Study On Structural Mechanics Properties Of Tube Sheet Heat Exchanger Tube To Tube Connections

Shell and tube heat exchangers are widely used in energy and chemical industry,aerospace,machinery manufacturing,shipbuilding,nuclear industry and other fields.Among them,the connection structure between the tube plate and the heat exchange tube is the weak link of the entire shell and tube heat exchanger,and once leakage occurs,failure will cause serious consequences.The use of a double tube plate structure can effectively prevent accidents such as combustion and explosion caused by leakage,and is widely used.This article focuses on the research of residual contact stress and tensile detachment during the expansion process between the inner and outer tube sheets of a double tube sheet heat exchanger and the heat exchange tubes,which has certain guiding significance for engineering practice.An elastic-plastic mechanical analysis was conducted on the expansion process of the tube sheet heat exchange tube,and the main factors affecting the residual contact stress and tensile detachment of the expansion joint were identified,including expansion pressure,initial gap,grooving situation,surface roughness,etc.The true stress-strain curves of Q345 R and 20 steel were fitted using the methods specified in ASME standards.The residual contact stress during the expansion process of the double tube sheet heat exchanger was simulated using ABAQUS,and compared with experimental results to verify the reliability of the numerical simulation;On this basis,the effects of expansion pressure,initial clearance,grooving situation,surface roughness on residual contact stress in expansion joints were analyzed,as well as the influence of the expansion process of the outer tube sheet on the expansion effect of the inner tube sheet.The analysis results indicate that the residual contact stress in expansion joints is positively correlated with the expansion pressure and negatively correlated with the initial gap;Slotting can effectively increase residual contact stress.The closer the groove position is to the edge of the expansion joint area,the better the expansion joint effect.Increasing the groove width and depth appropriately can increase the residual contact pressure.When the groove width reaches a certain value,further increasing the groove width has little effect on increasing residual stress;The tensile detachment force is related to residual contact stress and surface roughness.As the surface roughness increases,the residual contact stress slightly decreases,but the friction coefficient increases,and the overall tensile detachment force significantly increases,which is beneficial for improving the expansion joint strength;During the expansion process of the outer tube sheet of the double tube sheet heat exchanger,the residual contact stress of the inner tube sheet is also increased.The expansion of the outer tube sheet has a certain strengthening effect on the expansion effect of the inner tube sheet,and the smaller the distance between the two tube sheets,the greater the strengthening effect.This article clarifies the influence of expansion parameters on the residual contact stress and tensile detachment of double tube sheet heat exchangers during expansion,as well as the impact of external tube sheet expansion process on the expansion effect of internal tube sheet.This provides a theoretical basis for the design of expansion structures of double tube sheet heat exchangers and has certain significance for ensuring the safety of double tube sheet structures.