奥氏体钢富铬层保留清洗的可行性研究

Feasibility of Cr-rich layer retention during chemical cleaning of reheaters made of austenitic stainless steels

基于富铬层对过热器、再热器奥氏体钢氧化皮生长过程的影响分析,提出了富铬层化学保留清洗的方法。针对奥氏体钢材质的多样性、氧化皮状态的复杂性以及工程可实施性,研制了一种由多种有机酸复配且适合多种奥氏体钢富铬层保留清洗的介质,在溶垢试验中采用失重法测得该清洗介质对氧化铁层的溶解量为富铬层的10倍,对TP347H、Super304及HR3C3种管材进行24h清洗后发现:TP347H和Super304材质表面易剥离的氧化铁层可完全去除,HR3C表面的氧化铁层较为致密,化学清洗后有少量残留,3种材质的富铬层得到了完整保留,且没有引起奥氏体钢的晶间腐蚀。

Based on effect of the Cr-rich layer on oxide scales formation process on boiler superheaters and reheaters,the Cr-rieh layer retention cleaning method was proposed. Considering the variety of austenitic stainless steels ,the complexity of oxide scale condition and the construction difficulties,a novel cleaning medium consisting of various organic acids was developed,which could achieve the aim of Cr-rich layer retention cleaning for various austenitic stainless steels . By losing gravity method, dissolving scale test showed the dissolution rate of Fe oxides layer was ten times higher than that of the Cr-rich layer on austenitic stainless steel,which ensures the Cr-rich layer＇s retention after long time cleaning. Application of this cleaning medium on TP347H,Super304 and HR3C steels shows that,after chemical cleaning for 24 hours, the Fe oxides on TP347H and Super304 steels could be totally removed,while oxides on HR3C steel had left little amount due to the compact structure. The Crrich layers of three steels were remained successfully. Moreover,intergranular corrosion didn＇t occur on the austenitic stainless steel during chemical cleaning using this novel cleaning medium.