红沿河核电项目除氧器超压问题分析及改进措施

Deaerator overpressure analysis and improvement measures for Hongyanhe Nuclear Power Plant

红沿河核电站现有除氧器在主蒸汽旁路工况下会发生超压问题,为了定量把握超压问题的实质,对现有除氧器在汽轮机旁路工况下的压力全变化过程进行了详细分析。分析表明,现有除氧器将在切入旁路工况5.2 s后内部压力超过设计压力,引起安全阀起跳并向大气排放蒸汽。为了提高系统的安全性,文章提出了将正常抽汽管道和旁路蒸汽管道分离设置,并在现有除氧器内增设鼓泡管系统的改进设计方案,利用新建立的数值分析模型对改进方案进行了理论验算。计算结果表明,改进后的方案可保证在主蒸汽旁路工况50 s内除氧器内部压力不会超过设计压力。

An overpressure problem will occur in the tray and spray type deaerator of Hongyanhe nuclear power plant at the turbine steam bypass process.To get knowledge about the overpressure problem quantitatively,all the course of pressure change at turbine bypass process has been analyzed.The results show that internal pressure will exceed the design pressure of the deaerator in 5.2 seconds after turbine steam bypass operation,causing safety valve open and starting steam ejection into the air.To improve the safety of the deaerator system,an improved design has been made.In the design,normal steam inlet nozzles and bypass steam inlet nozzles are placed separately,and a steam bubbling system is added into the present tray and spray type deaerator.Effectiveness of the improved design was checked by using a newly established numerical method.The result is that the internal pressure will not exceed the design pressure of the deaerator within 50 seconds of all the turbine bypass process.