The condensate water temperature and quality,temperature and pressure in deaerator, and parameter variation of water pumps were investigated in an ultra supercritical 1 000 MW unit during runback (RB)process.The results show that,during the fast load rej ection process,the NPSHa of feedwater pumps falls by a significant margin and cavitation may occur in the booster pump.Thus,several suggestions were proposed,such as taking the RB condition as the standard to account the NPSHa drop value of booster pump to prevent the cavitation occurring when arran-ging the deaerator,setting the enthalpy of water in the deaerator as the enthalpy value of saturat-ed water corresponding to pressure at middle point of the water tank when calculating the NPSHa values.%研究超超临界1000 MW机组 RB 过程中除氧器系统的暂态试验特性，分析除氧器系统凝结水温度、质量、除氧器温度及压力以及给水泵组的参数变化。结果表明：RB过程中，给水泵组的有效汽蚀余量大幅下降，前置泵有可能发生汽蚀，建议布置除氧器时以RB工况为标准核算前置泵有效汽蚀余量下降值，防止汽蚀现象发生；计算前置泵有效汽蚀余量下降值时，将除氧器水焓值设为水箱中间位置处压力所对应的饱和水焓值。
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