Research On Hazard Source Identification And Explosion Risk Assessment Of Refueling,add Gas,and Charging Stations

In response to the growing demand for natural gas and charging for new energy vehicles,and at the same time saving urban construction land as much as possible,a multi-functional vehicle energy supply station that can add gasoline,diesel,natural gas and charging has emerged as the times require.More and more of traditional gas stations are looking the possibility of adding gas and charging facilities.However,the addition of gas and charging facilities will inevitably bring new safety risks to the station.Therefore,this paper takes a multifunctional energy supply station in Xi’an as an example to carry out hazard identification,Dow Chemical fire and explosion hazard index method evaluation,FLACS,SAFETI numerical simulation,systematically study the risk source of the multifunctional energy supply station and further quantitatively studied the severity of its harmful consequences.Firstly,the hazard sources in the multi-functional energy supply station were systematically identified from the perspectives of material hazard and equipment hazard,and a risk superposition analysis was carried out for the hazard sources.It was found that the line overload,short circuit,the risk of spontaneous combustion of new energy vehicle batteries and the risk of explosion of gasoline,diesel storage tanks and CNG gas storage wells have superimposed effects.Sufficient safety distance between charging facilities and oil and gas f acilities should be reserved during the construction of charging piles.In the evaluation of Dow Chemical’s fire and explosion hazard index method,gasoline storage tanks,diesel storage tanks and CNG gas storage wells are selected as three process units.According to the Dow Chemical Fire and Explosion Index Method(Seventh Edition)guidelines,the general process hazard factor,the special process hazard factor and the compensation factor for safety measures are selected.The evaluation results show that the hazard levels of gasoline storage tanks,diesel storage tanks,and natural gas storage wells are light,lightest,and very large,respectively.After taking into account the compensation coefficient of the existing safety measures,the hazard levels of gasoline storage tanks,diesel storage tanks,and natural gas storage wells are reduced to the lightest,lightest,and medium,respectively.The safety measures taken at present have a certain effect,but further safety measures should be taken for CNG gas storage wells.The FLACS numerical calculation results show that when a CNG tanker leaks with a 25 mm aperture,the gas diffusion in the+X and-Y directions will spread to the charging pile area,especially under southwest wind conditions,a large amount of combustible gas will accumulate in the charging pile area.The SAFETI numerical calculation results show that the maximum distance to reach the lower limit concentration of natural gas explosion when a 25 mm leak occurs in a CNG tanker is 37.34 m,and it’s of CNG gas storage well is 40.37 m.When natural gas leaks with an aperture of 25 mm,the range that reaches the lower explosion limit concentration completely covers the charging pile area.When all possible leaking parts of the multi-functional energy supply station leak,the entire station is within the flash fire range.Through the identification of hazard sources,the evaluation of the fire and explosion risk index method of Dow Chemical,the numerical calculation of the scope of natural gas leakage and the numerical calculation of the explosion risk scope of oil and gas leakage,it is believed that the addition of natural gas and charging facilities to the traditional gas station will increase risks of the station.Adding natural gas facilities will increase the severity of harmful consequences,and adding charging facilities will increase the probability of fire and explosion accidents.Therefore,a higher degree of attention and higher management requirements should be given to the multi-functional energy supply station.The results of this study have important guiding significance for the safety management of multi-functional energy supply stations.