Structure Design And Construction Technology Of The Large-opening Nozzles On Two Vessels With Embedded Reinforcing

Two devices refers to reactor and regenerator,they are core devices of catalytic cracking in petroleum refining process.To meet their functions,the pressure vessels need to implement opening nozzles.Sometimes the size of the openings far exceeds the scope of "steel pressure vessel" defined in the standard,it's called large-opening.Current,the technology for the reinforcement of opening nozzles include paste plate reinforcement,taking over reinforcement and entire forging reinforcement.However,these reinforcement technology in practical applications will have a variety of problems,mainly in the following two points: paste plate reinforcement and taking over reinforcement will bring a large stress concentration at the intersection of the vessel and nozzles,and the two reinforcing technique can not be used for large area and a wide range of reinforcement;whole forging reinforcement causes a significant increase in processing costs,and it requires a long manufacturing cycle.In order to solve these two problems,the thesis carries out research about structure design and construction technology of large-opening nozzles on two vessels with embedded reinforcing.The main research content is mainly reflected in the following three points:(1)The reason for the stress concentration caused by the opening of the pressure vessel is analyzed,and the stress of the situation around the opening has been studied.Then a method of reinforcement is proposed to reduce the stress around the opening,also a widely used equivalent rrea reinforcement method in engineering is introduced.Then commonly used forms of current reinforcements are introduced,and the advantages and disadvantages of these forms of reinforcement are analyzed.Finally,the theory of two intersecting cylindrical shell is studied by introducing a small amount in the thin-shell theory,so that the accuracy of the solution of the equation increases from(7)(8)1/2O T/ R to(7)(8)3/4O T/ R.(2)From the finite element analysis of a force bar,the idea of finite element analysis is introduced.Nonlinear finite element stress analysis process is proposed,and the nonlinear finite element method is validated through a pressure reforced by paste plate.Analysis showes that the calculated stress nonlinear methods closer to the real situation.Finally,the embeddedreinforcing structure is described in detail,and the stress situations is analyzed by nonlinear finite element method.As can be seen from the stress cloud,embedded reinforcement structure can greatly improves the stress concentration of the vessel,and maximum stress occurs at the intersection of the cylinder with the nozzle.(3)Construction techniques of embedded reinforcement are studied,the researth are expanded from the three main aspects,indluding the assembly layout,assembly welding and heat treating respectively.The quality of the layout is the beginning of a successful construction,the assembly sequence and welding quality is the key to success,the last post-treatment is an effective method of eliminating welding residual stress.