Keywords: large steam turbines, numerical modelling, steam turbine run-up, transient fluid dynamics, load rejection, simulation, pressure, temperature, flow rate, mechanical load, rotor speed, aperture curve speed, start-up valve, overspeed
Numerical simulation of a large power steam turbine run-up
The purpose of this paper is to propose a new behavioural evaluation of a large steam turbine during the run-up period based on a numerical simulation of the transient fluid dynamic processes that occur in the turbine during start-up. The transient process begins when the run-up valve starts its opening trip and ends when the rotor speed achieves the required value. This original approach is a follow-up of a methodology describing the steam turbine load rejection. Several primary operational parameters, such as pressure, temperature and flow-rate are revealed by the simulation, allowing the computation of secondary ones, like mechanical load and rotor speed. The results of this method are useful to equipment designers, in order to set-up both the aperture curve speed of the start-up valve and the response of the turbine protection against overspeed.