A Model for the Simulation of Large-Size Single-Shaft Gas Turbine Start-Up Based on Operating Data Fitting

Start-up is an important aspect of gas turbine operation. In the last years plant operators have shown an ever increasing interest in this critical phase, with particular focus on start-up reliability and start-up time. Several issues should be considered in order to achieve optimal start-up behavior: operability issues (e.g. compressor aerodynamics, combustor light-off and light-around, shaft acceleration), impact of thermal stresses on cyclic life, proper sizing of external starting devices. Models for the simulation of gas turbine behavior during start-up are very useful both for the design of new gas turbines and for the analysis and improvement of engines already in operation. In this paper, a physics-based model for the simulation of the start-up phase of large-size single-shaft gas turbines is presented. The model is based on operating data fitting and covers machine operation from combustor light-off to compressor blow off valve closure. The model makes use of steady-state component characteristics, while dynamics is taken into account through shaft power balance. Special features are also included to properly model the effects of heat soakage, i.e. the dependence of the engine behavior on its thermal status before the start-up. The quality of the model has been proven by application to the gas turbine engine ALSTOM GT13E2 and by comparison between measured and simulated data.Copyright © 2007 by ASME