Economic Design of Small Scale LNG Tankers and Terminals. Björn Munko TGE Gas Engineering

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1 Economic Design of Small Scale LNG Tankers and Terminals Björn Munko TGE Gas Engineering

2 Trends in LNG shipping Larger LNG carriers for classical LNG transportation market (up to 270,000 m³) Smaller LNG carriers for new LNG transportation market Clean fuel power plants for remote industrial areas or islands Regions without pipeline grid (e. g. Norwegian coast) Short sailing times in relation to LNG consumption Design requirement for partial filling LNG Conference 2

3 Trends in LNG shipping Smaller LNG carriers A Japanese yard is building a 19,000 m³ vessel with 3 spherical tanks (delivery: 2007). An Australian company is developing projects of up to 30,000 m³ transport capacity. Standard designs for LNG ships (spherical aluminium tanks or membrane tanks) are expensive economics for such niche markets have to be improved. LNG Conference 3

4 Trends in LNG shipping Very Small LNG carriers (for coastal trade) First very small ship (1,000 m³) 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) LNG Conference 4

5 Design approach to small LNG terminals Market: Small consumption (islands, remote industrial area) Utilizing the know-how from design of large LNG terminals and of small ethylene terminals Tank concept depends on throughput and storage capacity above abt. 10,000 m³: flat bottom tank (like large terminals) o containment type depends on local rules and safety requirements up to abt. 10,000 m³: pressure vessel type tanks BOG handling, tank pressure depends on send-out conditions LNG re-gasification concept depends on capacities and local conditions LNG Conference 5

6 Example: 30,000 m³ flat bottom tank: built in Urumqi/China (single containment) LNG Conference 6

7 Containment types acc. BS7777 single containment type: inner tank for containing the product, outer container for retaining and protecting the insulation only roof inner roof insulated suspended deck loose filled insulation outer shell ( not able to contain liquid ) inner tank external insulation with weather barrier inner tank wall inner tank bottom Bund wall base insulation base insulation bund wall elevated concrete base concrete foundation with bottom heater LNG Conference 7

8 Containment types acc. BS7777 double containment type: inner tank for containing the product, outer container for retaining the insulation and in case of inner tank failure the product liquid ( but not the vapour ) roof inner roof rain cover rain cover insulated suspended deck prestressed concrete outer tank wall loose filled insulation outer shell ( not able to contain liquid ) inner tank external insulation with weather barrier inner tank wall outer tank shell ( able to contain the liquid ) inner tank bottom base insulation base insulation elevated concrete base concrete foundation with bottom heater LNG Conference 8

9 Containment types acc. BS7777 full containment type: inner tank for containing the product, outer container for retaining the insulation and in case of inner tank failure both the product liquid and the vapour roof inner roof outer roof loose filled insulation insulated suspended deck insulation at inside outer tank outer tank wall liner prestressed concrete outer tank inner tank base insulation wall insulation at inner side of outer tank ( or loose filled insulation ) inner tank wall base insulation inner tank bottom outer tank shell or prestressed concrete wall with liner elevated concrete base concrete foundation with bottom heater LNG Conference 9

10 Pressure vesesel type storage tanks: Example: 5 x 1,200 m³ ethylene storage (China) LNG Conference 10

11 Pressure vesesel type storage tanks: Ethylene storage built in China: Inner Diameter: 4.6 m Length TL TL: 75 m Volume: 5 x 1,200 cbm Material: 5% Nickel steel Insulation: foamglas Design pressure: 23 bar g LNG storage: Material: stainless steel (AISI 304) Insulation: foamglas or vacuum Design pressure: depending on send-out situation LNG Conference 11

12 LNG re-gasification equipment Preferred equipment depends on required capacities and local ambient condition (air, sea water): Open rack vaporizer (ORV) using sea water as heat source Submerged combustion vaporizer (SCV) using gas energy Ambient air vaporizer (AAV) using ambient air as heat source LNG Conference 12

13 Open Rack Vaporizer low operating cost: water pumping energy higher investment costs need of sea water intake min. temperature for seawater required LNG Conference 13

14 Submerged combustion vaporizer lower investment costs need of dedicated fuel gas installation high operating cost by gas consumption ( ~ 1.5% of gas send-out) LNG Conference 14

15 Ambient air vaporizer moderate investment costs need large installation areas dry ambient air preferred application currently under investigation (qualification program) for larger capacities LNG Conference 15

16 TGE s design approach to small LNG carriers Objective: minimize the CAPEX Utilize the know-how from design of Ethylene carriers Ethylene ships: TGE s market share for delivery of gas handling systems and cargo tanks is more than 80% Actual order book: 32 ethylene carriers Maximize operation flexibility for a combined LNG/Ethylene/LPG-carrier Main questions: Cargo tank design Boil-off gas handling / propulsion system LNG Conference 16

17 Types of cargo tanks for gas carriers (Internal insulation tanks) (Integral tanks) (Semi-membrane tanks: very few applications) Membrane tanks Independent tanks (Type A) Type B Type C LNG Conference 17

