LNG板翅式换热器板翅结构热应力分布规律分析
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摘要
为保证LNG板翅式换热器冷箱安全运行,建立了板翅结构热应力有限元耦合分析物理模型,采用热-力直接耦合方法分析了大型LNG板翅式换热器冷箱正常运行时板翅结构的热应力分布规律,分析结果表明:实际运行工况下板翅结构的第一主应力、第三主应力以及基于第三强度理论的等效应力在钎焊位置处变化梯度较大,并且等效应力最大值出现在翅片和隔板钎焊位置处,从而使钎焊位置可能发生疲劳破坏;对于整个板翅结构,结构最薄弱区在最外层隔板与翅片的钎焊位置处。上述研究成果将为大型LNG冷箱内板翅式换热器结构设计和安全可靠运行提供重要参考依据。
In order to ensure the safe operation of large- scale cold- box,a finite element model( FEM)based on thermal elastic theory was proposed to simulate thermal stress distribution of plate- fin structure in large LNG cold box under the normal operating conditions. Thermal- stress direct coupling method was adopted in this analysis. By the thermal stress distribution in four paths marked in the structure,it is found that,in actual operating conditions,the first principal stress and the third principal stress reach to maximum value in brazed joint,the stress gradient is larger than that of other region and a crack would be occurred in this region. And the equivalent thermal stress based on third strength theory was also calculated in four paths. The result is consistent with the simulation results. Meanwhile,it also concluded that the most dangerous region is the outermost brazed joint between plate and fin for the whole plate- fin structure. These results will provide some constructive instructions in the design and safe operation for large- scale LNG cold- box.
In order to ensure the safe operation of large- scale cold- box,a finite element model( FEM)based on thermal elastic theory was proposed to simulate thermal stress distribution of plate- fin structure in large LNG cold box under the normal operating conditions. Thermal- stress direct coupling method was adopted in this analysis. By the thermal stress distribution in four paths marked in the structure,it is found that,in actual operating conditions,the first principal stress and the third principal stress reach to maximum value in brazed joint,the stress gradient is larger than that of other region and a crack would be occurred in this region. And the equivalent thermal stress based on third strength theory was also calculated in four paths. The result is consistent with the simulation results. Meanwhile,it also concluded that the most dangerous region is the outermost brazed joint between plate and fin for the whole plate- fin structure. These results will provide some constructive instructions in the design and safe operation for large- scale LNG cold- box.
引文
[1]Liu,Z.and R.H.S.Winterton,A GENERAL CORRELATION FOR SATURATED AND SUBCOOLED FLOW BOILING IN TUBES AND ANNULI,BASED ON A NUCLEATE POOL BOILING EQUATION[J].International Journal of Heat and Mass Transfer,1991.34(11):p.2759-2766.
[2]Peng,H.and X.Ling,Optimal design approach for the plate-fin heat exchangers using neural networks cooperated with genetic algorithms[J].Applied Thermal Engineering,2008.28(5-6):p.642-650.
[3]Ligterink,N.E.,S.V.Hageraats-Ponomareva,and J.F.M.Velthuis,Mechanical integrity of PFHE in LNG liquefaction process[C]//in 2nd Trondheim Gas Technology Conference,M.Barrio and H.J.Venvik,Editors.2012.p.49-55.
[4]Picard,F.,et al.,Modelling and Dynamic Simulation of Thermal Stresses in Brazed Plate-Fin Heat Exchanger[C]//16th European Symposium on Computer Aided Process Engineering and 9th International Symposium on Process Systems Engineering,2006.21:p.659-664.
[5]Mizokami,Y.,et al.Development of structural design procedure of plate-fin heat exchanger for HTGR[J].Nuclear Engineering and Design,2013.255:p.248-262.
[6]Aiyangar,A.K.,et al.The effects of stress level and grain size on the ambient temperature creep deformation behavior of an alpha Ti-1.6 wt pct V alloy[J].Metallurgical and Materials Transactions a-Physical Metallurgy and Materials Science,2005.36A(3):p.637-644.
[7]Galli,M.,J.Botsis,and J.Janczak-Rusch,Relief of the residual stresses in ceramic-metal joints by a layered braze structure[J].Advanced Engineering Materials,2006.8(3):p.197-201.
