Study On Coupling Mechanism Of Lightning Induced Fire Disasters And Pre-Control Strategy In Oil Depots

With the development of petrochemical industry in our country,the storage volume and use scale of petroleum are becoming larger and larger.In the process of construction of oil depots in China,generally,areas such as open or coastal areas are chosen.However,the existing problem is that the risk of lightning and lightning in these areas is very high,and it is extremely easy to cause lightning fire or even explosion accidents,it would also affect the surrounding tanks and cause a serious domino effect.Therefore,the problem of lightning fire in oil depots can not be ignored.It is of great practical significance and engineering application value to study the coupling mechanism of lightning fire and domino effect prevention and control in oil depots.At present,the research on lightning fire accident mainly focuses on the direction of lightning fire risk and failure probability of storage tanks near the target,which involves single accident scene and unclear coupling mechanism of lightning fire disaster,furthermore,the failure mechanism of the adjacent target tank is not studied thoroughly from the point of view of thermal effect.Therefore,this paper establishes the law of leakage diffusion and cause and effect of oil tank under the complicated conditions of lightning,temperature and wind,and establishes the weighted Mudan model which can improve the accuracy of prediction of thermal radiation of lightning fire,the method of judging the failure of storage tank adjacent to the target in lightning fire environment is established.The main research contents are as follows:(1)Study on the regularity of lightning disaster in oil depots.This paper analyzes the causes of lightning and tank fire,and makes use of the Datsan of lightning,the law of accident evolution and the mechanism of fire.(2)Analysis of influencing factors of oil and gas leakage and diffusion.FLACS software is used to simulate the oil and gas leakage law at the seal ring of external floating roof tank,and the influence of temperature and wind on the distribution of oil and gas concentration is investigated.(3)Research on prediction method of thermal radiation of oil tank fire caused by lightning stroke.Based on Thomas Model,the Variation Law of flame height and flame heat radiation flux with height was calculated,and FDS was used to simulate and verify the results,it solves the problem that the traditional Mudan model does not consider the uneven distribution of the heat radiation of the fire source.(4)Study on thermal failure mechanism of target tank under lightning fire environment.Based on the analysis of the temperature field and thermal stress of the storage tank adjacent to the target under the lightning fire environment,a method for judging the thermal failure of the target storage tank is proposed,the thermal failure mechanism of the target tank is revealed from the point of view of the total stress on the wall of the target tank and the decrease of the mechanical properties of the pipe.(5)Lightning fire prevention and control strategy for oil depots.Based on the established method of judging the failure of target tank in lightning fire environment,the influence of protection distance and cooling spray system on the thermal failure of target tank is quantified,and the control strategy of lightning fire is proposed.