太阳能光热发电汽轮机转子热机械应力分析及启动优化

Start-up Optimization and Analysis of Thermo-mechanical Stressof Solar Thermal Steam Turbine Rotor

分析了太阳能光热发电汽轮机区别于传统火电汽轮机的主要技术特点,采用数值方法研究了某50MW光热发电汽轮机高压、中低压转子冷态启动过程中的热、机械应力的变化及其影响因素。研究表明:与火电汽轮机高压转子较危险不同,光热汽轮机转子最大等效应力、低周疲劳裂纹较易出现在中低压转子,其启动过程中热机械应力是制约光热汽轮机快速启动、频繁启停、变负荷运转的重要因素。并对原启动曲线中不合理、偏保守的地方进行了优化,减少未带负荷的冲转暖机时间,适时升速减少中低速暖机时间,增加低负荷暖机时长。优化方案缩短了24.4%的启动时长,关键部位最大等效热机械应力降低了23.46%,其疲劳寿命总损伤降低为1.83%,较好地满足了光热电站对光热汽轮机转子25年服役寿命周期内250次冷态启动的许用寿命要求。该优化方案较大地提升了机组的经济性及安全性,保障了光热汽轮机频繁快速启动的性能要求。

The different technical characteristics between the solar thermal steam turbine and the traditional steam turbine are studied.The numerical method was used to study the thermal and mechanical stress changes and influencing factors of a 50MW solar thermal steam turbine during HP,ILP cold start-up process.Research shows that:It is different from the high pressure rotors of thermal steam turbines,which are more dangerous,the maximum stress and low cycle fatigue cracks are more likely to occur in the intermediate and low-pressure rotor of solar thermal steam turbine.During the start-up process,the thermal mechanical stress is an important factor that restricts the rapid start-up,frequent start-stop and variable load operation of the steam turbine.It optimizes the original cold start-up curve,reduces the unloaded warm-up time,reduces the medium-low speed warm-up time and increases the low-load warm-up time,the starting time and the maximum thermal stress of the rotor are obviously reduced.The optimized scheme shortened the start-up time by 24.4%,the maximum thermal mechanical stress by 23.46%,and the total fatigue life damage was reduced to 1.83%.It can satisfy the requirements of the Solar-thermal power station for the allowable 25-year service life cycle.The economic and safety of the rotor are greatly improved,the performance requirements of the frequent and quick start of the solar steam turbine are guaranteed.