乙烯裂解炉炉管失效形式及其原因分析研究进展

总结了乙烯裂解炉炉管的失效形式,分析了炉管失效原因。发现乙烯裂解炉炉管失效形式主要表现为弯曲失效、穿孔失效和开裂失效,其失效原因通常表现为多种因素共同作用的结果。     

炼油厂HP型制氢转化炉炉管破裂失效分析

采用宏观检查、金相组织、力学性能测试方法对某炼油厂制氢车间运行3.5万h即发生开裂的HP型制氢转化炉炉管进行了析。结果表明:炉管破裂失效的主要原因是高温蠕变破裂,长期超温运行是导致炉管提前失效的直接原因。     

乙烯裂解炉对流段炉管破裂失效原因分析

针对某厂一起乙烯裂解炉对流段换热炉管破裂事故,通过调研操作参数、对失效部位进行宏观检验、测定化学成分及材料性能、分析金相及断口等方法,确定了炉管失效原因。结果表明,该炉管是因S、Na、Cl等元素及其化合物引起的应力腐蚀开裂所诱发,并在高温腐蚀环境和热应力波动交互作用下以腐蚀疲劳形式扩展。探讨了引起炉管失效的间接原因。     

裂解炉用36XS炉管开裂的原因分析

通过对裂解炉管进行宏观变形检查、化学成分分析、显微组织分析和力学性能分析等,找出炉管开裂的失效原因。结果表明：裂解炉管变形开裂的主要原因是由于该处实际使用温度偏高,因而造成渗碳和氧化较严重。氧化减薄使炉管膨胀蠕变,渗碳不均匀,由此造成炉管严重鼓胀变形直至开裂。     

加热炉管的失效形式及分析

介绍了以乙烯裂解炉为主的加热炉炉管在工程上常见的13种失效形式，包括光管或翅片管基管的高温损伤、对焊接头组织恶化、热疲劳开裂、热应力开裂、奥氏体的氯离子晶间腐蚀、碱蚀、过热及其他失效，还包括翅片的高温磨损、应力腐蚀开裂及翅根积垢以及化学工业炉的介质腐蚀失效。对各种失效的表现特点及失效原因进行了简单的分析。     

合成辅锅炉管泄漏原因分析及对策

描述合成辅锅炉管开裂的外观形貌,通过对炉管的材料进行化学成分分析、金相检查以及蠕胀检查,找出炉管失效的原因是管子外表面有裂纹,内表面结垢而导致局部过热,引起了管子蠕胀后开裂,直至穿透,提出工艺监护及管理措施.     

锅炉过热管开裂失效分析

某炼化厂锅炉在高温过热器炉管背火面发生泄漏,漏点位置集中于出口管束管道背火侧。通过液体渗透、化学分析、力学分析、金相分析,得出其开裂失效的原因为水化学控制不当引起的应力腐蚀。     

浅析加热炉对流室炉管管壁缺陷分析及应对措施

石油炼化企业加热炉炉管的工作条件十分恶劣,长期工作在高温、高压和腐蚀介质环境下,因此炉管要求具有良好的抗高温蠕变性能、抗热疲劳性能、抗氧化性能、抗渗碳性能、耐腐蚀性能、导热性能以及焊接性能。根据生产应用实际,炉管的失效主要形式有蠕变失效、氧化腐蚀失效、热疲劳失效、组织劣化失效、炉管严重弯曲造成的失效、母材冶金缺陷导致的失效等。主要针对对流室炉管管壁壁厚测定减薄缺陷处通过割管,进行宏观检查、材质分析、金相检验、电镜分析,确定该缺陷为炉管本身带有的原始冶炼、制造加工缺陷,提出管理及技术改进措施。     

EDC裂解炉炉管失效分析

通过力学性能测试、金相、扫描电镜(SEM)、电子探针显微分析(EPMA)和x射线衍射等手段对齐鲁石油化工股份有限公司氯碱厂EDC裂解炉炉管辐射段的穿孔失效进行了解剖分析。探讨了材质劣化和腐蚀对炉管失效的影响,认为腐蚀是造成炉管穿孔失效的直接原因,并对在用炉管的剩余寿命进行了评估。     

锅炉炉管开裂泄漏原因分析

通过宏观观察、能谱分析化学成分、金相组织和扫描电镜分析等方法。对某热电厂蒸汽锅炉炉管开裂问题进行研究。结果表明:焊接温度使炉管表面的组织发生了改变,屈氏体使炉管脆化,塑性和韧性降低,变形能力变差。焊接收缩拉应力和其它应力是炉管产生开裂及裂纹扩展的主要原因。     

