为防止某压水堆核电厂在满负荷平台瞬态试验过程中发生因汽轮机轴向位移超过跳机阈值导致的跳机和跳堆问题。通过分析HN1755-7.55/291/275.8-H型汽轮机轴向推力平衡设计方案，得出甩负荷时中压缸轴向推力大于高压缸轴向推力的结果。根据汽轮机节流调节下负荷与蒸汽需求量为1∶〖KG-2mm〗1的关系分析给出了甩负荷过程中轴向位移最大值与负荷的计算式，并给出了经验性的计算系数；基于1号机组54.7%FP跳机试验结果，计算出了100%FP平台瞬态试验过程中的轴向位移值最大值，该计算结果大于轴向位移正向跳机阈值，得出该阈值设计过小的结论。根据汽轮机安装和运行数据，调试方与设计方联合分析后将轴向位移正向跳机阈值由0.50 mm调整为0.80 mm。1号机组在100%FP平台瞬态试验过程中测得轴向位移最大值介于0.61~0.67 mm；2号机组在100%FP平台瞬态试验过程中测得轴向位移最大值介于0.48~0.58 mm。通过调整汽轮机轴向位移正向跳机阈值成功避免了在1、2号机组的100%FP平台瞬态试验过程中发生跳机和跳堆问题。

There is a need to prevent a pressurized water reactor nuclear power plant from turbine trip and reactor trip problems caused by the axial displacement of the turbine exceeding the trip threshold during the transient test of rated load (100% full power,100% FP) platform.The axial thrust balance design scheme of HN1755-7.55/291/275.8 type steam turbine was analyzed,and it was found that the axial thrust of the medium pressure cylinder was greater than the axial thrust of the high pressure cylinder when the load rejection occurred.The calculation equations for the maximum axial displacement and the load during the load rejection process were obtained according to the relationship between the load and the steam demand under the throttling governing of the steam turbine at a ratio of 1∶〖KG-2mm〗1,and the experiential calculation coefficient was provided in this paper.The maximum axial displacement during the transient test of 100% FP platform was calculated based on the test results of 54.7% FP trip of Unit 1,and was greater than the positivegoing trip threshold of turbine axial displacement,indicating too small turbine trip threshold.Then the positivegoing trip threshold of turbine axial displacement was adjusted from 0.50 mm to 0.80 mm after the joint analysis between commissioning department and design department according to the data of turbine installation and operation.The maximum axial displacement of turbine during the 100%FP platform transient tests was between 0.61 mm to 0.67 mm for Unit 1,and between 0.48 mm to 0.58 mm for Unit 2.The problems of turbine trip and reactor trip during the 100%FP platform transient tests in Unit 1 and Unit 2 were successfully avoided by adjusting the positivegoing trip threshold of turbine axial displacement.

TM623

中科院低温工程学重点实验室开放课题（CRYO20186）；陕西省重点研发计划（2018ZDXM-GY-057）