Finite Element Analysis of Steam Turbine Rotor of 210 MW Power Plant

Abstract

The steam turbine rotor is subjected to temperature variations in during start up and stop cycle which occurs in short intervals of time. This variation in temperature induces transient thermal stresses in the rotor due to large temperature gradients. The transient stresses occur due to change in the material properties like Young’s modulus of elasticity, coefficient of expansion, thermalconductivity, Poisson’s ratio, specific heat etc. The estimation of transient thermal stresses becomes essential before designing the rotor. The turbine rotor is subjected to thermal as well as mechanical stresses.This paper investigates finite element analysis of 210 MW steam turbine rotorsfor transient thermalloading. The rotor was made of 30Cr1Mo1V.The highpressure turbine model was prepared using CAD software (PRO-E). The model was solved using a 1 Degree slice model as the rotor was Axis-Symmetric about the axis of rotation. The FE modelwas analyzed for transient thermal stresses using Ansys 11. The Von misses stresses were highest at the 11th stage(Groove) at a time step of 12000secs (200 min) during 9 hours cold start up cycle. The transient thermal stresses were found to be much higher than the steady state thermal stresses.