Finite Element Analysis Of Shell-and-Tube Heat Exchanger Tube Sheet

The shell-and-tube heat exchanger is a heat exchange equipment which is used widely in the chemical industry. The tube sheet is one of most important parts in the shell-and-tube heat exchanger. The temperature load and the mechanical load make the tube sheet in a complex situation. Many great achievements of the tube plate design and the analysis have been made and many realistic theories have been put forward at home and abroad. Some insufficiencies also exist in the same time. In order to find out the most dangerous working condition, stress analysis for the model of tube sheet has been completed by using ANSYS under various conditions. In this way, structure design for tube sheet becomes easier and some reference of tube sheet safety has been provided.This paper has established three dimensional finite element model of tube sheet of shell-and-tube heat exchanger and has analyzed the temperature field distribution of tube sheet model under the condition of the convective heat transfer. The result of temperature field analysis indicates that the temperature distribution in the perforated region of the tube sheet is that the temperature of the tube sheet from its tube-side face and along most of its thickness is between the temperature of the tube-side and the temperature of the shell-side fluid flowing through the tubes, and only in a very thin area from its shell-side face the temperature is close to the temperature of the shell-side fluid near the tube sheet. This is the skin effect theory of ASME specification.The paper has carried out stress analysis and stress evaluation on the tube sheet under different conditions, which includes alone affects, joint action and together of shell pressure, tube pressure and temperature. The stress evaluation shows that the stress strength of tube sheet under every conditions is conforms to the standard of strength design.The stress analysis shows that the most dangerous condition is not the steady operating case, but the transient case at the moment that the tube-side fluid is just shut down, but shell-side pressure load and thermal load still retain.Through the analysis we know that the original design of the tube sheet was safe and conservative and it is possible to reduce the thickness of the tube sheet. A tube sheet model which has 90% thickness of the original one is also analyzed, and the result shows that the tube sheet is still safe after thickness reduction.