This paper examines the problem of evaporation of Liquefied Natural Gas (LNG) occurring at different places in the LNG supply chain. Evaporation losses in the LNG supply chain are one of the key factors for LNG safety, technical and economic assessment. LNG is stored and transported in tanks as a cryogenic liquid, i.e. as a liquid at a temperature below its boiling point at near atmospheric pressure. Due to heat entering the cryogenic tank during storage and transportation, a part of the LNG in the tank continuously evaporates creating a gas called Boil-Off Gas (BOG), which changes the quality of LNG over time. The general methods of handling and utilization of the Boil-Off Gas at different points in the LNG supply chain are presented. Attention is given to the issue of LNG energy content transferred during loading and unloading of LNG tankers, as well as to the Boil-Off Gas generated by evaporation of the cargo during maritime transport.

Increasing the energy efficiency of the marine propulsion systems currently represents one of the priorities that have been placed in front of all subjects of maritime shipping market. More and more ship owners aspired to larger and more powerful diesel engines demanded from the marine engine manufacturers to implement various technological modifications to increase the engine efficiency, extend the life of engine components, and thus prolonge regular overhauling period of them. One of the way to meet these demands, among other things, is to improve the tribological characteristics of engine components. The aim of this paper is to present structural modification of tribological system “cylinder liner - piston ring - piston” of large bore slow speed marine diesel engine to reduce friction problems in mentioned system.

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