摘要
以某液化天然气(LNG)燃气-蒸汽联合循环机组为例,分析了该类机组锅炉汽水管道部件的失效机制。结果表明,LNG电厂汽水管道部件发生失效的部位及时间具有规律性。由于LNG机组采用日启日停调峰运行方式,经常处于急剧变负荷工况,导致部件内外壁会产生很大的热应力,且变化幅度较大,使应力或应变集中部位产生疲劳损伤。调峰运行停机过程中,部件内部易停留积水,产生点蚀。此外,当管子的外壁温度低于烟气露点温度时,易形成应力腐蚀。因此,疲劳、腐蚀是LNG燃气-蒸汽联合循环机组锅炉部件失效的主要原因。
The failure mechanism of steam pipe in boiler of a liquid natural gas(LNG)gas-steam combined cycling unit was investigated.The results showed that,the position and time of failures occurred on steam pipe of the LNG gas-steam combined cycling unit were regular.Peak load operation with daily startup and stop of this power plant led to sharp varying load conditions,causing large thermal stress on inner and outer wall of the boiler components.Furthermore,large variation of the thermal stress resulted in fatigue damage in stress/strain concentration area.Besides,during the unit stop process for peak operation,water was easily accumulated inside the components,causing pitting corrosion.When the outside tube wall temperature was lower than the flue gas dew point,stress corrosion may occur.Therefore,fatigue and corrosion are the main failure mechanisms of steam pipes in the LNG gas-steam combined cycling units.
出处
《热力发电》
CAS
北大核心
2013年第8期112-115,共4页
Thermal Power Generation
