| 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... |
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