Steam separator is the most important thick-wall pressure element in ultra-supercritical utility boilers.Quantitative analysis on steam separators in various operating conditions has great significance in safe and optimized operation of thermal power units.Numerical simulation on stress field and temperature field of the steam separator of a 1 000 MW ultra-supercritical boiler during cold state start was performed.On this basis

the law of thermal stress

mechanical stress and the total stress was investigated.Then

the elastic analysis based creep-fatigue evaluation algorithm was adopted to calculate the service life damage of the separator during coal state start.The results show that

during cold state startup

thermal stress of the separator increases first and then decreases

while the mechanical stress increases gradually and eventually replaces the thermal stress as the major factor affecting the value of the total stress.The stress concentrated largely in intersection line zone of the induced tube and cylinder of the separator

indicating this separator has large safety margin.