炼油厂焦化装置的腐蚀与防护

简述了南京炼油厂焦化装置加热炉辐射炉管、加热炉注水管、加热炉空气预热器、焦炭塔和分馏塔的腐蚀情况,介绍了一些防护成功的经验。     

U形无缝钢管交错排列的空气预热器

1.前言预热器的作用通常是利用加热炉排出的高温烟气将煤气或空气预热到适当的温度,使煤气或空气进入炉内燃烧或助燃时带入一部分物理热,以节约燃料和提高燃烧温度。众所周知,预热带入加热炉内的物理热比同样热量的化学热更加有用,预热器回收热量     

空气预热器搪瓷管腐蚀失效分析

空气预热器搪瓷管在投入运行后三个月便发生腐蚀，腐蚀形貌与一般低温腐蚀有较大区别。用扫描电镜观察样品微观腐蚀形貌，用水溶性物质成分分析法测定腐蚀产物中阴离子含量，用X射线能谱分析仪分析腐蚀产物中元素成分及含量，结果表明：空气预热器搪瓷管的腐蚀为点蚀发展的全面腐蚀，含有F、S、Cl的烟气是腐蚀产生的原因，烟气中F元素破坏表面搪瓷涂层后，S、Cl元素进一步造成基体碳钢材料低温腐蚀,腐蚀产物为S、Cl含量较高的铁氧化物。     

天然气加热炉防腐防垢技术探讨

加热炉内水通常来自于地下,常含有引起加热炉腐蚀的物质,影响着加热炉的平稳安全运行。通过对某天然气集气站加热炉用水及炉内壁物质分析,得到运行一段时间后水质变化以及腐蚀与结垢产物的化学组成,进一步探究了加热炉材料、氧、CO_2、溶解盐、闭塞电池对加热炉腐蚀与结垢的影响机理。结果表明:不同加热炉材料的腐蚀速率相差不大,炉内腐蚀主要由运行温度下水、氧、CO_2、溶解盐、闭塞电池引起的。在分析腐蚀结垢机理的基础上提出了防腐防垢的具体措施以及炉内清洗的工序,介绍了清洗评价标准,可为其他天然气企业加热炉防腐防垢提供参考。     

炉用预热器的发展与应用

烟气余热回收是加热炉节能工作重点。国外先进工业国家预热器使用较为广泛,并有定型产品出售,有些国家如日本还用法律形式予以保证。我国加热炉烟气余热回收工作较差,尤其是量大面广的锻造加热炉预热器使用更差。本文介绍炉用预热器的发展与应用,期望预热器的使用情况有所改善。     

锅炉热管常见早期失效形式分析

分析了水冷壁管、过热器管、再热器管、省煤器管、空气预热器管等锅炉热管的工作条件和主要失效形式。介绍了高温蠕变、短时过热、高温烟气腐蚀、飞灰磨损、低温腐蚀等热管失效形式的宏观形貌特征及失效机理。     

下排烟加热炉应用空气预热器的经验

我厂有10座加热炉,其中9座采用地下烟道排烟。近几年来,为了节能,不但在新建加热炉时安装空气预热器。而且,还相继在原有加热炉的烟道里安装了空气预热器。通过实践体会到:在地下烟道里安装预热器,除需正确选型外,更重要的是要解决好烟道内的排水问题。否则,预热器使用寿命短,热风温度低,达不到预期效果。 1.影响预热器效果的原因 1982年,我厂新建了2座下排烟轧钢加热炉,空气预热器直接安装在地下烟道底     

水套加热炉的烟气腐蚀及防护

本文对一台水套加热炉烟气系统的腐蚀情况进行了现场调查，分析了导致水套加热炉的烟气腐蚀的原因，阐建亍腐蚀机理，纠正了四川天然气田生产中设计水套加热炉只考虑硫化氢腐蚀，忽略烟气中二氧化碳腐蚀的论点。在使用和制造方面提出相应的建议方案。     

