锅炉筒体上小间距大开孔区域的应力分析

Stress analysis of small spacing and large opening area on boiler cylinder

锅炉设计中经常出现超出现行强度标准或者传统理论分析方法的新结构,应力分析是对其进行强度验证的有效方法,对锅炉筒体上小间距大开孔区域进行应力分析,可为开孔补强以及锅炉整体设计提供依据。文章以85t/h角管锅炉锅筒上互成孔桥的4个大直径接管结构为例,利用有限元分析软件对孔排高应力区进行建模和应力分析,根据应力分解曲线及数值结果判定强度。结果表明:高应力区位于接管和筒体连接区的管端内壁以及纵向孔桥区,应力最大点位于纵向孔桥端部对应的管端内壁圆弧顶点,并沿其两侧方向递减;筒体壁厚为32mm、接管壁厚为25mm时,该区域因开孔应力集中而导致的强度减弱可以得到有效补强,强度判定结果符合要求。

When the diameter of the opening on the drum of a water tube boiler is larger than the maximum allowable diameter of the unreinforced hole,the area reinforcing method should be used to reinforce the opening.When two or more small spacing and large opening structures are arranged on the cylinder due to design requirements,the strength of the structure can only be determined by stress analysis because of lack of standard basis.Taking four large diameter nozzle structures of an 85 t/h corner tube boiler with cross-hole bridges on the drum as an example,the stress in the high stress zone of the hole row is analyzed,and the strength is determined according to the stress decomposition curve and numerical results.The results show that,the high stress area is located in the inner wall of the pipe end and the longitudinal hole bridge area of the connecting area between the nozzle and the cylinder.The maximum stress point is located at the arc apex of the inner wall of the pipe end corresponding to the end of the longitudinal hole bridge,and decreases along both sides of the pipe end.When the tube wall thickness is 32 mm and the nozzle wall thickness is 25 mm,the strength weakening caused by the stress concentration of the opening in the area can be effectively strengthened,and the strength judgment results meet the requirements.