Nikulenkova T. Complex evaluation of the surplus life for high capacity steam turbines

Thesis for Ph.D. degree in speciality 05.14.14 "Thermal and nuclear power installations", National technical university "Kyiv polytechnic institute", Kyiv. 2013. The thesis deals with the improvement of the complex evaluation scheme of the life-cycle extension for steam turbine rotors with the exhausted parking resource. It is based on the technical auditing of the electric power equipment with the application of a low-cycle fatigue, creep fatigue and a long-lasting strength and damage investigation caused by rotary oscillation. A low-cycle fatigue estimation has been calculated for high- and low-pressure cylinder rotors of a steam turbine at the Starobeshiv thermal power plant which has worked for 220 000 hours. The state of rotor's metal made of steel 25X1M1ФА, which has worked for 275 000 hours under the actual operating conditions influenced by torque has been investigated for the first time. There has been obtained the investigated curve of the cyclic fatigue under symmetric torsion for rotor steel 25X1M1ФА and the amplitude dependence of rotary oscillation logarithmic decrement for steel 25X1M1ФА under symmetric cycle of loading in the process of torsion. Taking into consideration the fatigue damage caused by rotary oscillation and experimental investigation of a low-lasting strength based on 375 hours, the remainder life-cycle of high- and low-pressure cylinder rotors has been calculated for steam turbines K-200-130 at the Luhansk thermal power plant.