Natural Cooling and Startup of Steam Turbines: Validity of the Over-Conductivity Function
Natural Cooling and Startup of Steam Turbines: Validity of the Over-Conductivity Function
复制标题
汽轮机自然冷却和启动：过导函数的有效性
DOI：
10.1115/1.4030411
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发表时间：
2015
影响因子：
1.5
通讯作者：
M. Sell
中科院分区：
文献类型：
--
作者：
G. Marinescu;P. Stein;M. Sell
自然冷却期间的温度下降和蒸汽涡轮机重新启动的方式对关键部件的循环寿命和整个机器的循环寿命具有重大影响。为了保证最快的启动而不降低涡轮机关键部件的寿命，必须在计算中准确地捕获自然冷却并优化启动过程。在冷却和重新启动期间，所有涡轮机部件在热和机械方面相互作用。为此，热分析人员必须在其数值模型中包括所有涡轮机重要部件-转子、壳体及其内部流体腔、阀门和管道。这种与真实的现象相关的条件-自然冷却超过100小时-使得分析耗时，并且不适用于常规项目。在过去的几年中，Marinescu等人提出了一个称为“过电导率”的概念。（2013年，"Experimental Investigation Into Thermal Behavior of Steam涡轮机冷凝器-Temperature Measurements With Optical Probes and Natural Cooling Analysis"，ASME J.Eng.Gas Turbines Power，136（2），p.021602）以及Marinescu和Ehrsam（2012年，"对蒸汽涡轮机部件的热行为的实验研究：第2部分-蒸汽涡轮机的自然冷却和对LCF寿命的影响"，ASME论文号GT 2012 - 68759）。根据这一概念，流体对流和辐射的影响被称为过导热系数的标量函数K（T）所代替，其具有与真实的对流和辐射相同的传热效果。K（T）相对于Alstom KA 26 - 1蒸汽涡轮机上的测量温度进行校准（Ruffino和Mohr，2012，"Experimental Investigation on Thermal Behavior of Steam涡轮机Components：Part 1-Temperature Measurements With Optical Probes，" ASME Paper No.GT 2012-68703）。这一概念允许显着减少的计算时间，这使得该方法适用于常规瞬态分析。下面的论文显示了过电导率概念的理论背景，并证明了当应用于KA26 - 1以外的其他机器时，计算温度的准确度与测量数据相比保持在15 - 18 ° C范围内。详细分析了过电导率和能量方程之间的联系。
The temperature drop during natural cooling and the way in which the steam turbine restarts have a major impact on the cyclic lifetime of critical parts and on the cyclic life of the whole machine. In order to ensure the fastest startup without reducing the lifetime of the turbine critical parts, the natural cooling must be captured accurately in calculation and the startup procedure optimized. During the cool down and restart, all turbine components interact both thermally and mechanically. For this reason, the thermal analyst has to include, in his numerical model, all turbine significant parts—rotor, casings together with their internal fluid cavities, valves, and pipes. This condition connected with the real phenomenon lead-time—more than 100 hours for natural cooling—makes the analysis time-consuming and not applicable for routine projects. During the past years, a concept called “over-conductivity” was introduced by Marinescu et al. (2013, “Experimental Investigation Into Thermal Behavior of Steam Turbine Components—Temperature Measurements With Optical Probes and Natural Cooling Analysis,” ASME J. Eng. Gas Turbines Power,136(2), p. 021602) and Marinescu and Ehrsam (2012, “Experimental Investigation on Thermal Behavior of Steam Turbine Components: Part 2—Natural Cooling of Steam Turbines and the Impact on LCF Life,” ASME Paper No. GT2012-68759). According to this concept, the effect of the fluid convectivity and radiation is replaced by a scalar function K(T) called over-conductivity, which has the same heat transfer effect as the real convection and radiation. K(T) is calibrated against the measured temperature on a Alstom KA26-1 steam turbine (Ruffino and Mohr, 2012, “Experimental Investigation on Thermal Behavior of Steam Turbine Components: Part 1—Temperature Measurements With Optical Probes,” ASME Paper No. GT2012-68703). This concept allows a significant reduction of the calculation time, which makes the method applicable for routine transient analyses. The paper below shows the theoretical background of the over-conductivity concept and proves that when applied on other machines than KA26-1, the accuracy of the calculated temperatures remains within 15–18 °C versus measured data. A detailed analysis of the link between the over-conductivity and the energy equation is presented as well.