加热炉管式预热器的优化设计及使用

阐述了钢管加热炉使用空气预热器节能的重要性。从热工参数选取、结构设计及材质选用方面介绍了预热器的设计、预热器的制造质量管理及检查方法、预热器的安装等。提出了正确使用、维护预热器的方法。采用此方法,可以达到改善燃烧条件,节约燃料,减少环境污染以及延长预热器使用寿命的目的。     

制氢装置空气预热器腐蚀失效分析及措施

对某石化公司制氢装置低温空气预热器的腐蚀失效原因进行了分析,根据工艺状况、外观检查、材料成分分析、金相检验、微观腐蚀形貌及腐蚀产物成分分析等结果的判定,空气预热器腐蚀失效主要是由焊缝缺陷所致,最后根据失效原因提出了防护措施和建议.     

某汽油加氢脱硫装置引风机系统腐蚀原因及处置措施

通过对汽油加氢脱硫装置加热炉引风机系统腐蚀产物的现场目测、操作条件和介质组成的考察,探讨了该系统的腐蚀原因。结果表明:汽油加氢脱硫装置加热炉引风机系统腐蚀的原因是烟气中的硫化物在低温条件下形成的露点腐蚀,并对此具体问题提出了相应的防护措施。     

锅炉省煤器弯管焊接接头裂纹行为分析

省煤器是现代锅炉的一个必备部件,其作用就是利用锅炉尾部烟气的热量加热锅炉的给水,降低排烟热损失,减小因温差造成的热应力,改善了汽包的工作条件。省煤器的弯管焊接接头的裂纹是造成省煤器泄漏的主要原因之一。     

烟气保护在普通辊底式热处理炉上的运用

烟气保护式辊底炉是通过向炉内注入烟气来充当保护气体,从而使炉内气氛达到微氧环境的热处理炉。攀钢集团成都钢钒有限公司金堂分公司于2011年7月成功对1台普通辊底式热处理炉进行了改造,并取得良好效果。从炉体结构、烟气循环系统、冷却水系统、含氧量检测、电器及仪表控制系统等方面对将普通辊底式热处理炉改造为烟气保护式辊底炉进行了简要分析。     

富氧燃烧条件下钢坯加热特性的数值模拟

以某轧钢厂步进式加热炉为研究对象,利用Fluent软件对炉内气相流动与燃烧和钢坯加热过程建立数学模型,并开发了用户自定义函数处理钢坯移动。炉膛内气体流动采用Realizable k-ε模型,燃烧过程采用非预混燃烧模型,辐射传热采用DO模型来计算。通过所建立的数学模型,模拟研究了氧气体积分数为21%～35%的助燃气体与燃料燃烧对钢坯加热特性的影响。结果表明,随着氧气浓度的增加,燃烧区的烟气温度逐渐升高,导致钢坯具有更快的升温速率;由于富氧燃烧在燃烧区产生了更均匀的温度场,因此在氧气浓度为35%时,钢坯的黑印温差仅为15 K,比空气工况下的黑印温差低了20 K;当助燃气体中氧气体积分数从21%增加至35%时,钢坯的辐射传热量也随之增加,加热炉热效率从41.1%提高至48.4%。     

Korrosion in Rauchgasen bei 1000 °C

Corrosion in flue gas at 1000 °C An improvement in efficiency of coal combustion power plants can be achieved by the combined cycle process with gas and steam turbines. The effective power is also optimized if the energy generated in the boiler is discharged by utilizing a liquid sodium heat exchanger, working at a temperature of 1000 °C. In this case the heat exchanger materials are exposed to severe conditions. Liquid sodium at a temperature ranging up to 1000 °C flows through the heat exchanger tubes and the outer surface of the tubes is exposed to the flue gas. The materials are stressed mechanically and are also subjected to high temperature corrosion. Therefore high temperature corrosion tests were carried out with Fe-Ni-Cr- and Ni-base alloys in a laboratory furnace in which the alloys are exposed to the flue gas at a temperature of 1000 °C for a total period of 3000 h. The experiments have shown that most of the materials have a sufficient resistance to weight loss corrosion but in some cases severe internal oxidation occurs. This kind of corrosion is mainly observed for materials with high concentrations of elements such as aluminium, silicon etc., i.e. by the elements with very high negative values of free energy of formation of oxides.     

