RESEARCH ON LIFE ASSESSMENT AND MONITORING SYSTEM OF STEAM TURBINE

摘要

Since steam turbine always operates at high temperature and pressure, life of the key components of steam turbine, such as, rotor, cylinder, bolt etc., must be considered. Furthermore, the involvement of large-scale steam turbine set in load adjustment makes the life assessment of those key components more important, which are main objects of life assessment and monitoring of steam turbine. Steam turbine suffers very large thermal stress and strain while startup, slowdown and load change, therefore, thermal stress is one of the significant monitoring parameters. Stress field is an important and full-distributed graphics. The 2-D discrete models and its finite element models of rotor and cylinder of steam turbine are analyzed in this paper. Taking rotor and cylinder as control objects; the boundary conditions are given, so that the temperature fields, thermal stress field and thermal strain, etc. are solved. Consequently, a life assessment and online monitoring system of steam turbine is developed, in which the temperature fields and stress fields of rotors and cylinders of high pressure (HP) and intermediate pressure (IP) of steam turbine are calculated and displayed on-line. In accordance with the stress fields, the life wastages caused by the operations, such as, start-up or slowdown or load change, etc., are calculated The life remainder is the foundation of decision making of management and control of steam turbine operation, maintenance, safety etc.