化工化纤生产中醋酸设备腐蚀与用材分析

对化工化纤生产中的精对笨二甲酸、聚乙烯醇、乙醛氧化生产醋酸与甲醇羰基合成醋酸4个装置醋酸设备用材进行分析,并对含Cl^-、含Br^-、含I^-的醋酸及含Cl^-的甲乙混酸对不锈钢、铜、钛与镍基合金等金属材料腐蚀原因作了讨论。     

纯钛醋酸精馏塔的制造

醋酸精馏塔是维尼纶生产中的关键设备.维尼纶生产采用乙烯直接合成醋酸乙烯的工艺方法.该方法存在醋酸和醋酸乙烯的腐蚀问题.液相法还存在着氯离子的腐蚀作用.原有设备大多为进口设备,采用不锈钢制造,使用一段时间后腐蚀、结垢严重,经常泄漏,塔内塔盘使用Cr18Ni12Mo2Ti.不锈钢使用2～3年后,厚3mm的塔盘被腐蚀减薄到0.5～1mm,筛孔也被腐蚀增大.由于纯钛在同样的介质中耐腐蚀性能远远优于不锈钢,采用钛材可解决上述问题,从而可大大提高设备的使用寿命,减少停车次数和停车损失.     

氯乙烯装置OC急冷塔出料钛管的失效分析及防护措施

介绍了氯乙烯装置ＯＣＡ急冷塔出料钛管三种不同牌号钛材的运行情况。根据钛的耐蚀机理和对三种牌号钛材的耐蚀性能试验结果，分析了三种牌号钛材的腐蚀失效原因，由此选取了合适牌号钛材，并提出了防护措施。     

钛,铜和不锈钢在醋酸中的腐蚀行为

评述了金属在无氧醋酸，含氧醋酸中的腐蚀机理，叙述了铜，钛和不锈钢在醋酸介质中的腐蚀行为；讨论了醋酸介质中的耐蚀选材。     

钛在醋酸环境中的应用分析

介绍了钛在醋酸生产环境中作为结构材料的使用情况;比较了几种材料在醋酸环境中的腐蚀速率;分析了钛在醋酸环境中可使用的条件,得出钛在氧化性醋酸环境中可以作为结构材料安全使用,而在还原性缺氧、缺缓蚀剂以及副反应中有氢生成,或与活泼异种金属接触的情况下不能作为设备结构材料使用。     

钛材在焦化工业中的应用

金属钛强度高,具有优异的抗腐蚀性能,因而钛材在化工设备中正在获得广泛应用。焦化生产接触多种酸、碱及腐蚀性流体,设备腐蚀严重,设备选材是焦化工业中一项重要课题。本文以鞍钢化工总厂使用钛制熄焦塔除尘装置为例,论述钛材在焦化工业中的应用。     

口腔微生物对钛及其合金的腐蚀影响研究进展

钛及其合金以其良好的耐蚀性能、机械性能和生物相容性,被广泛应用于牙科领域;口腔是一个极其复杂的微生物环境,微生物对钛及其合金的腐蚀影响不可忽视。综述了几种常见口腔微生物对钛及其合金的腐蚀研究现状,探讨了钛材在口腔环境中的腐蚀机理,并对钛及其合金的口腔微生物腐蚀研究趋势进行了展望。     

钛材在环氧丙烷装置生产中的应用

1 几家大型环氧丙烷装置厂家使用钛材的情况由于钛材具有密度小、强度高、耐腐蚀性能好等突出优点,成功地解决了石化工业生产中不少设备存在的严重腐蚀问题而倍受青     

制订钛焊管技术标准的依据

由于钛的优良的耐蚀特性,钛管在化工生产中获得了广泛应用,也日益成为电力工业部门制作冷凝器和冷却器的标准用材。尽管钛原料费用高,但它能避免昂贵的腐蚀消耗,因此用钛仍是经济合理的。特别是,选用壁厚为0.4～0.9毫米的缝焊管,经济效益比用无缝管更好,因为加工壁厚小于0.9毫米的无缝管困难多,要花费更多的钱。     

低成本的不锈钢

普通不锈钢在一般环境中使用不容易生锈,但在接触到海水时,由于海水中氯离子的作用,不锈钢表层受到破坏而产生腐蚀。使用钛材虽然可以耐海水腐蚀,但钛材价格较贵。     

Korrosionsinhibitoren in der chemischen Industrie

Corrosion inhibitors in the chemical industries On the basis of some examples form industrial practice potential applications of inhibitors for the solution of specific corrosion problems are shown. It was e.g. possible to prevent corrosion of titanium equipment in a chemical factory by adding chlorine to the hydrochloric acid use for cleaning; in this case chlorine acts as a gaseous passivator. In another case titanium could be protected against attack by formic acid vapours by aerating the vapours; crevice corrosion encountered in this case was suppressed by adequate increases of the aeration rate, the inhibition efficiency being controlled by built-in reference electrodes. Protection by aeration was also successful in the case of columns of CrNiMo steal in contact with contaminated acetic acid. Difficulties were encountered with salt like inhibitors when a liquid as well as a gaseous phase was present. Emphasis is also placed on the importance of water additions to liquid ammonia in the case of steel vessels.     

