制氢转化炉集合管加强接头裂纹原因分析及处理

Reason Analysis and Treatment Measures of the Crack on the Strengthened Joint of the Collection Tube of the Hydrogen Reformer Furnace

中国石化塔河炼化有限责任公司2#制氢转化炉对流室转化原料预热段出口集合管的加强接头出现了裂纹,导致装置紧急停车。对开裂的炉管进行了有限元分析,分析结果表明:工作时由于炉管与旁边的横梁接触,使加强接头在外壁产生了最大应力,最大应力值为90.3 MPa,此应力高于632℃下材料的许用应力,因此导致炉管开裂。同时,还对炉管开裂位置的母材进行了金相分析,发现开裂位置的母材晶粒粗大,并有碳析出,导致晶界弱化。根据应力分析和金相分析结果,对炉管热膨胀定位方式进行了整改,有效地消除了炉管应力。整改后对裂纹部位进行了打磨、焊接,并在检验合格后再次投用生产。

Cracks were found on the strengthened joint of the export collection tube in the preheating section for transformation materials of the 2# hydrogen reformer furnace convection cell in Tahe branch. In this paper, the cracked furnace tube was analyzed through finite element method. It was shown that the maximum stress of the strengthened joint was located at the outer wall because of the contact between the furnace tube and the beam beside during the work. The maximum stress was as high as 90.3 MPa, which is higher than the allowable stress of the material at 632 ℃, resulting in the cracking of the furnace tube. At the same time, the metallographic structure of the parent metal at the crack of the furnace tube was also analyzed. It＇s found that the grain of the parent metal was coarse, with carbon precipitating out, thus causing the grain boundary weaken. According to the results of the stress analysis and metallographic analysis, the position method for the thermal expansion of the furnace tube was rectified, and the stress of the furnace tube was eliminated effectively. After the rectification, the crack position was then ground and welded. The device was put into service again after passing inspection.