Keywords: externally fired combined cycle, air heater, EFCC, SPECO method, supplementary firing, gas turbine cycle, clean coal technology, thermodynamics, performance indicators, thermoeconomic analysis, exergy analysis, plant performance, gas turbines
Performance of externally fired combined cycle (EFCC)
The externally fired combined cycle (EFCC) which utilises coal as the primary fuel through a gas turbine cycle is a clean coal technology. Natural gas is used as the supplementary fuel, but the ultimate goal of the EFCC concept is a coal only option. In this study, the performance of the EFCC plant is evaluated based on the first and the second laws of thermodynamics, considering various levels of supplementary firing together with the coal only option. Effects of certain plant parameters on the performance indicators are analysed. In addition, thermoeconomic analyses are performed based on the SPECO method and the results of the exergy related analysis. Results indicate that supplementary firing improves the plant performance whereas the cost of products also increases. However EFCC offers performance figures comparable to those such as IGCC.