There are several proposed specifications for CO2 transport regarding how much impurities that could be allowed. Many of these specifications are based on health, safety, and environment (HSE) considerations in case of accidental spill with only limited focus on the pipeline integrity. Experimental testing has demonstrated that many of the impurities that are expected to be present in CO2 captured from a combustion process may react and form corrosive species.
The present paper discusses the results from novel transparent autoclave experiments. Carbon steel corrosion coupons were exposed to impurities levels within established specifications at simulated transport conditions (25 °C and 10 MPa of CO2). Reactions between the impurities at low level ppmv occurred and it seemed like several different reactions contributed the production of other compounds. The result was formation of nitric and sulfuric acid together with formation of elementary sulphur. Visual examination of the specimens indicated low corrosion, but the amount of acids and solids produced is not acceptable for a specification.
Keywords: CCS, CCUS, CO2 corrosion, carbon steel, CO2 specification, high pressure, impurities, NO2, SO2, H2S, O2, H2O.