CO2 purification. Part I: Purification requirement review and the selection of impurities deep removal technologies

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 negative impacts on pipeline transportation, geological storage and/or Enhanced Oil Recovery (EOR) applications. All negative impacts require setting stringent quality guidelines 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 guidelines 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.

► CO2 purification is required to fulfill the requirement of the final CO2 destination.
► Full CO2 impurities matrix was developed.
► Water and oxygen are the major impurities to be removed from the CO2 stream to 10 and 50 ppm levels, respectively.
► Catalytic oxidation of hydrogen was found to be the best technology for de-oxygenation.
► Refrigeration and condensation was proven to be effective for water deep removal.