增压锅炉锅筒应力及疲劳寿命分析
摘要
锅筒是锅炉中重要的受压元件,它连接上升管与下降管组成自然循环回路,同时接受省煤器来的给水,向过热器输送饱和蒸汽,它是加热、蒸发、过热这三个过程的连接点。锅筒运行工况极其复杂,不仅要承受内部较高的压力,还要承受冷、热态启停及变负荷时的循环机械应力和热应力,这些交变应力很容易产生疲劳破坏。因此,对锅炉锅筒进行应力分析,得出增压锅炉锅筒稳态及启动工况下应力的变化规律,可为增压锅炉最优启动方案提供一定的理论支持。
运用ANSYS软件建立了某增压锅炉锅筒的三维模型,对锅筒内压应力、热应力以及总应力分布进行三维有限元数值模拟分析。得出了6.5MPa压力下的稳态内压机械应力以及压力从常压增加到6.5MPa时的瞬态应力,按照第三类边界条件从常温增加到额定工况下的瞬态热应力。最后计算出压力以及温度共同作用下的稳态总应力和瞬态总应力。得到了锅筒的应力集中状况,并根据应力值和材料特性对锅筒进行了强度评定,为锅筒的安全运行和设计提供了依据。
模拟结果表明：此型增压锅炉最大应力值在锅筒孔沿轴向截面的内点,与压力成正比；而热应力值分布相对复杂,水汽交接面处较大,与上下锅筒温差成正比。总应力是内压应力和热应力的矢量和,在A点总应力小于机械应力,说明适当大小的热应力对内压应力有削弱作用；而在孔区的锅筒外壁总应力增大,热应力对内压应力有叠加的作用。
通过分析对比在不同标准下的锅筒低周期疲劳寿命,确定了最优的锅筒低周期疲劳寿命计算方法。为今后进行锅筒低周疲劳问题的研究打下了基础。
The drum is the most important pressurized component of boiler, and it connects with the riser tubes and downcomers of the natural circulation loop, at the same time drum gets the feed water from economizer and provides saturated steam for superheater. It is the junction of heating, evaporation and overheating. Drum running conditions are very complicated because it not only bear a high internal pressure but also endure cyclic mechanical stress and thermal stress induced easily fatigue wreck during cold, heat starting and stopping and variable conditions. Therefore, variable rules on stress of supercharged boiler drum in steady and startup period can provide theoretical support for optimal starting scheme of supercharged boiler through analysis of the boiler drum stress.
Three-dimensional model of a supercharged boiler drum was found using ANSYS software.3D finite element numerical simulation analysis was carried out for the internal pressure stress, thermal stress and total stress of the drum. Steady internal pressure mechanical stress on 6.5MPa, transient stress from normal pressure to 6.5MPa and the transient thermal stress from normal temperature to rated condition were attained. Finally, the steady and transient total stress was calculated when pressure and temperature imposed on the drum together. Then the drum stress concentration status was obtained. The intensity assessment according to stress value and material properties could provide evidence for the safety running and design.
The simulation results showed that the largest stress, which was proportional to the pressure, was on the internal point of drum hole along the axial section for the supercharged boiler. While the thermal stress distribution was relatively complicated, it was larger in the connecting face of steam-water, and proportional to the temperature difference between the steam drum and water drum. The total stress was vector sum of internal pressure stress and thermal stress. The total stress was smaller than mechanical stress on point A. It showed that appropriate thermal stress can weaken effect of internal pressure. But the total stress outside wall of drum around hole increased, which demonstrate that the thermal stress has superposition effect to the internal pressure stress.
The optimum calculation methods of low-cycle fatigue life for drum were determined by analysis and contrast of low-cycle fatigue life of drum for different standard. It established foundation for advanced research of low-cycle fatigue life of drum.
