天然气集输管道内腐蚀分析及防护
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摘要
管道集输是目前天然气长距离输送的重要方式。由于天然气内含有CO_2,溶于水后呈现出弱酸性,对铁等金属材料产生电化学腐蚀,其中阳极端形成FeS沉淀,阴极端发生还原反应,造成管道内腐蚀,影响管道输送安全。以S气田为例,采用腐蚀挂片实验方法对CO_2腐蚀影响因素进行研究,分析了时间、温度及不同浓度下的Cl~-、HCO_3~-、SO_4~(2-)、Ca~(2+)、Mg~(2+)对挂片腐蚀速率的影响,以及4种缓蚀剂JS-19、KR-16、WX-11、WD-03在不同浓度下的缓蚀效果。研究表明,JS-19、WX-11缓蚀剂具有较好的抗腐蚀效果,并对这2种缓蚀剂进行复配,推荐采用20 mg/L的JS-19+40 mg/L的WX-11缓蚀复配方案,缓蚀率可达到98.1%,腐蚀速率降低到0.007 1 mm/a。
Pipeline gathering and transportation is an important way for long-distance transportation of natural gas. Because of the CO_2 in natural gas, it shows weak acidity after dissolving in water and produces electrochemical corrosion on iron and other metal materials. Among them, FeS precipitation is formed at the anode end and reduction reaction occurs at the cathode end,which causes corrosion in pipeline and affects the safety of pipeline transportation. Taking S Gas Field as an example, the influence factors of CO_2 corrosion are analyzed by the corrosion hanging test method. The effects of Cl~-,HCO_3~-, SO_4~(2-), Ca~(2+) and Mg~(2+) on the corrosion rate of hanging piece under different concentration,time and temperature are analyzed. And the corrosion inhibition effects of four corrosion inhibitors JS-19,KR-16,WX-11 and WD-03 at different concentrations are analyzed. The study shows that JS-19 and WX-11 have better corrosion resistance, and the two corrosion inhibitors are compounded.The corrosion inhibition compound formula with 20 mg/L of JS-19 and 40 mg/L of WX-11 is recommended. The inhibition rate is reached 98.1% and the corrosion rate is reduced to 0.0071 mm/a.
Pipeline gathering and transportation is an important way for long-distance transportation of natural gas. Because of the CO_2 in natural gas, it shows weak acidity after dissolving in water and produces electrochemical corrosion on iron and other metal materials. Among them, FeS precipitation is formed at the anode end and reduction reaction occurs at the cathode end,which causes corrosion in pipeline and affects the safety of pipeline transportation. Taking S Gas Field as an example, the influence factors of CO_2 corrosion are analyzed by the corrosion hanging test method. The effects of Cl~-,HCO_3~-, SO_4~(2-), Ca~(2+) and Mg~(2+) on the corrosion rate of hanging piece under different concentration,time and temperature are analyzed. And the corrosion inhibition effects of four corrosion inhibitors JS-19,KR-16,WX-11 and WD-03 at different concentrations are analyzed. The study shows that JS-19 and WX-11 have better corrosion resistance, and the two corrosion inhibitors are compounded.The corrosion inhibition compound formula with 20 mg/L of JS-19 and 40 mg/L of WX-11 is recommended. The inhibition rate is reached 98.1% and the corrosion rate is reduced to 0.0071 mm/a.
引文
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[3]尹恒,董华清,原徐杰,等.川气东送管道内腐蚀调查分析[J].腐蚀与防护,2014,35(10):1051-1055.YIN Heng,DONG Huaqing,YUAN Xujie,et al.Investigation and analysis of internal corrosion of Sichuan-East Gas Transmission Pipeline[J].Corrosion and Protection,2014,35(10):1051-1055.
[4]李天成.榆济天然气管道内腐蚀原因[J].腐蚀与防护,2014,35(3):282-285.LI Tiancheng.Reasons for internal corrosion of Yuji Natural Gas Pipeline[J].Corrosion and Protection,2014,35(3):282-285.
[5]李宁.天然气管道内腐蚀的原理及直接评价[J].腐蚀与防护,2013,34(4):362-366.LI Ning.Principle and direct evaluation of internal corrosion in natural gas pipeline[J].Corrosion and Protection,2013,34(4):362-366.
[6]辜新军,罗小武,熊小琴,等.夏-百天然气管道内腐蚀缓蚀剂的筛选[J].油气田地面工程,2012,31(10):36-37.GU Xinjun,LUO Xiaowu,XIONG Xiaoqin,et al.Selection of corrosion inhibitors for Xia-Bai Natural Gas Pipeline[J].Oil-Gas Field Surface Engineering,2012,31(10):36-37.
[7]许罡,姜子涛,杜艳霞.廉溪大道并行天然气管道腐蚀风险检测与分析[J].腐蚀与防护,2012,33(1):88-90.XU Gang,JIANG Zitao,DU Yanxia.Detection and analysis of corrosion risk of parallel natural gas pipeline in Lianxi Avenue[J].Corrosion and Protection,2012,33(1):88-90.
[8]杨锦林,颜慧敏,刘磊,等.天然气管道腐蚀与防护系统[J].油气田地面工程,2011,30(12):48-50.YANG Jinlin,YAN Huimin,LIU Lei,et al.Corrosion and protection system of natural gas pipeline[J].Oil-Gas Field Surface Engineering,2011,30(12):48-50.
[9]蒋明龙,陈庆国,李先明.普光气田集输系统腐蚀监测技术与应用[J].油气田地面工程,2018,37(5):91-95.JIANG Minglong,CHEN Qingguo,LI Xianming.Gathering and transportation system corrosion monitoring technology and application in Puguang Gas Field[J].Oil-Gas Field Surface Engineering,2018,37(5):91-95.