LNG as a marine fuel - possibilities and problem

The limitations of marine fuels use incorporated sulphur on levels 4-5% for HFO and 0.5-1% for MDO were caused a necessity of possessing on ship a few types of fuel: conventional and with limited amount of sulphur. It is a necessary to separate the installation of different fuels caused that the ship fuel system are complicated. It is needed to change the fuel with time advance on areas with SOx controlled emissions (SECA areas) for example Baltic and North Sea. In the same time it is needed to change the engine adjustment in the aim of decreasing NOx emission. It allows for fulfilling the emission on tier 2 level (IMO regulations). It was announced for January 1st 2016 the time of tier 3 requirement of being in force. It is seemed to be impossible the fulfilling of that standard on marine liquid fuels (HFO and MDO). It was interested on gas fuels, especially on popular one the liquid natural gas (LNG). In the liquid state LNG is seemed to be an attractive marine fuel. It is remaining a problem of marine engines adaptation for burning that type of fuel in the aim of fulfilling the tier3 standard. At present, available dual fuel for marine diesel engines burn natural gas for ship operating reasons. Fulfilment these requirements needs an engine modernization or the alternative way is use of piston spark engines. There is an additional problem the assurance of repeatability of natural gas combustion process. During the change of engine load changes the fuel-air mixture composition, it is heterogeneous in the cylinder volume caused the ignition loss, the knocking combustion and the risk of out-of-control fuel self-ignition. The paper presents a probe of analysis these problems.