焦炭塔热应力分析计算

Analysis on the Stress and Strain of Coke Tower

利用ABAQUS软件模拟出了焦炭塔工作周期内的温度变化、应力变化。采用顺序耦合的方法分析焦炭塔所受的热应力。分析从新塔准备直至老塔处理,其中共包括5个工作阶段。结果显示,几个阶段的温度场分布对应力结果有显著影响。试压、油气预热、生焦的初始阶段比较类似,都处于温度上升阶段,最大应力出现在裙座部位,分别为183.6、242.7、250.4 MPa,且焊缝处应力大于筒体。吹汽阶段塔体温度下降,焊缝处应力小于筒体应力。水冷阶段的应力分布类似于温度分布,存在一个随冷焦水不断移动的高应力截面,其中最大应力可达400.4 MPa,已超过了材料的屈服极限,导致筒体出现了局部塑性变形。经反复循环,会引发"热应力棘轮"现象,由于塑性变形的不断积累,故造成焦炭塔的鼓胀现象。

Software ABAQUS was used to simulate the changes of temperature and stress of coke tower in the working period. The sequential coupling method was used to analyze the thermal stress of coke tower. Thermal stress analysis of the five periods was conducted firstly. The results showed that, the temperature field distribution obviously affected the thermal stress results. There was a temperature rising during the period of pressure test, oil preheating and coking, the thermal stress of these three periods was similar, the max stress located in the skirt and the maximum values were 183.6, 242.7 and 250.4 MPa, respectively. The stress of the weld was greater than that of the cylinder. The temperature reduced at the stage of steam blowing, and the stress of the weld was less than that of the cylinder. The stress distribution was similar to the temperature distribution during water cooling. There was a high stress gradient section which was moving with the water. The max stress was 400.4 MPa, which exceeded the yield limit of the material to cause the local plastic deformation. Thermal stress ratchet will occur after lots of process cycles. The plastic deformation will accumulate constantly, which can eventually lead to the distortion of the tower.