Exergy Analysis of Gas-Turbine Combined Cycle With CO

Hanne M. Kvamsdal, Ivar S. Ertesvåg, Olav Bolland, Tor Tolstad
2002 Volume 2: Turbo Expo 2002, Parts A and B   unpublished
A concept for natural-gas fired power plants with CO 2 capture has been investigated using exergy analysis. The present approach involves decarbonization of the natural gas by authothermal reforming prior to combustion, producing a hydrogen-rich fuel. An important aspect of this type of process is the integration between the combined cycle and the reforming process. The net electric power production was 47.7% of the Lower Heating Value (LHV) or 45.8% of the chemical exergy of the supplied
more » ... the supplied natural-gas. In addition, the chemical exergy of the captured CO 2 and the compression of this CO 2 to 80 bar represented 2.1% and 2.7%, respectively, of the natural-gas chemical exergy. For a corresponding conventional combined cycle without CO 2 capture, the net electric power production was 58.4% of the LHV or 56.1% of the fuel chemical exergy. A detailed breakdown of irreversibility is presented. In the decarbonized natural-gas power plant, the effect of varying supplementary firing (SF) for reformer-feed preheating was investigated. This showed that SF increased the total irreversibility and decreased the net output of the plant. Next, the effects of increased gas-turbine inlet temperature and of gasturbine pressure ratio were studied. For the conventional plant, higher pressure led to increased efficiency for some cases. In the decarbonized natural-gas process, however, higher pressure ratio led to higher irreversibility and reduced thermal-plant efficiency.
doi:10.1115/gt2002-30411 fatcat:kk3lfjbjynfh7gso5rssefee3e