Effects of Impurities on Anthropogenic CO₂ Pipeline Transport

Efficient transportation of anthropogenic CO2 from emission sources to storage sites or utilization facilities is vital to realize full-scale Carbon Capture, Utilization, and Storage (CCUS). The CO2 captured from emission sources is often contaminated with impurities that can significantly affect its thermophysical properties and flow behaviors during pipeline transportation. A holistic understanding of the impacts of these impurities is necessary to establish a cost-efficient and reliable CO2 pipeline transport system. In this study, we utilized an integrated thermophysical and fluid flow model and systematically analyzed the impurity effects of H2, N2, CH4, CO, O2, Ar, SO2, H2S, and H2 on the phase-envelopes, critical properties, density, viscosity, and pressure drop of CO2 streams. Each impurity was studied from zero to its highest concentration encountered in CCUS. The impacts of different impurities might be positive or negative to CO2 pipeline transportation depending on the system parameters being evaluated. H2 generally produces the most negative impacts on transportation, greatly enlarging the two-phase region, most significant reductions in density and viscosity, and highest pressure loss. In contrast, H2S has a much milder effect on most system properties. In this paper, we also ranked the impacts of impurities on different system properties by grading the effect of each impurity at 5 vol % concentration and discussed their indications on CO2 pipeline transportation. These results offer practical insights into the design, operation, and management of CCUS CO2 pipelines nowadays and in the future.