钛材设备化学清洗工程实践

钛材设备磁性氧化铁垢化学清洗具有一定的技术难度,国内对这一问题发表的文献不多,国外使用了羟基乙酸和甲酸的混酸清洗技术,国内因羟基乙酸价格昂贵,使用较少.对某钛材制盐设备,配制了以柠檬酸为主剂的清洗剂并制定了清洗方案,进行了工程实施.清洗结果满意.     

锆与钛耐蚀性比较及应用互补性

概述了锆与钛在各种环境下全面腐蚀与局部腐蚀性能比较,认为它们是互补的姐妹金属,是处理高温高压强腐蚀化工过程不可缺少的重要结构材料。对这两种材料在尿素、醋酸等化工环境中的应用作了比较分析。     

Acetic acid – direct corrosive mediator in SCC of titanium/ethanol system

Although so many researchers paid attention on stress corrosion mechanism of titanium/ethanol system, few papers explained why ethanol, a very weak corrosive mediator, caused severe anodic solution. We found that the anodic polarization process of the titanium/ethanol system produced lots of acetic acid, which caused the pH value decreased rapidly. Maybe the acetic acid was the direct reason of stress corrosion susceptibility of titanium alloy in ethanol. And SSR tests proved that acetic acid could accelerate SCC of this system seriously. Also we found that in this system when the specimen was in the yield region, its corrosion potential fluctuated and PDS analysis showed this fluctuation was not a pure random process but a random fluctuation superposed with a definitive quasi‐sine wave. We thought that it was acetic acid made the passive film unstable and this unstable state was the main reason caused SCC in this system.     

Korrosionsuntersuchungen an ausgewählten metallischen Werkstoffen im System Essigsäure/Esigsäureanhydrid

Corrosion tests of selected metallic materials in the system acetic acid/acetic anhydride The corrosion behaviour of the ferritic austenitic stainless steels X2 CrNiMoN 22 5 (UNS S31803) and X2 CrNiMoN 25 7 4 (UNS S32750), the nickel base alloy NiMo16Cr16Ti (alloy C-4) and the titanium grades Ti2 (Grade 2) and Ti2Pd (Grade 7) was investigated by immersion tests in boiling mixtures of acetic acid and acetic anhydride in the presence of air. All materials tested were corrosion resistant in acetic acid and acetic anhydride but were corroded rapidly by the mixtures with a corrosion loss up to 1 mm/a, except the nickel base alloy (alloy C-4). It was corrosion resistant in all solutions with a corrosion loss not exceeding 0.01 mm/a. Electrochemical tests show that all materials tested exhibit stable passivity in glacial acetic acid and active corrosion in the presence of 10% acetic anhydride.     

Inhibitors for the corrosion of reactive metals: Titanium and zirconium and their alloys in acid media

The search for effective corrosion inhibitors for titanium and zirconium in acid media is growing because of the considerable increase in the use of these materials in chemical process equipment. It still remains limited, as appears from this review, because of the exceptionally high corrosion resistance of the metals. Titanium has received the greater attention. Its corrosion rate can be lowered by introduction in the medium of multivalent ions, inorganic and organic oxidants. Care should be taken to hold the concentration at a level exceeding some critical value, otherwise the corrosion rate increases. Complexing organic agents do not show such hazardous behaviour. The very rapid corrosion of titanium and zirconium in fluoride media may be lessened by complexing the fluoride ions. Though rarely encountered, localized corrosion may be avoided by using inhibitors. In some cases good corrosion inhibitors for titanium are dissolution accelerators for zirconium.     

高温含杂醋酸环境中设备选材的探讨

对接触高温醋酸生产装置腐蚀行为及其选材进行了讨论.提出了醋酸对材料的腐蚀,既要考氧的影响,也不能忽视杂质的作用;对铜、不锈钢、钛三种材料作为高温醋酸塔器用材进行了评价比较.     

化工设备选用锆的基本考虑

化工设备设计只有在不锈钢与钛难以胜任时才考虑选用工业级锫.讨论了锆的耐蚀性与经济性,并分析了焊区晶间腐蚀、氢脆、点腐蚀与应力腐蚀破裂等及对应的防护方法.     

钛制再沸器管板接头焊缝腐蚀开裂的原因及改进措施

钛制再沸器是维尼纶生产厂醋酸精馏系统中的重要设备，使用工况苛刻、复杂，投入使用2年后，发现管板与换热管接头连接处焊缝产生腐蚀开裂。从钛制再沸器的选材、设计、制造、运行状况、使用条件、应力状态等几方面人手，分析管板接头焊缝产生腐蚀开裂的原因是：①工作介质醋酸酐和甲酸含水量低，不能维持钛在沸腾醋酸中的钝态；②在环境介质中，钛制再沸器管板接头焊缝长期受交变应力的作用，导致管板焊缝开裂。提出了避免钛制再沸器管板接头腐蚀开裂的4项措施。