Energy and exergy analyses for the carbon capture with the Chilled Ammonia Process (CAP)

Abstract

Abstract Post-combustion carbon capture in existing power plants is a strategic technology that can reduce emissions from power generation. The proven approach is scrubbing with amines. However, its drawbacks are energy requirement, 3 to 5 MJ per kg of captured CO 2 , as well as solution corrosion and solvent degradation. An alternative approach is scrubbing with chilled aqueous ammonia. This technology aims at mitigating energy usage and solving corrosion and degradation issues. Here an approximate model of the CO 2 - H 2 O- NH 3 system is coupled with a proposed process to evaluate mass, energy and entropy flows. For 1 kg of captured CO 2 , the simulation yields a steam extraction of 0.59 kg, equivalent to a heat duty exceeding slightly 1.5 MJ and a generation loss approaching closely 0.1 kWh, an auxiliary consumption of 0.1 kWh and a delta of almost 0.18 kWh with respect to the ideal case. Assuming a cost of electricity of 7c/kWh, the sole operation of the capture system totals 14C/ton_ CO 2 .