Research On Unbalanced Response Characteristics And Typical Vibration Fault Of The Nuclear Wet Steam Turboset

Since Twenty-first Century,China’s nuclear power industry has entered a stage of rapid development,and several million kilowatts of wet steam nuclear power generating units have been built and put into operation.Compared with the conventional thermal power turbine generator set,the wet steam turbine generator unit of nuclear power has obvious difference from the aspects of structure size,unbalanced response dynamics and dynamic load dynamic response.Combined with the practical experience of engineering,it comprehensively studies the unbalanced response characteristics of this type of unit and the control strategy of typical static and static friction faults.It has important engineering application value.This paper studied the largest number of ARABELLE type nuclear power steam turbine generator set in China.The main factors that may affect the static and static friction,such as the structural characteristics,installation mode and operating conditions of the ARABELLE type wet steam nuclear power turbine generator set,are analyzed.On the basis of previous research results,combined with the operating characteristics and typical boundary conditions of the variable working conditions of the wet steam turbine,the change law of the heat transfer coefficient of the key components,such as the cylinder block,rotor and steam seal of the steam turbine,was qualitatively analyzed,and the change law of the dynamic and static clearance between the steam seal and the rotor shaft was preliminarily explored.Basing on the theory of rotor dynamics,a comprehensive dynamic model of the mass base bearing rotor coupling of ARABELLE type nuclear power steam turbine unit is constructed.The unbalanced response of HIP rotor and LP rotor on the basis of spring damping,which is based on the dynamic characteristics of the rotor,operating conditions and the way of adding weight block on site was studied,and evaluation and treatment of the HIP rotor dynamic and static friction established after the bending accident occurred,and a system based on the rotor dynamic model for the HIP rotor bending failure of the nuclear power steam turbine was established.The experimental data show that the proposed model is correct and the constructed system is effective.The research method proposed in this paper has an important engineering application value for evaluating the bending degree of the HIP rotor of the nuclear power steam turbine generator set.The rotor bending degree assessment system is of great theoretical reference value for the subsequent decision making.At the same time,the research results of rotor unbalance response characteristics are applied to analyze the causes of typical vibration faults of HIP rotor,LP rotor and generator rotor,and the operation control strategy and treatment measures are put forward.Because of the large volume and low stiffness of the nuclear wet steam turbine cylinder,it is easy to have the concave deformation under the external disturbance of the variable working condition,and the long distance of the LP rotor and the length of the end seal are easy to stimulate the static and static friction between the two ends of the LP rotor.This kind of friction has the characteristics of slow response and so on.In engineering practice,it is often solved by running in.Improving the dynamic balancing accuracy of LP rotor is conducive to reducing the magnitude of static and dynamic friction.Due to the long span and high quality,the half speed rotor of the unit is prone to heat imbalance due to the uneven material of the forging.For the high defect of vibration in the process of heat imbalance,the improvement degree of the first order mode is not obvious.It is necessary to control the dynamic balance precision of the factory to solve the problem.Since the commissioning of the ARABELLE type wet steam turbine,there have been irregular fluctuations of shaft vibration in several nuclear power plants.The possible causes of the defect are analyzed and field tests are carried out,and some vibration rules are summarized.The problem is still in the exploratory stage,which needs further study.