Study On Stress And Vibration Characteristics Of Heat Exchanger Tube Bundles Based On Heat-fluid Coupling

Fixed tube-plate heat exchangers have a wide range of applications in the modern industrial field because they are relatively stable,reliable,and easier to operate.Of course,these heat exchangers are used for a variety of reasons.The phenomenon of shortened life span is also common,and the main reasons that affect its service life mainly come from two aspects: 1.The thermal stress caused by the heat exchange between the tube and the shell during the heat exchanger working process;2.The fluid flow due to the shell side.Damage caused by vibration.It is precisely because of the above phenomenon that the life of the heat exchanger is shortened.Therefore,according to the study of heat exchanger failure and fatigue under actual conditions,it is imminent and meaningful to increase the lifetime of the heat exchanger and reduce the economic cost.The research object of this article is a fixed pipe-plate brine-copper crude heat exchanger of a petrochemical company.According to the above two problems,the corresponding methods were used to carry out targeted research.1.Thermal stress damage caused by heat exchange: Using fluid-solid coupling method,Fluent software is used to simulate the flow field characteristics of the heat exchanger inner tube and shell side,and the pressure and temperature data obtained are transmitted through the coupling surface.Into the structural analysis,and as a load imposed on the heat exchanger model,the stress analysis results under different loads of the heat exchanger are obtained,and compared with the heat exchanger damage position,the temperature load is caused.The stress damage is larger than the stress caused by the pressure load,and the stress concentration caused by the temperature load coincides with the actual fatigue failure position of the heat exchanger,which verifies the rationality of the simulation method,and from the perspective of thermal stress damage The life extension of the heat exchanger provides a theoretical basis.2.In this paper,based on the vortex shedding of the tube bundles,the stress state of the heat exchange tube bundles in the vortex shedding mode is analyzed by two methods.Firstly,the vibration of the heat exchange tube bundle was further studiedby vibrational mode analysis.According to the simulation results of the shell-side flow field,the heat exchange tubes were divided into three categories according to the different constraints of the heat transfer tubes.The results show that the A-type and C-type tubes are susceptible to vortex shedding and resonance occurs,and these two kinds of tube stress easily reach the fatigue limit and are destroyed.In addition,the cylindrical flow around the heat exchange tube bundle is simulated.Based on this,the single tube in the flow field is subjected to bidirectional coupling stress analysis.The results are compared with the results in the previous analysis step,and the difference is small.The accuracy of the two analysis results also proves the feasibility of the two research methods,and provides a theoretical basis for the life extension of the heat exchanger from the perspective of beam-induced vibration damage.The above analysis shows that the main reasons for the failure of this type of heat exchanger are the thermal stress caused by heat exchange and the vibration of the tube bundle induced by the fluid.Through this research,it provides a theoretical basis for the life extension of the heat exchanger.