Gastech 2017 Development of SPB LNG Fuel Tank for Ships Structure Engineering Group Gas Project Department Offshore and Engineering Division
Contents (1)Introduction (2)Concept Design of SPB LNG Fuel Tank (3)Development of the Simplified Vibration Calculation (4)Development of High Manganese Steel 2
(1)-1 Emission Control Requirement (1) Introduction 2011 2012 2013 2014 2015 2016 2017 2018 2019 2020 2021 NOx Tier II Tier III (only ECA) SOx Global Cap 4.5% 3.5% 0.5% ECA 1.0% 0.1% ECA Coast of USA/Canada (from August) Baltic Sea, North Sea Puerto Rico,US Virgin Islands (Caribbean Sea) CO2 EEDI Base 10% 20% 3 Source: Environmental Protection Agency (U.S.A.)
(1) Introduction (1)-2 Use of LNG as Fuel Advantage - Emission Reduction NOx: -80% SOx: -100% CO2: -25% - LNG Price Cheaper than Low Sulfur Fuel Oil Disadvantage - Increase Tank Space Double in Fuel Volume (= 1/2 density of heavy fuel oil) Reduction of cargo volume - Complexity of LNG fuel handling - Undeveloped Infrastructure Fuel Type SOx (g/kwh) NOx (g/kwh) CO2(g/kWh) Heavy Fuel Oil 3.5% S 13 9-12 580-630 LNG 0 2 430-480 4
(1) Introduction (1)-3 Feature of SPB LNG Fuel Tank SPB (Self-supporting, Prismatic-shape IMO type B) In case of LNG fuel tank.. Hull Tank Insulation Assumed Problem Tank Space LNG handling (pressure and temperature) Intermediate liquid level (sloshing problem) Damage (accidental, fatigue etc.) Solution Flexible tank shape & volume Support (Best space efficiency for any size & type of ships) Easy operation and less maintenance (Strong against outer / inner pressure) Any level loading without sloshing (Eliminate sloshing phenomenon by internal bulkhead) Robust & Reliable tank system (Proven by robust tank concept and experience) 5
(2) Concept Design of SPB LNG Fuel Tank (2)-1 Concept Design Study for Container Ship Ship s Principal Particular Length: Breadth: Depth: Container Loading Capacity Sea Route: Range: app. 330.0 ~ 400.0 m app. 45.0 ~ 65.0 m app. 25.0 ~ 35.0 m 10,000 ~ 20,000 TEU Far East to Europe app. 20,000 miles LNG Fuel Tank Capacity: 5,000 ~ 10,000 m 3 L x B x D: Arrangement: In front of Engine Room Engine Room LNG Fuel Tank Space app. 9.0~10.0m x 35.0~55.0m x 15.0~20.0m 6
(2) Concept Design of SPB LNG Fuel Tank (2)-2 Development of Cost-competitive Tank 14,000TEU container ship Rationalization (optimization) of tank structure - Reduction of tank weight - Increasing of machinability and construction workability Standardization of tank support construction - Improvement of design and construction efficiency (divided into three patterns by assumed reaction force) FE modelling tool - Efficiency and Speeding up of FE modelling Trans. Section of Tank 7
(2) Concept Design of SPB LNG Fuel Tank (2)-2 Development of Cost-competitive Tank 14,000TEU container ship Optimization Result of Longitudinal Girder Ring Thin Thickness Thick Condition for Optimization Before After Target Structure Long. Girder Ring Optimization Item Tank Material Tank Status Weight A5083-O Full 10% reduction LNG Density 0.5 ton/m 3 Vapor Pressure 0.07 MPa Loading Condition - Static Heel Case - Max. Trans. Acceleration Case - Collision Case 8
(2) Concept Design of SPB LNG Fuel Tank (2)-3 High Design Vapor Pressure Tank Approval in Principle (AIP) JMU received an AIP for the design procedure for increasing design vapor pressure SPB tank up to 0.4 MPa (4.0 barg) from American Bureau of Shipping in January 2017. 9
(3) Development of the Simplified Vibration Calculation (3)-1 Background Diesel Engine -Typical main engine for merchant ships -Larger exciting force of vibration than turbine engine Location -Close to engine room Severer environment of vibration Engine Room LNG Fuel Tank Space comparing to LNG carrier, FLNG, etc. 10
(3) Development of the Simplified Vibration Calculation (3)-2 Tank Vibration Assessment -Obtaining the Natural Frequency- Conventional way FEM: Time-consuming Simplified method Time can be saved. Accuracy shall be verified. f = 0.057 π2 l 2 EI ρa SPB fuel tank f =??? 11
(3) Development of the Simplified Vibration Calculation (3)-3 Tank Vibration Assessment for Container Ships Tank height is taller than that of other types of ship 12
(3) Development of the Simplified Vibration Calculation (3)-4 Rigid Body Model (Step 1) and Elastic Body Model (Step 2) FEM Simplified method + Rigid + Elastic vibration Step 1 Rigid body vibration Step 2 Elastic body vibration 13
(3) Development of the Simplified Vibration Calculation (3)-5 Coupling of Step 1 and Step 2 Actual Phenomenon- FEM Simplified method Rigid + Elastic vibration 1 f 2 1 2 f + 1 2 1 f 2 f: Natural frequency of the coupling mode f 1 : Natural frequency of Step 1 mode f 2 : Natural frequency of Step 2 mode 14
(3) Development of the Simplified Vibration Calculation (3)-6 Verification of the Accuracy The Ratio of Natural Frequency (Simplified method vs FEM) Filling level Longitudinal vibration Transverse vibration Full 1.06 1.18 Empty 1.05 1.14 Enough accuracy for initial planning stage. 15
(4) Development of High Manganese Steel To confirm Adequate Quality and Manufacturing Cost - Creation of New Material and Welding Material - Basic Test for Material Property - Confirmation of Workmanship (4)-1 Creation of New Material and Welding Material Effect of Higher Strength compared to other cryogenic materials Comparison with Aluminum Yield Stress: 3 times as that of Aluminum Plate Thickness : 60% of Aluminum (Stiffener size can be reduced similarly) 16
(4) Development of High Manganese Steel (4)-2 Basic Test for Material Property SPB Tank Design - Fatigue Strength Analysis - Crack Propagation Analysis - Leakage Quantities Estimation SN curve Data Fatigue Crack Growth Rate Curve Data (4)-3 Confirmation of workmanship - workability (cutting, bending etc.) - welding - corrosion resistance during construction 17
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