A Simplified Analysis Method Of Heat Exchanger Tubesheet Based On Elastic Theory In ASME

Fixed tubesheet heat exchangers are widely used in petrochemical industry. Where the tubesheet play the role of fixing the tubes and isolating the cold fluid from hot fluid, so as to realize the function of heat exchange. The tubesheet design is important because it is subjected to complex loads, such as mechanical loads, inner pressure and thermal loads. The dimension of heat exchangers increase greatly as the requirements in petrochemical industry improvement. While there are no rules for the design of large-scale heat exchangers that beyond the dimension limit of the standards, so finite element analysis method is widely used to design heat exchangers. For the large numbers of tubes fixed to the tubesheet, it is complex to establish the numerical model and calculate. Therefore, two simplified finite element models of large-scale tubesheet are proposed according to the method offered in ASME VIII Div-1&2 and previous research results.The simplified model 1 replace the perforated plate by equivalent solid plate with effective elastic modulus E* and effective poisson ratiov*, the tubes are meshed by BEAM 188 and other components are SOLID 185 to establish a 3-D simplified model. The simplified model 2 replace the tubular by a bunch of cylinders which stiffness equal to the tubular, the cylinders are meshed by BEAM3 and other components are PLANE182 to establish an axisymmetric model. The effective ligament efficiency ?*is used to obtain the real results of perforated plates by modify the results of above two simplified models. By comparison of model 1, model 2 and solid model, the accuracy and feasibility of the two proposed simplified models are verified? Accordingly the two simplified models can save computing resources, increase efficiency of analysis & design at the same time.Finally, the influence on the result of axisymmetric model under various quantity cylinders is studied and the results show that more cylinders means more accurate. Additionally, there are isotropic and anisotropic effective elastic constants for square patterns according to ASME, the calculate results of two cases are approximated, it indicates that both of the two effective elastic constants can be used. But the anisotropic effective elastic constants is more difficult to derive compare to isotropic effective elastic constants, so it is better to use isotropic effective elastic constants.