管壳式换热器换热管与管板焊接接头疲劳性能研究

Study on Fatigue Performance of Welded Joints Between Tube and Tubesheet of Shell-and-tube Heat Exchanger

现今发电运行工况趋于复杂化,具有启停频繁、温升快速等特点,对换热器的使用寿命造成显著影响。对于管壳式换热器,换热管与管板的焊接接头易发生疲劳破坏。基于标准ASMEⅧ-2篇等效结构应力幅值的方法,使用有限元分析,对不同焊接形式的换热管与管板焊接接头的疲劳损伤进行评定,探讨应用在复杂工况下的最佳焊接形式。通过对不同设备中换热管与管板焊接接头在运行时许用循环次数进行计算,研究不同管板厚度以及不同换热管规格对最佳焊接形式选择的影响,得到坡口焊接为最佳焊接形式。随着管板厚度增加,换热管外径增大,更能体现此类焊接形式的优势。

At present, the complexity of operation conditions in power plant, such as frequent start and stop, rapid temperature rise and so on, has a significant impact on the service life of heat exchanger, especially causing fatigue failure of the welded joint between tube and tube sheet. Based on the method of structural stress in the standard ASME VIII-2, the fatigue damage of different types of tube and tube sheet welded joints is evaluated by finite element analysis, and the best welding form is obtained. By comparing the allowable cycles of welded joints between tube and tube sheet in different equipment, the effects of tube sheet thickness and tube specification on the optimal welding form are obtained. The results show that the groove weld is the best welding form, and the larger the tube sheet thickness and the larger the outer diameter of the tube, the greater the advantage of this type of weld.