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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 MW_e. 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 SO_x 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 MW_e, a net output of 555 MW_e, and a net LHV efficiency of 31%, while Plant B has a gross output of 650 MW_e, a net output of 555 MW_e, 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/lb_{CO2, captured} [1400 vs 3500 kJ/kg_{CO2, 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.