佛山市顺德新城区降水中污染物的监测和分析

为掌握佛山市顺德新城区降水中污染物的情况,2015年7月至8月,文章作者分别在雨天进行了降水取样,对降水中的pH、电导率、常见阴离子(F-、Cl~-、NO_3~(2-)、SO_4~(2-))及部分重金属(铅和镉)进行监测分析。选择有相关数据的珠江三角洲和石家庄、厦门等地的降水中污染物的情况进行对比。结果表明,顺德新城区降水中的p H和部分阴离子浓度优于珠江三角洲平均值,酸雨类型属于硫酸和硝酸混合型;其水体洁净程度略差于石家庄;铅和镉的浓度也高于厦门,甚至部分超出了人体能直接接触的安全范围。     

Metabolism of trideuterated iso-lignoceric acid in rats in Vivo and in human fibroblasts in culture

Saturated very long chain fatty acids (fatty acids with greater than 22 carbon atoms; VLCFA) accumulate in peroxisomal disorders, but there is little information on their turnover in patients. To determine the suitability of using stable isotope-labeled VLCFA in patients with these disorders, the metabolism of 22-methyl[23,23,23-²H₃]tricosanoic (iso-lignoceric) acid was studied in rats in vivo and in human skin fibroblasts in culture. The deuterated iso-VLCFA was degraded to the corresponding 16- and 18-carbon iso-fatty acids by rats in vivo and by normal human skin fibroblasts in culture, but there was little or no degradation in peroxisome-deficient (Zellweger’s syndrome) fibroblasts, indicating that its oxidation was peroxisomal. Neither the 14-, 20-, and 22-carbon iso-fatty acids nor the corresponding odd-chain metabolites could be detected. In the rat, the organ containing most of the iso-lignoceric acid, and its breakdown products, was the liver, whereas negligible amounts were detected in the brain, suggesting that little of the fatty acid crossed the blood-brain barrier. Our data indicate that VLCFA labeled with deuterium at the ω-position of the carbon chain are suitable derivatives for the in vivo investigation of patients with defects in peroxisomal β-oxidation because they are metabolized by the same pathways as the corresponding n-VLCFA. Moreover, as iso-VLCFA and their β-oxidation products are readily separated from the corresponding n-fatty acids by normal chromatographic procedures, the turnover of VLCFA can be more precisely measured. A preliminary report of part of this work (Reference 18) was presented at the 5th International Symposium on the Synthesis and Applications of Isotopes and Isotopically Labelled Compounds, Strasbourg, France, June 20–24, 1994.     

高效液相色谱法分析化妆品中微量成分的研究进展

综述了高效液相色谱法在化妆品中防腐剂、防晒剂中紫外线吸收剂以及性激素的检测等几个方面的应用;同时,介绍了分析所用的色谱柱、流动相、使用的检测手段以及样品的提取方法;最后针对目前存在的问题,提出了高效液相色谱用于化妆品中微量成分分析的研究方向和发展前景。     

Denitrification in shallow groundwater in a coastal agricultural area in Japan

In a coastal agricultural area in the central part of Japan (Shizuoka), we found decreasing nitrate concentration with depth in a shallow groundwater, where the depth to water table varied between 0.6 and 1.2 m below ground surface. High nitrate concentrations (5–29 mg N L^–1) were often observed in the upper layer (0–2 m) of the groundwater, but the concentration decreased to less than 1 mg N L^–1 in the deeper layer. Ammonium was scarcely detected, and the concentration of dissolved oxygen was usually low (< 1 mgO₂ L^–1) in the groundwater. Nitrate in the groundwater often had very heavy nitrogen stable isotope ratios (>20{}). There was a negative relationship between nitrogen stable isotope ratio of nitrate and its concentration. When nitrate was injected into the groundwater with acetylene and bromide (a conservative tracer), nitrate concentration decreased to 20% of the initial level within 5 days, accompanied by the increase in nitrite and nitrous oxide concentration and a little change in bromide concentration. These results indicate that microbial denitrification plays a potential role in the decrease of nitrate in shallow groundwater at the study site.     

我国硝酸工业生产技术新进展

系统叙述了我国硝酸工业2000-2007年生产现状及主要技术成果,尤其指出了国产"四合一"机组的成功投运,使我国硝酸国产化装置取得较大的进步,表现在吨酸的铂耗、氨耗和能耗等方面接近国外引进装置水平,同时介绍了国外双加压法硝酸生产技术的进展.我国已成为硝酸生产大国,仍需以先进的技术改造和发展我国硝酸工业,确保我国硝酸工业健康有序地发展,加快从硝酸生产大国向强国迈进的步伐.