Feature 3 | ENGINE TECHNOLOGY


Figure 7: Layout of a high-pressure SCR system, as supplied by Hitachi Zosen


degree of flexibility for the operator, accommodating the economic advantages of choice of fuel type, environmental benefits of gas fuel operation and accessibility of fuel oil. The ME-GI engine has similar, if not


improved, performance in gas operation compared to fuel-oil operation. The fundamental design of the engine is unchanged when compared to ME engines, meaning that the application potential for the ME-GI engine applies to the entire ME engine programme. Furthermore, as the GI concept is


already class approved, all MAN B&W ME-engines can be considered “gas ready”, as the GI is simply an add-on to the existing engine. In order to convert an ME engine to an ME-GI engine, both the mechanical and electrical components for gas operation need to be installed and the soſtware enabled. Te conversion of the engine itself can be performed by MAN Diesel & Turbo’s PrimeServ organisation during a docking period.


The implementation of MARPOL


Annex VI (14.8) from 1 January 2015 for operation on fuels containing less than 0.1% sulphur in ECAs has forced many owners and operators to make their own investigations into economic feasibility of alternative fuels to HFO. Natural gas is of particular interest,


which has been reduced somewhat in cost due to increased global production and has become increasingly available in the form of LNG, mainly due to political and financial initiatives for increased funding of the construction of LNG bunker stations within ECAs. However, the investment required


for bunkering of LNG onboard and consequent use for propulsion can be prohibitively expensive, and as the volatile fuel prices dictate, any business case can be broken down. Terefore, a compromise is emerging in the marine industry whereby a vessel can be considered “gas ready” without requiring full investment in LNG bunkering or gas operation. This allows the owner or operator the


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opportunity to upgrade the vessel to operate on gas by implementing all the relevant requirements for gas operation at the design stage.


Applications – ship types With the exception of LNG tankers, the fundamental reasons for selecting gas operation are essentially the same whether the vessel is gas-ready or a fully prepared gas vessel. Te key factor for differentiating between the two lies in the availability of the LNG bunker. If the LNG bunker station on the vessel’s route is expected to come on-stream just five years aſter the vessel enters service, it is likely to be more economically feasible to have the vessel “gas ready” rather than have the investment cost installed onboard and lying idle in the meantime.


The ME-GI engine MAN Diesel & Turbo’s ME-GI engine is capable of operating on conventional fuel oil or gas fuel, depending on the operator’s fuel preference. Tis provides an unprecedented


Ship design The majority of the aspects required for a “gas-ready” vessel are related to all the auxiliary equipment required for gas operation. This starts at the LNG bunker station and follows the whole process to the gas inlet on the main engine. Furthermore, at the 95th MSC (Maritime Safety Committee), IMO has formally adopted the international code of safety for ships using gases or other low flashpoint fuels (IGF code). A careful study of these requirements is necessary.


Classification societies Depending on the class of the vessel, the specific rules must be examined. Tere is typically a conceptual design approval, and then a detailed design approval where the vessel is granted a state of gas readiness of equivalent status denoting compliance of design and construction with their own design guidelines for gas fuelled vessels. Additionally, there are various notations, which indicate that there may already be gas equipment approved and installed on the vessel prior to entering service.


The Naval Architect March 2016


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