| This study examines how gas turbine specifications affect the performance of Integrated Gasification Combined-Cycle (IGCC) power plants. Three gas turbines characterized as "current," "advanced," and "future" technology machines (with turbine firing temperatures of 1985 F, 2300 F, and 2500 F, respectively) were simulated in computer models of IGCC plants based on Texaco coal gasification technology. A gas turbine modeling procedure was developed to predict the on- and off-design performance of these machines. Central to this gas turbine modeling effort was the prediction of maximum capacity performance when firing medium-Btu coal-derived synthetic fuel (syngas) in a gas turbine designed for natural gas operation. A one-dimensional, stage-by-stage axial compressor model was developed to generate the performance maps (including the effects of variable inlet guide vanes) needed for the gas turbine model. Computer simulation models for six IGCC plant configurations were constructed, spanning the three gas turbines, two syngas firing strategies (increase pressure ratio or close inlet guide vanes), and non-reheat as well as reheat steam systems. Plant thermal efficiencies were dominated by the gas turbine firing temperature, ranging from 35.6% for the current technology machine to 39.2% for the future technology machine. The effect of syngas firing strategy on plant thermal efficiency was small, but the plant power capacity was 6% lower when inlet guide vane closing was employed. The advantage of reheat over non-reheat steam systems was five- to eight-tenths of a point in plant thermal efficiency. |
