In this study, the effects of operational parameters on the thermodynamic performance of a FBCC steam power plant with a rated output of 7.7 MW are investigated by the developed model such as excess air, coal type and steam pressure based on the first and second laws of thermodynamics. The plant consists of a FBCC, a WHB and an economizer as subsystems and fans, pumps, cyclone and chimney as auxiliary systems. The model results are shown to agree well with plant operational data. As a result of this study. it is observed that the first and the second law efficiencies of the system decrease 5.1% and 5.2%, respectively, as the excess air increases from 10% to 70%. As the steam pressure increases from 4 to 12 bar, the energy efficiency of the system decreases to 2.1% but the exergy efficiency of the system increases to 19.9%. The amount of irreversibility occurring in the system is also calculated at each location through the developed model. The FBCC has the largest irreversibility, of about 80.4% of the total irreversibilities in the plant, mostly due to the irreversible combustion process. It is also observed that the coal type does not affect the first and the second law efficiencies considerably. (c) 2008 Elsevier Ltd. All rights reserved.