为了满足电网深度调峰和供热的要求，低压缸需要长期在低负荷甚至零出力工况下运行。本文以某660 MW汽轮机为对象，对其深度调峰和供热工况下低压叶片的通流特性和运行安全性问题进行了研究，得到了不同排汽压力时低压末级叶片的流场分布以及相关参数随背压变化的规律，分析计算了叶片所受汽流弯应力，确定了汽流弯应力随背压的变化。结果表明：该机组在深度调峰和供热的小容积流量工况下，叶片所受汽流弯应力很小，满足不调频叶片的设计要求，能够保证机组安全稳定运行；小容积流量工况下，汽轮机的排汽压力降低，真空度提高，其低压部分摩擦鼓风损失大幅度降低，鼓风发热问题减少，汽流弯应力降低，汽轮机可以安全稳定运行。

In order to meet the requirements of depth peak regulation and heat supply of the power grid, the low pressure cylinder needs to operate under low load or even zero output conditions for a long time. In this paper, a 660 MW steam turbine is taken as an object to study the flow characteristics and operation safety of lowpressure blade under deep peak load and heating conditions. The flow field distribution of lowpressure last stage blade under different exhaust pressures and the law of the change of related parameters with back pressure are obtained. The bending stress of the blade subjected to steam flow is analyzed and calculated, and the change of the bending stress with back pressure is determined. The results show that the steam flow bending stress of the blade is very small under the condition of deep peak regulation and small volume flow of heat supply, which can meet the design requirements of the blade without frequency modulation and ensure the safe and stable operation of the unit; under the condition of small volume flow rate, the exhaust pressure of the turbine is reduced, the vacuum degree is increased, the friction blast loss of the low pressure part is greatly reduced, the problem of blast heating is reduced, the bending stress of the steam flow is reduced, and the steam turbine can operate safely and stably.

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