Numerical Simulation of Temperature and Stress Field of Steam-Water Separator during Ultra-supercritical Boiler Start-Stop
With the development of renewable energy,more thermal power units participate in peak-regu-lating operation,which puts forward higher requirements for the boiler's starting and stopping speed,the flexibility of operation and the safety and stability.The thick-walled steam-water separator is the core pres-sure-bearing part of the ultra-supercritical unit.During the start-stop process,thermal stress can be gener-ated due to the change in the temperature field,which causes stress damage and fatigue damage.Through having finite element numerical simulation adopted to investigate temperature field and stress fields of a steam-water separator under different start-stop process,the variation of temperature,thermal stress and to-tal stress with time were obtained.The analysis results show that,the dangerous point in the start-stop pro-cess concentrates at the connection area between cylinder body and leading pipe,and the amplitude stress during cold starting process becomes the largest(362 MPa)in all calculated conditions.Simulating and an-alyzing three acceleration schemes under cold start shows that,no significant difference can be found in the total transient stress at the end of different start schemes(365 MPa).