Effect of SO2 and NO2 on Corrosion and Solid Formation in Dense Phase CO2 Pipelines

Internal corrosion of carbon steel pipelines for dense-phase CO2transport in carbon capture and storage (CCS) – a review

“…Nonetheless, the results highlight the potential severity and importance of understanding the extent of localised attack in such systems. It is also clear from a review of the work of Dugstad et al [3,25] Hua et al [70][71][72] and Sim et al [69] that localised corrosion of mild steel does appear to be prevalent in supercritical CO2 systems containing water. Hence, it is critical that the occurrence of localised corrosion in such environments is taken into account when defining the safe water content.…”

“…Some of the most recent work performed to evaluate the influence of NO and NO2 has been performed by Brown et al [76] (as part of the second phase of the CO2PIPETRANS Joint Industry Project) as well as by Dugstad et al [3] . The results from these two studies are provided in Table 7 and discussed in the following sections.…”

“…Currently, the minimum water content required in dense phase CO2 for acid formation in the presence of SO2 is not known [26] , but the detection of FeSO3 and FeSO4 on the steel surface in numerous experiments indicate that reactions occur at water contents considerably lower than the water solubility in pure CO2-H2O systems [3,4,26,76,78,79] . It is still not clear whether SO2 reacts with water in the bulk solution to form an acid, or if a thin condensed layer of water is initially formed on the steel surface which then reacts with SO2.…”

“…[2] Furthermore, researchers have suggested that the only logical choice to achieve such deep reductions in CO2 emission would be to construct an extensive pipeline network from carbon steel. [3] CO2 pipelines must be constructed and designed at an optimal cost such that they are reliable and safe to operate, posing minimal risk to the local population and environment.…”

“…[28] Consequently, because of the inherent risk associated with corrosion, pipeline operators set their own limits for water content in CO2 streams, with some limits being as strict as 50 ppm. According to Dugstad et al [3] , 500 ppm tends to be the accepted limit in literature, although little reasoning exists behind this specific value.…”