A prototype test of dynamic boil-off gas in liquefied natural gas tank containers

Abstract

The safety concern of transporting liquefied natural gas (LNG) by tank container is still an unsolved problem. One of the key issues for LNG tank container transportation is that the dynamic boil-off gas (BOG) generation during the shipping has not been systematically characterized. Due to the limitation in previous studies, prototype test for the BOG during shipping is demanded. Therefore, in this paper, a prototype test was carefully designed and conducted on an actual 40-ft tank container, which filled in real LNG. The characteristics of BOG generation in the tank container during shipping were systematically tested. The results showed that ship motion facilitates BOG generation, therefore, dynamic BOG is significantly important to evaluate the safety of the tank container. However, the fluctuation on BOG generation are stable in dynamic conditions from long perspectives. The liquid temperature is more sensitive to the external excitations. Monitoring liquid temperature will be helpful to predict the trend of BOG generation. The holding time of the tank container would significantly shorten in the most severe test conditions. Thus, the shipping voyage time should be well arranged, which is very important to the ship operation.