Evaluation of CO₂ purification requirements and the selection of processes for impurities deep removal from the CO₂ product stream

Depending on the reference power plant, the type of fuel and the capture method used, the CO₂ product stream contains several impurities which may have a negative impact on pipeline transportation, geological storage and/or Enhanced Oil Recovery (EOR) applications. All negative impacts require setting stringent quality standards for each application and purifying the CO₂ stream prior to exposing it to any of these applications. In this paper, the CO₂ stream specifications and impurities from the conventional post-combustion capture technology are assessed. Furthermore, the CO₂ restricted purification requirements for pipeline transportation, EOR and geological storage are evaluated. Upon the comparison of the levels of impurities present in the CO₂ stream and their restricted targets, it was found that the two major impurities which entail deep removal, due to operational concerns, are oxygen and water from 300 ppmv to 10 ppmv and 7.3% to 50 ppmv respectively. Moreover, a list of plausible technologies for oxygen and water removal is explored after which the selection of the most promising technologies is made. It was found that catalytic oxidation of hydrogen and refrigeration and condensation are the most promising technologies for oxygen and water removal respectively.