[8]Jiang,W.C.,et al.Finite element analysis of creep of stainless steel plate-fin structure[J].Acta Metallurgica Sinica,2007.43(5):p.539-545.
[9]Jiang,W.C.,et al.The effect of filler metal thickness on residual stress and creep for stainless-steel plate-fin structure[J].International Journal of Pressure Vessels and Piping,2008.85(8):p.569-574.
[10]Jiang,W.C.,et al.Numerical modelling and nanoindentation experiment to study the brazed residual stresses in an X-type lattice truss sandwich structure[J].Materials Science and Engineering a-Structural Materials Properties Microstructure and Processing,2011.528(13-14):p.4715-4722.
[11]Xie,Q.Y.and X.A.Ling,Numerical Analysis of Residual Stress for Copper Base Brazed Stainless Steel PlateFin Structure[J].Journal of Materials Engineering and Performance,2010.19(5):p.611-615.
[12]Jiang,W.C.,J.M.Gong,and S.T.Tu,A new cooling method for vacuum brazing of a stainless steel plate-fin structure[J].Materials&Design,2010.31(1):p.648-653.
[13]Jiang,W.C.,et al.Finite element analysis of the effect of welding heat input and layer number on residual stress in repair welds for a stainless steel clad plate[J].Materials&Design,2011.32(5):p.2851-2857.
[2]Peng,H.and X.Ling,Optimal design approach for the plate-fin heat exchangers using neural networks cooperated with genetic algorithms[J].Applied Thermal Engineering,2008.28(5-6):p.642-650.
[3]Ligterink,N.E.,S.V.Hageraats-Ponomareva,and J.F.M.Velthuis,Mechanical integrity of PFHE in LNG liquefaction process[C]//in 2nd Trondheim Gas Technology Conference,M.Barrio and H.J.Venvik,Editors.2012.p.49-55.
[4]Picard,F.,et al.,Modelling and Dynamic Simulation of Thermal Stresses in Brazed Plate-Fin Heat Exchanger[C]//16th European Symposium on Computer Aided Process Engineering and 9th International Symposium on Process Systems Engineering,2006.21:p.659-664.
[5]Mizokami,Y.,et al.Development of structural design procedure of plate-fin heat exchanger for HTGR[J].Nuclear Engineering and Design,2013.255:p.248-262.
[6]Aiyangar,A.K.,et al.The effects of stress level and grain size on the ambient temperature creep deformation behavior of an alpha Ti-1.6 wt pct V alloy[J].Metallurgical and Materials Transactions a-Physical Metallurgy and Materials Science,2005.36A(3):p.637-644.
[7]Galli,M.,J.Botsis,and J.Janczak-Rusch,Relief of the residual stresses in ceramic-metal joints by a layered braze structure[J].Advanced Engineering Materials,2006.8(3):p.197-201.
[8]Jiang,W.C.,et al.Finite element analysis of creep of stainless steel plate-fin structure[J].Acta Metallurgica Sinica,2007.43(5):p.539-545.
[9]Jiang,W.C.,et al.The effect of filler metal thickness on residual stress and creep for stainless-steel plate-fin structure[J].International Journal of Pressure Vessels and Piping,2008.85(8):p.569-574.
[10]Jiang,W.C.,et al.Numerical modelling and nanoindentation experiment to study the brazed residual stresses in an X-type lattice truss sandwich structure[J].Materials Science and Engineering a-Structural Materials Properties Microstructure and Processing,2011.528(13-14):p.4715-4722.
[11]Xie,Q.Y.and X.A.Ling,Numerical Analysis of Residual Stress for Copper Base Brazed Stainless Steel PlateFin Structure[J].Journal of Materials Engineering and Performance,2010.19(5):p.611-615.
[12]Jiang,W.C.,J.M.Gong,and S.T.Tu,A new cooling method for vacuum brazing of a stainless steel plate-fin structure[J].Materials&Design,2010.31(1):p.648-653.
[13]Jiang,W.C.,et al.Finite element analysis of the effect of welding heat input and layer number on residual stress in repair welds for a stainless steel clad plate[J].Materials&Design,2011.32(5):p.2851-2857.