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由于循环清洗液的量大,且材料种类繁多,如果铜管表面上又粘附着各种氧化物,则酸洗大型发电厂铜合金凝汽器管束的过程中将涉及许多问题。因清洗液中有三价铁离子,碳钢和铝铜合金两者的腐蚀率都非常高,为此加入缓蚀剂以抑制三价铁离子的作用,并将碳钢的腐蚀率由20mm/y以上降低到2mm/y,铝铜合金的腐蚀率由数mm/y降低到20～30微米/年。但是,缓蚀剂的加入给清洗过程终点的判断带来了不便。由于配制和排放清洗液的时间较长,且在这种大型凝汽器中清洗液流速较低,所以还必须把清洗时间考虑进去。本文以不同浓度,流速的盐酸及硫酸溶液在同一试验装置中进行试验;并应用了电化学技术,测定了腐蚀电位及线性极化电阻,以判断清洗过程的终点。
Due to the large volume of circulating cleaning fluid and the wide variety of materials involved, pickling of copper alloy condenser bundles in large power plants involves a number of problems if various oxide adheres to the surface of the copper tube. Due to the presence of ferric ions in the cleaning solution, the corrosion rates of both carbon steel and aluminum-copper alloy are very high. To this end, a corrosion inhibitor is added to suppress the action of ferric ions and the corrosion rate of carbon steel is increased from 20 mm / y Reduced to 2mm / y above, the corrosion rate of aluminum-copper alloy from a few mm / y to 20 ~ 30 microns / year. However, the addition of a corrosion inhibitor brings inconvenience to the judgment of the end of the cleaning process. The cleaning time must also be taken into consideration because of the long time of preparation and discharge of the cleaning fluid and the low velocity of the cleaning fluid in such large condensers. In this paper, different concentration and flow rate of hydrochloric acid and sulfuric acid solution in the same test device for testing; and the application of electrochemical techniques, measured the corrosion potential and linear polarization resistance to determine the end of the cleaning process.