制氢装置中变气系统奥氏体不锈钢设备失效问题分析

近年来,国内各石化企业常有制氢装置中变气系统设备与管道失效的报道,绝大多数是300系列奥氏体不锈钢设备在使用过程中发生了不同程度的泄漏、破裂等。文章根据制氢装置的工艺特点进行腐蚀分析,并列举近年来国内石化企业制氢装置中该系统的几次有代表性的失效案例,简要分析了该系统不锈钢设备失效的潜在规律,并提出了一些预防及检验的建议。     

制氢装置脱碳系统管道爆破原因分析

对某制氢装置脱碳系统管道爆破原因进行了分析。通过宏观观察分析，认为管道爆破是由于该管在运行中产生汽蚀，管壁严重减薄而造成的，并提出了预防制氢装置脱碳系统管道爆破的措施。     

制氢装置中变气不锈钢管件开裂失效分析及对策

制氢装置空冷器入口中变气不锈钢管件多处焊缝热影响区出现穿透性裂纹,通过对失效管件进行宏观检查、射线检测、渗透检测、硬度测试、化学成分分析、金相组织观察、电镜扫描和残余应力分析等检测试验,确定所有裂纹均为沿晶裂纹,呈树枝状分布并在热影响区及母材内扩展;断口形貌具有典型的冰糖块特征,能谱分析显示有大量S、局部存在Cl,晶界Cr质量分数达到20.0%,超过基体中Cr含量;管件局部硬度超过190HB,裂纹尖端的残余应力超过了0Cr18Ni9的屈服应力。从材料方面、介质因素与应力条件三个方面综合分析后,认为管件失效的原因是H2SCO2-H2O酸性腐蚀环境下氯离子、硫化物和残余应力共同作用的晶界应力腐蚀开裂。对失效管线进行了材质升级,消除了装置存在的隐患,并提出了有关的预防措施和建议。     

制氢装置中变系统管道腐蚀开裂原因分析

介绍了某石化公司制氢装置中变系统不锈钢管道多次发生腐蚀开裂的情况,通过分析确定裂纹形成的主要原因是奥氏体不锈钢应力腐蚀开裂。从机理分析,在温度60~150℃时,二氧化碳腐蚀产物厚而疏松、易破损,所以中变系统管道出现裂纹现象较多。通过对腐蚀部位材质检测,其名义材质为0Cr18Ni10Ti合金,但实际不含钛成分;硬度值在HB 230以上,也高于此类材质要求硬度指标HB 187。这些问题说明供货材料合金组织控制不良,在施工过程中焊接工艺又参差不齐,最终导致焊接部位存在过大的残余应力,这些残余应力先破坏了焊接热影响区的晶间钝化膜,再形成点蚀坑并逐步形成裂纹。通过采取消除应力、水质控制、材质升级、操作优化等措施,取得良好效果,确保了装置的长周期运行。     

FSC系统以及在制氢装置的应用

简要介绍HONEYWELL公司的FSC（FAIL-SAFE CONTROL）连锁系统的结构、功能以及FSC在制氢装置的应用和启动备用鼓风机回路的讨论。     

硫酸装置过程气冷却器管束失效原因分析

文章对长岭分公司湿接触法酸性气制硫酸(WSA)装置过程气冷却器管束弯头焊缝及近焊缝区腐蚀穿孔原因进行了分析,指出主要是由于焊接质量问题所致,而融盐中含有的氧和水分则是加速腐蚀穿孔的另一个重要原因。通过控制焊缝质量、更换仪表风和选用耐蚀的Cr-Mo钢材质可使腐蚀得到控制。     

制氢装置转化炉炉管催化剂支托失效分析

对两次检修中所发现的中国石油化工股份有限公司石家庄炼化分公司1号制氢装置转化炉炉管催化剂支托出现损坏的情况做了介绍,并对两种批次的催化剂支托进行了成分分析,对使用Incoloy800H材料、损坏严重的催化剂支托表面宏观照片进行了分析,对损伤支托的横截面进行金相、电镜及能谱检验分析。通过对Cr25Ni20和Incoloy800H两种材料的抗渗碳能力的比较,得出了以下结论:催化剂支托损伤的原因是材料在含氢高温环境下发生了表面渗碳现象,直接导致材料表面组织相变、材料分层、表现材料组织疏松和隆起,并在表面区域晶界上产生了大量的微裂纹,同时引起材料内部有大量的碳化物析出,使得材料的韧性急剧下降,塑性不足。热膨胀后的支托难以回复到原始形态,故在部分破坏的支托管上出现类似"蠕胀"的胀粗现象。结果表明,使用Cr25Ni20材料的抗渗透能力比Incoloy800H要好。     

