420t/h锅炉再热器外接管座温度测试及计算研究

【作者】 李伟荣；

【导师】 胡亚才；

【作者基本信息】 浙江大学 ， 热能工程， 2002， 硕士

【摘要】 在对420t／h锅炉的规范检查当中发现，再热器集汽箱管座及其附属管道外壁出现由内而外发散的放射状裂纹，并且有不断扩大的趋势。长期下去将会构成对再热器母管的威胁，成为锅炉安全运行的一大隐患。 据分析这是由于热应力引起的，为此本文对再热器集汽箱向空排汽管管座及三通管座的温度场及热应力进行了实验和数值计算分析研究。 实验中采用了现场管壁测温的手段。借助于高精度热电偶，测量事先布置在向空排汽管上的数十个特征点在锅炉启机和负荷变化时的温度，并用数字巡检仪自动记录下来。利用先进的绘图软件绘出了所有特征点处温度随着时间的变化图。通过图形的变化趋势和大小可以看出管壁裂纹和管壁的温度波动的确存在很大的关系，为以后的计算分析提供了实验根据。 借助于有限元分析程序工具ANSYS对三维管道实体模型进行了建模、加载、求解和后处理等工作。得到了三维温度场和应力场数据结果。在计算过程中采用了根据实测值反算的思路，使计算得到的温度场有可靠的实验依据。通过前人的一些经验公式得出假设的边界条件并算得初步温度场。具体方法是：比较特征点上的温度值与现场实测值，修改边界条件直到两者误差在控制范围内，最后得到典型工况下，再热器集汽箱管座及三通管连接附近的三维温度场和应力场的数值解。实际计算结果与实验结果温度值偏差不超过5％。根据得到的解，绘出了典型边界条件下三维管道的等温线、热流线、热梯度线及等应力线的各种云图。同时解释了温度、热流、热梯度及应力存在差异的具体原因，为计算出再热器钢管材料12CrlMoV的热疲劳寿命提供了有价值的数据。 通过研究国内外计算疲劳寿命的一些方法，给出了适合于本课题的解决方案，为计算热疲劳寿命提供了可以利用的公式。并估算了相应的热疲劳寿命。 文中最后介绍了根据研究结果，采用了加强放空管内滞留蒸汽流动，防止凝结水产生的措施。经实测管座温度场，热冲击大大减少，可望提高管座的可靠性。更多还原

【Abstract】 In 420t/h boiler inspecting, the collecting-steam box of reheater and correlative pipelines are detected to appear diffuse crack, which has expansive trend. If to let this state go on, there will exist hidden-trouble for the reheater and safe running of the boiler.This paper places emphasis on the reheater pipes’ basement and wye pipe, which are studied through onsite experience and numerical calculating method.Onsite pipes’ temperature has been measured by high precise thermocouple. These temperature data are automatically recorded by recorder instruments and then been plotted into variation graphs. From the variety and size of these graphs we can find out that the relationship between the pipes’ crack and the acutely fluctuant temperature of the pipes. These temperature data have given the warranty for the future calculation of temperature field.With the aid of FEA software ANSYS, the numerical and soluble analyses can be gotten from the three dimension pipe model. First by estimative calculation the final boundary condition can be gained, then the accurate result of three-dimension temperature field and stress can be gotten through placing accurate boundary condition. In this paper the no. 50, 100,150,200 and 480 minute’s pipes’ temperature field and stress have been calculated with this method. Compared with the experimental result the temperature result is very accurate. The maximal error is no more than 5%.This paper also gives some methods applied for estimating the fatigue life and discusses the domestic and foreign developing state. Finally the fatigue life solution of the project has been presented更多还原