Carbon-steel corrosion in multiphase slug flow and CO2

Hydrocarbon multiphase flow may exhibit various geometric configurations or flow patterns. One of these flow patterns is known as multiphase slug flow. If CO₂ is present in hydrocarbons, the steel pipelines can be corroded as this process is probably enhanced by slug flow turbulence. A hydrodynamic circuit was built to study the CO₂ corrosion rates under different slug flow conditions. The experimental results show how the corrosion rate of a carbon-steel electrode varies according to the flow turbulence. The higher slug frequency used in this study was 80 slugs/min. Experimental results for pressure drop and slug length are in agreement with the Dukler and Hubbard [A model for gas-liquid slug flow in horizontal and near horizontal tubes, Ind. Eng. Chem. Fundam. 14 (1975) 337-347] multiphase flow model. Furthermore, the experimental slug frequencies are well correlated by the Shell and Gregory [Correlation of the liquid volume fraction in the slug for horizontal gas-liquid slug flow. Int. J. Multiphase Flow 4 (1978) 33-39] equations in horizontal pipes.     

CO2饱和溶液中缓蚀剂的电化学行为及缓蚀性能

利用电化学交流阻抗（ＥＩＳ）、极化曲线和高压釜实验装置,分别在ＣＯ２饱和及高ＣＯ２分压下的模拟油田产出水中,对ＩＭＣ－８７１－Ｇ缓蚀剂的电化学行为及缓蚀性能进行了研究,结果表明：随着缓蚀剂的加入,阴阳极腐蚀电流密度明显减小,腐蚀电位逐渐正移,阳极过程受到较大程度的抑制,表明药剂为阳极吸附型缓蚀剂,且附合Ｌａｎｇｍｕｉｒ等温吸附规律。     

酸洗缓蚀剂ZZF缓蚀性能研究

采用失重法、动电位扫描法、电化学交流阻抗法和SEM分析,研究了咪唑啉类缓蚀剂ZZF的缓蚀性能.结果表明:在50℃的5%HC l溶液中,4 mmol/L ZZF缓蚀剂能有效地提高碳钢的耐蚀性能;ZZF的缓蚀作用机理系几何覆盖效应,它在金属表面吸附成膜后,使阴极和阳极过程都受到了阻滞;ZZF试样膜质均匀、致密,厚度为6μm;根据EIS提出了相应的特征等效电路.     

P110钢盐酸酸化缓蚀剂QL-1的合成及应用性能

选用非离子表面活性剂平平加-O溶液作为合成反应的溶剂,喹啉和卤代烃经季铵化反应合成一种喹啉季铵盐酸化缓蚀剂QL-1。借助红外光谱仪对合成产物结构进行了表征,并采用静态失重法和电化学极化曲线和电化学阻抗法对药剂QL-1进行了缓蚀性能评价及电化学机理分析。红外光谱分析证明了该产物分子结构符合预先设定结构。静态失重法结果表明,随着该缓蚀剂浓度的增加,P110钢试片在15%和20%盐酸溶液中的腐蚀速率随之减小;随腐蚀时间的延长和腐蚀温度的升高,P110钢试片在盐酸溶液中的腐蚀速率均逐渐增大。电化学交流阻抗谱和极化曲线结果表明,该缓蚀剂在P110钢表面形成了明显的保护性膜,并且是一种以抑制阴极反应过程为主、作用机理属于"负催化效应"的混合型缓蚀剂。     

一种咪唑啉缓蚀剂在碳钢表面成膜的电化学研究

利用动电位扫描法研究了咪唑啉缓蚀剂MCI在碳钢表 面成膜的耐蚀性能；通过电化学交流阻抗技术.测量了碳钢表面成膜的EIS谱，并提出其特征等效电路.探讨了缓蚀剂在碳钢表面的缓蚀机理.实验结果表明，在高温高压下碳钢表面经咪唑啉缓蚀剂MCI处理成膜后具有很好的耐蚀性能.     

Cefotaxime sodium: A new and efficient corrosion inhibitor for mild steel in hydrochloric acid solution

The corrosion inhibition of mild steel in 1 M HCl solution by cefotaxime sodium has been studied by Tafel polarization, electrochemical impedance spectroscopy (EIS) and weight loss measurement. The inhibitor showed 95.8% inhibition efficiency at optimum concentration 300 ppm. Results obtained revealed that inhibition occurs through adsorption of the cefotaxime on metal surface without modifying the mechanism of corrosion process. Potentiodynamic polarization studies suggest that it is a mixed type of inhibitor. Electrochemical impedance spectroscopy techniques were also used to investigate the mechanism of corrosion inhibition.     

