Thermodynamic analysis of cycle arrangements of the coal-fired thermal power plants with carbon capture

The electricity production by combustion of organic fuels, especially coal, increases the atmospheric CO2 content, which contributes to global warming. The greenhouse gas emissions by the power production industry may be reduced by the application of CO2 capture and storage systems, but it remarkably decreases the thermal power plant (TPP) efficiency because of the considerable increase of the auxiliary electricity requirements. This paper describes the thermodynamic analysis of a combined cycle TPP with coal gasification and preliminary carbon dioxide capture from the syngas. Utilization of the heat produced in the fuel preparation increases the TPP net efficiency from 42.3% to 47.2%. Moreover, the analysis included the combined cycle power plant with coal gasification and the CO2 capture from the heat recovery steam generator exhaust gas, and the oxy-fuel combustion power cycle with coal gasification. The coal-fired combined cycle power plant efficiency with the preliminary CO2 capture from syngas is 0.6% higher than that of the CO2 capture after combustion and 9.9% higher than that with the oxy-fuel combustion and further CO2 capture. The specific CO2 emissions are equal to 103 g/kWh for the case of CO2 capture from syngas, 90 g/kWh for the case of CO2 capture from the exhaust gas and 9 g/kWh for the case of oxy-fuel combustion.