Techno-economic analysis of CO2 conditioning processes in a coal based oxy-combustion power plant

Abstract

Oxy-combustion is a competitive technology to enable the capture of CO2 from coal based power plants. The CO2 conditioning process is an important contributor to the power penalty related to CO2 capture in such power plants. The two-stage flash process is commonly proposed in literature. This paper presents a study on the CO2 conditioning process in three cases: one-stage flash, two-stage flash and three-stage flash. The composite curves are applied to investigate the improvement potential. A detailed exergy analysis has been performed to compare the plant performance in the three cases. Considering the one-stage flash process as the base case, the specific power consumption is reduced by 7.3% in the two-stage flash process and 8.1% in the three-stage flash process. The investment cost will of course increase. The economic analysis shows that the two-stage flash process is the most cost effective alternative. However, a higher recovery rate can be achieved in the three-stage flash process when the CO2 purity is designed to be the same for the three cases.