Influence of SO2 on CO2 Transport by Pipeline for Carbon Capture and Storage Technology: Evaluation of CO2/SO2 Cocapture

CO2 capture and storage (CCS) is an important technology for avoiding atmospheric CO2 emissions, which are principally originated from fossil fuels combustion. Anthropogenic CO2 contains impurities that can strongly modify the properties of the stream. Several authors have shown that some of these impurities, such as SO2 present in emissions from sulfur-containing fuels, could be favorable for some steps of the process, and the possibility of cocapture has been proposed. To assess this possibility with regard to the transport stage of CCS, we determined the influence of SO2 on selected parameters of transport by pipeline (minimal operational pressure, pressure and density drops, distance between boosters, booster power, and inner diameter of the pipeline, and the Joule-Thomson coefficient). For this purpose, we obtained new and accurate experimental data for the density and vapor liquid equilibrium of five CO2 + SO2 mixtures under conditions of interest for CCS and speed of sound data for four of them. We compared our results to those found in the literature and to the values calculated using two equations of state for their validation: perturbed-chain statistical associating fluid theory (PC-SAFT) and an extended version of equation of state for combustion gases (EOS-CG) that includes a binary model for the CO2 + SO2 mixture. Allowing for the fact that chemical effects due to the presence of SO2, such as pipeline corrosion, have not been considered, we conclude that CO2/SO2 cocapture might favor and decrease the costs of the transport step of this technology, helping to avoid emissions of a highly toxic gas to the atmosphere without high desulfuration expenses.