二次再热汽轮机初参数高、技术先进、系统效率高，近年来已成为电力装备市场的最前沿产品。创新结构型式的汽轮机部件设计需重点考察高品质蒸汽参数所带来的转子、内缸等高温部件包括长时蠕变强度、热膨胀、流场规律等一系列复杂影响。上海汽轮机厂已成功开发的二次再热汽轮机高压缸一般采用双流对称通流布置，采用内部涡流冷却。本课题研究过程中，在公司深厚的技术积淀的基础上进行二次创新，设计了二次再热高参数单流高压缸的冷却方式，并进行具体结构实施和优化，对技术方案进行了论证和评估。基于有限元强度计算理论、蠕变的设计准则及对应的考核标准，通过对有无冷却、不同冷却方式和参数、不同冷却汽流量等多方案下单流高压转子进行多轴等效蠕变应变等的定量分析对比，揭示了在二次再热高参数单流高压模块中采用冷却汽的必要性，完成了冷却汽源选择和冷却蒸汽的定量，指导了冷却系统的方案性设计。采用CFX流固热耦合的数值计算方法对进汽高温、冷却腔室、平衡活塞汽封等几个重点流场区域进行计算分析，验证了冷却汽进入腔室后的流量分配规律，大部分冷却蒸汽从平衡活塞汽封侧漏出；验证了冷却效果，转子表面温度大幅下降；验证了冷却汽流以形成热汽隔绝的方式保护转子敏感区域。通过有限元方法完成了二次再热高参数单流高压缸各部件的强度计算考核。计算结果表明无论在考核规范要求的常规工况，还是极端泄漏工况-有高温蒸汽从通流经冷却腔室参混时，转子的安全性都能满足要求。另外，通过改进局部结构的各措施，减小抽汽盲管力、调整支撑位置、加设狭长型撑筋和增加定位螺栓等，优化设计的内缸结构能够满足高参数单流高压缸强度、密封等各项考核要求。综上，最终完成了二次再热高参数单流高压缸冷却方式和结构的技术方案研究。
In recent years, the double reheat steam turbine has become the most advanced product in the power equipment market due to its high initial parameters, advanced technology and high system efficiency. In the design of steam turbine components with innovative structure, it is necessary to focus on a series of complex effects brought by high-quality steam parameters, such as rotor, inner cylinder and other high-temperature components, including long-term creep strength, thermal expansion, flow field law and so on. The HP casing of double reheat steam turbine, which has been successfully developed, generally adopts symmetrical flow and internal eddy current cooling. In the research process of this project, based on the rich technical accumulation of the company, the secondary innovation is carried out, the cooling mode of single flow HP casing with high parameters of double reheat steam turbine was designed, and the specific structure was implemented and optimized. The technical scheme was demonstrated and evaluated. Based on the FEA strength calculation theory, creep design criteria and corresponding assessment criteria, a quantitative analysis was conducted for multi axial equivalent creep strain of single flow high pressure rotor with or without cooling. Different cooling methods and parameters, different cooling steam flow and other multiple schemes were compared. the necessity of using cooling steam in the high parameter single flow HP module of double reheat steam turbine was revealed, the cooling method, parameter and quantity are completed, guiding the design of cooling system. The numerical calculation with fluid structure heat coupling was used in CFX to calculate and analyze several key flow fields, such as high temperature inlet steam chamber, cooling chamber and balance piston gland. The flow distribution law of cooling steam after entering the chamber was verified, most of cooling steam was leaked from the gland side of balance piston. The cooling effect was verified. The temperature of rotor surface drops greatly. The cooling steam flow was verified to form hot steam to protect the sensitive area of the rotor in an isolated way. Through the FEA method, the strength calculation and evaluation of the components of the single flow HP casing with high parameters of double reheat turbine were completed. The calculation results show that the safety of the rotor can meet the requirements of both the normal condition and the extreme leakage condition. In addition, by improving the local structure measures, such as reducing the extraction blind pipe force, adjusting the support position, adding long and narrow braces and adding positioning bolts, the optimized structure design of the inner casing can meet the strength and sealing assessment requirements. In conclusion, the research on the cooling mode and structure of single flow HP casing with high parameters of double reheat steam turbine was finally completed.
