Modal Analysis Of Low Pressure Rotor Of High Back Pressure Heating Steam Turbine

Turbine high back pressure heating technology recovery part of the cold source loss for heating,reduce the amount of steam extraction,making the turbine can be used for high power generation,low energy can be used to heat,to achieve the use of energy cascade,increase the cycle heat efficiency of the unit.Although the high back-pressure steam turbine has some advantages,there are some safety problems in the operation of the unit.There are many new technical problems that need to be analyzed and studied.High back pressure heating technology,high pressure rotor used in the heating period,condensing rotor used in summer,the mass and stiffness distribution is different after the transformation,you need to ensure that the rotor after transformation safety work.The low pressure rotor bearing of the steam turbine is a seat cylinder bearing,easy to be influenced by the deformation of the cylinder,the temperature and pressure of the exhaust steam during the operation of the high back pressure unit are unstable,which affects the elevation of the bearing support of the low pressure rotor,causes the bearing load redistribution of the shafting,causes the static and dynamic friction and oil film instability,and even causes the unit to shut down.In view of the above problems,this paper takes the low pressure rotor of the high back pressure steam turbine as the research object,and has carried out the following work:(1)For the low pressure rotor and high back pressure steam turbine,using 3D modeling software SolidWorks to establish the model of low pressure rotor and its equivalent simplified.Analysis using Ansys Workbench modal analysis function of steam turbine rotor bearing system calculation mode,get the modal parameters of the rotor-bearing system,and the high back pressure steam turbine before and after retrofit low pressure rotor modal characteristics were analyzed,Study on the variation of modal frequency and vibration mode of low pressure rotor of steam turbine before and after high back pressure heating.(2)The increase of the exhaust temperature of the high back pressure heating unit,the influence of the change of the elevation of the bearing on the low pressure rotor bearing on the modal parameters of the rotor is analyzed.Using the load calculation program of the ROTLINE shaft system to calculate the bearing load corresponding to the different elevation of the shaft system,the Reynolds equation is solved by the finite difference method.dynamic characteristic coefficient of bearing corresponding to the load of different bearing is solved.Finally,the dynamic characteristic coefficient of the bearing is changed in ANSYS.The modal analysis of low pressure rotor at the standard height of different bearing bearings is carried out.The influence of the change of the height of the bearing on the low pressure rotor bearing on the modal parameters of the rotor is studied.