A Preliminary Investigation on the Risk Arising From the Use of High Pressure Fuel Gas Supply System in LNGC by Analyzing Risk Contributors Comparatively

Abstract

This work is motivated by the need to identify the fire and explosion risk on liquefied natural gas carriers (LNGCs) developed by Daewoo Shipbuilding & Marine Engineering Co., Ltd., because the main engines are designed to use highly pressurized natural gas (about 300 bar), which has caused vague fears of fire and explosion risks. In this context, to identify the risk of fires and explosions quantitatively, a fire and explosion risk analysis (FERA) was carried out for the LNGCs. This paper, as a part of the FERA, presents the results of a preliminary investigation on the effect of introducing the highly pressured fuel gas system into LNGCs on the fire and explosion risk especially in the cargo compressor room. This study is conducted in a comparative way considering the risk contribution of each parameter that could impact on the fire and explosion risk. The effect of the highly pressured fuel gas is indirectly taken into account by the change of the initial leak rate in the system. To identify effects of the considered parameters quantitatively, dozens of simulations for the selected gas dispersion, explosion, and fire scenarios were carried out using FLACS and KFX. Based on the simulation results, it is concluded that, in case of the LNGCs, the effects of the initial large leak rate due to the high pressure in the fuel gas pipes on the fire and explosion risk are not significant compared with the effects of other parameters such as leak amount, leak location, and leak direction.