大容量电站锅炉受热面管子的可靠性设计与寿命评定

以传统的设计方法为基础，提出了大容量电站锅炉受热面管子的振动和强度可靠性设计方法以及寿命的评定方法。在振动可靠性设计方面，把卡门漩涡频率和声学驻波频率处理为随机变量，使用概率设计法确定锅炉尾部受热面振动设计的可靠度。在强度可靠性设计方面，把锅炉受热面管子的外径、壁厚、管内压力、材料强度等设计量根据实际处理为随机变量，使用可靠性分析技术确定锅炉受热面管子强度设计的可靠度。在寿命评定方面，对锅炉受热面管子的寿命数据进行统计分析，确定锅炉受热面管子的平均寿命。通过对锅炉受热面管子壁厚的监测和跟踪，确定锅炉受热面管子的剩余寿命。给出了水冷壁、过热器、再热器和省煤器管子强度可靠性设计的实例、管式空气预热器管束振动的可靠性设计实例和锅炉过热器管子寿命评定的实例。表1参9     

某热电厂锅炉过热器管爆管原因分析

通过宏观检查、化学成分分析、金相分析、硬度试验和扫描电镜分析等分析方法,对锅炉过热器管爆管原因进行了分析,结果表明:管子存在严重超温运行情况,导致管子完全脱碳强度降低,同时导致管子过热,加重了内表面氧化和外表面烟气腐蚀情况。内表面氧化和外表面烟气腐蚀同时作用使管子壁厚严重减薄,管子因承压能力不足最终爆管。     

排管及管子计算程序开发

在高加设计中，需要确定筒体内部排管的数量、位置，以及管子的重量、有效面积等，由于管子的数量较多，人工计算比较复杂而且易出错，因此开发并利用软件来进行计算，速度快且准确，为高加排管及管子计算、管子订货提供了重要参考。     

某超超临界机组末级过热器泄漏原因分析

针对发生泄漏的末级过热器管进行失效分析。通过宏观检查、金相检验、硬度检验及扫描电镜分析,对管子泄漏原因进行综合评判。结果表明：管子在制造过程中成型工艺控制不当,导致管内壁存在大量轴向分布的线性缺陷,在服役过程中缺陷向管子内部扩展,造成管子有效壁厚减小;服役过程中随着管子组织的老化,性能逐渐劣化,导致管子承压能力下降,最终某处裂纹失稳扩展导致泄漏,引起多处裂纹扩展,形成天窗状爆口。     

循环流化床锅炉水冷壁布风板管爆管失效分析

根据现场调研及取样分析,对某电厂的循环流化床锅炉水冷壁布风板管进行了失效分析。通过采用光谱分析、硬度测量、金相显微观察等实验手段,对失效管子的化学成分、力学性能以及显微组织进行了表征分析。确定了管子失效是由于浇注料脱落造成管子受热不均,结合管子自身组织缺陷,产生导致贯穿性疲劳裂纹从而导致管子泄漏。最后根据实际情况,提出了预防措施和建议。     

机器人激光焊接装置改善蒸发器的返修

为了蒸发器管子腐蚀的返修开发了一种使用机器人和CO_2激光的新的焊接方法,与其它溶化焊方法相比,它能适应更宽的温度范围和几何形状,并且在比利时的许多核动力工厂已经成功地得到了证实。早期蒸发器返修主要是剥蚀管子的赌塞,这最终将导致降低发电厂的效益或者更换整台蒸发器。套管是在原来的管子内插入一根新的管子,并且在已腐蚀的管子上、下     

鉴别临危管子预防锅炉爆管

该文计算分析了锅炉受热面管子热应力松弛，内壁氧化膜生长及管子壁厚损失的进展过程及它们在管子破坏中的作用，并把分析结果用到高参数锅炉管子寿命计算中，得到了合理的结果。     

一起循环流化床锅炉屏式再热器爆管原因分析

通过宏观检查、尺寸测量、厚度和硬度测定、化学成分分析、金相分析、X衍射分析,分析了某电厂屏式再热器管子发生爆管的原因。经分析爆管主要是由于超温运行使管子内外壁产生大量氧化层,并导致管子过热所致。通过分析原因,为电厂提出了可行的改进措施和建议。     

一种弹簧式烟管清灰机

一种弹簧式烟管清灰机是一种利用弹簧在管内，通过推或拉力使弹簧延管子轴向产生运动，弹簧运动时弹簧外径将管子内壁沾结的灰垢先从管壁上剥离下来，剥离下来的灰垢一部分会被弹簧直接带出管子，未被带出的灰垢可通过空气吹、吸或利用水冲等方式将其清理出管子，从而达到对烟管清灰的目的。     

某电厂660MW超超临界锅炉螺旋水冷壁超温事故分析

某超超临界锅炉启动初期螺旋管水冷壁超温。割管检查,发现超温管子焊缝内壁存在焊瘤,焊瘤的节流作用使管子内介质流量减少,导致管子超温停炉。     

欧洲管件标准与中国管件标准对比研究

  目的  为了满足近期欧洲电站工程建设需要,亟需了解电站工程中欧洲管道及管件标准的要求。  方法  针对管件,将欧洲管件标准与国内管件标准相应条款逐一对比。  结果  经过对比,获得了欧洲管件标准与国内管件标准的差异:欧标管件在行业使用范围、管材使用范围上更全面;欧标管件的尺寸偏差、焊接端壁厚偏差、形位偏差,总体比国标要求严格;欧洲管件强度计算标准保守一些,更偏于安全;欧洲管件在管件端部坡口、通流面积、弯头弯曲半径等方面相对国标管件有其特点;另外,进入欧洲市场的管件需要遵守欧盟行政指令PED指令。  结论  通过上述标准差异,基本掌握了欧标管件标准的基本要求,可为电站工程欧标管件实际应用提供指导。     

