economic design concept for small lng carriers rev 3

Economic Design Concept for S G CSmall LNG Carriers

Klaus Dieter GerdsmeyerTGE Gas EngineeringTGE Gas Engineering

Trends in LNG shippingLarger LNG carriers for “classical” LNGLarger LNG carriers for classical LNG transportation market (up to 270,000 m³)

S ll LNG i f LNG t t tiSmaller LNG carriers for new LNG transportation market

Clean f el po er plants for remote ind strial areas orClean fuel power plants for remote industrial areas or islandsRegions without pipeline grid (e g Norwegian coast)Regions without pipeline grid (e. g. Norwegian coast)Short sailing times in relation to LNG consumptionDesign requirement for partial fillingDesign requirement for partial filling

Gastech 2006 2

Trends in LNG shipping

Smaller LNG carriersA Japanese yard is building a 19 000 m³ vessel with 3A Japanese yard is building a 19,000 m vessel with 3 spherical tanks (delivery: 2007).

An Australian company is developing projects of up toAn Australian company is developing projects of up to 30,000 m³ transport capacity.

Standard designs for LNG ships (spherical aluminiumStandard designs for LNG ships (spherical aluminium tanks or membrane tanks) are expensive economics for such niche markets have to be improved.

Gastech 2006 3

Trends in LNG shipping

Very Small LNG carriers (for coastal trade)First very small ship (1,000 m³) for Norwegian coastFirst very small ship (1,000 m ) for Norwegian coast delivered in 2004 (stainless steel tanks, electric propulsion)Two LNG ships of 2,500 m³ delivered in 2003/5 for Japanese coast (cylindrical aluminium tanks)Anthony Veder (NL) is building a 7,500 m³ LNG/Ethylene carrier for coastal transport in Norway (vessel design and gas plant supplied by TGE)

Gastech 2006 4

TGE’s design approach to small LNG carriersObjective: minimize the CAPEXObjective: minimize the CAPEX

Utilize the know-how from design of Ethylene carriersEth l hi TGE‘ k t h f d li fEthylene ships: TGE‘s market share for delivery of gas handling systems and cargo tanks is more than 80%Actual order book: 32 ethylene carriersActual order book: 32 ethylene carriers

Maximize operation flexibility for a combined LNG/Eth l /LPG iLNG/Ethylene/LPG-carrier

Main questions:Cargo tank designBoil-off gas handling / propulsion system

Gastech 2006 5

Types of cargo tanks for gas carriers

(Internal insulation tanks)

(Integral tanks)( g )

(Semi-membrane tanks: very few applications)

M b t kMembrane tanksIndependent tanks

(Type A)Type BType BType C

Gastech 2006 6

TGE’s design approach: independent Type C tanksself supporting pressureself-supporting pressure vesselcylindrical or bilobe with youtside insulationno secondary barrier

i drequiredno restriction concerning partial fillingpartial filling

Gastech 2006 7

Cargo tanks for 22,000 m³ Ethylene-carrier5 700 m³ (4 tanks)5,700 m (4 tanks)4.7 bar g480 t480 t5% Nickel steel

Gastech 2006 8

Type C tanks for LNG

Ship capacity below 15,000 m³Cylindrical tank designCylindrical tank designo 2 tank design up to abt. 10,000 m³

3 tank design up to abt 15 000 m³o 3 tank design up to abt. 15,000 m³

Ship capacity above 15,000 m³Bilobe tank designo 3 tank design up to 25,000 m³

o 4 tank design up to 35,000 m³ (or even 40,000 m³)

Gastech 2006 9


Tank design temperature: -163°C

Tank material:Tank material:(Aluminium)

(9% Ni-steel)

SS AISI 304L

Gastech 2006 10


Ship design example: 30,000 m³ capacity:

4 Bilobe tanks each abt 7 500 m³ capacity4 Bilobe tanks each abt. 7,500 m capacity

Min. design pressure @ density 500 kg/m³:AISI 304L 2 74 bo AISI 304L: 2.74 bar g

Tank weights:o AISI 304L: abt. 530 tons

Gastech 2006 11

30,000 m³ LNG-Carrier

lbp = 175.2 mb = 27.6 md = 8.8 mspeed = 17.5 kn

Gastech 2006 12


Design constraints for LNG compared to Ethylene:

Higher material shrinkage due to:Higher material shrinkage due to:o Larger delta T during cooling down

Higher material shrinkage factor for AISI 304Lo Higher material shrinkage factor for AISI 304L

Problem especially for bi-lobe tanks:for 15 m diameter tanks the shrinkage is 35 mm (304L)for 15 m diameter tanks the shrinkage is 35 mm (304L)

Detailed design review and complete re-design of supports necessary (displacement and stress analysissupports necessary (displacement and stress analysis, temperature profiles)!

