A Fuzzy Bayesian Network–Based Method for Evaluating the Leakage Risk of STS LNG Bunkering

Abstract

As a promising clean fuel, the liquefied natural gas (LNG) has been considered as the alternative energy for ships and the LNG-fueled vessels has sharply increased in recent years. However, the leakage of LNG has become a serious challenge for the wide application of LNG-fueled vessels, especially during ship-to-ship (STS) bunkering. This study analyzes leakage accidents during STS LNG bunkering, considering its operation process, and develops a fuzzy Bayesian network model to evaluate the probability of LNG leakage during STS LNG bunkering. Sensitivity analysis is carried out to identify the critical risk factors. Moreover, the study simulates the consequence of LNG leakage using the Fire Dynamics Simulator (FDS) software and derives the F-N curve to determine the risk levels of LNG leakage considering the thermal radiation criteria. A case study of LNG-fueled vessel in Ningbo is conducted to verify the proposed method. The results show that the probability of LNG leakage and fire accidents during STS bunkering is 0.93% and 1.3829×10−4 respectively, which is located in the as low as reasonably practicable (ALARP) zone. Afterwards, it is found that uneven force on the ropes and fenders are the crucial factor influencing LNG bunkering. The simulation experiments demonstrate that the high-risk areas of STS LNG bunkering are 4 to 16 m away from the LNG-fueled ship. This study analyzes leakage accidents during ship-to-ship (STS) liquefied natural gas (LNG) bunkering, and develops a fuzzy Bayesian network model to evaluate the probability of LNG leakage during STS LNG bunkering. A case study of LNG-fueled vessel named XINAO in Ningbo is conducted to verify the proposed method. Moreover, the study simulates the consequence of LNG leakage using the Fire Dynamics Simulator (FDS) software and derives the frequency versus number of fatalities (F-N) curve to determine the risk levels of LNG leakage considering the thermal radiation criteria. The results show that the probability of LNG leakage and fire accidents during STS bunkering is 0.93% and 1.3829×10−4 respectively, which is located in the as low as reasonably practical (ALARP) zone. Then, it is found that uneven force on the ropes and fenders are the crucial factor during STS LNG bunkering. The simulation experiments demonstrate that the high-risk areas of STS LNG bunkering are 4–16 m away from the LNG-fueled ship. This paper delivers a remarkable research work providing rule-makers with an insight into the safety management during STS LNG bunkering.