一台垃圾焚烧锅炉低温过热器管爆管原因分析及建议

某热电厂一台垃圾焚烧锅炉(型号为SLC400-5.3/450)于2019年8月投入使用,2020年3月开始出现低温过热器管频繁爆管,通过宏观检查、壁厚测定、硬度分析、金相检验、扫描电镜能谱分析等方法对失效低温过热器管进行分析。结果表明,低温过热器管爆管的机理是锅炉内部产生了酸性环境,使管子外表面发生腐蚀,加上烟气冲蚀,管子壁厚减薄强度不足而爆管。并给出相应的预防及改进建议。     

胀接工艺对镍基合金换热管残余应力的影响

胀接残余拉伸应力是造成核岛换热设备换热管应力腐蚀开裂的主要原因。选取SB -163 UNS N06690镍基合金换热管开展胀接试验,检测分析换热管胀接残余应力。研究结果表明：换热管胀接过渡区残余拉应力最大,胀接区域次之,未胀接区域最小;机械胀接工艺使管子变形量明显大于液压胀接,过渡区域残余拉应力相对较大,且随壁厚减薄率的增加而变大。     

锅炉受热面产品不同规格T91材料里氏与布氏硬度设备检测对比研究

里氏硬度计检测效率高，但其测量精度受到设备设定和多种外界因素影响，一般低于实际硬度，特别是对于锅炉受热面小管，误差较大。本文针对不同规格的锅炉受热面小径管T91材料开展同位置里氏与布氏设备的对比研究，分析两种设备测量值的差异。通过对比过程和结果表明，布氏设备测量稳定、准确，但在采用C型设备进行测量时建议使用辅助工装进行定位，以保证设备测量探头与管子轴线对中垂直；管子表面打磨状态对测量硬度值影响不大；不同检测人员的里氏测量值变化不大。不同布氏与里氏测量对比差值与管子壁厚存在一定的规律，管子壁厚越薄，对比差值越大，里氏测量值更偏低；管子壁厚越厚，对比差值越小，里氏测量值更偏高。     

B30白铜管的多频涡流检测

1前言B30白钢管是化工厂制盐的重要生产设备，这些设备工作在高温、高压和强腐蚀介质中，管壁容易受到损伤和破坏，严重威胁着化工设备的安全生产和运行，为了确保工厂B3O白铜管经常处于完好状态，必须对化工设备中B30白钢管进行定期在役检测维修，对拟更换的新管也需进行役前检测，防止带缺陷服役，造成不应有损失。涡流无损检测方法是B3O等金属管材役前和在役检测的主要手段。B30白钢管的涡流检测主要检验管材的机械损伤（凹坑和刮伤等），裂纹和壁厚腐蚀减薄等缺陷，通过涡流信号分析管道内，外壁的缺陷情况。我公司制盐设备，每台换…     

钻杆内壁腐蚀的交直流复合磁化漏磁检测方法

钻杆长期服役后内壁出现的腐蚀是造成钻杆断裂的主要原因,针对钻杆内壁腐蚀的检测,提出了一种基于复合磁化的漏磁检测方法.该方法通过阵列感应线圈拾取钻杆外壁交流磁场的变化,进而评价内壁腐蚀产生的壁厚减薄状态,规避了强背景磁场下用霍尔元件测量磁场时量程范围不足、灵敏度不够等问题.利用有限元仿真软件分析壁厚减薄上方的相对磁导率分...     

基于参数反演算法的铁磁构件腐蚀减薄缺陷脉冲涡流检测方法北大核心CSCD

为减小脉冲涡流检测技术在承压设备壁厚腐蚀减薄检测中的误差,基于铁磁平板脉冲涡流场的时域解析式,建立时域感应电压测量值与理论计算值之间的最小二乘参数反演。将被检构件的电导率设为固定常数,然后将2处检测点壁厚的反演结果作对比,得到2处检测点之间壁厚相对变化量。在钢板上加工矩形槽缺陷,实验验证了文中相对壁厚检测方法,可消除构件电导率设定值的影响。当腐蚀区域面积大于探头足底面积时,可准确扫查出腐蚀区域的剩余壁厚,且对腐蚀区域的边缘有较好的识别能力;当减薄区域面积小于探头足底面积时,局部腐蚀缺陷的减薄程度会被低估。利用脉冲涡流法检测铁磁构件相对壁厚,无须与被检构件接触,检测结果直观,重复精度高,可用于工业上带包覆层铁磁构件壁厚腐蚀减薄的无损检测与评估。     

