超超临界机组水汽加氧系统改造

Retrofit on Oxygenated Treatment for Steam-Water System of Ultra-supercritical Units

针对管路流动加速腐蚀(FAC)严重的问题,提出给水系统进行加氧处理改造。结合一台600 MW超超临界机组改造实例,给出汽水系统中给水加氧和高加疏水加氧系统的流程、加氧点和取样点的位置分布。实践表明:改造半年后,省煤器表面原来的Fe3O4氧化膜完全转化为形态致密的Fe2O3晶体颗粒,流动阻力减少;与未实施给水加氧改造的机组相比,改造过的机组汽轮机低压转子叶片氧化铁沉积量少。

To reduce the flow-accelerated corrosion in piping system of a 600 MW ultra-supercritical unit, a retrofit scheme was presented by oxygenated treatment to its steam-water system, including the flow chart of oxygenated treatment covering the feed-water system and high-pressure heater drainage system, as well as the arrangement of oxygen-adding and sampling points. Results show that the flow resistance reduces half a year after retrofit due to complete transformation of original Fe3O4 film into compact Fe2O3 film on surface of relevant economizer tubes, and the deposition of iron oxide on rotor blades of the steam turbine reduces accordingly after the retrofit.