制氢装置脱碳系统的腐蚀及措施

本文针对辽阳石油化纤公司化工一厂制氢装置脱碳系统的腐蚀问题进行分析。提出了防止脱碳系统腐蚀的具体措施,并经过多年的实际运行使脱碳系统的腐蚀问题基本得到解决。同时减少了脱碳系统中的结垢物,延长设备的使用寿命,具有一定的现实意义。     

制氢装置中变气换热流程运行分析

分析了制氢装置中变气换热流程运行过程中出现的问题,包括除盐水上水和空冷器入口温度超高10~20℃,锅炉给水泵和除盐水上水线腐蚀,除盐水预热器管束断裂以及空冷器入口不锈钢管件应力腐蚀开裂等。采取对有关设备、工艺管线进行材质升级,中温气换热流程实施优化改造,除盐水预热器管束更换等措施,消除了设备、管线存在的隐患;合理利用中变气余热回收副产0.4 MPa蒸汽部分替代1.0 MPa蒸汽,中变气、除盐水温度下降至正常温度,降低了蒸汽、电、除盐水、循环水等公用工程的消耗。经过数次检修和技术改造,提高了装置运行的安全性和可靠性,实现了较好的节能效果。     

制氢装置中温变换流程改造

中国石油化工股份有限公司洛阳分公司制氢装置采用轻烃水蒸气制氢技术。装置自2009年开工以来,中变气进空气冷却器入口温度及除盐水换热后进除氧器的上水温度均超出设计值,存在PSA联锁停车风险及水气系统管线氧腐蚀等问题。对中温变换流程进行如下改造:在第一分水罐后面增设1台蒸汽发生器,并拆除除盐水预热器限流孔板。装置改造后,解决了中温变换后路热量过多的问题,利用中温变换余热可产出0.5 MPa蒸汽外送管网,产生经济效益约604.8×104RMB$/a;空冷风机由停工前的4台全开,改为目前的2开2备,可节约电费约19×104RMB$/a;利用自产的0.5 MPa蒸汽代替1.0 MPa蒸汽,满足生产要求,装置能耗可降低4 186.8 MJ/t;除氧器上水温度得到有效控制后,自产除氧水除氧效果改善明显,有利于制氢装置的长周期安全生产。     

裂解器不锈钢换热管失效分析

采用宏微观观察、光谱分析、能谱分析、元素分析等方法对裂解器不锈钢换热管失效原因进行了系统分析。结果认为,温度较低的液体焦油与温度较高的换热管外壁接触时,在换热管外壁表面产生气泡并随即破裂,气泡破裂产生的力作用在管外壁上,是导致管壁厚度减薄直到失效的主要原因。     

乙二醇冷却液中316L和304不锈钢的腐蚀行为研究

以乙二醇为冷却液,设置冷却系统的温度为25℃和50℃,工作压力为4 MPa和8 MPa,研究了不同温度、不同压力下系统中316L和304不锈钢的腐蚀行为。研究结果表明:温度和压力对冷却系统中不锈钢的腐蚀均有影响,随着温度的升高和压力的增大,不锈钢腐蚀更严重;相同条件下,304不锈钢的腐蚀速率比316L不锈钢更高,同时由于不锈钢的氧化作用使得试验后的冷却液颜色变浅。冷却系统中的不锈钢腐蚀是一个复杂而又缓慢的过程,温度、压力及水分等因素对腐蚀均有影响。     

PTA装置不锈钢设备的腐蚀及防护

介绍了中国石油化工股份有限公司天津分公司精对苯二甲酸装置在2008年设备检修期间进行的腐蚀调查情况,重点介绍了奥氏体不锈钢设备的露点腐蚀、晶间腐蚀和点蚀等事例。指出精对苯二甲酸装置316L钢设备普遍发生点蚀,主要与卤素离子(主要是Br~-和Cl~-)有关;晶间腐蚀分敏化态(焊缝)及非敏化态(母材)两种形式;干燥机筒体的酸露点腐蚀是由于壳程温度比列管温度低,产生的电位差使筒壁侧易遭受腐蚀。针对以上腐蚀原因,提出了防护措施。     

