某电厂高压加热器换热管开裂泄漏原因分析

Cause Analysis on Cracking Tube Leakage of High-Pressure Heater in a Power Plant

某电厂高压加热器(高加)换热管开裂泄漏,影响发电机组安全生产。通过宏观形貌分析、断口观察、腐蚀产物能谱分析和金相观察等方法,对高加换热管裂纹原因进行分析。研究结果表明:管口径向裂纹由应力腐蚀引起,管板附近换热管的环向裂纹由腐蚀疲劳和应力腐蚀共同引起,而导致腐蚀的主要原因是由于凝汽器泄漏使给水中氯离子超标及疏水侧空气的漏入。对此,提出了防范措施。

In a power plant, cracking tube leakage oecurs in the high-pressure heaters, which has thratened the operatinn security of the generating units. In this paper, the causes of the cracking are analyzed by using macro morphology inspection, macro fracture analysis. X-ray energy spectrum analysis of corrosion products and metallographic observation. The analysis results reveal that the radial cracks al the tube orifice are induced by stress cotTosion, and the circumferential cracks at the tubes around the tube plate by both corrosion fatigue and stress corrosion, while lhe nlain causes of the corrosion are the over-numhered chloride ionsin the water and the air leakage at the drainage side due to the condenser leakage. Some preventive measures are therefore put forward.