CAP1400型非能动余热排出热交换器支撑组件的关键制造工艺

Research on key manufacturing processes of support assembly of CAP1400 passive residual heat removal heat exchanger

非能动余热排出热交换器的换热管束通过不锈钢支撑框架以及管束支撑组件精确固定,但是不锈钢材质线膨胀系数高、导热率低,焊后易产生收缩变形造成管束支撑组件位置偏移,影响换热管在框架内侧的精确安装。CAP1400型核电机组是我国在现有AP1000型压水堆核电技术基础上改进研发的新型压水堆核电机组,由于新机组总体尺寸规格有所增大,焊接收缩和变形趋势更明显,更难以满足关键设备的焊接与定位精度要求。为此对新机组中换热管束支撑框架的结构和制造工艺进行详细研究,改进和优化了H型钢的焊接制造工艺和坡口加工工艺,有效降低H型钢组装时的误差。针对焊接变形问题,提出反变形支撑及水冷却方法,防止支撑框架中各部分型钢变形;提出管束支撑组件精准定位方法,实现了管束支撑组件在框架内的精准定位安装。实践证明,用上述改进与优化的工艺和提出的方法能够大大提高支撑框架的制造精度,达到换热管在支撑框架内的顺利引入以及与管板管孔精准对接的效果。

The heat exchange tube bundle of passive residual heat removal heat exchanger(PRHR)was accurately fixed through a stainless steel support frame and tube bundle support components.Due to the high linear expansion coefficient and the low thermal conductivity of stainless steel material,it is easy to cause shrinkage deformation after welding,resulting in the displacement of the tube bundle support components and affecting the accurate installation of heat exchange tubes on the inner side of the frame.The CAP1400 nuclear power unit is a new type of nuclear power unit for pressurized water reactor improved and developed by China based on the existing nuclear power technology of the AP1000 pressurized water reactor.Since the overall size specifications of the new unit are increased somewhat,the trend of welding shrinkage and deformation is more obvious,making it more difficult to meet the welding and positioning accuracy requirements of key equipment.The author of this article conducted a detailed study on the structure and manufacturing process of the support frame for the heat exchange tube bundle in the new unit,innovatively improved and optimized the welding manufacturing process and groove processing technology of H-shaped steel,which effectively reduces errors during the H-shaped steel assembly.Regarding welding deformation,a method of anti-deformation support and water cooling was proposed to effectively prevent deformation of various steel sections in the support frame.A precise positioning method for tube bundle support components was also proposed,which achieves precise positioning and installation of tube bundle support components within the framework.The practice in factory has proven that using the improved and optimized processes and the proposed methods mentioned above can greatly improve the manufacturing accuracy of the support frame,and achieve the smooth introduction of heat exchange tubes into the support frame,and good results in precise docking with the tubesheet and tube holes.