The Numerical Simulation For The Drum Of A Marine Boiler In Startup Procedure

The performance of the Steam boiler as one of the important equipments in steam powered ships has a direct impact on the entire power installation and ship performance. The mobility of the steam power installation is mainly depends on the stress which the evaporation area thick-walled components (Drum, Header) can bear.During the process of starting or stopping and altering loads, especially under the accident, the pressure rising or dropping and temperature varying will make mechanical and thermal stress of the drum greatly change. The varying of the stress will result in fatigue damage to drum material and shorten the service life of the drum.In this paper, adopting 3-D finite element theory and ANSYS software , the transient temperature field, thermal stress, mechanical stress and whole stresses of the marine boiler drum were computed by finite element methods under the 3-D dimension model in the process of starting and altering loads.The results show that: mechanical stress and internal pressure assume the approximate linear relations, the mechanical stress increases along with the pressure increase. The distribution of the thermal stress is more complex than the mechanical stress ,and the max of the thermal stress is 50MPa.The whole stress is the result of the mechanical stress and thermal stress, under the Condition of the design, the mechanical stress has more impact on the total stress .The spot of maximum stress and its varying tendency with the time was obtained to provide theoretical support of the optimization start.