LNGreen LNG carrier of tomorrow - Joint development project GREEN4SEA Forum George Dimopoulos, PhD DNV GL R&D and Advisory, Greece 1 SAFER, SMARTER, GREENER
Introduction LNG vessels: forefront of innovation, technology, safety and quality in the merchant shipping fleet. Complexity: high in LNG vessels & increasing Highly volatile market conditions: necessary for vessels to be designed to account for market uncertainty. Machinery, containment systems and hull form: key components of the design mix. Other shipping segments already had to adapt to changing market conditions. LNGreen s objective: develop tomorrow s LNG carrier using latest developed technology, within the bounds of existing shipbuilding methods. 2
LNGreen Partners rationale Aiming to be at the forefront of innovation by maximizing fleet efficiency and performance, ensuring operational flexibility to meet future trading patterns and operating profiles Looking to investigate the potential for energy consumption reduction of LNGCs by optimising hull form and machinery for actual operational conditions using CFD and in-house COSSMOS software Developing their membrane tank cargo containment systems, with increased insulation capabilities enabling reduced boil off Exploring possibilities for further improving their latest LNGC design 3
Philosophy Maximise hydrodynamic performance Utilise twin-skeg hull form Maximise cargo volume & minimise boil off Utilise GTT Mk III Flex system Increase overall machinery and system efficiency Base case for comparisons is a DFDE LNGC Whilst maintaining current max beam, draft & length (overall) 4
Design for trade 4 1 2 5 3 6 Operational data from GasLog provided the operating profile for LNGreen. Traditional design: optimise for a single design speed. Advanced design: optimise for the actual trade, with some generalisation included so as not to limit trading flexibility. 1 2 3 4 5 6 5
Optimized tank layout From 174 000m 3 to 182 800m 3 + 5% capacity Hybrid prismatic and 48 116 m3 48 291 m3 48 291 m3 38 182 m3 bi-oblique shape Trapezoidal in longitudinal direction Length increased 6
Hydrodynamic optimisation Overview Hull optimisation operational profile new tank shape sharper fore waterline Performance evaluation CFD simulations (HHI & DNV GL) Model and Full scale Hull pressure distribution Base design Optimised LNGreen Added resistance evaluation Environment conditions Installed power verification Added resistance due waves & wind 7
Hydrodynamic optimisation Aftbody and propeller The LNGreen overall efficiency improvements: 4-bladed propeller twisted rudder rudder bulb. HHI also considered a 3-bladed propeller: CFD simulation indicated noticeable improvement of propulsion efficiency No vibration analysis performed. Propeller grid in StarCCM+ The 3-bladed propeller could be an option for a future LNGreen LNGC. Aftbody arrangement with rudders, rudder bulbs and propellers 8
COSSMOS supports design-by-trade Compare alternative machinery configurations and energy recovery options to support improved decision making at the pre-contract / design phase A. Consider vessel characteristics Size / dimensions Operational profile Trading pattern B. Identify machinery configuration alternatives Engine / propulsion Energy recovery technologies C. Analyse integrated ship machinery system in COSSMOS Components and systems model Operational profile model Round-trip techno-economic simulations & ranking Investment & sensitivity analysis 9
LNG carrier integrated machinery system model in COSSMOS Mechanical propulsion BOG compression trains x2 Auxiliary engines AE Economisers x2 BOG management Electricity demand ME Economisers x2 Operational profile Reliquefaction 200+ component models included Main engines Auxiliary Boiler Shaft generators PTO x2 Propulsion demand Steam demand & management 10
Roundtrip comparison of alternative configurations and energy saving technologies 11
General arrangement Twisted rudders, with bulbs Twin skeg, with 4- bladed propellers 2 stroke gas main engines, with economisers Auxiliary DF engines with economisers No. 4 tank; hybrid prismatic and bioblique shape No. 3 & 2 tank; similar to conventional designs No. 1 tank; trapezoidal shape in longitudinal direction. Tank length is particularly increased. Short bulb bow (Option - PTO on main engines) 12
Summary Maximise hydrodynamic performance 2.5% hull resistance improvement Hull form optimised for reduction of added resistance in design waves and winds Twisted rudder, rudder bulb, positive indication of efficiency improvement with 3 bladed propeller Maximise cargo volume & minimise boil off 5% increase in cargo volume within the same overall dimensions (182 800 m3 vs 174 000 m3 ) Boil-off rate reduced to 0.085% per day, without change of insulation type (vs 0.09% day) New cargo tank shapes introduced by GTT Increase overall machinery and system efficiency 6.0% increase in efficiency compared to DFDE base case Validation of the 2 stroke option as the most efficient Consideration of mechanical energy saving devices (economisers, shaft generators) 13
Conclusions The key finding for LNGreen versus the base case is: overall energy consumption improvement = 8.5 % Managing uncertainty & flexibility needs of significant importance New LNG carrier design Trade and operational practice @ the core Improved energy efficiency & cargo capacity Can be built today Advanced methods that manage complexity in practice Robust decision making supported 14
LNGreen : innovation in practice Contact: George Dimopoulos George.Dimopoulos@dnvgl.com +30 2104100200 +30 6956200947 15