459 / 2018-12-30 23:20:17

660MW超超临界汽轮机高中压转子冷态起动优化

超超临界；汽轮机；高中压转子；有限元分析；冷态起动优化

全体主题 > 涡轮机

本文介绍了某660MW超超临界汽轮机的冷态起动（中压缸）过程，并对高中压转子进行了全尺寸有限元建模。根据汽轮机结构与热力参数，结合制造厂提供的冷态起动曲线，确定了起动过程中高中压转子各级叶轮、轴封以及光轴处的边界条件。采用有限元计算求解了高中压转子在冷态起动过程中典型位置处不同时刻的瞬态温度场与应力场,分析了汽轮机“切缸”前不同阶段暖机操作过程对高中压转子应力大小以及总体起动时间的影响。结果表明，制造厂提供的冷态起动曲线安全裕度较大，且存在暖机时间过长的问题。针对该问题，本文给出了起动曲线的优化方法，并结合汽轮机结构与运行特点制定了优化起动方案,特别对中速暖机和低负荷暖机阶段的持续时间以及蒸汽温升率进行了合理选择，并进一步结合有限元结果得到了优化后的起动曲线。通过与传统起动方式的对比，发现在保证安全的前提下，优化起动过程大大减少了起动时间。计算、分析结果可为660MW超超临界汽轮机的冷态起动优化提供参考。
The cold-start process (IP Casing) of a 660MW ultra-super-critical steam turbine is introduced. A full size finite-element model of high and intermediate pressure rotor was established. Based on the structure and thermal parameters of the unit and combining with the cold start-up curves provided by manufacturing plant, the boundary condition for the wheel rim, steam seal gland, glossy surface of the rotor are determined.The transient temperature and stress fields of typical positions of the rotor during the cold start-up process are calculated by the finite element analysis. The influences of the warm-up operation of the different stages before the "cylinder switching" of the steam turbine on the stress of the rotor and the overall starting time are analyzed. The results show that the safety margin of the cold start-up curves is too large and the warm-up time is too long. The optimization methods for these problems are given. And considering the structure and operation characteristics of the unit, the optimized start-up processes were made. In particular, the time of the medium-speed warm-up process and the low-load warm-up phase and the rising rate of steam temperature were reasonably selected. Moreover the optimized start-up curve was obtained combining with the finite element results. Compared with the traditional cold start-up process, it is found that optimized processes shorten the starting time greatly under the safety condition. The whole calculation and analysis results of this paper can provide a reference for the cold start-up optimization of the same type unit.