Approval in Principal (AiP) from DNV on LNG fuel tank design
Offshore oil and gas engineering specialist NLI Solutions (NLI) has developed a concept for a LNG Bunker Barge based on the NLI LNG tank design. The concept has been further developed in a design study together with the Marine division of Rolls-Royce and Wilhelmsen Technical Solutions (WTS).
Interest in LNG as a marine fuel is rapidly increasing, but one limiting factor is practical availability of LNG bunker facilities. LNG Bunker Barges are often described as the ’missing link‘ in the LNG supply chain. Today, only one example exists, capable of carrying 187 m3 of LNG, even though ocean-going ships need to bunker several thousand cbm.
Onboard power and propulsion for the HighTechBarge (HTB) are fed by an environmentally-friendly gas engine. The HTB has a large pressure tank on the aft deck for boil off gas handling and gas delivery to engine.
The NLI LNG tank is designed to IMO-B standards and is a prismatic, atmospheric and self-supporting LNG steel tank with state of the art cryogenic insulation. It has a capacity of 4000 m3 of LNG and will be fitted with a new insulation system with very low levels of boil off gas.
Since re-condensation equipment is expensive, takes a lot of space, and has very low efficiency for small installations like this, excess boil of gas can be delivered to a shoreside gas grid when the barge is not on bunkering operations. The barge can also deliver electric power to a shoreside electric grid.
Planning for the study has been carried out between:
- NVC – responsible for design, Bergen gas engine, pod drives and bridge systems;
- TI Marine Contracting (part of WTS) – responsible for insulation systems;
- NLI – responsible for tank, LNG/gas systems, bunkering systems.
- DNV (Norwegian class society Det Norske Veritas)– evaluation of the barge concept with respect to limitations and possibilities within the existing codes and regulations
LNG Tank Design AiP
WTS and NLI have received Approval in Principal (AiP) from DNV on their jointly-developed LNG fuel tank design. The two companies have worked on the development of a LNG fuel tank design since 2009 in response to growing interest from shipowners to the use of LNG as a marine fuel. The tank
The first stage of the LNG Fuel Tank development project was co-financed by the Norwegian Research Council’s MAROFF program, and Wilhelmsen Marine Consultants, Liquiline, DNV and Marintek participated as partners in the development.
The NLI LNG tank is designed for applications including ship board LNG bunker tanks, tanks for LNG bunker vessels, small LNG carriers and small to medium sized tanks on land. This first AiP from DNV is valid for the system to be used as marine LNG fuel tanks.
The shift towards the use of LNG for marine propulsion is said to be as significant as the shift from coal to oil but with the additional environmental benefit of lower CO2 emissions. There will also be a significant financial benefit for ship owners as gas prices are expected to remain competitive over time compared with to diesel and distillate products.
(Source: Wilhelmsen Technical Solutions and NLI Solutions)