框架立式退火炉炉壳开裂成因分析及对策

Cause analysis for and measures against the cracking of annealing furnace shell

某引进的立式退火炉投用3个月后缓冷段炉壳就发生开裂现象,分别对框架式炉壳、风管支撑梁和膨胀节在各种温度变化工况下进行应力分析,结果表明,炉壳及风管支撑梁在温度变化时由于膨胀和收缩相互之间产生应力,该应力无法释放是导致炉壳最终开裂的主要原因。根据分析,采用框架结构上设置滑块和预留胀缩空间、强化炉壳保温减少温差的修补措施。改进后,缓冷段的氧含量由修补前的60×10-4%下降到12×10-4%以下,消除了炉壳开裂引起的氧气进入炉内的隐患。

Cracks occurred on the shell of a vertical annealing furnace in the slow cooling section 3 months after it was put into operation. Stress analysis was made for the frame-type furnace shell, the support beams of wind pipes and the expansion joints under various temperature conditions. The results showed that stress would be generated due to the expansion and contraction of the furnace shell and the support beams of wind pipes when the temperature changed. The stress, which could not be released, was the main cause of furnace shell cracking. Based on the results of force analysis, the following measures were taken： arranging sliding blocks on a frame structure and leaving space for expansion; improving the furnace shell insulation to reduce the temperature difference. After improvement, the concentration of oxygen in the slow cooling section decreased from 60 x 10-4% to lower than 12 ~ 10 -4% , thus eliminating the hidden trouble of oxygen entering the furnace through cracks on the furnace shell.