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Pulverized Coal Plant with CO2 Capture - Comparison

Pulverized Coal (PC) power plants are widely used around the world and will continue to play a large role in the future of energy production. THERMOFLEX has the capability to model complex PC plants and can be used to quickly and easily analyze the effects of varying parameters in any of the plant’s constituent components. In this sample, we will compare an amine-based method of post-combustion CO2 capture with a more advanced chemical absorption method.

The PC plants examined below both have nominal outputs of approximately 555 MWe. These plants use a high efficiency double reheat supercritical steam cycle with nine feedwater heaters and employ Electrostatic Precipitators and Flue Gas Desulfurization units to control particulate and SOx emissions, respectively. Both capture CO2 from the combustion product gas streams, but Plant A uses a conventional amine-based absorption system while Plant B uses an advanced chemical absorption method.

Amine-Based CO2 Capture Component

Advanced Chemical Absorption CO2 Capture Component

The two plants both utilize the same steam cycle with high pressure turbine inlet conditions of 4050 psi/1080°F (279 bar/582°C), first reheat conditions of 1150 psi/1110°F (79 bar/599°C), second reheat conditions of 360 psi/1110°F (25 bar/599°C), and a condenser pressure of 0.7 psi (48 mbar). With these steam conditions and the CO2 capturing systems as described above, Plant A has a gross output of 680 MWe, a net output of 555 MWe, and a net LHV efficiency of 31%, while Plant B has a gross output of 650 MWe, a net output of 555 MWe, and a net LHV efficiency of 36%. For comparison, a similar plant which does not have a CO2 capturing system has a net LHV efficiency of 42%. 

Based on the results above, it is clear that the advanced CO2 capture process imposes less of an energy and efficiency penalty on the power plant than the amine-based process does. This is due to the lower thermal energy consumption of the advanced process (600 vs 1500 Btu/lbCO2, captured [1400 vs 3500 kJ/kgCO2, captured]) and the higher CO2 stream pressure of the advanced process (300 psia/20.7 bar vs 25 psia/1.7 bar) relative to the amine-based process before compression to delivery pressures.