Research Of Modeling For LNG Carriers Moving Safety Zone During Inland River

With the adjustment of China's energy structure,natural gas has become the hottest clean energy source for replacing petroleum and coal because of its advantages of easy transportation,high energy storage efficiency and environmental protection.At present,the main form of China's natural gas supply is Liquidfied Natural Gas(LNG).China has become a major trading country of LNG in the world,and a large amount of LNG is transported to China through vessels.The low temperature,flammability and explosiveness of LNG make the safety management of LNG in ship transportation process extremely strict.However,there is no LNG carriers currently in operation in China inlandwater,so in order to ensure the safety of navigation of LNG carriers entering the Yangtze River in the future,it is necessary to study the navigation risk prevention and control measures and to quantify the moving safety zone of LNG carrier.Firstly,this paper,by reference to domestic and foreign literatures,analyzes the research results from domestic and foreign scholars and some LNG terminals in the navigation and moving safety zones of LNG carriers.Based on the research status of LNG carrier safety zone,this paper finds the current problems,clarifys the research content and research methods of this paper.Then identify the source of navigation safety risks for LNG carriers.Firstly,combining Delphi and expert experience method,this paper analyzes the risk factors of LNG carrier navigation in the Yangtze River downstream from four aspects:human,vessel,environment and management,and puts forward 15 risk indicators that affect the navigation of LNG carriers,and establishes a risk evaluation index system.Then,the entropy weight fuzzy model is used to reduce the influence of subjective judgment on the index weight and the segmentation and overall evaluation of the navigation risk of the LNG carrier in Bailusha Waterway.Finally,the cloud model is used to verify the consistency of the entropy weight model.The results show that the scale of LNG carrier's moving safety zone is related to the scale of LNG carrier and encounter ships,maneuvering characteristics and speed.Third,establish a quantitative calculation model for the moving safety zone of LNG carriers.The main research steps in this paper are questionnaire survey,model building,and application analysis.By investigating the crew of inland vessels,the safety spacing of inland LNG vessels and other vessels is investigated and analyzed,providing reference data for horizontal and vertical safety distances.Then,considering the consequences of the accident,the handling characteristics of the LNG carrier,the ship collision avoidance operation and the existing ship domain theory,the following models are referenced: fire hazard model,the ship following model,the geometric collision model and the asymmetric ship domain model.At last,a quantitative calculation model for the moving safety zone of inland river LNG carriers is proposed.Finally,considering the construction of the channel in the lower reaches of the Yangtze River,combined with traffic flow statistics and the key navigational points of waterway,a 40,000-cubic meters C-type LNG carrier and a 50,000-ton bulk are selected as representative ship types.Then,this LNG carrier is assumed to sail into Yangtze River passing the Baishasha waterway.By calculating the scale of the navigation moving safety zone at certain key points,we finally obtain the setting scheme for the moving safety zone of the LNG carrier when navigate in Baijisha Waterway.The results show that in the traffic organization of inland river LNG carriers,the safety zone size of inland river LNG vessels can be quantified in real time according to the traffic environment and channel characteristics of the waters where the LNG carriers are located.It has been verified that the calculation results meet the current laws and regulations and are reasonable and feasible.The established model of the navigation moving safety zone can provide reference to the transportation organization and protection for the inland river LNG carrier in the future.