Hazardous Consequence Dynamic Simulation and Risk Analysis of LNG Spill on Water for Ship-to-Ship Bunkering

Abstract

The inland transportation of LNG (liquefied natural gas) by small and medium scale carriers has been acknowledged as an innovated way in the main rivers of China, and the safety issues for LNG bunkering practices have been highly concerned. The significant hazards related with LNG ship-to-ship bunkering could involve LNG vapour dispersion, LNG pool fire and deflagration. LNG vapour initially behaves as a denser-than-air vapour cloud and then is dissipated in surrounding environment. LNG pool fire occurs when bulk LNG releasing on water and encountering ignition source, which could cause thermal radiation damage to the surrounding properties and people. If the dispersed vapour cloud reaches the flammable limits and is ignited, deflagration could occur, as well as flash fire or explosion. The present study aims to capture the feature of these hazards and analyse the potential hazardous area by applying computational fluid dynamics analysis. The pool fire is investigated in order to obtain the thermal radiant flux and temperature and the material effectiveness on both LNG tanker and cargo vessel. The ship side water curtain, which is commonly used to prevent material stress cracking in case of LNG leaking, is considered to mitigate the radiation hazard. In combining with hazardous consequence simulation, a QRA (quantitative risk assessment) was performed to evaluate both individual and social risks of the LNG waterway transportation, with consideration of the crews and social environment at the ship to ship bunkering place. The Pearl River Estuary (PRE) area, which is located at the Southern China Sea coast, was taken as a study case to perform the QRA analysis.