合成氨转化废热锅炉管板-管子焊接应力有限元分析

FEM analysis of welding stress in the welds between tubes and tube-sheet of waste heat bolier in the secondary reformer of ammonia plant

针对合成氨二段转化废热锅炉管板易出现大量泄漏的问题,对管板与换热管角焊缝焊接应力进行了有限元分析。结果表明,气侧焊缝区与近焊缝区存在很高的焊接残余应力。在交变载荷作用下,高应力区易发生疲劳裂纹扩展,导致泄漏。通过采取焊前预热和焊后热处理工艺可以降低焊接接头的焊接残余应力,提高焊接接头的断裂韧度。

As to the leakages of tube-crust of the waste heat boiler in the secondary reformer of synthetic ammonia plant,welding stress in the welds between tubes an tube-sheets was analyzed via the finite element numerical computation. The result show that there was very high welding residual stress on the welding joints and their adjacent area in the gas side. Under the alternative load, fatigue crack extension tends to happen and leads to leakages in the high-stress area. Rssidual stress on the welding jonints was reduced by preheat before welding, fracture toughness property was improved by post heat treatment.