列管式石墨换热器管束的失效分析  

Failure analysis of tube graphite heat exchanger′s tube bundles

作　　者：蒋凤易 田蒙奎[1] 郝立通 邵珠花 杨颖 罗祥丽 Jiang Fengyi;Tian Mengkui;Hao Litong;Shao Zhuhua;Yang Ying;Luo Xiangli(College of Chemistry and Chemical Engineering,Guizhou University,Guiyang 550025,China;Guizhou Lanxin Graphite Electrical Equipment Manufacturing Co.,Ltd.)

机构地区：[1]贵州大学化学与化工学院,贵州贵阳550025 [2]贵州兰鑫石墨机电设备制造有限公司

出　　处：《无机盐工业》2018年第9期67-71,共5页Inorganic Chemicals Industry

基　　金：贵州省石墨装备制造及应用科技创新人才团队(黔科合人才团队[2015]4004号);贵州省优秀青年科技人才计划项目资助(黔科合平台人才[2017]5605);贵阳国家高新区高层次人才创新创业项目资助

摘　　要：针对贵州某化工厂用于磷酸浓缩的列管式石墨换热器因结垢堵塞及点腐蚀而导致的石墨管束失效现象和问题,对垢层及石墨管束等开展了宏观检查以及扫描电镜观察、化学成分分析、X射线衍射分析、热重分析和开孔气孔率测试等,以期掌握其失效机理并能有效控制。研究表明,垢层主要成分为碳酸钙、氟化钙和二氧化硅,结垢堵塞是由于磷酸中的杂质碳酸钙、二氧化硅和金属氧化物(氧化镁和三氧化二铁)含量偏高,且未及时定期对石墨管束进行除垢清理造成的;点蚀坑主要是由于垢下腐蚀引起的,垢层的疏松程度不同,点蚀坑的大小、数量和分布有所差异。垢层越疏松,磷酸越容易渗透,到达管内壁形成局部腐蚀,随着腐蚀时间的延长,管内壁出现点蚀坑现象。In allusion to a chemical plant in Guizhou Province,it′s pointed the situation that scaling jam and pitting corrosion phenomena inside graphite tube during phosphoric acid condensation,and thus the tube graphite heat exchanger loses its efficiency.Using the test methods of macroscopic examination and scanning electronic microscope observation,chemical composition analysis,XRD analysis,thermogravimetric analysis and open porosity test to analyze the graphite tube scaling layer and the graphite tube,so as to comprehend the mechanism of the inefficacy of the tube graphite heat exchanger and control it effectively.Results showed that the main contents of scaling layer were CaCO3,CaF2 and SiO2;scaling jam was due to high content of impurities,such as CaCO3,SiO2 and some metallic oxide(MgO and Fe2O3)in phosphoric acid and un-timely scaling removal in graphite tube bundle.Pitted corrosion mainly caused by corrosion under the scale,and the size,quantity and distribution of corrosion pits varied according to the porous degree of scaling layer.The looser of scaling layer,the easier of phosphoric acid to penetrate the scaling layer to form localized corrosion on the inner wall,and inner wall would appear pitted corrosion phenomena with the increase of etching time.

关 键 词：列管式石墨换热器 石墨管束 结垢堵塞 点腐蚀 失效分析 

分 类 号：TH145.13[一般工业技术—材料科学与工程]