回用污水中的溶解氧腐蚀研究

Study of Dissolved Oxygen Corrosion in Recycle Wastewater

对某炼化企业膜生化曝气处理后污水回用管线的腐蚀穿孔原因进行了分析,通过腐蚀产物分析、表面形貌观察及水样分析表明管线内壁发生了氧腐蚀。另外针对其回用的水质情况,采用浸泡实验以及电化学实验方法研究了回用污水中的溶解氧对20号碳钢腐蚀性能的影响,结果表明溶解氧质量浓度对20号碳钢的腐蚀速率影响较大,是造成回用管线泄漏的一个不可忽视的因素,当溶解氧质量浓度从接近饱和到小于1 mg/L变化时,腐蚀速率由0.2mm/a降低到0.02 mm/a,并且腐蚀速率随着流速的增加而增加,通过极化曲线可以看出降低溶解氧含量抑制了阴极反应,从而使总的腐蚀速率下降。

The causes of corrosion leakages of pipelines for recycle wastewater after membrane biochemical aeration treatment in a petrochemical company were studied. The analysis of corrosion products surface morphology observation and sample analysis showed that the internal wall of pipelines suffered from oxygen corrosion. In addition, the impact of dissolved oxygen on the corrosion performance of 20 # carbon steel was studied by immersion test and electrochemical testing methods. The results demonstrated that dissolved oxygen has a great impact on corrosion rate, and it is an important factor for pipeline leakages, which cannot be ignored. When the dissolved oxygen content changed from saturation to less than 1 mg/L, the corrosion rate was reduced from 0.2 mm/a to 0.02 mm/a, and the corrosion rate was increased with the increase of flow velocity. It can be seen from polarization curve that the reduction of dissolved oxygen content has inhibited the catholic reaction, so that the total corrosion rate is reduced.