Effect of supplementary firing on the performance of an integrated gasification combined cycle power plant

The effect of supplementary firing on-the performance of an integrated gasi fication combined cycle (IGCC) power plant is studied. The results are pres ented with respect to a simple 'unfired' IGCC power plant with single press ure power generation for both the gas and the steam cycles as reference. Th e gases are assumed as real with variable specific heats. It is found that the most favourable benefit of supplementary firing can be obtained for a l ow temperature ratio R-T only. For higher R-T, only a gain in work output i s possible with a reverse effect on the overall efficiency of the plant. Th e second law analysis reveals that the exergy loss in the heat-recovery ste am generator is most significant as the amount of supplementary firing incr eases. It is also noteworthy that, although the total exergy loss of the pl ant decreases with higher supplementary firing for a low R-T (= 3.0), the r everse is the case for a higher R-T (= 6.0).