加氢裂化空冷器管束多相流冲刷腐蚀数值模拟

基于某加氢裂化空冷器管束的冲刷腐蚀实际状况分析,建立了数值模拟模型。采用mixture模型和标准k-ε模型描述多相湍流流动过程,以此对空冷器的管箱、管束进行全流场数值模拟,获得湍动能分布状况;进而对空冷器腐蚀状况进行研究,获得不同位置处的冲刷腐蚀和电化学腐蚀速率。结果表明,最大冲刷腐蚀速率达到4.76 mm/a,且腐蚀损伤集中在空冷器管束进口端,模拟结果与空冷器管束实际腐蚀状况一致。模拟结果表明,与电化学腐蚀相比,冲刷腐蚀是导致空冷器管束腐蚀损坏的主要原因。在此基础上,提出对空冷器结构进行改进的技术方案;模拟计算表明,结构改进后的空冷器管束的冲刷腐蚀速率大大降低,显著提高了空冷器运行的安全与稳定性。     

炼油厂酮苯装置空冷器腐蚀原因分析

炼厂酮苯装置空冷器因空冷管束腐蚀穿孔被迫停工检修，经取样分析和现场调查，得出结论：溶解氧含量偏高，设备本身存在震动，无盐水质量不稳定及空冷管束选材不当是造成空冷器管束腐蚀穿孔的主要原因，提出有效大的防腐措施。     

蒸发器管束腐蚀失效分析

针对蒸发器管束腐蚀穿孔进行了分析,采用表面腐蚀形貌分析、金相显微组织分析、力学性能测试、SEM微观形貌分析、电化学测试和水质分析等手段,分析了管束腐蚀穿孔的原因,结果表明,蒸发器管束外表面腐蚀穿孔的腐蚀类型为垢下腐蚀,水中溶解氧含量过高是导致蒸发器管束发生腐蚀穿孔的主要原因.     

重油加氢装置脱硫系统再生塔顶空冷器出口管束腐蚀穿孔原因分析

对失效的重油加氢装置脱硫系统再生塔顶空冷器出口 管束进行了外观检查，分别用X射线衍射技术和SEM分析了管束腐蚀产物的相组成、元素含量 与形貌.结果表明，腐蚀减薄穿孔原因是由高温下乙醇胺引起的碱腐蚀所致，硫化氢腐蚀也 起到了辅助作用.     

冷凝器管束腐蚀穿孔原因分析

采用宏观腐蚀形貌分析、化学成分分析、金相显微组织分析、SEM微观形貌分析和EDS成分分析等手段,对某冷凝器管束腐蚀穿孔进行失效分析.结果表明,壳程冷却水中添加二氧化氯是导致管束发生腐蚀穿孔的主要原因.     

油气计量装置弯管接头腐蚀失效的原因

采用宏观形貌、显微组织观察,腐蚀产物成分分析和电化学方法,分析了某采油厂计量装置采用的弯管接头在原油介质中发生穿孔的原因。结果表明:失效弯管接头热影响区存在焊接缺陷,导致其耐腐蚀性能减弱;腐蚀产物主要成分为FeOOH,氧腐蚀为主要腐蚀类型;弯管接头外弧侧耐腐蚀性能最弱,且不断受到流体冲蚀,腐蚀加剧,最终形成穿孔。     

某石化厂循环水冷凝器管束腐蚀穿孔原因与建议

通过对天津石化分公司某石化厂循环水冷凝器管束腐蚀部位检查,腐蚀部位的垢样组成,循环水中微生物分析等项目测试分析,对该厂循环水冷凝器管束腐蚀穿孔原因进行了分析,并提出了有针对性的腐蚀控制建议.     