浅谈制氢装置事故处理经验

制氢装置在全厂流程中处于平衡氢气供需的重要位置,通过对事故案例的分析,论述 了制氢装置事故处理的经验。     

Technical and Economical Analysis of Hydrogen Sulfide Removal from the Recycled Hydrogen in a Diesel Hydrodesulfurization Plant

Hydrodesulfurization (HDS) is a catalytic process used to remove sulfur compounds, which leads to very low sulfur concentrations. HDS turns more complicated and severe according to the feedstock boiling range, since sulfur compounds present in light cuts, normally sulfides and mercaptanes, are easy to remove, and sulfoaromatic compounds, specially polycyclics, are the more refractive ones (Speight, J. G. (1981). The Desulfurization of Heavy Oils and Residua. 2nd ed. Marcel Dekker, Inc.: Chemical Industries 4.) The hydrogen sulfide (H₂S) produced in the HDS has an inhibiting effect on the same reaction, as it has been widely observed (McCulloch, D. C. (1983). Applied Ind Catal. I:69; National Petroleum Refining Association (NPRA). (1993). Questions & Answers, 99; Leglise, J., Van Gestel, J., Duchet, J. C. (1994). Symposium on Advances in Hydrotreating Catalysts Presented before the Division of Petroleum Chemistry Inc. In: 208th National Meeting American Chemical Society. Washington D.C. p. 533). This effect is well known even at relatively low H₂S concentrations (2 mol%) for commercial operation conditions (Leglise, J., Van Gestel, J., Duchet, J. C. (1994). Symposium on Advances in Hydrotreating Catalysts Presented before the Division of Petroleum Chemistry Inc. In: 208th National Meeting American Chemical Society. Washington D.C. p. 533). Due to this, the H₂S removal from the recycled hydrogen to the reactor is mandatory in order to increase the desulfurization levels or to increase the processing capacity of an HDS plant. There are many options to low the H₂S concentration in the H₂ loop (Cooper, A., Stanislaus, A., Hannerup, P. N. (June 1993). Hyd Process 84; Johnson, A. D. (1983). Oil and Gas J 10:78; Nash, R. M. (1989). Oil and Gas J 13:47; Suchanek, A. J., Dave, D., Gupta, A., Van Stralen, H., Karlsson, K. (1993). In: NPRA Annual Meeting AM-93-24; Tippett, T., Knudsen, K. G. (1999). In: NPRA Annual Meeting. San Antonio, TX. 1999 NPRA Annual Meeting, San Antonio, TX, AM-99-06.), which are from a simple purge adjustment for light naphtha HDS to a full treatment of the H₂ stream for middle distillate HDS, where the H₂S concentration can reach levels of 10 mol% (National Petroleum Refining Association (NPRA). (1993). Questions & Answers, 99). This work presents the economical analysis of the introduction of an Amine Treating Unit in an HDS plant in operation to remove H₂S from the H₂ stream recycled to the reactor.     

Technical and Economical Analysis of Hydrogen Sulfide Removal from the Recycled Hydrogen in a Diesel Hydrodesulfurization Plant

