Finite Element Analysis Of A Heat Exchanger With Annular Tubesheet

In this paper, a 3D FEA model including shell and tube of a fixed tubesheet heat exchanger is developed using ANSYS software. The discussed tubesheet equips a central pipe (whose diameter is significantly greater than other heat exchanger tubes).Since the fixed tube heat exchanger has a complex structure with extended tubesheet as a flange, in this research, the heat exchanger is being studied and analyzed in the following steps. First, two FEA models are developed about the tubesheet and flange connection system. One is a 3D and nonlinear finite element analysis model. On the other hand, the second FEA model considers that bolt load is uniformly applied directly. An optimal model is selected based on the simulation results from both models. Second, a global structure FEA model is developed to analyze temperature disturbation due to asymmetric temperature distribution nature of the tubesheet along the axial direction. In addition, apply thermal stress analysis to the global structure. According to the axial displacement results from temperature difference, verify the heat compensation of standard expansion joint building in this exchanger. Furthermore, based on the stress analysis standard JB4732-1995, stress analyses are done for 7 steady or transient operating cases which may occur during start-up, steady operating and shut-down.The following conclusions are made in this paper. First, in the 3D FEA analyses of a tubesheet (which extended as a flange), neglecting the local influence of contact problem, the stress distribution of two models are similar. Second, the result of temperature field analysis indicates that temperature distribution on the annular tubesheet is similar to that of convention tubesheet. The third, thermal stress in fixed tubesheet exchanger is the major factor influencing equipment strength. Thermal stress value depends on not only the coefficient of linear of material, but also the temperature distribution in shell, tubesheet and tube bundles. Hereby, the accuracy of simulation to temperature distribution and the heat structural coupling analysis is very important.The analysis result indicates that in the original design of the exchanger, tubesheet and shell are safe. The tubesheet flange is not safe, however. It can be also proved that by altering the gasket material, stress value of tubesheet flange can be reduced significantly. And the exchanger will satisfy the strength and process requirements.