基于热固双向耦合模型的二次再热超超临界汽轮机超高压转子热应力研究

Study on Thermal Stress of Ultra-high Pressure Rotor of Ultra-supercritical Double-reheat Steam Turbine Based on Thermo-structural Two-way Coupling Model

为准确预估二次再热汽轮机转子在启动、停机过程中的热应力,推导了轴对称结构热固双向耦合计算模型。采用热固单、双向耦合模型和有限元法,计算了二次再热超超临界660 MW汽轮机超高压转子在冷态启动过程中的瞬态温度场和热应力场,对启动曲线进行了优化。研究表明,在冷态启动时双向耦合模型最大热应力值比单向模型计算值小4%,热冲击越大,两者计算值相差也越大,热固双向耦合模型比单向模型计算精度高,但计算时间长。采用优化后的启动曲线,转子最大热应力比原最大值降低了27%,实际机组运行也表明采用优化启动曲线,机组运转良好。

To estimate thermal stress of steam turbine rotor accurately during start-up and shutdown process, an axisymmetric thermostructural coupling calculated model is introduced. The transient temperature field and thermal stress field of a ultra-high pressure rotor for double-reheat ultra-supercritical 660 MW steam turbine in the cold condition start-up process are calculated by the thermostructural one-way and two-way coupling model and the finite element method, and the start-up curve of rotor is optimized. The result shows that the maximum thermal stress calculated by the two-way coupling model is about 4% smaller than that calculated by the oneway coupling model. The larger the thermal shock, the higher difference of results between two models. The thermo-structural two-way coupling model is more accurate than the one-way coupling model, but the computation time is much longer at same time. The maximum thermal stress deceases about 27% using the optimized starting curve of rotor, and the unit operation process also shows that the unit works well with the optimized starting curve.