Analysis Of Expansion Stress Of Heat Exchanger Tube And Tube Sheet In Heat Exchanger

Shell-and-tube heat exchangers are widely used in many industrial fields,such as refining,chemical,nuclear power,etc.Because titanium has the same strength as common steel,its density is lower and corrosion resistance is better.With the development and innovation of technology,the advent of titanium alloy materials and composite materials,the use of heat exchangers based on titanium materials in industrial applications are increasing.Especially in shell-and-tube heat exchangers,titanium heat exchange tubes and steel tube sheets are used more.The guarantee of the performance of the pipe and tube plate joints in the shell-and-tube heat exchanger plays a vital role in the reliable operation of the heat exchanger.The expansion joint can eliminate the gap between the tube plate hole and the tube.It is better to prevent the mixing of the tube and shell side media,prevent the corrosion of the pipe joints,and eliminate the vibration-induced defects.However,if there is overexpansion or underexpansion during the expansion process,it will lead to the leakage of the pipe joint,the quality of the produced product is difficult to guarantee,and the equipment accident will be seriously caused.Therefore,it is very necessary to study the strength of the expansion joint.The expansion joints studied in this paper are composed of titanium tubes and steel tube sheets,which are expanded by a hydraulic tube expander.Through theoretical analysis and mathematical derivation of the expansion joints,a simple model of the tube sheets is established.The required parameters of the model are determined.The software is used to simulate the expansion process under different expansion pressures,and the variation of residual contact pressure is analyzed by experiment and simulation.The final conclusion is as follows:When?38×1.5mm TA2 heat exchange tube and Q345R seven-hole tube plate model are expanded,First,the magnitude of the residual contact pressure can be derived by the expansion pressure,Such as the formulaP_c^*=1?-2c?P_i-₃²?_stlnK_t;Second,a large residual contact pressure can be obtained by increasing the expansion pressure of the expansion joint.Slotting the tube hole can obtain a larger residual contact pressure than without slotting;Third,the expansion sequence has a certain influence on the residual contact pressure of the expansion joint.The residual contact pressure of the first expansion pipe hole is increased by the extrusion of the rear expansion pipe hole.Then,the residual contact pressure of the expansion joint hole will decrease;fourthly,the hysteretic elasticity of the titanium heat exchange tube is the main cause Slacking the expansion joint.