柚子皮提取物对C38的缓蚀作用

目的研究柚子皮提取物对C38钢在1 mol/L HCl中的缓蚀作用。方法通过索氏提取器从柚子皮中提取天然绿色缓蚀剂,进而与0.01 mol/L KI进行复配,采用失重法和电化学测试法分析柚子皮提取物的缓蚀作用机理。结果失重实验表明,柚子皮提取物对C38钢的缓蚀作用最高达93%,而与0.01mol/L KI复配使用后缓蚀效率最高达98%以上。同时表明其在碳钢表面的吸附符合Langmuir吸附等温式;Tafel极化曲线表明其能同时抑制碳钢腐蚀的阴、阳极过程;碳钢的阻抗值随着柚子皮提取物浓度的增加而增大。结论柚子皮提取物是很好的缓蚀剂,与卤素离子复配后效果更佳。     

对相钢在流动中性含砂氯化物中的磨损腐蚀

研究了双相钢在流动含砂的3．5％NaCl溶液中的磨损腐蚀规律,测定、分析了流动体系中的电化学阻抗谱,揭示了双相钢磨损腐蚀过程中电化学的作用及其机制。结果表明,腐蚀曜 磨损腐蚀过程中起主要作用,流体力学因素只是加速了腐蚀电化学过程,阻抗谱在低频区出现一直线段和低频收缩现象。分别是双相钢在磨损腐蚀过程中电极处于自钝化状态,并受离子在钝化膜中的扩散、迁移过程控制和电极表面局部遭受破坏的特征,对于流动体系中电化学阻抗谱的分析,曹氏阻抗理论同样适用。     

桐油酸咪唑啉季铵盐的缓蚀性能

以桐油为原料合成了桐油酸,使之先后与二乙烯三胺和氯化苄反应,制备了桐油酸咪唑啉苄基氯季铵盐,对其结构进行了红外表征。利用失重法和动电位极化曲线考察了合成的季铵盐在盐酸溶液中对N80钢的缓蚀性能。结果表明,桐油酸咪唑啉季铵盐能有效抑制N80钢在盐酸介质中的腐蚀;随着缓蚀剂浓度的增大,缓蚀效率增加;随着温度升高,腐蚀速率增大,缓蚀效率减小;随着盐酸浓度的增大,N80钢的腐蚀速率增大,缓蚀剂的缓蚀效率变化不明显;该缓蚀剂为阴极抑制为主的混合型缓蚀剂。     

多相流动状态下缓蚀剂对X70钢CO2腐蚀的影响

目的 研究在多相流动状态,尤其是段塞流动条件下,各种浓度的不同缓蚀剂对X70钢腐蚀的影响.方法 采用自制实验装置模拟起伏管路段塞流动条件,通过电子显微镜、挂片失重等方法,对挂片表面形貌、腐蚀速率进行分析,数值仿真了多相流动状态下缓蚀剂乙二醇对X70钢CO2腐蚀速率的影响.结果 自制实验装置的挂片表面形貌、挂片失重速度与真实环道实验相似.实验用缓蚀剂的质量浓度超过35 mg/L后,均匀腐蚀缓蚀效率提升明显,继续提高缓蚀剂的浓度,均匀腐蚀缓蚀效率变化不大.多相流动条件下,缓蚀剂对局部腐蚀的缓蚀效果不明显.仿真用缓蚀剂乙二醇的质量浓度达到250 mg/L后,缓蚀效率变化与实验结果类似.结论 自制实验装置可以模拟起伏管路内气液两相流动状态,实验结果可靠.缓蚀剂的最佳缓蚀效率存在临界浓度,小于临界值时,对挂片的缓蚀作用甚微,超过临界浓度时对挂片表面的腐蚀速率影响不大.段塞流动状态下,缓蚀剂的缓蚀作用仅针对挂片均匀腐蚀,对局部腐蚀影响不大,甚至会促进局部腐蚀的发展.     