Effect of reinforcement on plastic limit loads of branch junctions

This paper provides effects of reinforcement shape and area on plastic limit loads of branch junctions under internal pressure and in-plane/out-of-plane bending, via detailed three-dimensional finite element limit analysis assuming elastic-perfectly plastic material behaviour. It is found that reinforcement is most effective when (in-plane/out-of-plane) bending is applied to the branch pipe. When bending is applied to the run pipe, reinforcement is less effective when bending is applied to the branch pipe. The reinforcement effect is the least effective for internal pressure.     

Limit moment of local wall thinning in pipe under bending

In engineering practice, pipe containing local wall thinning may be subjected to bending load. The existence of local wall thinning on pipe surface impairs the load-carrying capacity of pipe. In order to maintain the integrity of the pipe containing local wall thinning, it is very important to develop a method to evaluate such a pipe with local wall thinning under bending. In this paper, the limit moment of local wall thinning pipe under pure bending is computed employing 3D elastic–plastic finite element analysis. The results show that the limit moment of pipe is affected not only by the width of defect but also by the longitudinal length of defect. When the longitudinal length of defect overpasses some critical value, the results from net-section collapse criterion (NSC) are in very reasonable agreement with the results from finite element analysis. Therefore, the NSC formula can conservatively be used to assess the limit load-carrying capability of local wall thinning pipe under bending.     

缠绕拉拔式弯管主要工艺参数数值模拟

利用美国大型通用有限元软件ANSYS模拟缠绕拉拔式弯管工艺过程。通过模拟，计算管子弯曲变形所需的弯矩，计算管子弯曲部分外壁减薄率和椭圆度。利用ANSYS的参数化设计语言，使所做的分析适用于不同的管子直径、材料、弯曲半径。     

Limit loads for piping branch junctions under internal pressure and in-plane bending—Extended solutions

The authors have previously proposed plastic limit load solutions for thin-walled branch junctions under internal pressure and in-plane bending, based on finite element (FE) limit loads resulting from three-dimensional (3-D) FE limit analyses using elastic–perfectly plastic materials [Kim YJ, Lee KH, Park CY. Limit loads for thin-walled piping branch junctions under internal pressure and in-plane bending. Int J Press Vessels Piping 2006;83:645–53]. The solutions are valid for ratios of the branch-to-run pipe radius and thickness from 0.4 to 1.0, and for the mean radius-to-thickness ratio of the run pipe from 10.0 to 20.0. Moreover, the solutions considered the case of in-plane bending only on the branch pipe. This paper extends the previous solutions in two aspects. Firstly, plastic limit load solutions are given also for in-plane bending on the run pipe. Secondly, the validity of the proposed solutions is extended to ratios of the branch-to-run pipe radius and thickness from 0.0 to 1.0, and the mean radius-to-thickness ratio of the run pipe from 5.0 to 20.0. Comparisons with FE results show good agreement.     

Limit loads for pipe bends under combined pressure and in-plane bending based on finite element limit analysis

Approximate plastic limit load solutions for pipe bends under combined internal pressure and bending are obtained from detailed three-dimensional (3-D) FE limit analyses based on elastic-perfectly plastic materials with the small geometry change option. The FE results show that existing limit load solutions for pipe bends are lower bounds but can be very different from the present FE results in some cases, particularly for bending. Accordingly closed-form approximations are proposed for pipe bends under combined pressure and in-plane bending based on the FE results.     

Buckling analysis of flanged curvilinear pipes in pure bending

The geometrically nonlinear problem of pure bending of a thin-walled elastic curvilinear pipe terminated by totally rigid flanges is studied by the finite-element method. The stiffening effect of the flanges is modeled by imposing special boundary conditions on the end cross sections. The buckling behavior is studied and the values of the critical bending moment are obtained for a wide range of geometrical parameters of the pipe.     

The interaction of pressure and bending on a dented pipe

Results are presented from an FE numerical study of the capacity of a dented pipe to withstand combined pressure and moment loading. The denting process was modelled with internal pressure applied at the design level. The pipe support was modelled by a saddle-type arrangement. The strength of the dented pipe was first assessed under pure bending, applied in such a way that the dent was either on the tension side or the compression side. The strength of the dented pipe was then assessed under internal pressure loading. Finally, the behaviour of the dented pipe under combined bending and pressure loading was assessed and interaction diagrams prepared.     

金属管件的弯曲工艺和弯管模结构形式

对管子的弯曲方式、应力分布及方案选用进行了比较、确定。     

Cross-sectional flattening of pipes subjected to bending

Pipes subjected to bending may fail by cross-sectional flattening due to a plastic hinge mechanism occurring at the mid-section. In this paper the relationship between the applied bending moment and the stresses and strains at the neutral axis is calculated, using a power law stress-strain relationship. As a tentative failure criterion, a critical local bending radius of the pipe wall was selected. It can be expected that failure by the flattening mechanism occurs in the medium range of wall thickness to pipe radius ratio. For smaller ratios buckling on the compressive side—and, for larger ratios, fracture on the tensile side—of the pipe is shown to be the failure mechanism.