Effect of Start-up Operating Modes on the Cyclic Damage of Thermal Power Plant Units

The paper presents a comparative assessment of the impact of the nature of start-up schedule of the power unit on the cyclic damage of turbine equipment. Two different start-up schedules for real power plants are considered. They differ in the steam parameters and in the duration of some stages of start-up. A mathematical model for calculating low-cycle fatigue in high-temperature turbine rotors is presented. The calculation of the thermal and stress-strain state of the rotor in a non-stationary setting is performed. The areas of concentration of stresses in the rotor are established. It is established that when working on one of the start-up schedules, due to more uniform heating of the flowing part of the turbine and rational start-up time, it was possible to reduce the temperature gradients and the amplitude of stresses in most areas of the rotor. As a result, the permissible number of start-up cycles increased by 15.7%.