CFD Based Simulation of LNG Release during Bunkering and Cargo Loading/Unloading Simultaneous Operations of a Containership

In order to reduce waiting time in port for large LNG (liquefied natural gas) fueled ships, it is suggested that LNG STS (ship to ship) bunkering and cargo loading/unloading should be carried out simultaneously. This study investigated the safety zone of an LNG bunkering vessel with 10,000 cubic meters capacity transferring LNG fuel to an LNG fueled 18,000 TEU containership. Four LNG leakage scenarios were identified based on failure frequencies analysis of piping systems and severity of consequence, three-dimension CFD software FLACS was adopted to calculate flammable cloud dispersion after LNG leakage. As a result, we obtained a rectangle dangerous zone (41.3 m 126 m), outside of this dangerous zone can be defined as safety zone. It is concluded that safety zone of LNG STS bunkering and cargo loading/unloading SIMOPS (simultaneous operations) cannot keep the same, there are different results for different designs and operation locations. Due to high frequencies and severe consequences, two typical scenarios, the leakage of LNG hose and the natural gas releases from bunkering tank's safety relief valve during bunkering, cannot be ignored in similar study.