On Thermal Stres Control Of Steam Turebine For Unucer Power Plant

Speeding up development of nuclear power plants is the strategic policy of the nation now.Instrumentation and control (I&C) system for turbine set of nuclear power plants has received widely attention these years.Operational experience and theoretical analysis well show that thermal stress of rotor is the main cause for failure of the turbine during start/stop and load changing, which implies that some limitations should be imposed on its load chang-ing eed and load rate. Comparing with traditional thermal turbines, the turbines used in nuclear power plants have larger size of the rotor, higher changing rate bf its surface tem-perature. Moreover, thesteam for the turbines has lower enthalpy (heat capacity) than that for the traditional ones.How to control and monitor thermal stress of the turbine rotor is the key issue, which should be considered in the I&C system for the turbine of nuclear power plants. This work focuses on development of the method and its procedure for thermal stress computation, monitor and control problems.The main contributions of this thesis are described as following.Based on the analysis model for rotor thermal stress, the theoretical computational ap-proach and the stress limitation are obtained. Furthermore, operational cycles before happening fatigue crack on the rotor surface is also obtained.Assisted by the thermal control and monitoring method proposed, the computational methods for the stress calculation and control online are developed, which makes the turbine start at fastest speed as possible without beyond the limited rotor thermal stress to guarantee the turbine working safely.The initial conditions of thermal stress calculation and control for the specified turbine used in C2 project are proposed.The proposed methods for thermal stress computation and control are well demonstrated their effectiveness in the site application The methodology of thermal stress control and monitor proposed sets up a starting point for further research the mechanism of thermal stress,and native development of I&C systems for nuclear power plants.