Struktur-Wirkungs-Prinzipien von Korrosionsinhibitoren für die Rohöl- und Erdgasförderung

Structure efficiency relationships of corrosion inhibitors for oil and gas production Structure efficiency relationships for quarternary ammonium compounds as corrosion inhibitors for oil and gas production were investigated in the system mild steel/aqueous NaCl solution (5 weight%, CO₂ saturated) at T = 298 K and T = 343 K by Electrochemical Impedance Spectroscopy (EIS) and weight loss measurements. In-situ EIS measurements rapidly gave relatively accurate results on differential inhibitor efficiencies. Composition, thickness and inhibitor content of the inhomogeneous 3-D protecting layers formed on highly pure iron surfaces were determined by XPS measurements. The inhibition mechanism of the inhibitor used could be determined by its distribution within the 3-D protecting surface layer and is interpreted in terms of the interphase inhibition concept.     

Polyamine compound as a volatile corrosion inhibitor for atmospheric corrosion of mild steel*

Bis‐piperidiniummethyl‐urea (BPMU) was developed as a volatile corrosion inhibitor (VCI) for mild steel. Its vapor corrosion inhibition property was evaluated by volatile inhibiting sieve test (VIS). Electrochemical measurements were conducted in simulated atmospheric corrosion water. Electrochemical impedance spectroscopy of a volatile corrosion inhibitor monitor cell (VCIM) was applied to study the effect of BPMU on the corrosion inhibition of mild steel under a thin electrolyte layer. The results show that BPMU has good protection effect for steel. It suppressed the anodic reaction of the steel electrode in a manner of promoted passivation. Fourier transform infrared (FT‐IR) spectroscopy was used to characterize the adsorption of BPMU on the steel surface.     

米糠提取液作为盐酸酸洗缓蚀剂的研究

用盐酸酸化浸取法从米糠中提取植酸,并将其作为盐酸酸洗缓蚀剂的主要成分;采用失重挂片、线性极化和电化学阻抗等方法评价该缓蚀剂的缓蚀效率,并初步探讨其缓蚀机理。结果表明：该缓蚀剂对碳钢在1 mol/L HCl 溶液中有良好的缓蚀效果,且缓蚀效率受温度影响较小,属于阴极型缓蚀剂。     

Effects of Solution Hydrodynamics on Corrosion Inhibition of Steel by Citric Acid in Cooling Water

Corrosion is a major problem in cooling water systems, which is often controlled using corrosion inhibitors. Solution hydrodynamics is one of the factors affecting corrosion inhibition of metals in these systems. The present work focuses on the study of the combined effects of citric acid concentration (as a green corrosion inhibitor) and fluid flow on corrosion of steel in simulated cooling water. Electrochemical techniques including Tafel polarization and electrochemical impedance spectroscopy were used for corrosion studies. Laminar flow was simulated using a rotating disk electrode. The effects of solution hydrodynamics on inhibition performance of citric acid were discussed. The citric acid showed low inhibition performance in quiescent solution; however, when the electrode rotated at 200 rpm, inhibition efficiency increased remarkably. It was attributed mainly to the acceleration of inhibitor mass transport toward metal surface. The efficiencies were then decreased at higher rotation speeds due to enhanced wall shear stresses on metal surface and separation of adsorbed inhibitor molecules. This article is first part of authors’ attempts in designing green inhibitor formulations for industrial cooling water. Citric acid showed acceptable corrosion inhibition in low rotation rates; thus, it can be used as a green additive to the corrosion inhibitor formulations.     

天然气集输管道积液对有机胺缓蚀性能的影响

采用室内动态循环多相流高温高压釜模拟气田集输管线的服役环境,在流速5m/s,有无积液存在条件下进行腐蚀试验、电化学试验和接触角测量,研究了积液对于有机胺缓蚀剂缓蚀性能的影响。结果表明:积液的存在使管材的腐蚀速率增大,相对降低了有机胺缓蚀剂的缓蚀率,且加大了试样发生点蚀的概率。建议合理设计各设施的位置、管线的走向和适当的监测,尽量减少管道的落差,从而减少管道中的积液的形成,同时使用具有一定抗冲刷能力的缓蚀剂。     

Study on corrosion inhibitor in large pipelines under multiphase flow using EIS

An imidazoline based inhibitor behavior in carbon dioxide environment has been studied in large pipelines under different slug flow conditions by electrochemical impedance method. It is found that, for each of the slug flow condition, charge transfer resistance, R_t, and Warburg impedance coefficient, σ, increase with increasing exposure time. It is suggested that the performance of the corrosion inhibitor is dependent on exposure time. The corrosion inhibitor has a good performance of corrosion protection by forming more compact inhibitor films on the metal surface at longer exposure time. Experimental results also show that, at a given time, both R_t and σ decrease with increasing the Froude number of slug flow. This fact implies that the inhibitor film is damaged and washed away from the metal surface by high turbulence and the higher frequency of bubble pulse in high Froude number of slug flow, thus leading to low corrosion resistance.     

