A Evaluation of the Dynamic Strength of the Shaft Line with Welded Rotors of Low Pressure Cylinders of the K-220-44-1 Turbine

Abstract

To assess the danger of resonance vibrations, the calculations data of the critical rotational speeds and strength in case of a sudden short circuit in the generator of the shaft line of the upgraded K-220-44-1 turbine unit have been presented. The turbine unit comprising a high-pressure cylinder and two low-pressure cylinders has been in operation at nuclear power plants since the early 1970s. The shaft-line consists of a high-pressure all-forged rotor, two low-pressure welded rotors, an intermediate part and a generator rotor. For the rotors of the turbine unit constituting the shafting, rod models with concentrated masses and elastic-damping support were used. Recommendations on the choice of vertical compliance of supports for computational studies are given. Estimates of the critical speeds of the shafting are obtained without taking into account the lubricant layer of the support bearings. The dynamic state of the shafting is considered for two-phase and three-phase short circuits in the generator. The maximum twisting moments in the rotors' necks under the support bearings are estimated, and the safety factors for the limiting table torque in the plasticity state are determined. The calculations were performed using software packages developed in the A. Podgorny Institute of Mechanical Engineering Problems of NASU, Joint Stock Corporation "Turboatom". The calculation data show that no dangerous resonance vibrations of the shaft-line of the upgraded K-220-44-1 turbine unit are detected and the strength of the shaft-line in case of a sudden short circuit in the generator is in conformity with the requirements of regulatory and technical documents.