注水海底管道穿孔原因分析

采用宏、微观形貌观察,化学成分、腐蚀产物分析等方法对某油田平台注水穿孔海底管道的穿孔原因进行了分析。结果表明:穿孔弯管段碳含量超标,管道内壁疏松的腐蚀产物为Fe_2O_3和Fe_3O_4,是氧腐蚀产物;弯管段穿孔由冲蚀和垢下腐蚀共同作用引起,垢层下的穿孔则是由于垢下腐蚀导致的。     

加氢反应流出物空冷器系统的腐蚀机理

系统地探讨了加氢反应流出物空冷器及其上、下游管路系统的腐蚀机理．重点探讨了NH4HS和NH4Cl的沉积规律；FexSy保护膜的组成、结构、性能；运行工况和杂质元素的来源及影响．以镇海炼化公司加氢裂化高硫扩能改造后的运存工况为示例，详细分析了以上因素引起加氢反应流出物空冷器管束冲蚀的实际危害源，提出了该类装备优化运行的工艺防护措施。     

减压塔顶板式空冷器腐蚀失效分析及建议

利用宏观形貌观察、化学成分分析、金相观察和X射线衍射等方法,分析了某石化公司减压塔顶预冷板式空冷器的腐蚀失效原因.采用电化学测试对常用不锈钢在3.5% NaCl溶液和减顶冷凝水中的腐蚀性能进行对比研究.结果表明,316L不锈钢材料合格,预冷板式空冷器板束腐蚀失效是由于冷却水垢下腐蚀造成的.304和316L不锈钢均在减顶...     

炼油厂重催装置换热器管束的泄漏原因

某炼油厂重催装置E203换热器在运行过程中发生了管束泄漏,采用光学显微镜、扫描电镜、以及能谱分析等方法对失效原因进行了分析。结果表明:换热管内表面发生了严重的点蚀,腐蚀产物主要有Fe(OH)3、FeS和FeCl2;换热管内表面腐蚀产物中含有腐蚀性离子(Cl-和S2-),这是导致管束腐蚀失效的主要原因。     

焦化加热炉炉管腐蚀失效分析

应用扫描电子显微镜、能谱分析以及X射线衍射仪对焦化加热炉炉管的高温腐蚀形貌，腐蚀物成分以及物相进行了分析，结果表明，由于炉膛操作温度过高，且燃料中含硫，Cr5Mo钢炉管不但发生高温氧化腐蚀，还发生硫化腐蚀，使破坏加速，最终导致炉管失效.同时提出了预防措施     

HSn70-1船用冷凝管腐蚀穿孔失效分析

某船用HSn70-1冷凝管使用过程中出现腐蚀穿孔。通过化学成分、金相组织和能谱分析以及扫描电镜等方法对失效样品进行了分析。结果表明,介质中的Cl~-引起管内壁局部点蚀,加上冲刷腐蚀、脱锌腐蚀、晶间腐蚀的交互作用,引起腐蚀加速,最终导致穿孔。提出了预防或延缓腐蚀穿孔的措施。     

二次过热器炉管的腐蚀损伤分析与表征

采用金相检验、扫描电镜、三维视频系统及能谱分析等方法，对350MW火力发电机组经13万h运行后二次过热器炉管内表面严重腐蚀损伤进行了检测与表征。结果表明，该炉管内表面的损伤主要是由水中的氯离子及溶解氧作用下引起的点腐蚀所致，为此提出了相应的预防措施。     

Comparison of the corrosion behavior of copper tubes in formic acid and acetic acid environment

Carboxylic acids with different carbon chains have different corrosion behaviors on copper tubes. In this paper, corrosion behavior and corrosion mechanisms of copper tubes in formic acid (HCOOH) and acetic acid (CH₃COOH) were analyzed by vapor corrosion tests, electrochemical tests, contact angle examination, optical microscopy, Fourier transform infrared spectroscopy, and X-ray diffraction. The corrosion process of copper tubes in the HCOOH environment is more complex than in the CH₃COOH environment and HCOOH is easy to cause “ant nest” corrosion on copper tubes. The corrosion rate is faster and the surface of the copper tube is more easily corroded in the CH₃COOH environment due to the formation of unstable and loose corrosion products, Cu(OH)(CH₃COO)₂·2H₂O. The results of the contact angle examination showed that the contact angles of HCOOH and CH₃COOH on copper tube surface were 25° and 9°, respectively, which means that CH₃COOH is more likely to be absorbed by the surface of the copper tube evenly. Differences in the wettability of these two carboxylic acids with copper tubes are the main reason for the different corrosion phenomena. The corrosion mechanisms of copper tubes in carboxylic acid are also discussed.     

