| With the continuous growth of national energy demand and the optimization of energy structure,thermal power generation is developing towards an ultra-supercritical unit with high efficiency and environmental protection.Secondary reheating ultra-supercritical turbogenerator technology is an effective way to further improve the thermal efficiency of thermal power plants.With the increase of unit parameters,the shafting structure becomes more and more complicated.So some models of the unit use a continuous three-support structure.Although the length of the shafting is effectively shortened,some bearing shells vibrations are unstable,low-frequency components exist,the situation of vibrations and the installation process of the tiles relatively sensitive,all these have become a hidden danger for the safe and stable operation of the unit.In this paper,a certain type of 1000 MW ultra-supercritical turbogenerator unit is taken as the research object,the dynamic characteristics and support characteristics of shaft system,the effect of elevation load and dynamic load and are studied through the establishment of mathematical model and field test,provide a basis for safe operation and fault diagnosis of the unit.In this paper,the finite element analysis model of the dynamic characteristics analysis of the turbogenerator shaft system is established.The unbalanced response and coupling characteristics of the continuous three-support structure turbogenerator shaft system are studied by increasing the weight of the turbine rotor.The calculation results are combined with the field test data and the dynamic balance test data shows that the amplitude response of the front shoe is greater than that of the rear shoe under the effect of unbalanced force in the shaft system.The vibration coupling effect is mainly reflected in the unbalanced response of the rear rotor is transmitted forward,which is different from the traditional double support structure.Compared with the shaft system,the adjacent rotor of the three-support structure shaft system has a strong vibration coupling,especially near the critical speed.In the actual project,when the balance plan is made for the continuous three-support structure unit,it can be considered to balance the in-phase and reverse phase at the same time.In this paper,the theoretical and experimental research on the dynamic load of the support system is carried out.The influence of rotor weight,bearing seat preload,rotor speed and radial vibration on the dynamic load of the shaft system is analyzed.The results show that the more the turntable of the rotor,the greater the preload force of the bearing seat with the foundation,the greater the impact of the change in bearing vibration on the dynamic load of the shafting.In this paper,a concentrated parameter analysis model based on a continuous three-support shaft system is established and transfer matrix method is used to solve the problem.At the same time,the static elevation of the shaft system and the load distribution characteristics of the bearing are studied.The ideal lift curve and installation elevation of the shaft system are calculated and the load distribution of the following bearings is basically close to the result obtained by the finite element method.The bearing load sensitivity of the continuous three-support shaft system unit is analyzed,and the characteristics of the influence of the elevation change of the continuous three-support shaft system on the load are obtained.The sensitivity of the load of the continuous three-support shaft system to the change of elevation and a1000 MW double-support structure shaft are obtained.The sensitivity of the load of the system to the change of altitude is compared,and the results show that the sensitivity of the bearing load of the continuous three-support shaft system to the change of elevation is less than the sensitivity of the bearing load of the double-support shaft system to the change of altitude. |
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