向日葵盘提取物在0.5mol/L H2SO4溶液中对碳钢的缓蚀作用

以超声辅助法提取得到的向日葵盘提取物(HALE)为缓蚀剂,采用腐蚀浸泡试验、电化学试验研究HALE在0.5mol/L H2SO4溶液中对碳钢的缓蚀作用。结果表明:HALE对碳钢缓蚀效果良好,缓蚀率随HALE加量增加而增大,但随温度升高而降低;HALE在碳钢表面的吸附符合Langmuir吸附模型,是以物理吸附为主的混合吸附;电化学测试结果表明HALE是偏阳极混合抑制型缓蚀剂。     

酸性介质中N,N′-双(2-亚甲基吡啶)-1,2-亚氨基乙烷对AZ91D镁合金的腐蚀抑制作用(英文)

采用电化学方法研究N,N′-双(2-亚甲基吡啶)-1,2-亚氨基乙烷(BPIE)Schiff碱在0.010 mol/L HCl溶液中对AZ91D镁合金的腐蚀抑制作用。动电位极化曲线表明,BPIE Schiff碱是一种混合型缓蚀剂。电化学阻抗谱(EIS)测量证实了BPIE的腐蚀抑制作用。随着缓蚀剂浓度的增加,由于有更多的缓蚀剂吸附在AZ91D镁合金表面,电荷转移阻力减小,双电层电容减小。电化学噪声(EN)分析获得的数据在时间和频率域与EIS和极化曲线所得结果表现出良好的一致性。采用扫描电子显微镜(SEM)、X射线衍射(XRD)和能量色散X射线(EDX),研究BPIE的缓蚀作用。SEM照片显示,在存在BPIE的情况下,AZ91D合金表面的腐蚀损伤得到减轻。XRD分析显示,在存在BPIE的情况下,对应于富镁α相的谱峰强度增大,表明合金样品的腐蚀程度低。EDX分析也证实了BPIE的缓蚀作用。此Schiff碱化合物通过物理吸附在合金表面,吸附行为遵循Langmuir等温吸附模型。     

钼酸盐复合缓蚀剂在天然海水中的缓蚀机理

采用电化学阻抗与能谱图研究了钼酸盐复合缓蚀剂在天然海水中的缓蚀机理。阻抗谱表明,该缓蚀剂通过增大金属表面的电荷转移电阻而降低电化学腐蚀速率;X射线光电子能谱(XPS)显示钼酸盐复合缓蚀剂在海水中的碳钢表面主要形成了Fe3O4、Fe2O3,以及三价铁与钼酸根和缓蚀剂中有机成分形成的有机铁络合物。能量谱(EDS)测试结果表明,添加了钼酸盐复合缓蚀剂的碳钢表面膜中钙元素含量很低(0.08%),表明缓蚀剂中具有阻垢性能的有机瞵酸盐(HEDP)和葡萄糖酸盐对海水中的Ca2+起络合分散作用,阻止了钙盐在金属表面的沉积,这也表明该缓蚀剂具有缓蚀性能的同时又具有良好的阻垢性能。     

Effect of Si nanoparticles on the corrosion protection performance of organic coating on carbon steel in chloride environment

This work examines the effect of silicon (Si) nanoparticles on the corrosion protection performance of epoxy coating over carbon steel by Electrochemical Impedance Spectroscopy (EIS) and Transmission Electron Microscopy. The EIS was performed in a 0.1 M NaCl solution after a wet/dry cyclic corrosion and continuous immersion test. The addition of Si nanoparticles increased the film resistance (R_f) and the charge transfer resistance (R_ct) of the coated steel. The surface analysis showed that uniform and fine Si-Fe complex oxides layers were formed acting as barrier layers that enhanced the corrosion protection of the coated steel in the wet/dry cyclic corrosion test. The results of the EIS of the coated steel with Si nanoparticles suggested that Si nanoparticles play a beneficial role in enhancing the corrosion resistance of organic coated steel.