管子－管板液压胀接管内缺陷的产生机理及防止

全深度液压胀接技术是核电机组蒸汽发生器及其他换热器管子－管板接头普遍采用的制造工艺。液压胀接具有操作简单、胀后变形均匀、壁厚减薄率低、残余应力小等优点,但也会产生管内划伤、胀接长度超差等管内缺陷,薄壁管厚管板胀接时胀接过渡区的管子内部缺陷产生的几率更高。对液压胀接时管子长度缩短量、壁厚减薄率进行了理论计算和测量,对过渡区胀接芯轴和管子受力进行分析,表明过渡区管子内部缺陷是由于管子长度缩短效应及管子受力共同作用产生的,胀接区的划痕缺陷主要是由于芯轴损伤及金属颗粒残留引起的,未胀区胀接长度超差主要是由于芯轴设定失误引起的。通过改进胀接芯轴密封形式和限位止环的设计,证明采用芯轴保护套及非膨胀式的限位止环等工艺措施能够有效避免管内缺陷的发生。     

漏磁场法测量油管壁厚的研究

在石油开采中,油管内壁杆状磨损和内外壁大面积腐蚀引起的壁厚减薄缺陷是造成油管失效的主要原因之一,本文提出了一种油管壁厚漏磁场测量方法,结果表明,该方法具有精度和灵敏度高,可在线测量等特点,为表面受油泥或其它非导磁性材料覆盖的旧油管的现场检测提供了新的方法与手段。     

探讨超声波对小径管焊缝的检测

在超声波探伤中,对于管径≤57mm,壁厚〈6mm的管子,由于管径小,曲率大,管壁薄,用检测中厚壁管的超声波探伤方法进行检测是很困难的。因为一般斜探头的前沿距离长（在15mm左右）。用一次波探伤时,主声扫查不到焊缝的根部,用二次波探伤时,因探头发射的声束宽、声束扩散及小径管内弧面的折射和散射影响,造成屏幕上回波游动范围大,反射回波和声程信息杂乱,判定缺陷困难。     

管道腐蚀检测自动扫查器方案设计

该文设计了一款针对管道腐蚀检测的自动扫查器,该扫查器由圆周导轨加橡胶轮的组合结构实现在管道外表面的轴向移动;同时,直线导轨搭载相控阵探头,以圆周导轨为路径在管道外表面进行周向扫描,从而实现对管道腐蚀的全方位检测。相比于手动检测,避免了由于人为因素造成的误差,提高了检测效率,降低了作业强度。     

Minimal Realization of Linear Graph Models for Multi-physics Systems

An engineering system may consist of several different types of components,belonging to such physical"domains"as mechanical,electrical,fluid,and thermal.It is t...     

INTEGRAL EQUATION METHOD＇S APPLICATION IN HOLE-EDGE STRESS OF COMPOSITE MATERIAL PLATE WITH DIFFERENT SHAPED HOLES

The strength of composite plate with different hole-shapes is always one of the most important but complicated issues in the application of the composite material. The holes will lead to mutations and discontinuity to the structure. So the hole-edge stress concentration is always a serious phenomenon. And the phenomenon makes the structure strength decrease very quickly to form dangerous weak points. Most partial damage begins from these weak points. According to the complex variable functions theory, the accurate boundary condition of composite plate with different hole-shapes is founded by conformal mapping method to settle the boundary condition problem of complex hole-shapes. Composite plate with commonly hole-shapes in engineering is studied by several complex variable stress fimction. The boundary integral equations are founded based on exact boundary conditions. Then the exact hole-edge stress analytic solution of composite plate with rectangle holes and wing manholes is resolved. Both of offset axis loadings and its influences on the stress concentration coefficient of the hole-edge are discussed. And comparisons of different loads along various offset axis on the hole-edge stress distribution of orthotropic plate with rectangle hole or wing manhole are made. It can be concluded that hole-edge with continuous variable curvatures might help to decrease the stress concentration coefficient; and smaller angle of outer load and fiber can decrease the stress peak value.     

Non-monotonic material contrast in scanning ion and scanning electron images

30 keV Ga⁺ focused ion beam induced secondary electron (iSE) imaging was used to determine the relative contrast between several materials. The iSE signal compared from C, Si, Al, Ti, Cr, Ni, Cu, Mo, Ag, and W metal layers does not decrease with an increase in target atomic number Z₂, and shows a non-monotonic relationship between contrast and Z₂. The non-monotonic relationship is attributed to periodic fluctuations of the stopping power and sputter yield inherent to the ion–solid interactions. In addition, material contrast from electron-induced secondary electron (eSE) and backscattered electron (BSE) images using scanning electron microscopy (SEM) also shows non-monotonic contrast as a function of Z₂, following the periodic behavior of the stopping power for electron–solid interactions. A comparison of the iSE and eSE results shows similar relative contrast between the metal layers, and not complementary contrast as conventionally understood. These similarities in the contrast behavior can be attributed to similarities in the periodic and non-monotonic function defined by incident particle–solid interaction theory.     