Gastech 2006 13


D i i l b l ifi ti i tDesign appraisal by a classification societyFEM analysis of tank shell, supports and shipside steel structure for different loading casessteel structure for different loading cases

Gastech 2006 14

Tank insulation for LNGTank insulation for Ethylene:Tank insulation for Ethylene:

Typical Polystyrene panels glued to tank surface with abt 230 mm thicknessabt. 230 mm thickness

Tank insulation for LNG applicationSame insulation type may be applied (spherical LNG tanks use same technology)I l ti thi k f 300 (b il ff t bt 0 35Insulation thickness of 300 mm (boil-off rate abt. 0.35 –0.45 %/day)Design details modified (shrinkage stress)Design details modified (shrinkage, stress)

Gastech 2006 15

Type C tanks for LNG – new design

Concept approval certificate already issued by Class

Patent pendingPatent pending

30 … 35,000 m³ designs have been discussed for a ifi j t ith th hi d th b i fspecific project with three shipyards on the basis of

confidentiality agreements concerning design details

Gastech 2006 16

Boil-off gas handling / propulsion system

Alternatives for boil-off gas handling considering typically short voyages and small BOG quantities:yp y y g q

a) Burn the BOG in a thermal oxidiser (combustor)) ( )

b) Accept a pressure increase during voyage, provided that receiving terminal can accept itg p

c) Utilize BOG for propulsion (electric power production)

d) Reliquefactiond) Reliquefaction

Gastech 2006 17

Boil-off gas handlingg gb) Pressure increase

3,5

4

9% Ni

2,5

3

bar g

]

SS 304L

1,5

2

Pre

ssur

e [b

Basic LNG Composition N2:2%CO2:0%

0,5

1

C1:89%C2:5,5%C3:2,5%C4:1%

Tank Volume: 30.000 m³Insulation: 300 mm

PolystyreneInitial pressure: 140 mbar g

00 10 20 30 40 50 60

Sailing Time [days]

Gastech 2006 18

Boil-off gas handlingg gc) Utilize BOG for propulsion

Owner: Anthony Veder, NL (design and gas plant supplied by TGE)Project: Coastal transport in Norway

LNG to be used as fuelHFO to be used as fuel for transportation of other cargoes

Gastech 2006 19

Boil-off gas handlingg gc) Utilize BOG for propulsion

GASHFO

GASHFO

7,500 m³ LNG/LEG/LPG carrier for Anthony VederElectric propulsion (Gas, HFO):

HFO generator sets: 2 x 3,685 kW

Gas generator sets: 2 x 2 280 kWGas generator sets: 2 x 2,280 kW

thrusters for optimum manoeuvrability

Gastech 2006 20

Boil-off gas handlingg gd) Reliquefaction

Electric propulsion (utilize LNG and HFO as fuel)Electric propulsion (utilize LNG and HFO as fuel) high CAPEX

Conventional slow speed diesel-mechanic (HFO) BOG reliquefaction needed (CAPEX !), if pressure increase is not an optionincrease is not an option

Alternative concepts based on mature technology:pure LNG carriers: nitrogen system (Brayton cycle) combined LNG/LEG carrier: utilize cascade technology from Ethylene ships (under development)

Gastech 2006 21

Combined LNG/Ethylene/LPG Carrier

Ch i d f LNG t Eth l LPGChanging grade from LNG to Ethylene or LPG requires tank warming up

Changing grade is time consuming (especially from LNG to LPG)

Cargo contamination may be an issue (for some cargoes visual inspection may be required)g y )

Frequent grade changes are not economic

Gastech 2006 22

Combined LNG/Ethylene/LPG CarrierS ll LNG hi ith t C t k il bSmall LNG ships with type C cargo tanks can easily be “upgraded” to combined gas carriers (installation of BOG reliquefaction for Ethylene)BOG reliquefaction for Ethylene)

LNG transportation in smaller quantities is not a mature marketmarket

Combined LNG/Ethylene/LPG carriers – like 7,500 m³ vessel meet the demands of a developing marketvessel – meet the demands of a developing market

increase operating flexibility

seasonal LNG transportation demands

up to 35,000 m³

Gastech 2006 23

Economics of small LNG carriers

CAPEX:Little changes for ship‘s hull construction (steelLittle changes for ship s hull construction (steel grade of tank supports)

Tanks and cargo handling system moreTanks and cargo handling system more expensive than for Ethylene carriers

TGE estimation shows an overall CAPEX abtTGE estimation shows an overall CAPEX abt. 10 – 15 % above the corresponding Ethylene-carrier price, depending BOG handling concept

Gastech 2006 24

ConclusionTarget market: small gas consumers without access to aTarget market: small gas consumers without access to a pipeline gridTGE’s design approach with type C tanks is based in vast g pp ypexperience with Ethylene carriersThe combined 7,500 m³ LNG/Ethylene/LPG carrier d t t th t TGE’ h t th i t fdemonstrates that TGE’s approach meets the requirements of this developing marketSmall LNG carriers can be economical with type C cargo tanksSmall LNG carriers can be economical with type C cargo tanks up to 35,000 m³ capacityTGE has received a „Concept Approval“ of a modified tankTGE has received a „Concept Approval of a modified tank design with a classification societyA patent is pending for the new tank design

Gastech 2006 25

Thank you for your attention!

For any questions please contact TGE:email: sales@tge-marine comemail: sales@tge marine.comphone: +49-228-60448-160

economic design concept for small lng carriers rev 3

Documents