Safety Analysis Of Hydrogen Fuel Cell Ship Leakage And Explosion Accident

The energy problem is the fundamental problem of human society.The history of human civilization is also a history of energy use.With the global economic and industrialization development,the problems of energy shortage and environmental pollution are becoming serious.Hydrogen energy is known as the ideal energy source most likely to replace fossil fuels,and the development of hydrogen energy is valued by various countries with good development prospects.Fuel cell ships have the advantages of low emission,high efficiency,good stability,and low noise.Fuel cell ships have great potential in promoting pollution-free shipping and energy sustainability in the future.Hydrogen has the characteristics of a wide combustion range and low ignition energy in the air,so hydrogen safety is very important.The analysis of diffusion and explosion behaviors after hydrogen leakage is an important direction of hydrogen safety research,which is important for developing and improving the hydrogen safety guidelines.As the hydrogen storage capacity of hydrogen fuel cell ships is large,the hydrogen supply pipeline is complicated,and the shipping compartment is relatively confined.The hydrogen leakage can easily cause fire and explosion which cannot be ignored for ships with high personnel density and difficult rescue.The consequences of the hydrogen safety accident can directly have a large impact on humans and equipment.In the present work,a fuel cell ship cabin model was developed using the FLACS software,and the accident consequences such as over-temperature and over-pressure that may be caused by different leakage directions were predicted by numerical simulations.The hydrogen sensor arrangement is optimized based on the simulation results.The results show that hydrogen accumulates in the cabin and lateral leakage is more dangerous than upward leakage.If an explosion occurs in the cabin,the area affected by the accident is mainly confined to the cabin and the area around the ship.The top corners of the fuel cell cabin,the upper of the box and the upper of the potential leakage source are the best localization for the hydrogen sensor.This work also used natural ventilation and water spray to suppress the consequences of the hydrogen safety accident.The effects of natural ventilation on the diffusion of hydrogen leakage in the ship cabin were analyzed for different natural ventilation conditions such as total ventilation area and ventilation grille arrangement,The increase in the ventilation area can significantly accelerate the diffusion of hydrogen in the cabin.When the total ventilation area is constant,increasing the number of ventilation grille in the vertical direction can make the leaked hydrogen diffuse out of the cabin more quickly and effectively.The effects of the water spray system to suppress hydrogen combustion and explosion in the cabin were also studied,which provides a solution to reduce the consequences of hydrogen leakage accidents.The hazardous consequences of hydrogen leakage in a fuel cell ship were analyzed by using the quantitative risk assessment method.The risk indexes of leakage accidents were compared with the risk acceptability limits to determine whether they were acceptable.The result shows that the hazardous radius of dispersion,flash fire and explosion caused by hydrogen leakage accident are 1.3 m,41.4 m and 553.5 m,respectively.The risk indexes of leakage accidents were also obtained.The results of this paper can be used to analyze and evaluate the consequences of accidents caused by hydrogen leakage from fuel cell ships and provide a scientific basis for the safety design of fuel cell ships,which will be beneficial to promoting the application of fuel cell passenger ships in China.