Die Rolle der Begleitstoffe von Abgaskondensaten aus der Erdgasverbrennung bei der Korrosion von Wärmetauschern

Impurity constituents of flue gas condensates and their significance for the corrosion of heat exchangers This paper presents investigations concerning the acidic constituents of flue gas condensates which may be generated by the combustion of natural gas. Nature, origin and concentration of relevant constituents will be presented. Their corrosive impact on components of domestic heating facilities will be discussed taking into consideration usual materials based on aluminium, stainless steel and copper. It will be shown that condensates are considered as diluted and aerated acids with a moderately reduced pH. With respect to aluminium based alloys and stainless steels the corrosive potential of condensates is deduced from their content of strong acids. When condensing is forced due to techniques which are used in condensing boilers there is an effect of dilution active which results in a reduction of the corrosiveness. The primary corrosion mechanism of copper is related to the presence of oxygen in the condensate. Therefore the dilution of condensates is of restricted significance. Unprotected copper is known to be unsuitable for condensing conditions.     

Low temperature corrosion in domestic refuse boilers monitored with cooled corrosion probes and test heat exchangers

Corrosion properties of materials for utilizing of flue gas energy by cooling the gas below the acid dew point have been studied with cooled corrosion probes. The U-tube corrosion probe is found to be a reliable method where tests can be done in the actual plant environment. Results from one domestic refuse boiler plant with severe low temperature corrosion problems are reported and the results described indicating a minimum temperature of 75°C to avoid corrosion. Another set of results is reported with flue gas cleaning and cooling in an experimental heat exchanger. Unalloyed steel is found to show the same level of corrosion in both raw uncleaned and cleaned flue gas. AISI 316 and 254 SMO stainless steels have shown high corrosion rates in the raw gas but a satisfactory resistance in the cleaned gas.     

Abgasseitige Korrosion bei Öl- und Gasfeuerung

Flue gas side corrosion in oil and gas fired heating systems Corrosion of metallic material of heaters of chimneys in contact with flue gas is guided by the amount and composition of condensate occurring on the surface when the temperature of the surface lies below the dew point of the flue gas. The corrosivity of the condensate depends on its content of sulfuric acid which results mainly from the sulfur content of the fuel. In some cases a special corrosivity against stainless steel may arise from a chloride-ion content of the condensate due to pollution of fuel or air by organic chlorine compounds. As a result of experiences with corrosion damages of heaters and chimneys a corrosion test methode for prefabricated stainless steel chimney elements was developed. Acceleration of corrosion is reached by simulation of only those phases in which condensation may occur and by addition of sulfur dioxide to the combustion air.     

高效节能环保渗碳渗氮技术

介绍了四个内容：（1）新型高效、节能、环保渗碳技术,主要包括预抽真空双室多用炉和气氛控制装置,与通常的气体渗碳相比,渗碳速度更快,内氧化、渗碳气体消耗量及 CO2排放量大大减少;（2）控制气氛真空渗碳炉,该炉采用热传导探头和氧探头双探头进行碳势的闭环控制,可实施真空渗碳、气冷、重新加热至850℃淬火的工艺过程,渗层均匀性好,并能有效消除积炭;（3）预抽真空精密控制气氛渗氮炉,该炉采用独特的温度和氮势精确控制系统,可取代QPQ 技术对普通碳钢进行渗氮氧化复合处理,提高其耐磨、耐蚀和疲劳性能;（4）活性屏等离子渗氮技术,其独特之处是,高压直流电源的负极接在真空室内的金属活性屏上,等离子体加热金属屏,由从屏上辐射的热量将工件加热到所需渗氮温度,解决了传统的直流等离子渗氮技术难以克服的工件打弧等问题。