汽轮机调节级临界压比特性

为了实现汽轮机负荷的精确控制,提升自动发电控制(AGC)与一次调频能力,消除功率波动源,提高安全可靠性,通过理论计算准确得到汽轮机调节级的临界压比,研究级临界压比与流量、反动度和速比之间的关系,分析新蒸气参数、机组配气方式、结构尺寸对调节级临界压比的影响.得出调节级中全开阀后的喷嘴组最先达到临界,级临界压比是只与调节级结构尺寸有关的常数,与新蒸气参数、机组配气方式无关.对部分配气方式进行优化,消除不同配气方式之间的流量偏差,将流量误差控制在1%以内.以某600 MW超临界汽轮机为例,通过与流量特性试验、实际运行数据的对比,验证了理论计算和分析的准确性.

Critical pressure ratio characteristics of steam turbine governing stage

In order to realize the accurate control of steam turbine load, improve the abilities of automatic generation control (AGC) and primary frequency control, and eliminate the source of power fluctuation, which aim at improving the safety and reliability. The accurate critical pressure ratio was obtained by theoretical analysis. Relationships between critical pressure ratio and steam flow, reaction degree and speed ratio were studied. The effects of steam parameters, steam distribution modes and structure sizes on the critical pressure ratio of governing stage were analyzed too. The result shows that nozzles after full-arc opening governing valve reach critical state first. And the critical pressure ratio of governing stage is a constant only related to its structure parameters, which has no relation with steam parameters and steam distribution modes of units. Optimizing steam distribution modes and removing flow deviations between different steam distribution modes to control the error of flow within 1%. Take a 600 MW supercritical steam turbine as an example, comparing with flow characteristics test and actual operation data, the accuracy of theoretic calculation and analysis is verified．