Process safety challenges of CO₂ sequestration

Abstract

Sequestration of carbon dioxide (CO₂) is an increasingly popular method of reducing the environmental impact of natural gas and blue hydrogen development projects. While the hazards associated with natural gas processing are well understood, high pressure CO₂ presents unique challenges which must be overcome by designers to make sequestration a safe and practical option. Many of these hazards are ultimately due to the CO₂ phase envelope. Compression of CO₂ for injection into a reservoir can involve the creation of a dense phase fluid, which shares some of the properties of both liquid and gas. Upset conditions can also create either liquid or solid CO₂. These can create unforeseen consequences such as potential blockage and overpressure of vent piping, condensation and freezing of free water and inaccurate level transmitter readings. Further, the partial pressures of CO₂ involved mean that corrosion rates for any carbon steel exposed in the presence of free water may be as high as 1 mm per week. These safety challenges and potential solutions to them will be explored in this study.