火电厂锅炉再热器管高温腐蚀研究

对TP304H(0Crl9Ni9)钢锅炉再热器管内壁水蒸气氧化和外壁烟气高温腐蚀的锈层截面进行了观察与分析，确定了锈层的结构、成分和生长规律，并据此估算了管子的使用寿命。研究发现TP304H再热器管内壁在高温水蒸气环境下氧化产物层由外层和内层两部分组成，在外层与内层之间存在大量孔洞，并且外层发生了明显的剥落，剥落层厚度约为100μm。再热器管外壁则遭受含硫气氛的高温腐蚀和烟气冲刷磨损两种形式的破坏，烟气冲刷加剧了腐蚀的进行。     

凝汽器铜管腐蚀研究

某电厂凝汽器铜管在抽查中发现管内壁发生不均匀腐蚀,腐蚀区呈裂纹状,沿管轴向或沿与轴向45度方向扩展.对腐蚀后凝汽器黄铜管进行了成分分析、力学性能及残余应力测试、织构测试;用金相显微镜和扫描电镜进行观察及能谱分析;并用该黄铜管在实验室中进行了疲劳模拟试验.结果表明,凝汽器黄铜管内壁出现的裂纹状损伤是由于疲劳腐蚀引起的.     

船舶冷却系统铜镍合金管腐蚀穿孔原因

采用体视显微镜、金相显微镜、电子探针等分析测试方法对腐蚀穿孔失效的BFe10-1.6-1铜镍合金管进行失效分析。结果表明：失效管的内壁存在不同程度的划痕，且腐蚀坑内壁显微组织呈现“波纹”状，符合海水冲刷腐蚀的特征；腐蚀区的显微组织呈现“冰糖块”状，符合晶间腐蚀的特征；腐蚀坑内的泥沙沉积致使管道发生点蚀。结合船用铜镍合金管的使用工况，确认该失效管腐蚀穿孔失效的主要原因是海水冲刷腐蚀、晶间腐蚀及点蚀。     

超超临界火电机组热交换器BFe10-1-1白铜管泄漏分析

某超超临界火电机组热交换器BFe10-1-1白铜管运行4a(年)后发生泄漏失效。通过宏观观察、化学成分分析、金相检验、断口分析、管子内壁沉积物检验等方法对白铜管的失效原因进行了分析。结果表明:白铜管内壁存在明显的沉积物,沉积物下形成氧浓差腐蚀,导致管子内壁产生点腐蚀;点腐蚀坑区域Cl~-存在对于晶界部位的铁元素产生进一步腐蚀使得富集于晶界处的铁元素不断流失而形成空位,空位的不断形成及合并导致晶间裂纹的萌生,最终导致管子发生晶间腐蚀开裂。     

滑油管裂纹分析

采用显微组织、断口分析及微区成分分析等手段,对滑油管裂纹进行了分析.结果表明,在长期停放过程中,滑油管内壁由于氯离子作用产生局部腐蚀.在装机使用后,由于振动应力的作用,产生了早期疲劳裂纹.滑油管裂纹系装机使用前管内壁腐蚀损伤引起的疲劳裂纹.     

换热管束腐蚀分析及对策研究

大庆某炼油厂的换热器管束发生泄漏，利用进口扫描电镜和能谱仪对换热器管体内外壁和内壁涂层进行检测分析，发现泄漏原因是管体内壁的涂层存在质量问题，改进措施是采用钛纳米涂层换热管束，很好地解决了管束腐蚀泄漏问题。     

凝汽器黄铜管失效分析

采用宏观观察、化学成分分析、金相检验、氨重试验以及能谱分析等方法对凝汽器铜管存在坑点腐蚀的原因进行了分析。结果表明：在黄铜管的加工中使用了热裂解性能较差的内模拉伸润滑油而使其内壁粘附着炭质沉积膜，加上黄铜管未采用硫酸亚铁成膜处理以及机组运行中也未进行定期胶球清洗等是造成其腐蚀的因素，其中炭质沉积膜的存在是导致黄铜管在冷却水的作用下形成坑点腐蚀的主要原因。提出了预防凝汽器黄铜管坑点腐蚀的对策。     