Hot Corrosion Behavior of a High Velocity Arc-Sprayed Fe-Cr-B-C Coating

A Fe-Cr-B-C coating was prepared by electric arc spraying process to prevent the boiler tubes from hot corrosion at elevated temperatures.A hot corrosion resistance test was conducted in a mixed molten salt of Na2SO4 and K2SO4(7:3)at 700 ℃for a total period of 156 h.The microstructure and phases of the coatings before and after exposed to the hot corrosion were investigated by scanning election microscopy(SEM),optical microscopy(OM)and X-ray diffraction(XRD).The hardness and porosity were analyzed.The hot corrosion behavior of the coatings was examined by the measurement of corrosion mass gain and the observation of corrosion morphology.The results show that some splats of particles are formed on flat substrate surfaces and the coatings have a dense typical layer structure of electric arc thermally spraying deposits.Some amorphous phase exist in the coating.The coatings have an excellent resistance to hot corrosion.The formation of oxides of chromium on the exposed surface may be contributing better resistance to hot corrosion.The corrosion of the coatings follows the oxidation and sulfidation mechanism.     

燃煤火电厂锅炉“四管”的高温腐蚀

燃煤火电厂锅炉的高温腐蚀主要发生在受热面的“四 管”,即水冷壁管、过热器管、再热器管和省煤器管.腐蚀的主要类型是硫腐蚀、氯腐蚀、 水蒸汽腐蚀和钒腐蚀.本文综述了燃煤火电厂锅炉存在的典型高温腐蚀现象和机理,并简要 的介绍了一般防腐蚀措施.     

304和316L管材在两类模拟介质中的晶间腐蚀形貌

通过自制的模拟循环试验装置,对两种不锈钢管材进行冲刷腐蚀模拟试验,SEM形貌表明在模拟的河水和海水介质中,304和316L不锈钢均发生了晶间腐蚀。     

Enhancement of Service Life of Steam Generating Tubes in Oil-Fired Boiler for Power Generation Employing Plasma Spray Technology

The effects of Ni-50 mass% Cr alloy coating, that is plasma-sprayed onto the fire-side of steam generating tubes in a heavy oil-fired boiler, on the high temperature corrosion resistance were examined. One of the severe environments in the industrial manufacturing facilities, where thermal sprayed coatings are employed, is the high temperature corrosion such as the oxidation, sulfidation, and low melting fuel ash corrosion in the fire-side of boiler tubes. In the fossil fuel-fired steam generating boiler facilities, the degradation or failure of steam generating tubes that were derived from the contaminants in a lower grade fuel have often occurred. The situation of degradation of the water evaporator and superheater tubes and corrosion-preventing effects of plasma sprayed coating are described. The enhanced effects of plasma sprayed Ni-50 mass% Cr alloy coating for the suppression of hot corrosion failure of the steam generating tubes of boiler are summarized.     

某电厂锅炉水冷壁管爆裂原因分析

通过宏观分析、金相、SEM、能谱、XRD等手段分析了水冷壁管失效原因。结果表明,水冷壁管发生了酸性氢腐蚀,锅炉长期水质较差,且运行过程中pH值偏低是其腐蚀减薄的主要原因,而腐蚀产物中沉积的Cu及其氧化物,形成垢下腐蚀环境,加速了水冷壁管的腐蚀,最终在锅炉介质应力作用下发生脆性爆管。