Abstract:

Abstract:The pipes of the finishing superheater and the reheater of the boiler of a power plant were investigated experimentally.The pipe samples were obtained in different time periods under different oxygenation treatment modes. The experimental methods includes the microstructure analysis,the grain size measurement, the inner wall oxide layer metallographic analysis and the scanning electron microscope ( SEM) analysisand Xray energy dispersive spectrometer ( EDS) analysis for typical inner wall oxide layer structure.The results show that the feedwater oxygenatin treatment can acilitate forming of Fe2O3 outer shell of oxyde layer in pipe inner wall.The sample tubes of the finalstage reheater of a boiler were oxygenated most seriously, the percentage of the sample tubes,in which there was not the fine grain zone in inner wall, is larger. In the inner wall of the sample tubes,the uniform and continous Crrich layer did not formed, and this is one of the main reasons caused the oxide skin to shed concentratedly.The feedwater oxygenation treatment is a factor to promote the oxyde skin to shed.