球墨铸铁煤气管道泄漏原因分析

通过宏观和微观分析等手段,对某QT400-18球墨铸铁煤气管道泄漏原因进行了分析。由宏观分析可知管道腐蚀泄漏是由局部腐蚀穿孔所致,腐蚀从内壁开始,由内向外直至穿孔泄漏;微观分析没有观察到微裂纹等缺陷,成分分析可知管道内壁腐蚀产物中含有大量硫元素,说明管道腐蚀泄漏的产生与管内介质中含有硫元素有关。综合分析结果表明:由于所输送煤气中含硫杂质超标,与管内壁冷凝水共同作用产生局部电化学腐蚀,从而导致了煤气管道的局部穿孔泄漏。建议在生产中将煤气中的有害杂质和水分含量控制在工艺要求范围内。     

某井油管腐蚀原因分析

对某井油管检查发现,管体内外壁均有不同程度的腐蚀,但是在某些井段腐蚀最严重。对油管管体的化学成分分析、金相显微组织检测和SEM,EDS及XRD的分析结果表明:管体具有正常的化学成分和金相组织,腐蚀坑底部有大量的腐蚀产物堆积,Cl-在腐蚀产物层下富集。油管内壁产物为FeCO3,MgFe(CO3)2,FeO(OH),Mg3Ca(CO3)4和Fe3O4,外壁产物主要有FeCO3,MgFe(CO3)2,CaCO3和FeO(OH)。表明该井油管内壁腐蚀原因为CO2腐蚀,内壁腐蚀穿孔后,腐蚀性的介质和气体由此进入套管和油管的环空造成油管外壁CO2腐蚀。井深3279m处油管处于CO2腐蚀速率最大的温度区间,腐蚀最严重。Cl-的富集是诱发局部腐蚀的主要原因。     

冷凝器中的镍白铜管泄漏分析

对镍白铜管的材质、显微组织及其腐蚀产物进行了分析，结果表明，由于管内壁粘附有一层碳膜，并与基体形成了微电池，在浓缩的长江水中，促进了腐蚀作用，导致冷凝器管早期泄漏。提出了改进措施后，避免了冷凝管的早期失效。     

循环流化床锅炉高温再热器管泄漏原因分析

通过宏观和微观检验对某循环流化床锅炉一段焊接有螺柱的高温再热器管水压试验时泄漏的原因进行了分析。结果表明:泄漏是由连多硫酸应力腐蚀造成的,并指出循环流化床锅炉受热面不锈钢管利用螺柱焊焊接锚固件的工艺值得进一步探讨。     

Failure Investigation on Reheater Tube Due to Deposit and Wall Thinning

Failure analysis of a reheater tube showed that the failure was caused by overheating and wall thinning. Finite element modeling, dimensional measurements, and microscopic examinations were performed to investigate the root cause of the failure. Wall thinning, due to excessive coal-ash corrosion, and overheating, due to scale buildup on the tube were measured, and estimations, the average corrosion and scale growth rates, were made. The combination of excessive scale formation on the inner tube surfaces and wall thinning due to coal-ash corrosion on the outer tube surfaces combined to cause the failure of the reheater tube.     

P110油管腐蚀穿孔分析

通过化学成分分析、金相检验和腐蚀产物分析等方法对P110油管腐蚀穿孔的原因进行了分析。结果表明:CO2腐蚀是造成油管腐蚀穿孔失效的主要原因。     

铝合金导电管腐蚀失效原因分析

用于高压隔离开关的铝合金导电管存在着严重而普遍的腐蚀问题,危及高压隔离开关的正常运行.运用能谱分析、金相分析和电子探针等技术对铝合金导电管的破损原因进行了分析.结果表明,导电管存在着高度定向的纵向显微组织和局部脱溶,Cu,Fe等有害元素的相在晶界处大量连续析出,造成晶界附近出现贫化区,由于导电管的工作环境为近海海洋大气带,其中含有大量的侵蚀性阴离子,众多因素是导电管的腐蚀成因.其腐蚀过程为先在表面发生点蚀,然后发展成晶间腐蚀,在晶间腐蚀和内应力的协同作用下最终开裂形成剥蚀.     