18 TGE s design approach: independent Type C tanks self-supporting pressure vessel cylindrical or bilobe with outside insulation no secondary barrier required no restriction concerning partial filling LNG Conference 18

19 Cargo tanks for 22,000 m³ Ethylene-carrier 5,700 m³ (4 tanks) 4.7 bar g 480 t 5% Nickel steel LNG Conference 19

20 Type C tanks for LNG Ship capacity below 15,000 m³ Cylindrical tank design o 2 tank design up to abt. 10,000 m³ o 3 tank design up to abt. 15,000 m³ Ship capacity above 15,000 m³ Bilobe tank design o 3 tank design up to 25,000 m³ o 4 tank design up to 35,000 m³ (or even 40,000 m³) LNG Conference 20

21 Type C tanks for LNG Tank design temperature: -163 C Tank material: (Aluminium) (9% Ni-steel) SS AISI 304L LNG Conference 21

22 Type C tanks for LNG Ship design example: 30,000 m³ capacity: 4 Bilobe tanks each abt. 7,500 m³ capacity Min. design density 500 kg/m³: o AISI 304L: 2.74 bar g Tank weights: o AISI 304L: abt. 530 tons LNG Conference 22

23 30,000 m³ LNG-Carrier lbp = m b = 27.6 m d = 8.8 m speed = 17.5 kn LNG Conference 23

24 Type C tanks for LNG Design constraints for LNG compared to Ethylene: Higher material shrinkage due to: o Larger delta T during cooling down o Higher material shrinkage factor for AISI 304L Problem especially for bi-lobe tanks: for 15 m diameter tanks the shrinkage is 35 mm (304L) Detailed design review and complete re-design of supports necessary (displacement and stress analysis, temperature profiles)! LNG Conference 24

25 Type C tanks for LNG Design appraisal by a classification society FEM analysis of tank shell, supports and shipside steel structure for different loading cases LNG Conference 25

26 Tank insulation for LNG Tank insulation for Ethylene: Typical Polystyrene panels glued to tank surface with abt. 230 mm thickness Tank insulation for LNG application Same insulation type may be applied (spherical LNG tanks use same technology) Insulation thickness of 300 mm (boil-off rate abt %/day) Design details modified (shrinkage, stress) LNG Conference 26

27 Type C tanks for LNG new design Concept approval certificate already issued by Class Patent pending 30 35,000 m³ designs have been discussed for a specific project with three shipyards on the basis of confidentiality agreements concerning design details LNG Conference 27

28 Boil-off gas handling / propulsion system Alternatives for boil-off gas handling considering typically short voyages and small BOG quantities: a) Burn the BOG in a thermal oxidiser (combustor) b) Accept a pressure increase during voyage, provided that receiving terminal can accept it c) Utilize BOG for propulsion (electric power production) d) Reliquefaction LNG Conference 28

29 Boil-off gas handling b) Pressure increase 4 3,5 9% Ni 3 SS 304L Pressure [bar g] 2,5 2 1,5 1 0,5 Basic LNG Composition N2:2% CO2:0% C1:89% C2:5,5% C3:2,5% C4:1% Tank Volume: m³ Insulation: 300 mm Polystyrene Initial pressure: 140 mbar g Sailing Time [days] LNG Conference 29

30 Boil-off gas handling c) 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 fuel HFO to be used as fuel for transportation of other cargoes LNG Conference 30

31 Boil-off gas handling c) Utilize BOG for propulsion HFO HFO GAS GAS 7,500 m³ LNG/LEG/LPG carrier for Anthony Veder Electric propulsion (Gas, HFO): HFO generator sets: 2 x 3,685 kw Gas generator sets: 2 x 2,280 kw thrusters for optimum manoeuvrability LNG Conference 31

32 Boil-off gas handling d) Reliquefaction 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 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) LNG Conference 32

33 Combined LNG/Ethylene/LPG Carrier Changing 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) Frequent grade changes are not economic LNG Conference 33

34 Combined LNG/Ethylene/LPG Carrier Small LNG ships with type C cargo tanks can easily be upgraded to combined gas carriers (installation of BOG reliquefaction for Ethylene) LNG transportation in smaller quantities is not a mature market Combined LNG/Ethylene/LPG carriers like 7,500 m³ vessel meet the demands of a developing market increase operating flexibility seasonal LNG transportation demands up to 35,000 m³ LNG Conference 34

35 Economics of small LNG carriers CAPEX: Little changes for ship s hull construction (steel grade of tank supports) Tanks and cargo handling system more expensive than for Ethylene carriers TGE estimation shows an overall CAPEX abt % above the corresponding Ethylenecarrier price, depending BOG handling concept LNG Conference 35

36 Conclusion Target market: small gas consumers without access to a pipeline grid TGE s design approach with type C tanks is based in vast experience with Ethylene carriers The combined 7,500 m³ LNG/Ethylene/LPG carrier demonstrates that TGE s approach meets the requirements of this developing market Small LNG carriers can be economical with type C cargo tanks up to 35,000 m³ capacity TGE has received a Concept Approval of a modified tank design with a classification society A patent is pending for the new tank design LNG Conference 36

37 Thank you for your attention! For any questions please contact TGE: phone: