| Vertical dome roof tank is important storage equipment in the process of storage andtransportation of crude oil, and the tank overpressure mechanism, failure stress calculation,destruction condition judgment and weak roof design have been the key technical problemsof the tank design and safe operation. This paper carried out the mechanism of tankoverpressure, tank failure stress calculation in different forms of overpressure, the judgmentof storage tank damage and weak roof judgment and a weak roof design theory as well asnumerical analysis method of study, which have important academic value and goodprospect of engineering application. Based on the principle of from simple to complex,carry out the following research work.First of all, take vertical dome roof tank as the research object, two kinds of dynamicpressure rise inside the tank, combustible gas burning and explosion are analyzed. Using theconstant volume combustion method, combustible gas in the tank booster geometricanalysis, combustion temperature and combustion rate has been calculated, got thecalculation method of storage tank caused by combustible gas explosion; By TNT explosiveimpact on the factor analysis, established the TNT equivalent calculation method caused bycombustible gas explosion overpressure, considering the blast shock wave peak pressure inthe storage tank reflection, according to the geometrical analysis of the explosion shockwave, got to the overpressure peak value calculation method of combustible gas explosion.Secondly, in view of the storage tank overpressure problem under the action of staticpressure, analyzed two damage forms of the tank roof, local buckling failure caused bycompression ring yield and strength damage caused by the hanging wall connection weldstrength insufficient. The vault tank compression ring cross-section stress is analyzed,analyzed the calculation method of roof joint damage pressure and compressive ringcross-section in tank design standard. Established the tank damage conditions by makingthe average stress of dangerous section to achieve material yield strength. Through torquetheoretical analysis of storage tank roof joint, established tank roof joint damage stresscalculation formula considering bending.Thirdly, the shell element and solid element and beam element are adopted to roof rib,weld joint, edge Angle, roof, bottom plate, shell, foundation etc to discrete the structure,contact elements are adopted to simulate the roof and rib, bottom plate and the foundationof one-way contact friction problem, storage space numerical calculation model isestablished, based on different capacities of the storage tank under the empty, half loadedand full working conditions finite element analysis, the destruction of the roof and bottom pressure are obtained. Manufactured experimental tank using structure similarity principle,by the destruction test on the tank overpressure, two failure modes and failure pressurecalculation formulas and tank damage conditions are verified.Fourthly, the paper analyzed the two kinds of dynamic process of overpressure ofstorage tank caused by combustible gas combustion and explosion in storage tank, incombustion overpressure, pressure on different location is only related to the burning time;in explosion overpressure, pressure on different location is associated with both distancefrom blast point position and time. By establishing a dynamic computational model ofstorage tank, given the destruction of the storage tank under different pressure conditions,calculated the failure pressure of typical capacities storage tank under two kinds ofoverpressure, the destruction of the roof and bottom.Finally, based on different capacities of the dome roof storage tank in the empty, halfloaded and full working condition tank under various stress mechanics analysis, combiningof tank roof joint and the bottom joint damage conditions and destruction pressure,established the evaluation condition of a dome roof storage tank, and recommended thatwhen the storage tanks is with weak roof structure, k empty1.5(empty tank),k full2.5(full tank). Based on calculation on dome roof storage tank of different capacitiesunder different forms of overpressure, got the weak roof performance variation underdifferent liquid levels. In terms of the main influencing factors of the tank weak roofperformance, analyzed the weak roof performance of different capacities under differentworking conditions, and put forward weak roof design methods of the tank in differentcapacities. By changing a single or some parameters of storage tank to satisfy its weak roofperformance, to design a tank that satisfies the requirement of weak roof.This article research results can be used as tank disaster relief, prevention and rescue,fire control, and storage tank design, providing important theoretical basis and numericalcalculation method. |
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