Techno-economic evaluation of processes for oxygen and water removal from the CO₂ product stream

According to the findings of the first part of this work, the two impurities in the CO₂ stream, from post-combustion capture, which require deep removal are oxygen and water, down to 10 and 50 ppmv, respectively. In addition, a review and preliminary evaluation of the possible technologies which can be used for oxygen and water deep removal was conducted, and the results showed that the promising technologies are: catalytic oxidation of hydrogen and refrigeration and condensation, respectively. In this paper, detailed process modeling, design and a techno-economic evaluation are performed on these two technologies. Both selected technologies were designed and proved their potential by achieving the required levels of impurities with a total cost of treating and compressing one ton of CO₂ of $13.09 for the coal-fired power plant full purification case and $17.23 for the NGCC full purification process. The cost of CO₂ compression without the purification step was found to be approximately $10.12 per ton of CO ₂ for the coal-fired case. This means that adding the purification technologies to the coal fired case will increase the cost of CO₂ compression by around 29.3%. Assuming a total CO₂ capture and compression cost of $73-94 per ton of CO₂ shows that the total CO₂ purification cost is roughly 3-4% of the overall capture cost.