Field test corrosion experiences when co-firing straw and coal: 10 year status within Elsam

Abstract

In Denmark, straw is utilised for the generation of energy and district heating in power plants. Combustion of straw gives rise to high contents of potassium chloride and some sulphur dioxide in the flue gas. These compounds can lead to deposits with high content of potassium chloride and potassium sulphate on superheater tubes resulting in increased corrosion rates. From field experimental results this paper show, that by co-firing straw with coal, corrosion rates can be brought down to an acceptable level.

This paper firstly deals with the results from a demonstration program co-firing coal and straw at the 150MW pulverized coal fired boiler Studstrup unit 1. Two exposure series lasting 3000 hours each were performed for co-firing 10 and 20% of straw (% energy basis) with coal. Using built in test tubes in the hot end of the actual superheaters and air/water cooled corrosion probes, the corrosion during these experiments was monitored. Various ferritic and austenitic materials were investigated at steam temperatures ranging from 520 to 580°C and flue gas temperatures ranging from 925 to 1100°C.

The results obtained in the demonstration program led to the rebuilding of the 350MW pulverized coal fired boiler, Studstrup unit 4, into a co-firing boiler with straw in 2002. During the rebuilding, test tube sections of X20CrMoV12 1 and TP347H FG were built into the superheater and the reheater loops. The temperature ranges during these exposures was for the steam from 470 to 575°C and for the flue gas from 1025 to 1300°C. All these test tubes have been removed during the last three years at one year intervals for corrosion studies.

The corrosion studies performed on all investigated tubes included measurements of the corrosion attack, light optical microscopy and scanning electron microscopy of the corrosion products.     

Failure analysis of a copper tube in a finned heat exchanger

This paper reports on the failure analysis of a finned heat exchanger which leaked in the pressure test during commissioning. The heat exchanger was composed of panels made of thin-walled copper tubes and aluminum fins, and the structure was typical of equipment used in the heating, ventilation and air-conditioning industry. The tube material was phosphorus deoxidized copper Cu–DHP. In the pressure test, one of the tubes was found to have three leakage points. The investigation showed that the failure was a consequence of ant-nest corrosion, as all the experimental findings, together with the copper grade and the tube dimensions, were typical of this corrosion mechanism. Corrosion had initiated from the outer surface of the tube. The paper presents the morphology of the failure using optical and scanning electron microscope (SEM) micrographs. The presence of a contaminating organic substance on the outer tube surface and inside the corrosion crack was verified by SEM/EDS analyses. The corrosion mechanism and the relevant chemical reactions given in the literature are summarized, and the conditions in which the failure may occur are presented. Ant-nest corrosion is a special form of local corrosion, and associated most often with deoxidized copper tubes used in heat transfer applications as in this study.     

空调用翅片管式换热器腐蚀及防护研究进展

空调用翅片管式换热器长期使用会受到一定程度的腐蚀,影响换热器的换热性能,导致整个空调系统的能效降低.本文介绍了翅片管式换热器3种主要的腐蚀机理:蚁巢腐蚀、点蚀和间隙腐蚀,从形貌、压降及传热特性3个方面分析了腐蚀对翅片管式换热器性能的影响,结果表明:翅片管式换热器腐蚀后,传热系数和换热量均减小,空气侧压降受影响较小,在5...     

焦化加热炉炉管失效原因分析

通过对某炼油厂焦化炉失效炉管的材料成分，力学性能，显微组织等的分析，确定了其失效模式为高温硫腐蚀以及氧化腐蚀。加质变炉炉管内外壁结焦层硫含量超标，在烧焦时，局部炉管过烯，发生膨胀变形，使强度下降，最终导致炉管失效，提出了预防失效的措施。     

Corrosion of a copper U-shaped heating element: Some morphological and microstructural observations

In this work, observations of the corrosion on a failed copper U-shaped tube, of 1 mm nominal thickness, are presented. This tube was subjected to severe corrosion and subsequent cracking after a month of operation as the heating element of an electrical boiler. Morphological and microstructural observations of the failure area as well as cross sections of the corroded copper tube are presented. Moreover, the chemical composition of the material and the principal physicochemical characteristics of the tap water used for boiler operation were determined in the context of the failure investigation. The quality of the water used for boiler operation was a significant factor influencing the heating element efficiency and reliability. Hard water with high electrical conductivity accelerated salt precipitation and led to the corrosion and premature failure of the components.