On-line Fatigue Life Analysis For The Thick Wall Components Of Boiler Based On The Solution Of Inverse Heat Conduction Problem

Steel cylindrical thick-walled confined vessel is the most common pressure equipment, widely used in electric power, chemical and other industries. During the operation process, it endures high thermal stress caused by uneven temperature distribution and mechanical stress due to the internal pressure.A mathematic model for calculating the transient temperature field of thick wall component based on the inverse method is improved and a calculation module is compiled with Fortran. The thermal stress and mechanical stress of the thick wall component is derived according to the Finite Element Method (FEM) and the life expectancy of it is calculated by the rain flow method. Finally, the temperature field calculation module, finite element calculation module, life loss calculation module and database are combined with the C#, so a complete on-line fatigue life analysis software is accomplished. The software can collecte data online, monitor the temperature field and stress field, calculate the loss life of the component and save the date in database. It can provide the relevant functions, such as:over-temperature and over-press warning function; draw isotherm and isostress; historical data query; real-time display of temperature and data export. This software was to applied to the drum and the reheater outlet header of a650t/h boiler during a variable load operation process, The temperature field and stress field of each time were analyzed, and the life damage of each comment were calculated during this process. Test results show that the software had stable operation performance; and the calculated results are accuracy and can satisfy the operational requirements.