运用ANSYS软件建立了某增压锅炉锅筒的三维模型,对锅筒内压应力、热应力以及总应力分布进行三维有限元数值模拟分析。得出了6.5MPa压力下的稳态内压机械应力以及压力从常压增加到6.5MPa时的瞬态应力,按照第三类边界条件从常温增加到额定工况下的瞬态热应力。最后计算出压力以及温度共同作用下的稳态总应力和瞬态总应力。得到了锅筒的应力集中状况,并根据应力值和材料特性对锅筒进行了强度评定,为锅筒的安全运行和设计提供了依据。
模拟结果表明：此型增压锅炉最大应力值在锅筒孔沿轴向截面的内点,与压力成正比；而热应力值分布相对复杂,水汽交接面处较大,与上下锅筒温差成正比。总应力是内压应力和热应力的矢量和,在A点总应力小于机械应力,说明适当大小的热应力对内压应力有削弱作用；而在孔区的锅筒外壁总应力增大,热应力对内压应力有叠加的作用。
通过分析对比在不同标准下的锅筒低周期疲劳寿命,确定了最优的锅筒低周期疲劳寿命计算方法。为今后进行锅筒低周疲劳问题的研究打下了基础。
The drum is the most important pressurized component of boiler, and it connects with the riser tubes and downcomers of the natural circulation loop, at the same time drum gets the feed water from economizer and provides saturated steam for superheater. It is the junction of heating, evaporation and overheating. Drum running conditions are very complicated because it not only bear a high internal pressure but also endure cyclic mechanical stress and thermal stress induced easily fatigue wreck during cold, heat starting and stopping and variable conditions. Therefore, variable rules on stress of supercharged boiler drum in steady and startup period can provide theoretical support for optimal starting scheme of supercharged boiler through analysis of the boiler drum stress.
Three-dimensional model of a supercharged boiler drum was found using ANSYS software.3D finite element numerical simulation analysis was carried out for the internal pressure stress, thermal stress and total stress of the drum. Steady internal pressure mechanical stress on 6.5MPa, transient stress from normal pressure to 6.5MPa and the transient thermal stress from normal temperature to rated condition were attained. Finally, the steady and transient total stress was calculated when pressure and temperature imposed on the drum together. Then the drum stress concentration status was obtained. The intensity assessment according to stress value and material properties could provide evidence for the safety running and design.
The simulation results showed that the largest stress, which was proportional to the pressure, was on the internal point of drum hole along the axial section for the supercharged boiler. While the thermal stress distribution was relatively complicated, it was larger in the connecting face of steam-water, and proportional to the temperature difference between the steam drum and water drum. The total stress was vector sum of internal pressure stress and thermal stress. The total stress was smaller than mechanical stress on point A. It showed that appropriate thermal stress can weaken effect of internal pressure. But the total stress outside wall of drum around hole increased, which demonstrate that the thermal stress has superposition effect to the internal pressure stress.
The optimum calculation methods of low-cycle fatigue life for drum were determined by analysis and contrast of low-cycle fatigue life of drum for different standard. It established foundation for advanced research of low-cycle fatigue life of drum.
引文
[1]李章,张宁,刘祥源,姜滨,赵进刚,姜晓燕编著.舰用增压锅炉装置,海潮出版社,2000：1-8页
[2]郑思定,盛建国.调峰机组锅炉汽包壁温度场和热应力分析和低周疲劳设计[J].动力工程,1988,8(6)：18-25页
[3]邓文俭.1025t/h自然循环锅炉汽包的温度场和疲劳寿命损耗[J].华北电力技术.1994.(9)：13-16页
[4]商福民,吕邦泰,庞立平.锅炉汽包壁上下温差热应力有限元分析[J].华北电力大学学报.1999.26(01)：52-56页
[5]徐礼华.汽包上下壁温差对锅炉运行安全性影响的研究[J].电力技术.1992,(1)：2-7.
[6]联邦德国标准Technical Rules for Steam Boilers(TRD301),Edition April 1975.
