Three-dimensional Finite Element Analysis Of Tube Shell Heat Exchanger Tube Sheet Stress

Tube-and-shell heat exchangers are widely used in petrochemical industries. Tubesheet is the most important and complicated part of tube-and-shell heat exchanger. It determines the economic and security of the whole heat exchanger.In this paper a 3-D finite element solid model of tubesheet, with shell and tube, flang seal is replaced by equivalent even pressure, is established for the analysis of the tubesheet double as flange. With the model,the temperature field of the model is analyzed, and then, based on the stress analysis standard JB4732-1995, the stress analysis are done for 7 steady or transient operating cases which may occur during start-up, steady operating and shut-down.The result of temperature field analysis indicates that the temperature distribution in the perforated region of the tubesheet is that the temperature of the tubesheet from its tube-side face and along most of its thickness is close to the temperature of the tube-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 tubesheet.The result of stress analysis shows that temperature load induced remarkable thermal stress, and under pressure and temperature load, the distribution of the stress depend on the thermal stress. The most dangerous casse is not the steady operating case, but the transient case at the moment that the shell-side fluid is just shut down, but tube side pressure load and thermal load still retain.The analysis indicates that the original design of the tubesheet wasn' t safe at 4 cases later.The design' s improvement was made, and finally the tubesheet is safe.