A New Model for the Analysis and Simulation of Steam Turbines at Partial and Full Load

Abstract

A model is described that studies the behavior of a steam turbine on the basis of the law of conservation of energy even under wet-steam conditions at particular points in time. Initially, the hypothesis that steam expansion follows a polytropic function will be demonstrated, and a procedure for the calculation of the polytropic exponent will be introduced. Then, the real thermal power given by the steam turbine will be calculated when the steam at the discharge section is wet steam. This calculation has not been analytically developed until now. Two factors will likewise be introduced: a flow factor (used in order to simulate the discharge pressure) and a loss factor (used in order to simulate the discharge enthalpy). With these factors, the steam at the outlet section of a steam turbine will be fully simulated. Furthermore, the loss factor can be used to evaluate the efficiency of the steam turbine. All the equations are validated at both partial and full loads and will be implemented in a real case study: the High Pressure Turbine of the Santa María de Garoña Nuclear Power Plant, which operates at all times under wet-steam conditions, making it particularly relevant for this study.