[7]BS5500-91, Specification for Unfire Fusion Welded Pressure Vessel.1976
[8]Taler J, Weglowski B,Zima W,etal.Analysis of thermal stresses in a boiler drum during start-up.Journal of Pressure Vessel Technology.Transactions of the ASME.1999.121(1):84-93
[9]Isreb M.Superheater minimum stress unit start-up option of coal-fired power plants Computers and Structures.1997.62(5):865-875
[10]Kim T.S., Lee,D.K.;Ro,S.T.Analysis of thermal stress evolution in the steam drum during start-up of a heat recovery steam generator [J]. Applied Thermal Engineering.2000.20(11):977-992
[11]师俊平,李蹊,刘协会.汽包在复杂载荷作用下的应力分析[J].机械科学与技术.1997.16(2)：240-244
[12]赵铁成,沈月芬,梁艳明等.电站锅炉锅筒内压应力三维有限元分析[J].中国电机工程学报.1999.19(01)：31-33
[13]王运民.电厂锅炉锅筒寿命计算.热能动力工程,1997,12(6)：440-443
[14]任学平,高耀东.弹性力学基础及有限单元法[M].武汉：华中科技大学出版社,2007：61-65页
[15]邓凡平.ANSYS有限元分析自学手册[M].北京：人民邮电出版社,2007：24-44页
[16]王泽军.锅炉结构有限元分析[M].北京：化学工业出版社,2005：101-110页
[17]吴家龙,弹性力学[M].北京：高等教育出版社,2001：282-285页
[18]徐秉业,刘信声.应用弹塑性力学[M].北京：清华大学出版社,2003：188-191页
[19]唐兴伦,范群波,张朝晖等.ANSYS工程应用教程(热与电磁学篇).北京：中国铁道出版社,2003：79-80页
[20]刘长和.船用增压锅炉技术的新进展[J].热能工程.1999,14(4)：241-245页
[21]刘旭,商福民.锅炉汽包上下壁温差热应力的理论与数值计算[J].沈阳电力高等专科学校学报.1999,7：14-16页
[22]吉桂明,李汇文.应用于海军舰船的增压主锅炉[M].锅炉制造.1999,2(1)：23-29页
[23]杨世铭,陶文铨.传热学[M].北京：高等教育出版社,2002：424页
[24]黄飞,陶进庆.锅炉启停过程中汽包壁温度场的数值计算及温差应力估算[J].能源通讯.2000(1)：11-13页
[25]王栋,李余德,方钦志.蒸汽锅炉用钢与受压元件强度分析[M].北京：中国电力出版社,2005：65-69页
[26]余艳之,陈汝庆,马斌.锅炉汽包三维热应力及疲劳分析[J].电站系统工程.1999,15(6)：12-15页
[27]王海波.电站锅炉热应力分析及对策[J].科学技术与工程.2006,6(14)：2113-2115页
[28]吕瑞峰.火力发电厂锅炉汽包热应力分析及控制[M].内蒙古石油化工.2006,7：52-53页
[29]管德清,莫江春,吕黎明.300MW机组锅炉过程的优化研究[J].动力工程.2005,25(5)：609-613页
[30]徐钢.全面的锅炉寿命在线监测和管理系统的研究与开发.华北电力大学硕士学位论文.北京：华北电力大学.2003：43-52页
[31]王运民.电厂锅炉锅筒寿命计算.热能动力工程,1997,12(6)：442-444页
[32]李立萍,庞凯迈.锅炉汽包疲劳寿命的估算.华北水利水电学报,1999,20(6)：62-64页
[33]孟广波,潘效军.自然循环锅炉汽包寿命计算及影响因素分析.东北电力技术,1997,11：31-34页
[34]王金瑞,李益民等.电站高压锅炉汽包钢的疲劳性能及疲劳分析曲线.全国第四届电站构件失效分析与寿命管理学术会议,承德,1994.
[35]余庆芝,陈汝庆.HG670/140锅炉汽包壁三维温度场应力场分析及调峰优化.热力发电[M].1999(1)：18-20页
[36]吕邦泰,沈月芬.锅炉承压部件及寿命[M]北京：水利电力出版社,1992,124-132
[37]沈月芬,贾鸿祥.调峰机组锅炉汽包低周疲劳寿命与运行方式的关系[J].电力技术,1989,(2)：1-10
[38]赵志宏,杨春龙,薛锋等.2008t/h锅炉汽包疲劳寿命分析.华北电力技术.2007(8)：9-15页
[2]郑思定,盛建国.调峰机组锅炉汽包壁温度场和热应力分析和低周疲劳设计[J].动力工程,1988,8(6)：18-25页
[3]邓文俭.1025t/h自然循环锅炉汽包的温度场和疲劳寿命损耗[J].华北电力技术.1994.(9)：13-16页
[4]商福民,吕邦泰,庞立平.锅炉汽包壁上下温差热应力有限元分析[J].华北电力大学学报.1999.26(01)：52-56页
[5]徐礼华.汽包上下壁温差对锅炉运行安全性影响的研究[J].电力技术.1992,(1)：2-7.
[6]联邦德国标准Technical Rules for Steam Boilers(TRD301),Edition April 1975.
