Cause Analysis and Prevention of Drainage-Tank Leakage in Ultra-supercritical Power Plant

doi:10.11930/j.issn.1004-9649.201707073

Abstract

Abstract: The cause of drainage-tank leakage of the reheat steam pipe is analyzed in a 1000MW ultra-supercritical power plant which has been operated for less than two years. Firstly, the tank is examined using ultrasonic, then the crack is dissected, and finally the microstructure and fracture morphology of the crack are inspected carefully and analyzed. The results show that, the cracking of the pipeline hydrophobic tank in the reheating section can largely be attributed to the repeated reflux of the condensate water on the reheat pipe, which causes significant temperature difference between the upper and lower parts of the pipe, and hence the thermal fatigue cracks are generated. Eventually the thermal fatigue crack propagation leads to the leakage. Therefore, it is suggested that the structure of the drain tank should be improved and the superheat control mode should be adopted. Additionally the ultrasonic inspection for the tank should be carried out regularly.

Key words: 1 000 MW ultra-supercritical unit, thermal power plant, the reheat steam pipe, drainage-tank, thermal fatigue, crack

CLC Number:

YU Baoqing, PENG Xingna, CONG Xiangzhou, PENG Xiankuan, DU Zhanjiang, GAO Zhi. Cause Analysis and Prevention of Drainage-Tank Leakage in Ultra-supercritical Power Plant[J]. Electric Power, 2018, 51(9): 83-87,150.

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URL: https://www.electricpower.com.cn/EN/10.11930/j.issn.1004-9649.201707073

https://www.electricpower.com.cn/EN/Y2018/V51/I9/83

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