Study On The Influence Of Dead Point Setting Of Steam Turbine Cylinder On Differential Expansion Under Unsteady Condition

As an important part of thermal power plant,steam turbine is also a kind of mechanical equipment with high failure rate and great damage.Once there is a failure in operation,it is bound to cause significant economic losses.In order to ensure that the cylinder of the turbine and the whole unit expand in a certain direction after being heated,ensure concentricity and prevent static and dynamic friction,the cylinder of the unit is provided with a sliding pin system.As the capacity of the unit increases,the axial sizes of the rotor and the cylinder become larger.During the start-up and stop of the unit as well as during the off-design operation,the rotor and the cylinder will be subjected to large thermal deformation,which will lead to changes in the dynamic and static clearances.Therefore,how to study the influence of the dead center setting of the turbine on the expansion difference and the axial dynamic and static clearances during the steady-state and non-steady-state off-design is of great significance to the safe operation and optimal design of the turbine.In this paper,the structural characteristics of the high and medium pressure rotor cylinder of a subcritical N300-16.7/538/538 steam turbine in a power plant are taken as the research object.Combined with the actual operation conditions in the field,the finite element software is used to simulate and analyze the differential expansion of the high and medium pressure rotor cylinder under the rated load,and the calculation results are compared with the results obtained by the simplified mathematical model algorithm,thus the finite element method is used The meta algorithm is verified.According to the operation parameters provided by the power plant,the dead points of the rotor are respectively arranged at the high pressure side and the middle pressure side of the high and medium pressure cylinder under different unsteady state conditions,and the relative dead points of the inner cylinder are arranged at the high pressure side,the middle pressure side and the high and medium pressure cylinder joint,and these situations are arranged and combined to simulate and calculate the influence on the differential expansion under six conditions respectively.The results show that when the dead points of the rotor are located at the middle pressure cylinder The results of this study provide a reference for the optimal design of the sliding pin system of the turbine cylinder.