Vibration Absorption Study On Frame Foundation For The Steam Turbine-generator Set

The steam turbine-generator set is the core of the thermal power plant,and the large frame foundation is commonly used in supporting the stream turbine-generator set in the power plant.How to ensure it's normally and safely running performance of the whole system is concerned by manufacturers and designers.The key to the whole foundation which supporting the stream turbine-generator set is its vibration problem,the dynamic characteristics of foundation has extremely important influenced to the vibration of the entire system.With the development of the electric power industry and the increasing capacity of the stream turbine-generator set,vibration becomes a prominent problem,Therefore,it is very important and meaningful for the foundation of the stream turbine-generator to decrease the vibration.In this paper,the vibration problem of the frame foundation of a 50MW stream turbine-generator unit in one thermal power plant as the background.Firstly,the vibration response of foundation has been monitored on-site and analyzed under the different operating conditions,through comparatively analysis to identify the reasons for its vibration.Then the entire foundation has been simplified base on the norms and manuals,and established the finite element calculation of three-dimensional solid model of the whole foundation of the streams turbine-generator by the ANSYS,then did modal analysis to the model which had been established,the natural frequencies and mode shapes are acquired.And get the dynamic response(the structure displacement) through the dynamic harmonic response analysis.The dynamic response results which were acquired on-site are compared with those of the model, which shown that the correctness of the model and the vibration analysis.Finally, Spring-damper components are added to the local of the frame foundation and the vibration absorption is studied.Meantime,the rotor-bearing-foundation system interaction and the soil-structure interaction are considered.The dynamic responses of the whole system are acquired by the modal analysis and the dynamic harmonic response analysis,the dynamic response results of the isolated frame foundation are compared with those of the non-isolated frame foundations.The numerical examples indicate that it's a good way to control vibration by adding spring-damper components to the frame foundation in power plant,and also validate the correctness and feasibility of the method. In this dissertation,the numerical analysis as well as the comparative analysis is due to "Regulations on Machine Foundation Design"(GB50040-96).The Amplitude method is the method of dynamic analysis.In addition,the characteristics of the stream turbine-generator set impact on vibration absorption are analyzed and discussed,and obtained some useful conclusions.