Expander Models for a Generic 300 MW F Class Gas Turbine for IGCC

Gas Turbines (GTs) for large IGCC plants need some modifications because, usually, they have been developed to be fed with Natural Gas (NG) while the Syngas from the IGCC has a lower Low Heating Value (LHV). As a consequence, the larger flow in the expander raises the compressor exit pressure, producing some instability risks. One of the possible options consists in the modification of the Expander Flow Functions to accommodate the input pressure in a safe range. The above option modifies also the hot surface blade wall temperature with no changes in cooling flows. In this paper flow path data, average blade temperatures, cooling flows and global performance for the Reference GT (RGT) fed with CH4 and for the modified GT fed with syngas (H2R-GT) are reported and compared. The changes in the stagger angles to accommodate the Expander Flow functions for stable GT conditions are presented and results widely discussed.