeg
Spiral Tests
0
2
4
6
8
10
12
14
0 10 20 30 40 50
Lpp/V [sec]
Loop w
idth
[deg]
2. Hydrodynamic Aspect
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Speed Losses on Rough Seas
2. Hydrodynamic Aspect
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Pressure Fluctuation Levels
2. Hydrodynamic Aspect
Comparison of Measured Pressure Pulse LevelsDSME conventional size LNG Carrier
0
1
2
3
4
5
1st 2nd 3rd 4th
Order of Blade Frequency
Pre
ssure
Pulse (kPa)
Twin skeg
Single skeg
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3. Strength Aspect
SloshingNumerical Analysis
0.71.60.61.5SLOFE2D
0.91.90.51.6Marintek PGM
1.152.2< 1.01.4LR Fluids
250 K
5 tanks
250 K
4 tanks
200K
5 tanks
200 K
4 tanks
0
0.5
1
1.5
2
2.5
200K–4 tanks 200K–5 tanks 250K–4 tanks 250K–5 tanks
Pres
sure
rat
io t
o 13
8K
K
Pres
sure
rat
io t
o 13
8K
K
Pres
sure
rat
io t
o 13
8K
K
Pres
sure
rat
io t
o 13
8K
K LR Fluids LR Fluids LR Fluids LR Fluids
Marintek PGMMarintek PGMMarintek PGMMarintek PGMSLOFE2DSLOFE2DSLOFE2DSLOFE2D
0
0.5
1
1.5
2
2.5
200K–4 tanks 200K–5 tanks 250K–4 tanks 250K–5 tanks
Pres
sure
rat
io t
o 13
8K
K
Pres
sure
rat
io t
o 13
8K
K
Pres
sure
rat
io t
o 13
8K
K
Pres
sure
rat
io t
o 13
8K
K LR Fluids LR Fluids LR Fluids LR Fluids
Marintek PGMMarintek PGMMarintek PGMMarintek PGMSLOFE2DSLOFE2DSLOFE2DSLOFE2D
Figures mean the pressure ratio to conventional 138 K LNGC.
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3. Strength Aspect
y = 0 .8477x - 9 .1203
0
1
2
3
4
5
6
7
8
11 13 15 17 19 21% o f tank length/ ship length
Pres
sure
(ba
r)
Correlation between tank length & sloshing pressure
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3. Strength Aspect
Sloshing Model Test
- Joint project with DSME, LR, MARINTEK
- Test for 200K LNGC with 4tanks
- 1 : 50 scale model
- Filling ratio = 10, 70, 80, 90, 95%
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3. Strength Aspect
- Full scale drop test with information obtained from sloshing model test
Setup for drop testSetup for drop test
Drop Test of Insulation Box
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3. Strength Aspect
Failure Mode by Drop Test
Averaged Peak Pressure at Failure mode
> Allowable pressure of 14bar
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3. Strength Aspect
Structural Analysis (SDA)
Whole Ship Global Model
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3. Strength Aspect
Fine Mesh Analysis
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3. Strength Aspect
FE Analysis by DLA (Dynamic Load Approach)
Wave Load Generation
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3. Strength Aspect
- LR FDA 2 & 3
- ABS/SFA
- Critical Structural Details
Hopper Knuckle Connections
Upper Chamfer Connections
Inn. BTM / Bulkheads
No.2 Stringer Connection
- More than 40 years
Fatigue Analysis
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4. Propulsion Systems
� Steam turbine propulsion
� Slow speed 2-stroke diesel engine
propulsion with reliquefaction plant
� DF engine electric propulsion
� Gas turbine electric propulsion
Disposal/Treatment of BOG
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4. Propulsion Systems
Steam turbine propulsionBOGHFO
MainBoiler
MainBoiler
Condenser
Reduction
Gear
FPP
HP
LP
SWBD
G
G D/E
G
G
S/T
S/T
S/T
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4. Propulsion Systems
2-stroke diesel engine
Aux.Boiler
SWBD
FPP M/E
FPP M/E
HFO
G D/E
G D/E
G D/E
G D/E
ReliquefactionPlant
BOG
Emergency GasDumping(Oxidizer)
LNG ( Return to cargo tank)
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4. Propulsion Systems
DF engine + electric propulsion LNG Forcing vaporizer
SWBD
Emergency GasDumping(Oxidizer)
MDO
G
DF
G
DF
G
DF
G
DF
BOG
FPP
M
M
FPP
G
DF
G
DF
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4. Propulsion Systems
Gas turbine + electric propulsion
SWBD
Steam
LNG Forcing vaporizer
Emergency GasDumping(Oxidizer)
MDO
G
GT
G
GT
G
ST
BOG
FPP
M
M
FPP
HRSG Exhaust Gas
HRSG Exhaust Gas
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4. Propulsion Systems
Comparison
H : Higher M : More
GoodGoodBadModerateEmissions
GoodBadBadGoodMaintenance
HigherHigherBase-Initial cost
MMMBaseBaseCargo volume
HHHHHHBaseEfficiency
Gas/DO/DualGas/DOHFOHFO/Gas/DualMain fuel
G/T electric
(200K)
DF electric
(200K)
Slow speed diesel (200K)
Steam
(150K)
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5. Concluding Remarks
1. DSME has been developing various LNG carriers with different sizes and different propulsion systems in order to meet increasing demands for large LNG carriers of new generation.
2. Numerical analysis and comprehensive model tests confirmed the reliability of the large LNG carrier with 5 tanks having a capacity of 200,000 m3.
3. Structural strengths were verified through the ULS, FLS and buckling criteria.
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4. Following hydrodynamic advantages of the twin skeg type hull form have been verified through a comparative study:
� Reduced propeller loads, increased efficiency, very much reduced pressure pulses level
� Lower power consumption than the corresponding conventional single skeg hull form
� Higher level of maneuverability
5. Concluding Remarks
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5. The propulsion system of the LNG carrier shall preferably be evolved into alternatives to get better efficiency and more cargo capacity.
[Alternative propulsion systems]
� Slow speed diesel engine propulsion system with reliquefaction plant
� Electric propulsion system with dual fuel engines
� Electric propulsion system with gas turbines
5. Concluding Remarks
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Thank you
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