Abstract
Water and CO2 may form hydrates if certain pressure and temperature conditions are exceeded. Water, in the form of a separate phase, is normally not expected in CO2 streams for carbon capture and storage. If liquid water accidentally should be introduced in CO2 streams, it may result in corrosion and hydrate formation. Hydrates may clog the pipeline and it can be a long process to remove hydrate plugs. Although CO2 corrosion and CO2 hydrate have been well studied as separate phenomena, little is known about the potential corrosion rate that could be expected due to hydrate exposure.
The present work tested corrosion of carbon steel in low-temperature conditions, with and without hydrates. The experiments were carried out with a special electrochemical cell that was placed inside an autoclave with transparent windows. A camera was used to monitor the cell. Corrosion rates were measured with mass loss and linear polarisation resistance (LPR) using a standard three-electrode setup. The temperature and pressure were varied to create various test conditions with liquid water, ice and CO2-hydrate.