[7]BS5500-91, Specification for Unfire Fusion Welded Pressure Vessel.1976
[8]Taler J, Weglowski B,Zima W,etal.Analysis of thermal stresses in a boiler drum during start-up.Journal of Pressure Vessel Technology.Transactions of the ASME.1999.121(1):84-93
[9]Isreb M.Superheater minimum stress unit start-up option of coal-fired power plants Computers and Structures.1997.62(5):865-875
[10]Kim T.S., Lee,D.K.;Ro,S.T.Analysis of thermal stress evolution in the steam drum during start-up of a heat recovery steam generator [J]. Applied Thermal Engineering.2000.20(11):977-992
[11]师俊平,李蹊,刘协会.汽包在复杂载荷作用下的应力分析[J].机械科学与技术.1997.16(2)：240-244
[12]赵铁成,沈月芬,梁艳明等.电站锅炉锅筒内压应力三维有限元分析[J].中国电机工程学报.1999.19(01)：31-33
[13]王运民.电厂锅炉锅筒寿命计算.热能动力工程,1997,12(6)：440-443
[14]任学平,高耀东.弹性力学基础及有限单元法[M].武汉：华中科技大学出版社,2007：61-65页
[15]邓凡平.ANSYS有限元分析自学手册[M].北京：人民邮电出版社,2007：24-44页
[16]王泽军.锅炉结构有限元分析[M].北京：化学工业出版社,2005：101-110页
[17]吴家龙,弹性力学[M].北京：高等教育出版社,2001：282-285页
[18]徐秉业,刘信声.应用弹塑性力学[M].北京：清华大学出版社,2003：188-191页
[19]唐兴伦,范群波,张朝晖等.ANSYS工程应用教程(热与电磁学篇).北京：中国铁道出版社,2003：79-80页
[20]刘长和.船用增压锅炉技术的新进展[J].热能工程.1999,14(4)：241-245页
[21]刘旭,商福民.锅炉汽包上下壁温差热应力的理论与数值计算[J].沈阳电力高等专科学校学报.1999,7：14-16页
[22]吉桂明,李汇文.应用于海军舰船的增压主锅炉[M].锅炉制造.1999,2(1)：23-29页
[23]杨世铭,陶文铨.传热学[M].北京：高等教育出版社,2002：424页
[24]黄飞,陶进庆.锅炉启停过程中汽包壁温度场的数值计算及温差应力估算[J].能源通讯.2000(1)：11-13页
[25]王栋,李余德,方钦志.蒸汽锅炉用钢与受压元件强度分析[M].北京：中国电力出版社,2005：65-69页
[26]余艳之,陈汝庆,马斌.锅炉汽包三维热应力及疲劳分析[J].电站系统工程.1999,15(6)：12-15页
[27]王海波.电站锅炉热应力分析及对策[J].科学技术与工程.2006,6(14)：2113-2115页
[28]吕瑞峰.火力发电厂锅炉汽包热应力分析及控制[M].内蒙古石油化工.2006,7：52-53页
[29]管德清,莫江春,吕黎明.300MW机组锅炉过程的优化研究[J].动力工程.2005,25(5)：609-613页
[30]徐钢.全面的锅炉寿命在线监测和管理系统的研究与开发.华北电力大学硕士学位论文.北京：华北电力大学.2003：43-52页
[31]王运民.电厂锅炉锅筒寿命计算.热能动力工程,1997,12(6)：442-444页
[32]李立萍,庞凯迈.锅炉汽包疲劳寿命的估算.华北水利水电学报,1999,20(6)：62-64页
[33]孟广波,潘效军.自然循环锅炉汽包寿命计算及影响因素分析.东北电力技术,1997,11：31-34页
[34]王金瑞,李益民等.电站高压锅炉汽包钢的疲劳性能及疲劳分析曲线.全国第四届电站构件失效分析与寿命管理学术会议,承德,1994.
[35]余庆芝,陈汝庆.HG670/140锅炉汽包壁三维温度场应力场分析及调峰优化.热力发电[M].1999(1)：18-20页
[36]吕邦泰,沈月芬.锅炉承压部件及寿命[M]北京：水利电力出版社,1992,124-132
[37]沈月芬,贾鸿祥.调峰机组锅炉汽包低周疲劳寿命与运行方式的关系[J].电力技术,1989,(2)：1-10
[38]赵志宏,杨春龙,薛锋等.2008t/h锅炉汽包疲劳寿命分析.华北电力技术.2007(8)：9-15页
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