锅炉汽包下降管区域三维有限元应力集中分析

Stress Concentration of Boiler Drum's Downcomer by Finite Element in Three Dimension

针对亚临界锅炉汽包内插式接管结构，以３００ＭＷ机组锅炉汽包的６７０ｍｍ×１２５ｍｍ下降管接管为例，通过三维有限元计算方法，定量分析了几种不同插式接管的内压应力集中水平．为了减小内插式接管结构内伸段对锅炉水循环的影响，将其头部加工成马鞍形．通过对比分析，得出以下结论：有内伸段的内插式接管结构比平齐内插式接管结构的应力集中水平低得多；有马鞍形内伸段的内插式接管结构不仅能保持上述特点，而且能减小对下降管口区域工质流动的影响。

Consider the structure of a welded branch of subcritical pressure boiler drum. Calculation is made for a downcomer branch ( 670 mm×125 mm)of a 300 MW unit boiler drum. The internal pressure stress concentrations for several types of set through branches are analyzed quantitatively by the 3D finite element method. A saddle shaped weld branch could reduce the boiler′s water circulation and the influence to water flow near the entrance. This would enhance the safety of the boiler's water circulation system. The stress concentration is lowered in comparison with the standard flush weld branch.