Application of Feature Extraction through Convolution Neural Networks and SVM Classifier for Robust Grading of Apples

This paper proposes a novel grading method of apples,in an automated grading device that uses convolutional neural networks to extract the size,color,texture,an...     

分布动态载荷识别的抗噪处理

针对正交多项式频域法在用多种响应对矩形薄板进行载荷识别中抗噪性较差的问题,综合运用平均法、矩阵预处理和奇异值截断法等方法对之进行改善,并引入空间映射的思想,将该方法的应用范围拓展为复杂的模型.利用仿真算例,证实了该方法具有较好的抗噪性.     

基于MELTAC-N平台的核电厂安全级DCS环网研究与测试

针对工程实践中环网通讯相关问题的处理缺乏理论基础及国产化安全级DCS平台的开发缺乏成熟经验借鉴问题,对基于MELTAC-N平台核电厂安全级DCS环网的软硬件实现进行了研究。提出了安全级DCS环网双环网冗余设计、光切换开关设计等硬件设计方法,以及以RPR协议为基础,采用全数据收发策略的软件设计方法。在CPR1000安全级DCS平台上对安全级DCS环网的可靠性及实时性进行了评价,并进行了容错能力、响应时间及响应时间稳定性测试验证实验。结果表明,基于MELTAC-N平台安全级DCS环网软硬件设计具有较好的容错能力及响应时间稳定性。     

Short-Term Relay Quality Prediction Algorithm Based on Long and Short-Term Memory

The fraction defective of semi-finished products is predicted to optimize the process of relay production lines, by which production quality and productivity ar...     

End-to-End Multiview Gesture Recognition for Autonomous Car Parking System

The use of hand gestures can be the most intuitive human-machine interaction medium.The early approaches for hand gesture recognition used device-based methods....     

The laboratory simulation of abrasive wear

Abrasive wear has long been recognised as one of the most potentially serious tribological problems facing the operators of many types of plant and machinery; several industrial surveys have indicated that wear by abrasion can be responsible for more than 50% of unscheduled machine and plant stoppages. Locating the operating point of a tribological contact in an appropriate operational ‚map’︁ can provide a useful guide to the likely nature and origins of the surface degradation experienced in use, though care must be exercised in choosing the most suitable parameters for the axes of the plot. Laboratory testing of materials and simulations of machine contacts are carried out for a number of purposes; at one level for the very practical aims of ranking candidate materials or surface hardening treatments in order of their wear resistance, or in an attempt to predict wear lives under field conditions. More fundamentally, tests may be aimed at elucidating the essential physical mechanisms of surface damage and loss, with the longer term aim of building an analytical and predictive model of the wear process itself. In many cases, component surface damage is brought about by the ingress of hard, particulate matter into machine bearing or sealing clearances. These may be running dry although, more usually, a lubricant or service fluid is present at the interface. A number of standardised wear test geometries and procedures have been established for both two- and three-body wear situations, and these are briefly described. Although abrasive wear is often modelled as following an ‚Archard’︁ equation (i.e. a linear increase in material loss with both load and time, and an inverse dependence on specimen hardness) both industrial experience and laboratory tests of particularly lubricated contacts show that this is not always the case: increasing the hardness differential in an abrasively contaminated lubricated pair may not always reduce the rate of damage to the harder surface.     

ANGULAR DISTORTION ALLOWABLE VALUE AND ASSESS METHOD OF WELD ON COKE TOWER

A graph as the new engineering method for estimate the safety of bulging deformation of coke tower is proposed. Through stresses analysis of circumferential weld of coke tower and comparing the stresses produced by pressure with heat stress of steady state, residual stress, bending stress produced by both itself weight and wind loads, it showed that the stresses produced by pressure on the angle distortion are the main factor of equivalent stress of the combined stress. After comparing four kinds of stress controlling conditions, the relation to stress with depth of angular distortion, grade of curvature of angular distortion and half of region of angular distortion has been inferred. Graph of deformation allowable value of coke tower for different condition by angular distortion and half of region of angular distortion has been plotted. The five steps for its engineering use have been explained. The lighter the grade of curvature is, the larger of bulge allowance, may be, and the bigger of depth of angular distortion may pose too. For the coke tower with a popular structure of Dg 5 400 mm×28 mm, the result by graph is nearly more than the result of two formulas formed by other research, the error is less than 7.0%. But, the graph can be easily applied to different size of angular distortion.