Simulation And Hazard Analysis Of Leakage And Diffusion Model Of Hazardous Gas At Sea

Shipping accounts for a large proportion in the transportation of dangerous chemicals.When dangerous chemicals in shipping leak,especially the dangerous gases,which mostly leaks in the form of heavy gas,has the hazards of flammability,explosion,toxicity and others,which poses a huge threat to the environment and personal safety of the sea and port.Therefore,it is of great significance to carry out the simulation and hazard analysis of the leakage and diffusion of hazardous gas at sea for the subsequent emergency disposal.In this paper,the Slab model and Gaussian plume model are selected and improved to build a Slab-Gaussian plume model suitable for the marine environment,and the explosion hazard of combustible gas cloud is analyzed.The method is as follows:(1)Through the analysis of heavy gas at sea and the selection of appropriate models,a Slab-Gaussian plume model is designed,the Slab model is used in the heavy gas settlement and diffusion stage,the Gaussian plume model is used in the heavy gas turbulent diffusion stage,and the virtual source is designed,and the criterion of vf is selected to connect the two,so as to effectively simulate the whole process of heavy gas diffusion at sea.(2)Based on the improvement and optimization of the parameters of the Slab-Gaussian plume model in the marine environment,firstly,analyze the different leakage states of the leakage source and establish the corresponding calculation model;secondly,The influence of wind speed and speed of ships on heavy gas diffusion at sea is analyzed,and the vector of reverse speed of ships and wind speed is synthesized;then in the Gaussian plume model,the effective height of the leakage source is adjusted,then the atmospheric stability is determined by the hydrometeorological factors,and the corresponding diffusion parameters are selected.Finally,according to the model parameters to establish control experiments,the optimized parameters make the model more accurate.(3)Based on the improved TNO(the Netherlands Organization)multi energy method is used to simulate the explosion damage of combustible gas cloud.By selecting the fitting formula with modified explosion source intensity grade of 7,the relational data between the volume of gas cloud and the distance of damage grade are calculated by multi energy method,then regression analysis is made,and the calculation formulas of the volume of gas cloud and the distance of damage are fitted by power function,Then,a method for estimating the volume of diffused cloud in the Slab-Gaussian plume model is proposed.Finally,the probability of death was calculated and the mortality was obtained by referring to the mortality table.This method can simulate gas cloud explosion quickly and accurately.The above method is used to simulate the leakage accident of heavy gas at sea.The results show that the change of ship speed and,corresponding parameters has a significant impact on the diffusion of heavy gas.At the accident point,through the correction of model parameters,the two models still have a high degree of agreement.Through the field inspection by experts,the data of 0.025kg/m3 isoconcentration curve is taken as the reference,and(100m,0.025kg/m3)is taken as the verification point.The simulation results are basically consistent with the diffusion concentration point at that time.At the same time,the injury distance and death rate were effectively predicted and analyzed.Finally,the quantitative visualization and hazard analysis of the concentration area of heavy gas leakage and diffusion are realized.This provides theoretical and technical support for emergency rescue and hazard assessment of heavy gas leakage at sea.