Influence Of High Position Arrangement Of Steam Turbine On Vibration Charateristics Of Bearing-rotor System

The high position arrangement technology of the steam turbine can reduce the use of pipelines to the maximum extent,and the biaxial technology can break through the limitation of single machine capacity,thus expanding the thermodynamic performance of the secondary reheating unit and improving the unit economy.At present,the pingshan power plant of Shanghai shenneng company adopts this technology for the first time.Through actual production,it is proved that this technology can effectively improve power supply efficiency,reduce pollutant emission and reduce investment cost.This project is listed as the company’s demonstration project.Therefore,this technology has a good market prospect in the future.However,with the increase of the arrangement height,whether the instability factors that affect the rotor system,such as eccentric force and other non-equilibrium factors,will intensify the influence on the rotor subsystem due to the change of the arrangement mode,is a hot research issue facing this technology.Therefore,this paper mainly studies the stability factors of the reverse subsystem of high position arrangement technology.The specific research process is as follows:(1)The paper to a 300 mw power plant,high pressure steam turbine rotor model(only the high pressure cylinder high placement)as the research object,by combining the basic principles of rotor dynamics and the steam turbine unit,the general structure and the working conditions for field experiment cost risk is big,and the parameters of transfer matrix method is too big,so the use of finite element software ANSYS to establish a model rotor and rotor-support system model,and according to the research content of the corresponding equivalent simplified complex organization units.According to the simplified method of rotor and frame structure of steam turbine set,the mechanical calculation model of rotor and support of steam turbine is obtained,which is divided by structural grid.(2)Because of model size,parameters,the characteristics of complex structure,considering the operation cost so the modal synthesis method is adopted to model of rotor-bearing and rotor respectively-support system model for modal analysis,the extraction steam turbine working frequency,the number of order within observation of natural frequency and vibration mode,in view of the rotor-support system work mode number is too much,considering the factors influencing the natural frequency of the rotor system:quality and stiffness,and then from the two aspects of the analysis of high arrangement of steam turbine rotor vibration and the influence of natural frequency with the power plant based on the actual work unit data comparison,to verify this model accuracy.(3)Considering the gyroscopic effect and rotary damping,a solution method for rotor vibration of steam turbine with high position arrangement was proposed based on the dynamic equation,to simulate the mass and inertia of the rotor system and the gyroscopic effect,ignoring the influence of foundation elasticity on the natural frequency of the rotating subsystem.The working frequencies and vibration amplitudes of the rotors of the two models were calculated with the mass of the rotor,the eccentricity distance and the stiffness of the support as variables.The APDL language editing function is designed to simulate the starting process with the strongest vibration of the steam engine,and the rotor vibration amplitude from 0 to 3000 revolution is calculated,as well as the track of the center of the wheel and the reaction force of the shaft seat.The results show that the influence of the turbine frame on the vibration of the turbine rotor can not be ignored as the layout height of the turbine increases.The rigidity of rotor-bearing system will be reduced by the high position arrangement of the turbine frame,thus the natural frequency of vibration will be reduced and the amplitude of vibration will be increased.With the increase of unit larger wheel quality,leads to the increase of eccentric mass and the increase of eccentricity is to intensify the increase of the vibration amplitude of the rotor,but vibration peak corresponding frequency constant,but high positioning unit vibration amplitude increase significantly higher than the conventional unit,axle base reaction force also increase more,the bearing wear extent increase.Moreover,the connection between the unit and the frame will cause a certain stiffness loss.According to the above conclusions,this paper also provides a reasonable solution to reduce the vibration of high position arrangement steam turbine in parameter design.