Structural Stress Analysis Of Vertical Fixed-roof Storage Tanks Under Explosion Pressure

With the rapid development of petrochemical industry and the sharp decline in oil andgas reserves, the world has built a number of tanks to increase oil and gas reserves, mainly forlarge scale and the integration of storage tank capacity. Storage medium in the tank isinflammable, explosive, volatile, easy to produce static electricity, easy to heat expansion, etc.Once the storage tank for flammable gas explosion accident induced, the explosion is a veryviolent chemical reaction process, release a large amount of energy, the blast shock waveeffect on the storage structure, the tank can carrying and serious damage, casualties andproperty losses. If the tank explosion caused other the explosion of the storage tank to tankfarm produces "domino effect", it will lead to the serious consequences of a devastatingdisaster type, poses a serious threat to personnel life, has caused a serious loss of stateproperty. Therefore, carries on the security research has the vital significance.Based on the theory of engineering explosion, through the TNT equivalent method,considering the explosion shock wave propagation and attenuation in the air and crude oil.The mathematical model of storage tank structure is induced. According to the law ofconservation of the big three, the blast wave peak overpressure calculation method is set upwhen internal combustible gas of storage tank in a single point generates blast. For tank ofdifferent volume and liquid level explosion in different locations. Through calculation of theshock wave overpressure peak value at every point inside storage tank, it is concluded that thecloser the point position, the greater the peak pressure. Shock wave peak pressure increaseswith distance roughly as the exponential decay. This provides the ideas and calculationmethod, for storage of liquid pressure vessel explosion problem in the theoretical calculationof the explosion load.By ansys software considering geometric large deformation, material nonlinearity, roofrib welding, tank bottom and the foundation of contact and friction role, storage spacenonlinear finite element model is established. For the volume of3000m3,5000m3and10000m3of vertical dome tank in the empty cans, half cans and full tank under three kinds ofstorage level, different position of explosion condition has carried on the finite elementcalculation. Stress-strain characteristics of steel are analyzed from the points of the dynamicproperties of the materials under high strain rate loading, loading stress-strain characteristics.Material yield strength limit was obtained under the condition of the explosion using therelation between the dynamic yield strength and yield strength. Yield strength limit was obtained using the relation between the dynamic yield strength and yield strength materialunder the condition of the explosion.By the finite element calculation result analysis, thedifferent volume of storage tank under different storage level of explosion in differentposition of tank damage location and damage form is obtained. Under the equivalent peertank exploded at the same height when the condition of a large number of finite elementcalculation, storage tank at the hanging wall joint damage locations deviating from the storagetank structure of the central axis ratio, provides data reference for site safety.