Research On Regional Strength And Deformation Of Supercritical Steam Turbine Multi-structure Under Service Conditions

At present,inlet parameters of high pressure module for ultra-supercritical turboset has been as high as 26.25 MPa / 600?,has made great improvement in performance.However,the high-temperature and high-pressure working environment of the units reduces the physical properties of the materials.In the actual operation of the plant,it is found that the radial friction at the balancing piston and the sealing area greatly shortens the service life of the unit.Therefore,it is necessary to analyze the strength of multi-structure of high-pressure module of steam turbine,analyze the creep fatigue coupling damage under start-up and shutdown conditions,and evaluate the radial clearance change of the balance piston and sealing area to ensure that the unit meets the specified service requirements.In this paper,the structural strength and clearance variation of a supercritical steam turbine high pressure module are analyzed by using finite element method.The temperature field,stress field,displacement field and other results of each component of the high pressure module under service conditions are calculated and analyzed,and the creep strength and creep fatigue coupling damage are checked.At the same time,the radial clearance of the balance piston and seal area was analyzed,and the safety of the module was evaluated.The N-B constitutive equation of creep material was introduced to study the temperature field,displacement field,stress field and equivalent creep stress field of the high-pressure module for 2880 hours in the actual steady state operating condition.The results show that there are smallfluctuations in temperature field and stress field;stress relaxation and stress redistribution occur.According to the start-stop curve of the corresponding actual working condition,the temperature field,stress field and displacement field of the multi-structure of the high-pressure module were analyzed.The results showed that the temperature and stress fluctuated sharply in the start-up stage,and the minimum clearance at the balance piston and sealing area appeared in the start-up stage,but no friction occurred.Finally,based on the theory of continuous damage mechanics,the fatigue creep coupling damage post-processing program is compiled by Python,and the damage results and predicted life are checked to ensure that the unit meets the specified service requirements.