锅炉化学清洗中Fe3+的腐蚀控制研究

采用电化学法和腐蚀失重法在静态条件下以实际复合有机酸(羟基乙酸+甲酸)锅炉清洗液作为试验溶液,研究不同质量浓度的Fe3+对SA-213材料的腐蚀情况,以及清洗操作工况对Fe3+腐蚀的影响.结果表明,Fe3+对金属基体具有显著腐蚀性,且随着其含量的增加,腐蚀速率急剧增大；投加适量还原剂,能够有效控制Fe3+含量的增长,应根据测定的Fe3+含量的大小少量分批次加入.此外,应防止空气吸入系统,且保证一定的剩余酸浓度,控制酸洗液pH值处于较低水平,抑制Fe2+的转化.

CONTROLLING OF FERRIC ION CORROSION IN BOILER CHEMICAL CLEANING

In order to control the Fe3+ corrosion during boiler chemical cleaning,the corrosion of Fe3+ with different concentration on material SA-213 used in boiler was investigated with electrochemical method and corrosion weight loss method in static state,taking the actual boiler chemical cleaning liquid as the test liquid.In addition,the influence of operating conditions such as adding method of reductants in chemical cleaning process was studied.Results show that,3+ has an obvious corrosion on the metal substrate,and with the increasing of Fe3+ concentration,a sharp increment of corrosion rate is observed.Adding proper amount of reductants can efficiently restrain the rise of Fe3+ concentration.The reductants should be added in batches according to the concentration of 3+ in cleaning liquid.Besides,to inhibit the transformation of Fe2+,the authors suggest preventing the air from entering into the system,as well as ensuring a certain residual acid concentration and a low level value of pH in liquid.