Corrosion of pipeline and compressor materials due to impurities in separated CO₂ from fossil-fuelled power plants

Abstract

It is well known that transporting CO₂ via pipelines even in the supercritical state is not a problem from the corrosion point of view, as long as CO₂ is almost pure and dry. Depending on the CO₂ separation technology, however, the untreated CO₂ stream contains also various impurities such as oxygen, sulphur oxides, nitrogen oxides, carbon monoxide and water. These impurities can cause severe corrosion to pipeline and compressor materials. To avoid corrosion in existing pipeline systems the transported CO₂ is usually purified and dried, which causes high energetic and financial expenditures. The aim of this investigation is to identify the corrosion potential of impure CO₂ on pipeline and compressor materials as well as to determine the required purity minimum of the CO₂ stream from the power plant, from the corrosion point of view. This is done by performing experiments with different materials exposed to impure CO₂. It is shown that some impurities enhance the corrosion and with a combination of oxygen, water and nitrogen oxide significant corrosion rates occur.