配汽方式对汽轮机安全的影响及顺序阀优化研究

Impact of Steam Distribution on Steam Turbine Safety and Optimization of Sequence Valve

机组在变负荷过程中,由于喷嘴配汽方案设计不当,在调节级处会产生较大的配汽不平衡汽流力,从而会引发调节级附近的各轴承发生轴心偏移、瓦温升高、轴振不稳定等轴系故障,极大地危害机组的安全运行。基于调节级的变工况计算,首先研究了变负荷过程中配汽不平衡汽流力的产生机理和变化情况,非对称进汽是配汽不平衡汽流力产生的根本原因。结合实际运行数据,全面分析了配汽不平衡汽流力对机组带来的不良影响。最后,对配汽的优化问题进行了研究,提出了低负荷的对角进汽与高负荷的顺序阀进汽相结合的喷嘴配汽方案,实践证明,配汽的优化改造能明显提高机组运行的安全性和经济性。

Irrational design of steam distribution nozzle will cause large steam distribution imbalance at governing stage, during load change of the generating unit, such imbalance leads to shaft system failures such as bearing axis offset, tem- perature rising and instable vibration, which is harmful to the safe operation of the unit. Based on the calculations under variable conditions at governing stage, this paper presents the mechanism and variation of flow imbalance during load changes and the root cause for flow imbalance is identified to be asymmetric inlet of steam. Actual operation data is ap- plied to comprehensively analyze the adverse effects of distribution steam flow imbalance on the generating unit. Finally, based on optimization study of steam distribution, this paper put forward a steam distribution scheme that is combining diagonal steam admission at low load with sequence valve steam admission at high load. Practice proves that such opti- mization modification greatly improve the safety and economy of the unit.