Improvement in the corrosive fatigue damage to the low-pressure steam turbine blades due to unbalanced currents

This paper presents two improved methods for the corrosive fatigue damage to the blades of low-pressure steam turbines due to corrosive operating environments and power system unbalance. Two blade materials as AISI-403 and 17-4PH are chosen into the investigation, which provides an enhanced understanding on the effect of materials to reduce the corrosion fatigue damage of blades. To verify the validity of the proposed methods, simulated results of a 951 MW operating turbine generator for the corrosive fatigue damage are presented in this paper. From the simulated results, it can be found that the corrosive fatigue damage to the low-pressure steam turbine blades is significantly reduced. In addition, the effects of unbalanced currents (I-2) on the corrosive fatigue damage to the steam turbine blades are estimated when turbine generators operate in various stress concentration factors and corrosive conditions. The estimations may provide with the safe operating standard on the new or designed generator sets under corrosive environments. (C) 2001 Published by Elsevier Science B.V.