Abstract

Hydrodesulfurization (HDS) is a catalytic process used to remove sulfur compounds, which leads to very low sulfur concentrations. HDS turns more complicated and severe according to the feedstock boiling range, since sulfur compounds present in light cuts, normally sulfides and mercaptanes, are easy to remove, and sulfoaromatic compounds, specially polycyclics, are the more refractive ones (Speight, J. G. (1981 Speight, J. G. 1981. The Desulfurization of Heavy Oils and Residua Chemical Industries 4. , 2nd ed. Marcel Dekker Inc.  [Google Scholar]). The Desulfurization of Heavy Oils and Residua. 2nd ed. Marcel Dekker, Inc.: Chemical Industries 4.) The hydrogen sulfide (H₂S) produced in the HDS has an inhibiting effect on the same reaction, as it has been widely observed (McCulloch, D. C. (1983 McCulloch, D. C. 1983. Applied Ind. Catal., I: 69 [Google Scholar]). Applied Ind Catal. I:69; National Petroleum Refining Association (NPRA). (1993 National Petroleum Refining Association, NPRA. 1993. Questions & Answers 99 [Google Scholar]). Questions & Answers, 99; Leglise, J., Van Gestel, J., Duchet, J. C. (1994 Leglise, J., Van Gestel, J. and Duchet, J. C. Symposium on advances in hydrotreating catalysts presented before the division of petroleum chemistry Inc. 208th National Meeting. pp.pp. 533Washington, D.C.: American Chemical Society.  [Google Scholar]). Symposium on Advances in Hydrotreating Catalysts Presented before the Division of Petroleum Chemistry Inc. In: 208th National Meeting American Chemical Society. Washington D.C. p. 533). This effect is well known even at relatively low H₂S concentrations (2 mol%) for commercial operation conditions (Leglise, J., Van Gestel, J., Duchet, J. C. (1994 Leglise, J., Van Gestel, J. and Duchet, J. C. Symposium on advances in hydrotreating catalysts presented before the division of petroleum chemistry Inc. 208th National Meeting. pp.pp. 533Washington, D.C.: American Chemical Society.  [Google Scholar]). Symposium on Advances in Hydrotreating Catalysts Presented before the Division of Petroleum Chemistry Inc. In: 208th National Meeting American Chemical Society. Washington D.C. p. 533). Due to this, the H₂S removal from the recycled hydrogen to the reactor is mandatory in order to increase the desulfurization levels or to increase the processing capacity of an HDS plant. There are many options to low the H₂S concentration in the H₂ loop (Cooper, A., Stanislaus, A., Hannerup, P. N. (June 1993 Cooper, A., Stanislaus, A. and Hannerup, P. N. 1993. Hyd. Process., June: 84 June [Google Scholar]). Hyd Process 84; Johnson, A. D. (1983 Johnson, A. D. 1983. Oil and Gas J., 10: 78 [Google Scholar]). Oil and Gas J 10:78; Nash, R. M. (1989 Nash, R. M. 1989. Oil and Gas J., 13: 47 [Google Scholar]). Oil and Gas J 13:47; Suchanek, A. J., Dave, D., Gupta, A., Van Stralen, H., Karlsson, K. (1993 Suchanek, A. J., Dave, D., Gupta, A., Van Stralen, H. and Karlsson, K. NPRA Annual Meeting. AM-93-24 [Google Scholar]). In: NPRA Annual Meeting AM-93-24; Tippett, T., Knudsen, K. G. (1999 Tippett, T. and Knudsen, K. G. NPRA Annual Meeting. San Antonio, TX. AM-99-06 [Google Scholar]). In: NPRA Annual Meeting. San Antonio, TX. 1999 NPRA Annual Meeting, San Antonio, TX, AM-99-06.), which are from a simple purge adjustment for light naphtha HDS to a full treatment of the H₂ stream for middle distillate HDS, where the H₂S concentration can reach levels of 10 mol% (National Petroleum Refining Association (NPRA). (1993 National Petroleum Refining Association, NPRA. 1993. Questions & Answers 99 [Google Scholar]). Questions & Answers, 99). This work presents the economical analysis of the introduction of an Amine Treating Unit in an HDS plant in operation to remove H₂S from the H₂ stream recycled to the reactor.     

加热炉奥氏体不锈钢盘管的实效原因分析

某输送含CO2天然气的再生气加热炉盘管在运行49 h后出现了开裂泄漏。通过渗透检测、材料理化性能测试、晶间腐蚀试验、扫描电镜断口形貌分析、能谱分析,结合实际运行的工况环境对盘管的失效原因进行了综合分析。分析结果表明:加热炉的原始设计资料考虑的使用环境未提及氯离子,而实际进入加热炉盘管的湿气介质中含有较高浓度的氯离子,盘管材质的理化性能分析未发现材料质量问题,盘管断口特征具备典型的脆性开裂特征,结合高温、高氯离子的使用特点,推断出氯化物应力腐蚀开裂是造成奥氏体不锈钢盘管开裂破坏的主要原因,从材料选择和腐蚀环境控制两个方面提出了相应的防护措施建议。     

聚丙烯装置反应器温度控制失效分析及对策

论述了扬子石化聚丙烯装置1#反应器硕部冷凝器失去撤热能力与1#反应器飞温、波动、失控之间的关系,分析了温度控制失效的原因,并提出了相应措施。