Improved Design Of Lubricating Oil Parameters For Steam Turbine For Suppressing Oil Whirl

Vibration failure of sliding bearing rotor of steam turbine is the key factor affecting the long-term operation of steam turbine.As an important index for evaluating the operation of steam turbine,it has always been the focus of attention of the operation and maintenance personnel of steam turbine.With the increase of the vibration amplitude of the rotor,rubbing between the rotor and the bearing will occur,resulting in equipment accidents and even personal casualties.Therefore,it is necessary to study the vibration source of the rotor and the reduction measures.Oil film whirl is a common source of abnormal increase of rotor vibration.In engineering practice,the method of increasing lubricant temperature is often used to suppress it.But this way,the temperature of bearing surface is increased,and the service life of bearing may be adversely affected.Therefore,it is necessary to study the mechanism of oil film whirl and the life change of bearings at higher service temperature,and to develop a process control method that can prolong the life of bearings and reduce the vibration of rotors,so as to save the cost of steam turbine operation.Aiming at the above problems,the basic mathematical model derivation of rotor and lubricant,the computer simulation of rotor vibration and the life checking of bearings are studied,and the experiments are carried out on typical steam turbines.Firstly,based on the mechanism of oil film whirl and the basic data of lubricating oil,the mathematical models of oil film force and oil viscosity-temperature,density-temperature characteristics are established.The characteristics of oil film whirl fault are studied.The measures to reduce oil film whirl and the formula of oil viscosity-temperature and densitytemperature are obtained.The follow-up theoretical research provides a basis.Secondly,the XLROTOR software is used to simulate the vibration of the steam turbine in the process of speed-up.The time-domain waveform,frequency spectrum and axis trajectory are output,and these graphs are analyzed.It is inferred that the vibration of the steam turbine is increased due to the oil whirl.Then,by changing the lubricant brand and temperature in the software,the vibration of turbine rotor under different working conditions is simulated,and the changes of main parameters such as vibration amplitude and frequency components are observed,which illustrates the necessity of changing the lubricant brand.When TSA-32 steam turbine oil is used instead,the vibration of the turbine rotor can be stabilized at a lower level under the condition that the temperature of the lubricant is changed continuously.The results show that the vibration of the turbine rotor can be stabilized at a lower level under the condition that the temperature of the lubricant is 60 C.Then,according to the changed working conditions mentioned above,the purpose of ensuring the normal service life of bearings is checked.The bearing capacity of oil film is calculated numerically,and the metal creep of the Babbitt alloy on the bearing surface in three years is deduced theoretically based on the results of computer simulation.Both of them prove that the improved working condition mentioned above will not have a great adverse effect on the service life of the bearing.Finally,the above theoretical research results are validated according to the actual operation of steam turbines.This paper introduces the basic situation of steam turbine,the basic condition of each component and the data of maintenance,and describes the process of trial run of steam turbine in strict accordance with the established procedure under the condition that each component meets the requirements of normal operation.Combining the data of rotor vibration and bearing temperature during test run,as well as the data of lubricating oil detection and vibration trend in daily operation,the rationality of the theoretical research results mentioned above is illustrated.On the one hand,it ensures that the oil whirl will not have a great impact on the vibration of steam turbine,on the other hand,the bearing is not used because of its high usage.Temperature produces abnormal wear.The process control method of prolonging bearing life and reducing rotor vibration is studied,and the purpose of saving steam turbine operation cost is achieved.